Tuesday, July 31, 2012

July 31st Severe Weather Outlook

usa62

July 31st Severe Weather Outlook
Temperatures once again are going to continue to be on the hot side with the range between 80 degrees and up into the 90s....
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/31/00/NAM_221_2012073100_F18_TMPF_2_M_ABOVE_GROUND.png
Dew Points are going to be in the 60-70 range with the exception of further north in that zone they will be on the lower side..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/31/00/NAM_221_2012073100_F24_DPTF_2_M_ABOVE_GROUND.png
CAPE or Convective Available Potential Energy will be between 500-4000 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/31/00/NAM_221_2012073100_F24_CAPE_SURFACE.png
Lift index will be from about 0 to negative 8 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/31/00/NAM_221_2012073100_F24_PLI_30_0_MB_ABOVE_GROUND.png
SHEAR will be anywhere from 30-50 knots depending on where you are located
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/31/00/NAM_221_2012073100_F24_SHRM_500_MB.png
HELICITY is virtually a non factor today..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/31/00/NAM_221_2012073100_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
EHI however is above 1 across the southeast as well as across Indiana..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/31/00/NAM_221_2012073100_F24_EHI_3000_M.png
http://www.hpc.ncep.noaa.gov/basicwx/91fwbgus.gif
At the surface , one front extends from the lakes back to a low pressure over Montana. Another front is north to south along the Carolina coast line with a low pressure off the coast of DE with the front going south and then west/north west to a low over western TN. It will be these fronts along with the associated impulses moving along the fronts that will bring the chance for severe storms and heavy rains.

Friday, July 27, 2012

July 27th Severe Weather Outlook..

usa62

July 27th Severe Weather Outlook..
We want to start this off by saying that today is not going to compare to yesterday as far as severe weather is concerned. Two cold fronts will be moving across the east and while this is occurring the trough that is settling into that region will begin to amplify. It is these frontal systems along with an impulse of energy that will be moving thru the lakes into the Ohio Valley that will bring a chance of severe weather into that region and the southeast. These threats will only be winds and hail in these regions. Out west .. an upper trough will be moving inland into the West coast and this will serve as the trigger in that region.
Temperatures across the severe zone (eastern zone) as well as majority of the central part of the USA are going to be in the 80s to 90s..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/27/00/NAM_221_2012072700_F18_TMPF_2_M_ABOVE_GROUND.png
Dew points will be mainly in the 60s (cooler across the western zone)
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/27/00/NAM_221_2012072700_F18_DPTF_2_M_ABOVE_GROUND.png
Convective Available Potential Energy will be between 500 and 3000 depending on where you reside..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/27/00/NAM_221_2012072700_F24_CAPE_SURFACE.png
Lift Index will be about 0 to negative 6 once again depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/27/00/NAM_221_2012072700_F24_PLI_30_0_MB_ABOVE_GROUND.png
The greatest shear will be across the area we have stretched out in the central plains region where it will be 30-50 knots..elsewhere it is about 25-40 knots
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/27/00/NAM_221_2012072700_F24_SHRM_500_MB.png
The NAM has the greatest EHI from parts of Ohio stretching south southwest thru Central KY to and thru Western TN and south from there. We think the NAM is over doing this however there could be an isolated tornado into Ohio..
For the most part today will be a calmer day then yesterday which resulted in widespread severe reports.
Any storms will contain very heavy rains! Our thoughts go out to those families that were effected by yesterdays storms.
As a forecaster , and a storm chaser you like to see the severe weather so you can capture it on film but you hate to see any suffering or actual damage done to properties. As always keep an eye to the sky and enjoy the weather cause you can do nothing to change it anyway!

Tuesday, July 24, 2012

July 24th Severe Weather Outlook

usa62

July 24th Severe Weather Outlook
Temperatures are going to be warm to hot again across the central part of the US into the Mid Atlantic region with temperatures in the 8-90 + range.
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/24/00/NAM_221_2012072400_F18_TMPF_2_M_ABOVE_GROUND.png
Dew points are going to be in the 60-70 degree range..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/24/00/NAM_221_2012072400_F24_DPTF_2_M_ABOVE_GROUND.png
Convective Available potential Energy is 500 to about 4000 depending on where you are located
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/24/00/NAM_221_2012072400_F24_CAPE_SURFACE.png
Lift Index is 0 to negative 7 depending on where you are located ..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/24/00/NAM_221_2012072400_F24_PLI_30_0_MB_ABOVE_GROUND.png
Shear is going to be 25- 50 knots depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/24/00/NAM_221_2012072400_F24_SHRM_500_MB.png
Super cells are definitely a possibility with a tornado potential ..generally along and ahead of the front with the EHI being at one or above..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/24/00/NAM_221_2012072400_F24_EHI_3000_M.png
Greatest Helicity will be over Minnesota region ..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/24/00/NAM_221_2012072400_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
Looking at the surface the cold front is approaching western PA as of 2 AM.
http://www.hpc.ncep.noaa.gov/basicwx/91fwbgus.gif
By 12 Z not much progress will have been made by this cold front as it is still in the vicinity of western PA and to the north of the rest of Pa . A warm front will be moving across the state of Maine.. it will be this front that will be the trigger for severe weather potential across the zone highlighted.. Winds and hail will be the main threat but we are going to introduce a 2% tornado chance as well due to the EHI...

