Severe Weather Discussion For June 10th 2012

Severe Weather Discussion For June 10th 2012... Lets begin by looking at the Severe Parameters along with the temperatures expected and in the mid part of the country it is going to be WARM to hot with temperatures in the 80-90 degree range..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/10/00/NAM_221_2012061000_F24_TMPF_2_M_ABOVE_GROUND.png...DEW POINTS are going to be in the 60s . Now notice by this time the dew points are going to be much lower in the western part of the severe zone. (Dakotas Etc.) Any severe in the western part will happen in the overnight hours and early part of the day.. http://www.twisterdata.com/data/models/nam/221/maps/2012/06/10/00/NAM_221_2012061000_F24_DPTF_2_M_ABOVE_GROUND.png .... CAPE is 500 to about 2000 across the eastern part of the zone..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/10/00/NAM_221_2012061000_F24_CAPE_SURFACE.png .. LIFT INDEX is about 0 to negative 8 across the Eastern Part of the severe zone...http://www.twisterdata.com/data/models/nam/221/maps/2012/06/10/00/NAM_221_2012061000_F24_PLI_30_0_MB_ABOVE_GROUND.png ...SHEAR ..notice how the greatest shear is actually back over the Dakotas region ..this is actually going to be back behind where the front is expected to be located..First link will be the SHEAR image ..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/10/00/NAM_221_2012061000_F24_SHRM_500_MB.png ...Now where the cold front is expected to be at 00z this evening.. http://www.hpc.ncep.noaa.gov/basicwx/94fwbgus.gif ... ENERGY HELICITY INDEX..there is a thin line that is at 1 or above from north to south which means that Super cells are possible across the region..NE & Eastern Minnesota , Western Wisconsin, East Central Iowa. These would be the areas that we could expect to see Super Cells with the potential for Super cells to produce a Tornado. http://www.twisterdata.com/data/models/nam/221/maps/2012/06/10/00/NAM_221_2012061000_F24_EHI_3000_M.png ..HELICITY is greatest in Minnesota with 300 or above which would also point towards tornado potential. .. http://www.twisterdata.com/data/models/nam/221/maps/2012/06/10/00/NAM_221_2012061000_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png ..With the EHI and Helicity we will place the above mentioned areas at a 2% chance of tornados. The rest of the severe zone will mainly be concerned with Large Hail and Winds and Heavy rain associated with any storm!

June 8th Severe Weather Outlook And Discussion

http://www.hpc.ncep.noaa.gov/basicwx/93fwbgus.gif

http://www.hpc.ncep.noaa.gov/basicwx/94fwbgus.gif
Looking at what is anticipated to happen a area of low pressure is going to be dropping down out of central Canada with a cold front and this cold front is going to drop across the northern tier region. This cold front and area of low pressure will be the trigger to produce severe weather across the area's highlighted..
In the northeast we have more of an isolated low risk area because this area has less in the way of severe parameters and it is dependent upon a warm front as the trigger which we never are to enthused with warm fronts being a severe weather trigger.
Tonight's severe zones are based on more of a blend of the NAM/GFS and no use of the SREF because it was not available for the 21 Z run.
So lets look at the Parameters that will be in place..
TEMPERATURES
Temperatures are going to be on the warm side from the 70 degree range up towards 90 degrees. Coolest severe region will be the Northeast where temperatures will mainly be in the 70-80 degree range.
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/08/00/NAM_221_2012060800_F24_TMPF_2_M_ABOVE_GROUND.png
DEWPOINTS
Dewpoints in the Northeast are actually only going to be in the 50s but pretty much in the 2nd severe zone we are looking at humid conditions with dews in the 60s-70s range..
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/08/00/NAM_221_2012060800_F24_DPTF_2_M_ABOVE_GROUND.png
CAPE or INSTABILITY..
As expected in the NE we are looking at lower CAPE as compared to the northern tier severe zone. In the Northeast we are looking at about 500-1000 . In the northern tier zone we are looking at 750 to about 3500.
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/08/00/NAM_221_2012060800_F24_CAPE_SURFACE.png
LIFT INDEX
Lift index is a little lower then what we have been use to seeing lately in terms of severe weather with ranges from about 0 to roughly - 6 depending on where you are located.
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/08/00/NAM_221_2012060800_F24_PLI_30_0_MB_ABOVE_GROUND.png
SHEAR
Shear is also not as impressive as what we have seen in prior severe weather events with only about 30-40 knots across the region with the highest up in Canada where it is 50 knots
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/08/00/NAM_221_2012060800_F24_SHRM_500_MB.png
ENERGY HELICITY INDEX
When you look at the EHI you might think ..well supercells are definitely likely and Tornado's are definitely a possibility. We do have some pretty impressive EHI in place with ranges at 3.00 to 5.00
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/08/00/NAM_221_2012060800_F24_EHI_3000_M.png
HELICITY
You will see that the helicity is mainly at 300 and under. Generally for tornadic supercells you would want the HELICITY to be at 400 and above. So even though we have EHI that is supportive of a tornado threat ..the HELICITY is less supportive.
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/08/00/NAM_221_2012060800_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
LAPSE RATES
Lapse rates are generally supportive of severe weather. With a range around 6.5.
If the NAM is correct on the dewpoints being in the upper 60s and lower 70s then we could be looking at tornado potential from extreme western Upper MI back into Wisconsin , Minnesota and the Dakotas. For right now we will place that region in a 2-5 % chance. As these storms move east southeast with the cold front they will be going into less favorable parameters and would weaken...This is why we are not taking the threat any further east then extreme western Upper MI.