Monday, July 23, 2012

July 23rd Severe Weather Outlook

usa62

July 23rd Severe Weather Outlook
Looking at the surface map anticipated for 06 Z (2 AM)
http://www.hpc.ncep.noaa.gov/basicwx/91fwbgus.gif
We see low pressure across the southern tier of Canada with a cold front that extends to the south and then west across the Midwest to a warm front. This cold front is going to push off to the south and the east. In the northeast we will have amplification of a trough.
Temperatures are going to be from 80 into the 90s with dew points in the 60-70 range. The humidity will be increasing across portions of the mid Atlantic..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/23/00/NAM_221_2012072300_F18_TMPF_2_M_ABOVE_GROUND.png
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/23/00/NAM_221_2012072300_F18_DPTF_2_M_ABOVE_GROUND.png
Convective Available Potential Energy will be from 500 to 3000 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/23/00/NAM_221_2012072300_F18_CAPE_SURFACE.png
Lift Index will be 0 to negative 6 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/23/00/NAM_221_2012072300_F24_PLI_30_0_MB_ABOVE_GROUND.png
SHEAR will be from about 25-50 knots
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/23/00/NAM_221_2012072300_F24_SHRM_500_MB.png
The Nam is showing the EHI to be particularly high across the Ohio region. At the very least this should indicate super cell potential..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/23/00/NAM_221_2012072300_F24_EHI_3000_M.png
Helicity is also high in this area.
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/23/00/NAM_221_2012072300_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
With the EHI as high as what the NAM is indicating we are going to have to place a 2% tornado chance across Ohio into Western PA. If you are in these regions keep an eye tuned to the sky and a ear to your favorite weather source..

Sunday, July 22, 2012

July 22nd Severe Weather Outlook

usa62

July 22nd Severe Weather Outlook ..http://www.hpc.ncep.noaa.gov/basicwx/91fwbgus.gif ..Looking at the surface map expected for 6 Z (2 AM) we see the stationary front still along the southeast part of the USA..across the Midwest you see a cold front ..extending back west to a low pressure over south Dakota . You also see a low pressure over the southern tier of Canada with a front extending south of there. The low pressure in the southern tier of Canada will be moving east and this will bring a warm front thru the lakes ..followed by a cold front .. Temperatures today are going to start to warm back up in the east and continue to be warm in the central part of the country. Temperatures will be in the 80s and 90s.. http://www.twisterdata.com/data/models/nam/221/maps/2012/07/22/00/NAM_221_2012072200_F18_TMPF_2_M_ABOVE_GROUND.png .. Dew points in the Midwest to the lakes and in the southeast will be in the 60-70 degree range..http://www.twisterdata.com/data/models/nam/221/maps/2012/07/22/00/NAM_221_2012072200_F24_DPTF_2_M_ABOVE_GROUND.png .... Convective available potential energy will be anywhere from about 500 to 3000 .. http://www.twisterdata.com/data/models/nam/221/maps/2012/07/22/00/NAM_221_2012072200_F24_CAPE_SURFACE.png..Lift index will be from 0 to about negative 8 .. http://www.twisterdata.com/data/models/nam/221/maps/2012/07/22/00/NAM_221_2012072200_F24_PLI_30_0_MB_ABOVE_GROUND.png ... SHEAR will be 30-50 knots across the lakes region as well as the area out west.. http://www.twisterdata.com/data/models/nam/221/maps/2012/07/22/00/NAM_221_2012072200_F24_SHRM_500_MB.pngShear however will be lacking in the southeast ..where there is a lower chance at severe.. EHI is above 1 especially from Northern WI back into MN ..http://www.twisterdata.com/data/models/nam/221/maps/2012/07/22/00/NAM_221_2012072200_F24_EHI_3000_M.png ...HELICITY is also 250 + in these regions.. http://www.twisterdata.com/data/models/nam/221/maps/2012/07/22/00/NAM_221_2012072200_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png ... With the EHI and Helicity in the locations above we are going to be going with a 2% tornado chance in that region.

Saturday, July 21, 2012

July 21st Severe Weather Potential...

usa62

July 21st Severe Weather Potential...
For the most part today is going to be a rather low severe weather day with more garden variety type storms with heavy rain then severe weather.
Looking at the surface map for 2 AM (now)
http://www.hpc.ncep.noaa.gov/basicwx/91fwbgus.gif
We have one cold front across the southeast and a cold front that will be moving across the Midwest towards the great lakes region. These two fronts will act as a potential trigger for any severe weather. The more widespread area of precipitation is expected to be over the SE.
Looking at the temperatures ..the heat is returning to the central part of the USA where temperatures will be in the 90s..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/21/00/NAM_221_2012072100_F24_TMPF_2_M_ABOVE_GROUND.png
Dew points across the North will be in the upper 50s to around the upper 60s and across the southeast in the 60-70 range..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/21/00/NAM_221_2012072100_F24_DPTF_2_M_ABOVE_GROUND.png
Convective Available potential energy will be from about 500-3000 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/21/00/NAM_221_2012072100_F24_CAPE_SURFACE.png
Lift Index will be about 0 to negative 7 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/21/00/NAM_221_2012072100_F24_PLI_30_0_MB_ABOVE_GROUND.png
The greatest shear will be across the northern zone with 30-40 knots ..Down in the southeast we are really lacking the shear..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/21/00/NAM_221_2012072100_F24_SHRM_500_MB.png
The greatest Helicity is across South Dakota
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/21/00/NAM_221_2012072100_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
And this also coincides with the greatest Energy Helicity
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/21/00/NAM_221_2012072100_F24_EHI_3000_M.png
We rather be on the safe side then the sorry side and with the Helicity and the EHI across south Dakota we are going to go with a 2% tornado chance , at the very least the potential for super cells in the area. This area also will be under the influence of a strengthening lower level jet..so this will likely enhance severe in that area but this would not be till later in the evening...
Over all though severe anticipation is on the low side..

Friday, July 20, 2012

July 20th Severe Weather Outlook

usa62

July 20th Severe Weather Outlook
Two frontal features are going to be in play today that will be causing severe weather potential along with garden variety type storms and some heavy rain.
http://www.hpc.ncep.noaa.gov/basicwx/93fwbgus.gif
By 18 Z the first front will be just south of the PA/MD border and dragging a cold front thru KY...
The second front is back over the Midwest and extending back into the PNW. The front in the east will be dropping south while the front in the Midwest presses east south east. The weather in the east today will be cooler then as of late with temperatures only in the 70s and some rain showers about and perhaps a period of steadier rain.
The rainfall that has fallen over the last twenty four hours has greatly under performed considering HPC was expecting a widespread 2 + inches across the state of PA from west to east.. This is what has fallen..
http://i973.photobucket.com/albums/ae219/theweathergod2010/past24.png
And this is what they are anticipating over the next 48 hr. period and it is considerably dropped.
http://www.hpc.ncep.noaa.gov/qpf/d12_fill.gif
Now lets look at the temperatures that will be in play thru out the severe zones..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/20/00/NAM_221_2012072000_F18_TMPF_2_M_ABOVE_GROUND.png
Dew Points will be highest in the southeast with them in the 60-70 degree range..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/20/00/NAM_221_2012072000_F24_DPTF_2_M_ABOVE_GROUND.png
CAPE or Convective Available Potential Energy is between 500-4000 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/20/00/NAM_221_2012072000_F24_CAPE_SURFACE.png
Lift Index if from 0 to about negative 8 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/20/00/NAM_221_2012072000_F24_PLI_30_0_MB_ABOVE_GROUND.png
Greatest Shear will actually be across the region in the Midwest with 30-60 knots from the surface to 500 mb
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/20/00/NAM_221_2012072000_F24_SHRM_500_MB.png
EHI or Energy Helicity Index is indicative of super cell potential from Eastern Washington into Western Montana and then indicative of super cell potential with 2% tornado potential across Minnesota.. also from TN back thru Alabama and Mississippi and perhaps into Louisiana .
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/20/00/NAM_221_2012072000_F24_EHI_3000_M.png
Helicity is also 300 or above in these same general locations..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/20/00/NAM_221_2012072000_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
Once again if you are in any of the highlighted locations above please keep an eye and an ear tuned to your favorite weather source! As always enjoy the weather and be safe!

Thursday, July 19, 2012

July 19th Severe Weather Outlook..

usa62

July 19th Severe Weather Outlook..
The moderate risk never came to pass but there was a widespread amount of storms. They fell apart as they headed into SE PA and SNJ but re intensified further south of there.. regardless it was a pretty active and awesome day for severe weather.
Whenever you have a bolt just miss your roof of your porch and your mother in law..it really makes one look at the power behind the storm!
Temperatures today are going to be a touch cooler into the NE and eastern PA where they will only be 80-90 and in the 70s further Northeast... further west where the severe weather should be Ohio and west (greatest threat) temps are going to be in the 90s..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/19/00/NAM_221_2012071900_F18_TMPF_2_M_ABOVE_GROUND.png
Dew points are still going to be warm across the region with dew points in the 60-70 degree range..
CAPE or convective available potential energy is 500-3000 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/19/00/NAM_221_2012071900_F18_CAPE_SURFACE.png
Lift index looks to be from 0 to about -10 across the Dakotas (perhaps a little more negative in that region)
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/19/00/NAM_221_2012071900_F18_PLI_30_0_MB_ABOVE_GROUND.png
One ingredient that looks to be lacking from the surface to the 500 mb level is shear except for the region around the Dakotas..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/19/00/NAM_221_2012071900_F18_SHRM_500_MB.png
However this will be increasing by evening time..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/19/00/NAM_221_2012071900_F24_SHRM_500_MB.png
NAM is really showing some decent Energy Helicity Index..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/19/00/NAM_221_2012071900_F24_EHI_3000_M.png
HELICITY is fairly high as well especially along the lakes..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/19/00/NAM_221_2012071900_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
At the surface , a cold front has made its way to almost the PA/MD border
http://www.hpc.ncep.noaa.gov/basicwx/91fwbgus.gif
This front has become stationary and extends back to the west.. Low pressure over Indiana and another over Ohio will move along this stationary front. By 18 Z this stationary front is going to start lifting back towards the NE as a warm front..
http://www.hpc.ncep.noaa.gov/basicwx/93fwbgus.gif
And then become stationary once again...
http://www.hpc.ncep.noaa.gov/basicwx/94fwbgus.gif
It will be this front that the storms tend to use as a FOCI for development. Once again heavy rains will be a threat along with winds and hail. With the EHI in place we are going to go with 2% tornado chance ( we really SHOULD go 5% ) from Ohio to the south to KY...
Once again stay tuned and we will be here with all coverage!