June 7th Severe Weather Outlook

Discussion of Severe Weather Parameters.. TEMPERATURES will continue to be very warm across the severe zone with temperatures in the 70-90 degree range..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/07/00/NAM_221_2012060700_F24_TMPF_2_M_ABOVE_GROUND.png .. DEW POINTS will be in the 60s mainly across the area with some areas in the upper 50s..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/07/00/NAM_221_2012060700_F24_DPTF_2_M_ABOVE_GROUND.png .. CAPE or INSTABILITY is 500 to about 3500 across the severe zone..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/07/00/NAM_221_2012060700_F24_CAPE_SURFACE.png ...LIFT INDEX is 0 to about negative 8 across the region.. http://www.twisterdata.com/data/models/nam/221/maps/2012/06/07/00/NAM_221_2012060700_F24_PLI_30_0_MB_ABOVE_GROUND.png... SHEAR is about 30-45 knots across the area..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/07/00/NAM_221_2012060700_F24_SHRM_500_MB.png .. ENERGY HELICITY INDEX http://www.twisterdata.com/data/models/nam/221/maps/2012/06/07/00/NAM_221_2012060700_F24_EHI_3000_M.png ..Kind of widespread across the general severe zone area ..HELICITY is generally about 300 or less (very small area) and greatest is actually across the Canadian border..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/07/00/NAM_221_2012060700_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png .. Any where in the severe zone we are going to place a 2% chance of a tornado. Now of course this is not a very high chance... with the greatest chance from Nebraska south.. The main threats will be Wind and Hail... http://weather.unisys.com/satellite/sat_wv_us_loop-12.gif The water vapor image shows a shortwave trough that is moving across the great basin region and should continue to press east Northeastwards . By 18 Z a frontal system with a surface cyclone should be located from NE to SW with one area of low pressure over North Dakota and another one located over Wyoming . It will be this surface frontal system and ejecting shortwave trough that will be the trigger for the severe weather potential today..

Severe Weather Discussion For June 5th 2012

Severe Weather Discussion For June 5th 2012

http://www.hpc.ncep.noaa.gov/sfc/90fwbg.gif

Looking at the most recent surface map we see a stationary front across the TN area into the Southeast. This turns into a cold front back thru Oklahoma. This cold front will sag towards the south and will be the focus of severe weather potential across the southeast along that stationary front.
Further to the north.. this will be the same system that produced the severe weather yesterday in the region which was a trough which is negatively tilted with a surface low meandering thru MT with a strong cold front..

TEMPERATURES ..

Temperatures will be cool in the Northeast region but with a ridge in place into the south central region into the Midwest temperatures will be in the 70s to 90s range.
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/05/00/NAM_221_2012060500_F24_TMPF_2_M_ABOVE_GROUND.png

DEW POINTS
Dew points will not be as muggy as what they have been however with mainly 50s and 60s..
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/05/00/NAM_221_2012060500_F24_DPTF_2_M_ABOVE_GROUND.png

CAPE or INSTABILITY
CAPE across the region is between 500-3000 depending on where you live and reside in the severe potential zones...
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/05/00/NAM_221_2012060500_F24_CAPE_SURFACE.png

LIFT INDEX
Lift index is 0 to about - 8 depending on where you live / reside in the severe potential zones..