Tuesday, July 17, 2012

July 18th Severe Weather Outlook

usa62

July 18th Severe Weather Outlook
We have decided to get an early jump on this particular outlook and whether or not the Storm Prediction Center ends up agreeing with a low end moderate risk or not is really irrelevant to what we are forecasting. There is going to be some very high CAPE in place or "fuel" as the cold front drops slowly towards the region. Temperatures out ahead of the cold front are going to be quite toasty and dew points are already climbing which is going to make it a very "soupy" feel to the day come tomorrow. When ever we have a cold front and associated trough dropping south from Canada into such a "hot" air mass this is always a recipe for what could be considered "explosive" development of thunderstorms.
We have been referencing last Saturday as a reference point for this event today..
Last Saturday was a very soupy feel to the day with the heat index near 105 degrees and the temperatures were in the 90s. We also had a temperature drop once the front finally cleared..Deja vu? Pretty much a similar set up but this time the fuel is a little higher then that time..and the front appears to be slightly stronger.
So lets look at the temperatures for later tomorrow..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/18/NAM_221_2012071718_F24_TMPF_2_M_ABOVE_GROUND.png
The NAM is suggesting that temperatures will be from 80 to about 100 degrees. This heat alone with out the severe aspect is very dangerous. Do yourself a favor and stay indoors till the sun goes down. Drink plenty of water , even if inside because you can still dehydrate when the heat outside is this bad..especially if your AC's are having issues working in this heat.
You can see the strength of this cold front , though the GFS is potentially over doing it ..once the front finally clears the area temperatures become at least 10 degrees cooler..
http://www.twisterdata.com/data/models/gfs/3/maps/2012/07/17/18/GFS_3_2012071718_F72_TMPF_2_M_ABOVE_GROUND.png
CAPE or Convective Potential Energy is showing to be as high as 4000 ..
http://www.twisterdata.com/data/models/gfs/3/maps/2012/07/17/18/GFS_3_2012071718_F24_CAPE_SURFACE.png
The NAM is in relatively good agreement with the GFS with high CAPE as well
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/18/NAM_221_2012071718_F24_CAPE_SURFACE.png
Lift index across the area is at about negative 6 to negative 8.
http://www.twisterdata.com/data/models/gfs/3/maps/2012/07/17/18/GFS_3_2012071718_F30_LFTX_SURFACE.png
The one parameter on the down side is the SHEAR which is only about 30 knots across the red zone ..however..feel confident that the high CAPE amounts will cover the marginal shear.
http://www.twisterdata.com/data/models/gfs/3/maps/2012/07/17/18/GFS_3_2012071718_F30_SHRM_500_MB.png
HELICITY is not really a concern but the EHI is indicative of the potential for super cells across the region. Essentially PA east.
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/18/NAM_221_2012071718_F30_EHI_3000_M.png
This is something that we will be re evaluating once 00z guidance comes out and will determine at that time "if" a greater then 2% tornado chance is needed.
At this point and time we feel that the main threat is going to be damaging winds that could be anywhere between 60-75 MPH. These storms will have the potential to cause power outages where they occur. These storms will also contain very heavy rain with PWATS in the order of 2.00+.. This means Flash Flooding is possible.
Stay tuned to your favorite weather source thru out the day tomorrow and we will be updating part of this with the EHI & Helicity after the 00z guidance comes out!

July 18th Day 2 Outlook

usa62

Discussion will be done later tonight and fine tune any changes needed to the zone…

The following photos are from a Severe Storm that just clipped the south side of Allentown on July 15th and they were taken via cell phone…

Img_00002

Img_00003

Img_00004

Img_00005

Img_00006

Img_00007

Day 1 Outlook For July 17th

usa62

Day 1 Outlook For July 17th
We are also going to be issuing a Day 2 outlook which is something that we rarely do.
In the east we had had a slight break from the oppressive heat but as we mentioned it would be on the return (slowly beginning end of last week ) but not becoming oppressive until early this week.
Today is going to be once again on the down right hot and sticky side across the central USA into the east with temperatures mainly in the 90s ..and dew points will be in the 60-0 range ..
Temperatures
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/00/NAM_221_2012071700_F18_TMPF_2_M_ABOVE_GROUND.png
Dew points
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/00/NAM_221_2012071700_F24_DPTF_2_M_ABOVE_GROUND.png
CAPE is showing to be about 500-3500 across the severe zone in the east and about 500-2500 in the west..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/00/NAM_221_2012071700_F24_CAPE_SURFACE.png
Lift Index is about 0 to - 8 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/00/NAM_221_2012071700_F24_PLI_30_0_MB_ABOVE_GROUND.png
SHEAR about 25-40 over the West with about 40 to 60 coming across the Northeast region..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/00/NAM_221_2012071700_F24_SHRM_500_MB.png
ENERGY Helicity is kind of NNY into southern Maine ..and Helicity is also at 300 (and above further NE) in the same region . With the EHI and Helicity we are going to introduce a 2% tornado chance into the region of NNY into Maine..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/00/NAM_221_2012071700_F24_EHI_3000_M.png
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/17/00/NAM_221_2012071700_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
Looking at the surface expected for about an hour from now you see a cold front dropping thru the Midwest..
http://www.hpc.ncep.noaa.gov/basicwx/91fwbgus.gif
Which turns into a stationary front across the west..
http://www.hpc.ncep.noaa.gov/basicwx/92fwbgus.gif
It is these fronts along with their associated troughs that will serve as the trigger for severe weather potential. In the west we are mainly looking at strong wind gusts with more garden variety type storms...
Day 2 will be next but we are not going to include a discussion with that one until later in the evening..

Sunday, July 15, 2012

July 15th Severe Weather Outlook

usa62

July 15th Severe Weather Outlook
Today is another day where we think that the main threat will be garden variety and heavy rain with these garden variety thunderstorms. Some of these thunderstorms will have the potential to go severe as well with winds and hail being the main threats.
Temperatures are going to be anywhere from 70 to as high as 100 degrees depending on where you live..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/15/00/NAM_221_2012071500_F18_TMPF_2_M_ABOVE_GROUND.png
Dew Points are going to be between 60-70 degrees across the areas highlight with potential for severe
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/15/00/NAM_221_2012071500_F24_DPTF_2_M_ABOVE_GROUND.png
CAPE or Convective Available Potential Energy is about 500-3500 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/15/00/NAM_221_2012071500_F24_CAPE_SURFACE.png
Lift Index is only around 0 to negative 4 depending on where you are located
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/15/00/NAM_221_2012071500_F24_PLI_30_0_MB_ABOVE_GROUND.png
SHEAR is lacking in the Northeast but greatest at 40-60 knots to the northern zone..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/15/00/NAM_221_2012071500_F24_SHRM_500_MB.png
Energy helicity Index is showing to be around 4 across Northern Dakota
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/15/00/NAM_221_2012071500_F24_EHI_3000_M.png
Helicity is showing to be above 400 as well in the same location
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/15/00/NAM_221_2012071500_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
Normally when we see shear of 40-60 knots and high EHI and high Helicity we will issue a Tornado chance and in this instance we are going to go with a 2% chance over the Dakota region..
http://www.hpc.ncep.noaa.gov/basicwx/91fwbgus.gif
At the surface we have a cold front draped across the northern region with low pressure moving out of the Montana region off towards the NE while the front will become somewhat stationary across the region. This will serve as the trigger for severe in that part of the region..
For the east/northeast it will be a trough moving south south westwards from the great lakes region. Again ..with this particular severe outlook in the east northeast we think that the main threat will be the heavy rain with PWATS in the 1-2 inch range..

Saturday, July 14, 2012

July 14th Severe Weather Outlook

usa62

July 14th Severe Weather Outlook
Over all things are looking like they are going to be a low chance for severe with garden variety thunderstorms and heavy rain being the main threats. Temperatures are going to be in the 70 to 90 + degree range with the highest temps occurring into the central part of the USA and also SE PA thru NYC..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/14/00/NAM_221_2012071400_F18_TMPF_2_M_ABOVE_GROUND.png
Dew points will be highest over the east with 60-70 degrees..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/14/00/NAM_221_2012071400_F24_DPTF_2_M_ABOVE_GROUND.png
CAPE is going to be about 500 to about 3000 depending on where you are located..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/14/00/NAM_221_2012071400_F24_CAPE_SURFACE.png
LIFT index will be 0 to about negative 6 depending on where you are located
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/14/00/NAM_221_2012071400_F24_PLI_30_0_MB_ABOVE_GROUND.png
Surface to 500 MB Bulk shear is going to be very minimal with the greatest 30-40 knots across the small area in the NW at 30-40 knots
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/14/00/NAM_221_2012071400_F24_SHRM_500_MB.png
ENERGY HELICITY index is under 1 in essentially all locations
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/14/00/NAM_221_2012071400_F24_EHI_3000_M.png
HELICITY is also under 400 across all regions..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/14/00/NAM_221_2012071400_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
Time sensitive image
http://www.ssd.noaa.gov/goes/east/eaus/vis-l.jpg
Present cloud cover and present moisture will also play a role in hindering severe weather aspect. Across the region in the NW ..we will have a cut off upper level low. For the region in the east it will be an elongated upper level trough that will be moving east southeast that will bring the chance for thunderstorms /possible severe. Any severe that occurs should be limited to winds and hail.