ENERGY HELICITY INDEX
Energy Helicity Index is not very high except for MT where it is at 1 or above. This would mean we put a tornado chance in MT at about 2%
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/05/00/NAM_221_2012060500_F24_EHI_1000_M.png

HELICITY
Helicity going hand in hand with the EHI and not being impressive
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/05/00/NAM_221_2012060500_F24_HLCY_1000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png

SHEAR
Shear is greatest along the front in the SE and with the approaching front into Montana.
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/05/00/NAM_221_2012060500_F24_SHRM_500_MB.png

All and all we are not very impressed with severe weather today . Montana could be the exception to that rule. Main threats will be winds and hail with tornado possible in MT..

June 4th 2012 Severe Weather Outlook..

Discussion for June 4th 2012 Severe Weather Outlook.. It is going to continue to be a warm and muggy day across the areas anticipated to have severe weather potential with temperatures in the 80s and 90s..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/04/00/NAM_221_2012060400_F24_TMPF_2_M_ABOVE_GROUND.png ... DEW POINTS will also be in the 60s and 70s with the exception of the northern zone where they are only in the 50s.. http://www.twisterdata.com/data/models/nam/221/maps/2012/06/04/00/NAM_221_2012060400_F24_DPTF_2_M_ABOVE_GROUND.pngINSTABILITY or CAPE is quite impressive with 500-4000 depending on where you are located.. http://www.twisterdata.com/data/models/nam/221/maps/2012/06/04/00/NAM_221_2012060400_F24_CAPE_SURFACE.png ...LIFT INDEX is 0 to about negative 10 depending on where you are located..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/04/00/NAM_221_2012060400_F24_PLI_30_0_MB_ABOVE_GROUND.png... Once again there is no lack of SHEAR with 30-50 knots across the severe zones..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/04/00/NAM_221_2012060400_F24_SHRM_500_MB.png ..ENERGY HELICITY INDEX is above 1 in a good portion of the severe zone ..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/04/00/NAM_221_2012060400_F24_EHI_3000_M.png.. The greatest HELICITY however is over the Northern Severe Zone..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/04/00/NAM_221_2012060400_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png At the surface we are looking at a stationary front with waves of low pressure that will be moving along the stationary front.. http://www.hpc.ncep.noaa.gov/basicwx/92fwbgus.gif which will also bring a cold front into the region by late afternoon evening time..http://www.hpc.ncep.noaa.gov/basicwx/93fwbgus.gif ..Across the northern zone this will be due to a strong negatively tilted trough that will be coming on shore from the Pacific Northwest region. This will involve a cold front and a strengthening area of low pressure that should move from Nevada towards Montana and it is in the warm sector where we anticipate the storms to be. In addition to the storms will be heavy rainfalls. Tornado's can not be ruled out in the Northern severe zone which we will put at 2% ..especially the closer you are to the warm front and low pressure area.. Locations such as TN/KY are really going to depend on the activity that is occurring at the present time. This could help to make the atmosphere more stable and cause the main severe weather to be more off to the east/Southeast. Anywhere in the severe zone (s) however.. could potentially see a Tornado with the EHI and SHEAR such as is suggested by the guidance.. In the NORTHEAST..once again there is no severe being suggested by the SREF but isolated severe could again occur anywhere in the Northeast.