Thursday, July 12, 2012

Winter 2012-13 Preliminary Thoughts & Further Discussion

The Winter of 2011-2012 was a winter many of us will never forget . Essentially this winter started off with a BANG with delivering a Historical East Coast Blizzard across portions of the Northeast..delivering 6.8 inches of snow to Allentown Bethlehem Easton Airport on October 29th. This storm had set all kinds of records and many of us thought that this would set the stage for a snowier and colder winter. After all it got off to an early start.
However as winter went along we realized that the Alaskan Vortex was to strong and that blocking was not going to make it down to the lower atmosphere or surface which is where we need it to occur. So we ended up with a very warm winter and snowless winter instead. The winter of 2011-2012 ended up a La Nina Enso status. Matter of fact it was a two year La Nina. Since that time we have now gone to a Neutral Status but the question is where do we go for the winter ahead? This leads us to ENSO status and where it looks to be heading.
The El Niño-Southern Oscillation (ENSO) is a naturally occurring phenomenon that involves fluctuating ocean temperatures in the equatorial Pacific. The warmer waters essentially slosh, or oscillate, back and forth across the Pacific, much like water in a bath tub. For North America and much of the globe, the phenomenon is known as a dominant force causing variations in regional climate patterns. The pattern generally fluctuates between two states: warmer than normal central and eastern equatorial Pacific SSTs (El Niño) and cooler than normal central and eastern equatorial Pacific SSTs (La Niña).
Often, sea surface temperatures (SSTs) are used to identify this oscillation, but it is important to understand that changes in sub-surface ocean temperatures are the first to respond to an oncoming change in the ENSO phase. For instance, when ENSO is transitioning into a warm phase the sub-surface temperatures begin to warm above average, while a shallow layer of near average temperature remains at the surface. Eventually, the surface ocean temperatures will respond to the warming of the sub-surface temperatures, and a warm phase of the ENSO cycle ensues. The same cycle occurs, only opposite, for the cool phase of ENSO. When temperatures in the ENSO region of the Pacific are near average it is known as ENSO neutral, meaning that the oscillation is neither in a warm nor cool phase. Typically, atmospheric patterns during ENSO neutral are controlled more by other climate patterns (NAO, PNA) that vary on shorter timescales;


figure1
SST_table
According to the two images above it looks like we are heading into an El Nino for the winter ahead. What exactly is an El Nino?
1997_Nino_SST
El Niño (Warm Phase)
The warm phase of the ENSO cycle features warmer than normal SSTs across the central and eastern equatorial Pacific
along with:

Weaker low-level atmospheric winds along the equator
Enhanced convection across the entire equatorial Pacific
Effects are strongest during northern hemisphere winter due to the fact that ocean temperatures worldwide are at their warmest. This increased ocean warmth enhances convection, which then alters the jet stream such that it becomes more active over parts of the U.S. during El Niño winters.

So lets look at the history of past El Ninos, the years they covered and whether they were warm or cold. First the years:
Previous El Niño Years
1902-1903
1905-1906
1911-1912
1914-1915

1918-1919
1923-1924
1925-1926
1930-1931

1932-1933
1939-1940
1941-1942
1951-1952

1953-1954
1957-1958
1965-1966
1969-1970

1972-1973
1976-1977
1982-1983
1986-1987

1991-1992
1994-1995
1997-1998
2002-2003

2006-2007
2009-2010

We will look at the warm years first in which there were 12 warm years.
1906
1919
1924
1933
1952
1954
1973
1983
1992
1995
1998
2007
Now lets take a look at the colder years..
1903
1912
1915
1926
1931
1940
1942
1958
1966
1970
1977
1987
2003
2010
Now..we can see that the cold years slightly outweigh the warm years with 14 of the winters colder then normal across the east.
Things get a little more interesting when you narrow things down to El Ninos that followed La Nina's…
post-7634-0-34177800-1341955882
These are temperature anomalies for years that had an El Nino that was following a La Nina, the years that are included in it are: 1951-52, 1957-58, 1965-66, 1972-73, 1976-77, and 2006-07
So as you can see we have a colder outlook across the USA for el Ninos that have followed a La Nina.
However.. experience and knowledge also tells us that there are other factors that we have to look at ..
One of these factors it the North Atlantic Oscillation.
North Atlantic Oscillation (NAO)
The North Atlantic Oscillation (NAO) consists of two pressure centers in the North Atlantic: one is an area of low pressure typically located near Iceland, and the other an area of high pressure over the Azores (an island chain located in the eastern Atlantic Ocean). It is important to note that these two locations are most commonly used to measure the NAO, but studies have found that the pressure centers move around on a seasonal basis, and other locations have also been used for measuring this index. Fluctuations in the strength of these features significantly alters the alignment of the jet stream, especially over the eastern U.S., and ultimately affects temperature and precipitation distributions in this area. It is also important to note that the AO and NAO are two separate indices that are ultimately describing the same phenomenon of varying pressure gradients in the northern latitudes and the resultant effects on temperature and storm tracks across the continent.
NAO_POS_Pressure
NAO_POSITIVE_1972
NAO_POSITIVE_1972_TEMPS
Positive NAO
During a positive NAO there is a strengthening of the Icelandic low and Azores high. This strengthening results in an increased pressure gradient over the North Atlantic, which cause the westerlies to increase in strength. The increased westerlies allow cold air to drain off the North American continent rather than letting it build up and move south.
Above average geopotential heights  are observed over the eastern U.S., which correlates to above average temperatures
The eastern U.S. often sees a wetter pattern with stronger storms during the winter season in this phase due to increased upper level winds


NAO_NEG_Pressure
Negative NAO
A negative NAO indicates weakening of both the Icelandic low and Azores high, which decreases the pressure gradient across the North Atlantic. This decreased pressure gradient results in a slackening of the westerlies. The decrease in the westerlies allows cold air to build up over Canada, and this combined with below average heights (troughing) over the eastern U.S. gives the cold air a greater chance to move south and affect the eastern United States.
Below average geopotential heights  are often observed over the eastern U.S. during the negative phase of the NAO, which correlates to below average temperatures
The eastern U.S. typically receives colder, drier air masses during the winter season in this phase

When the Icelandic low and Azores high are weaker, above average 500mb heights are located near Iceland, and below average heights near the Azores Islands. This results in a phenomenon referred to as high latitude blocking, which allows cold air to drain from Alaska and Canada into the U.S. and become entrenched, resulting in cold air outbreaks and below normal temperatures.
Positional_NAO
Positional Effects
Favorable positioning of the geopotential height anomalies within the negative phase of the NAO appears to enhance snowfall potential in the eastern U.S. When negative NAO anomalies are positioned such that an area of high pressure is located near Greenland and a polar vortex (area of low pressure) is somewhere near 50°N 50°W, we find an increased potential for winter weather along the U.S. east coast.
Atmospheric features in a “west-based” negative NAO disrupt the polar jet stream, causing it to buckle and move southward into the Southeast
Allows cold, Arctic air to be transported south and increases the likelihood of interaction between the northern and southern jet streams
Jet stream interactions often result in a combining of energy (phasing), which leads to rapid, intense surface cyclogenesis over the southern U.S.

Another area we need to look at is the Arctic Oscillation.
AO_Positive_2
AO_WARM_2
Arctic Oscillation (AO)
The Arctic Oscillation (AO) is a climate index of the state of the atmospheric circulation over the Arctic. It consists of a negative phase, featuring below average geopotential heights , which are also referred to as negative geopotential height anomalies , and a positive phase in which the opposite is true. In the negative phase, the polar low pressure system (also known as the polar vortex) over the Arctic is weaker, which results in weaker upper level winds (the westerlies). The result of the weaker westerlies is that cold, Arctic air is able to push farther south into the U.S., while the storm track also remains farther south. The opposite is true when the AO is positive: the polar circulation is stronger which forces cold air and storms to remain farther north. The Arctic Oscillation often shares phase with the North Atlantic Oscillation (NAO) (discussed below), and its phases directly correlate with the phases of the NAO concerning implications on weather across the U.S.
AO_COLD_2
AO_Negative_2
The next area we have to look at is the Pacific North American Oscillation index.
The Pacific/North American teleconnection pattern (PNA) is one of the most recognized, influential climate patterns in the Northern Hemisphere mid-latitudes beyond the tropics. It consists of anomalies in the geopotential height  fields (typically at 700 or 500mb) observed over the western and eastern United States. It is important to note that the PNA has been found to be strongly influenced by the El Niño-Southern Oscillation (ENSO) phenomenon. The positive phase of the PNA pattern tends to be associated with Pacific warm episodes (El Niño), and the negative phase tends to be associated with Pacific cold episodes (La Niña).
PNA_POSITIVE_1981
Positive PNA
The positive phase consists of above normal geopotential heights over the western U.S. and below normal geopotential heights over the eastern U.S. This correlates to ridging over the western U.S., and deep troughing over the east. The net result of the height field pattern in this phase is that it forces cold air residing in Canada to plunge southeastward, which results in below normal temperatures over the eastern U.S. and above normal temperatures over the western U.S.
In the positive phase, above average geopotential heights are seen over the western U.S., and below average geopotential heights are seen across the eastern U.S. This results in warm air moving much farther north than normal over the western U.S., while cold, Canadian air is forced southward over the eastern U.S. resulting in below normal temperatures.
PNA_NEGATIVE_1985_TEMPS
Negative PNA
The negative phase features troughing and below normal geopotential heights over the western U.S. and ridging with above normal geopotential heights over the eastern U.S. The result is below average temperatures for the western U.S., and above average temperatures over the eastern U.S.
The negative phase of the PNA pattern features below average geopotential heights over the western U.S., and above average geopotential heights across the eastern U.S. This results in deep troughing over the western U.S., which allows cold air from western Canada to drain southward into this region. In the eastern U.S., warm, moist air from the Gulf of Mexico and the Atlantic Ocean is able to travel northward, often resulting in above normal temperatures and more humid conditions.
As you can see there is a lot to look into when putting together a winter forecast. There are still yet two more teleconnections we need to look at .. The next one is the Pacific Decadal Oscillation or PDO.
pdo_warm_cool3
The Pacific Decadal Oscillation (PDO) is a pattern of Pacific climate variability similar to ENSO in character, but which varies over a much longer time scale. The PDO can remain in the same phase for 20 to 30 years, while ENSO cycles typically only last 6 to 18 months. The PDO, like ENSO, consists of a warm and cool phase which alters upper level atmospheric winds. Shifts in the PDO phase can have significant implications for global climate, affecting Pacific and Atlantic hurricane activity, droughts and flooding around the Pacific basin, the productivity of marine ecosystems, and global land temperature patterns. Experts also believe the PDO can intensify or diminish the impacts of ENSO according to its phase. If both ENSO and the PDO are in the same phase, it is believed that El Niño/La Nina impacts may be magnified. Conversely, if ENSO and the PDO are out of phase, it has been proposed that they may offset one another, preventing "true" ENSO impacts from occurring.
PDO_WARM_2