June 3rd 2012 Severe Weather Outlook

June 3rd 2012 Severe Weather Outlook
Discussion and Parameters ...
In the severe zone the temperatures are going to be quite "hot" with TEMPERATURES between 80 and 100 perhaps some places in the 100's..
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/03/00/NAM_221_2012060300_F24_TMPF_2_M_ABOVE_GROUND.png
In addition to it being "hot" it is going to feel muggy in these areas with the DEW POINTS in the 60s and 70s.
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/03/00/NAM_221_2012060300_F24_DPTF_2_M_ABOVE_GROUND.png
The instability in the measurement of CAPE is quite impressive with the fuel available between 500 (marginal) and 4000 (extreme)
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/03/00/NAM_221_2012060300_F24_CAPE_SURFACE.png
The LIFT INDEX actually is from 0 to -12 depending where you reside.
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/03/00/NAM_221_2012060300_F24_PLI_30_0_MB_ABOVE_GROUND.png
SHEAR is sufficient at 30-50 knots..
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/03/00/NAM_221_2012060300_F24_SHRM_500_MB.png
The greatest area of HELICITY is across eastern Kansas where it is roughly between 250-300
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/03/00/NAM_221_2012060300_F24_HLCY_1000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
As far as the ENERGY HELICITY INDEX is concerned.. these are some pretty high values ...
http://www.twisterdata.com/data/models/nam/221/maps/2012/06/03/00/NAM_221_2012060300_F24_EHI_3000_M.png
From Central & eastern OK to Eastern Kansas to Eastern Nebraska, Western Iowa to majority of Missouri to NW ARK would be the region that you can expect to see the worst of the severe along with the potential for tornados. We would put the tornado chance in these locations between 5-10 %.
At the surface a trough located over the South central region should deepen and serve as the trigger for todays severe weather.
In addition to this will be a series of low pressure systems ..One that should be located over the Nebraska/Dakota border and another located over or just north of the OK panhandle region with a warm front extending eastward from the low pressure. This warm front will be slowly lifting north and will also enhance the potential for severe weather.

June 1st Severe Weather Outlook

Discussion for June 1st ...We are going to start off by looking at the surface map to see what is happening. http://www.hpc.ncep.noaa.gov/sfc/90fwbg.gif Low pressure is located over Southern Indiana. Accompanying this low pressure is a warm front to the east and a cold front trailing to the south. This low pressure is anticipated to move NE and take on a negative tilt to the trough as it does so. This will push a warm front into the region. This warm front will be followed by a cold front..http://www.hpc.ncep.noaa.gov/basicwx/93fwbgus.gif It will be this area of low pressure and the associated frontal systems that will bring the severe weather potential into the region.. So lets get down to the specific Parameters... TEMPERATURES are only going to be in the 60-80 degree range across the Northeast..Higher temperatures in the SW portion in the TX region of 80-90 degrees.http://www.twisterdata.com/data/models/nam/221/maps/2012/06/01/00/NAM_221_2012060100_F18_TMPF_2_M_ABOVE_GROUND.png ..DEWPOINTS will be in the 60-70 range ..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/01/00/NAM_221_2012060100_F18_DPTF_2_M_ABOVE_GROUND.png..CAPE is not all that impressive it is only in the 500-1500 range and generally that would fall into the marginal category when it comes to Instability.. http://www.twisterdata.com/data/models/nam/221/maps/2012/06/01/00/NAM_221_2012060100_F21_CAPE_SURFACE.png ..LIFT INDEX is from 0 to about -7 depending where you are located..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/01/00/NAM_221_2012060100_F21_PLI_30_0_MB_ABOVE_GROUND.png... Now where it gets a little on the dicey side is the EHI..Remember that anything at 1 or below that super cells are not likely but 1 and above super cells become more likely.. 1 to 5: Possibility of F2, F3 tornadoes ..http://www.twisterdata.com/data/models/nam/221/maps/2012/06/01/00/NAM_221_2012060100_F21_EHI_3000_M.png ..So you can see why things become a little bit on the dicey side here.. Another part of the dicey forecast is the HELICITY... to freshen peoples memories here is what the Helicity represents..Interpretation of values:
*150-300 Possible Super cell
*300 to 400 Super cell Severe Favorable
*400+ Tornadic Thunderstorms Favorable ..and here is what the Helicity looks like http://www.twisterdata.com/data/models/nam/221/maps/2012/06/01/00/NAM_221_2012060100_F21_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png ..So as you can see we have two very favorable parameters in place for Tornadic Activity across PA.. We have no lack of SHEAR either with 30 knots and above in place...http://www.twisterdata.com/data/models/nam/221/maps/2012/06/01/00/NAM_221_2012060100_F21_SHRM_500_MB.png ...Now one thing that may hinder Tornadic potential could be cloud cover that is presently moving into western PA..http://weather.unisys.com/satellite/sat_ir_us_loop-12.gif ..So what we are going to do is we are going to make one more map and this is going to be PA based and it is going to be based on Tornado potential only. We already know that the severe zone always represents the places with likely hood of hail and or wind... and the percentages of Hail are at 15% and winds we place at 15%.
Here is the tornado potential only map:

Those in southwest PA we feel you will be dealing with more along the lines of heavy rainfall potential and garden variety storms> it is possible that some isolated severe could occur but we think the initiation of the severe will be NW of you and east..
We encourage people across the state of PA ..to pay attention to there local weather source!