Warm PDO
The broad area of above average water temperatures off the coast of North America from Alaska to the equator is a classic feature of the warm phase of the Pacific Decadal Oscillation (PDO). The warm waters wrap in a horseshoe shape around a core of cooler-than-average water. Impacts from the PDO depend in part on how it is aligned with the ENSO cycle; if the cycles are in opposite phases, then effects will be weakened. However, when both the PDO and ENSO are in the warm phase, meaning ENSO would be in the El Niño phase, expected impacts on the southeast include:

Below average winter temperatures
Above average winter precipitation

PDO_COLD_2
Cold PDO
Opposite of the warm PDO, the expansive area of below average water temperatures off the coast of North America from Alaska to the equator signals the cold phase of the PDO. The area of warmer-than-average sea surface temperatures in the central Pacific are surrounded by below average temperatures near the North American continent. Expected impacts from a cold PDO and ENSO (La Nina) phase on the southeast include:

Above average winter temperatures
Below average winter precipitation

Where are we now with the PDO?
pdo-f-pg
We are clearly in a negative phase with the Pacific Decadal Oscillation..
This leaves us yet to look at the QBO or the Quasi Biennial Oscillation.
The quasi-biennial oscillation (QBO) is a quasi-periodic oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere with a mean period of 28 to 29 months. The alternating wind regimes develop at the top of the lower stratosphere and propagate downwards at about 1 km (0.6 mi) per month until they are dissipated at the tropical tropopause. Downward motion of the easterlies is usually more irregular than that of the westerlies. The amplitude of the easterly phase is about twice as strong as that of the westerly phase. At the top of the vertical QBO domain, easterlies dominate, while at the bottom, westerlies are more likely to be found.
Effects of the QBO include mixing of stratospheric ozone by the secondary circulation caused by the QBO, modification of monsoon precipitation, and an influence on stratospheric circulation in northern hemisphere winter (the sudden stratospheric warming's).

Current QBO
-25.90 (click here)
So with what we are looking at right now we can say with certainty we know the following:
1. We are heading into a weak to moderate El Nino. There is nothing indicating that we are going to be heading into a strong El Nino.
2. With a present negative PDO ..this would indicate a warmer winter across the southeast region with less precipitation. Of course if the PDO were to go to a warm phase this would change that scenario and we are only in the month of July…
What we do not know at this point and time:
1. What the state of the NAO will be come winter 2012-2013.
2. What the state of the PNA will be come winter 2012-2013
3. What the state of the AO will be come 2012-2013.
These teleconnections are ultimately important for the outcome of winter. At the present time this is what the JAMSTEC seasonal model is showing for the December thru Feb time frame..
temp2.glob.DJF2013.1jun2012
This closely resembles 2003 except the below normal temperatures are not as far west as 2003 was.
The purpose of this is to lay the foundation for the actual forecast once the teleconnections become more clear as to whether we will be dealing with a + NAO or a –NAO ..+ PNA or – PNA and + AO or – AO.
Perhaps one more thing to keep in mind is that when the Summer is hotter then normal.. a lot of times this can indicate a colder and snowier winter. A lot of variables to come into play this winter .
We will be updating this during the month of September when some of the teleconnections should be more clear

September 2012 Update...

Temperature Outlook for December to Feb 

Precipitation Outlook 

These two maps are what we think will entail the winter of 2012-2013. While it is to early to know what the AO & NAO & PNA will be like we looked back thru weather history to 1950 for El Ninos that followed at least a 2 year La Nina ...
First year we come across is 1957-1958 and that winter looked like this:
That winters precipitation...
The next El Nino that were to follow at least a 2 year La nina would be 1972-1973
And that precipitation was as follows:
Both 1957-1958 and 1972-1973 were strong El ninos...

The next year on the list would be 1976-1977 in which the temperature departures looked like this..
Precipitation for that year looked like this:
1976-1977 was a Weak La Nina ...

The final time that this has happened and as you can see it has not happened often at least since 1950 was 2002-2003..
And precipitation for the year was as follows:
It is obviously a small sample package that we have to work with this winter season but essentially what we have done is taken a blend of all the years above with more leaning on a blend of 1976-1977 and 2002-2003.. The first one being a weak El nino and the latter being a Moderate El nino. We think the winter of 2012-2013 should end up being between a weak and a moderate El Nino.