A light snow event is on the way for Friday. A clipper like system will be approaching the region and will be responsible for the light snow on Friday. This clipper will redevelop off the coast of Hatteras but instead of moving up the coast it will move more to the East North East and the coastal redevelopment will happen to late and to far in the Atlantic to have any additional effect on the snowfall.
Very cold air has been in place for the last couple days so whatever snow does fall will not have any problem sticking. With models generally printing out .1 to .25 across the region with the exception of parts of West VA and VA ..the general call is for 1-3 inches with lighter amounts to the north and heavier amounts in the area where guidance is printing out .25-.50 inch liquid equivalent.
The flow is just to fast and progressive to allow the two jet streams to phase together and so we are left with a lighter snowfall...
Where do we go from here? Guidance is suggesting temperatures will slowly moderate so that by the beginning of the week we will be looking at temperatures above normal with ridging occurring over the east as a trough will advance from the west central conus. This will result in a warm up with temperatures in the 40s to near 50 in the east and a low pressure forming in the southwest that will head up towards the Great Lakes into the Northeast dragging a cold front across the region and introducing our next chance for precipitation in the form of Rain . After this cold front goes by we will once again return to colder weather.
2nd call for 1/25/13. Final call will be issued on Thursday...
For now we are just issuing out first guess map which we put out yesterday at 3 PM in the afternoon. As the event gets nearer we will fine tune this and add some details.
As is always the case we are going to take a look at where we have been and we stand presently..
There is really no way to deny the fact that the first 17 days of January have been above normal and this occurred when many were claiming the month of January was going to become colder then normal.
If you recall we said that in order for the pattern to change it depended on two things:
A. The progression of the MJO and whether or not it would go back into phase 6 or if it would continue to propagate into 7 and perhaps phase 8.
B. The PNA and whether or not it would go positive being that it has been in a negative state.
Looking at the Current MJO we can see that this is in phase 7..
And the results of Phase 7 in the month of January?
As far as going forwards...there is only one model that wants to take the MJO back into phase 6 and that would be the Canadian.. which still takes it back into phase 7 there after.
All the rest of the guidance suggests Phase 7 or Phase 8 as the destination ..
Including the ECM ensembles ... but the ensembles then progress the MJO into the COD.
For those that are wondering this is what phase 8 looks like for the month of January..
So phase 7 and phase 8 both indicated colder weather across the east coast and this is exactly what the guidance is showing to occur with the up coming pattern which is about 72-96 hrs out.
Lets look at the European Computer guidance to see what this looks like at the 850 mb temperature level..
The model brings a shot of extremely cold air into the east and Northeast and the midwest. This lines up perfectly well with what the MJO is doing. And as we mentioned the second thing was the PNA had to take a turn to the positive. What that does is brings ridging into the west and troughing into the east.
And as you can see the PNA presently is neutral negative but it is shown to be sharply rising. However..the one thing to take note is that after this sharp rise we see that it goes back negative once again..
So how long is this colder pattern going to last? This is going to be dependent on two things once again...
1 The Arctic Oscillation.
As you can see the Arctic Oscillation is slightly negative but expected to take a dive but then majority of the members are showing the AO to rise to the positive side. The second thing to watch is for the PNA to see if it indeed does take a negative turn after the positive spike. If the AO goes positive and the PNA goes back to negative then we could be switching back into a more warmer pattern.
This could indeed be the reason why the ECM is showing a warming pattern at Day 10
And the GFS is showing this in the days 11-15
Both at the same time frame indicating a return to above normal weather across the Northeast (GFS) and a large chunk of the US on the 00z ECM.
In the meantime , after a one to two day warm up we are going to get colder once again as shown by the ECM above and while in this cold pattern.. we could be looking at the potential for an East Coast snowstorm. Both the 00z GFS and the 00z ECM suggest this could happen next weekend..
And the European shows the following:
Both models are plenty cold enough to support a snowstorm across the east coast and into the major cities as well. So we have a pattern change on the horizon and a potential snowstorm to keep an eye on across the east. How long does the pattern last with colder weather? This is something we will be keeping an eye on and be updating about in the days ahead.
Meanwhile if you have become use to the warmer weather ...the air coming in at 72 hrs is going to remind you that we are in the month of January and still have about 6 more weeks of winter to go.
Folks we figured we would take the time and post an update in regards to the pattern. We are going to touch on what we have been saying? Where we are going? Where we have been? And its going to be based on indisputable facts.
First off lets look at November of 2012
What we see here is that we had a below normal month on the east coast ..at least from NY to Florida. Seasonal north of that location and then in the west it was seasonal to above seasonal weather.
Along came December of 2012
What happened? Before we answer that we need to answer when does winter begin?
First Definition defined below in Wiki:
Winter is often defined by meteorologists to be the three calendar months with the lowest average temperatures. This corresponds to the months of December, January and February in the Northern Hemisphere,
December 1st marks the first day of meteorological winter (source)
Meteorological winter begins Saturday (Dec. 1), (source)
Meteorologists, however, observe seasons over different time periods. Meteorological winter begins December 1, spring begins March 1, summer begins June 1 and fall begins September 1. (source)
So as you can see from the sources above in the world of Meteorology winter begins on December 1st and consists of the months of Dec, Jan and Feb.
So what happened above in December? We had a reversal of the weather pattern and the east went warm and the west was seasonal to above seasonal and there was even a record warm month in the mix in december.
This was the opposite of what majority of your weather outlets saw coming as they foresaw a colder december (Us included) ... December passes and we head into January..
This is just the first 13 days and it does not include yesterday the 14th where temperatures were in the 50s and 60s so this map is only going to get warmer in the departures come later today. The warm pattern from december continued. This was part and partial because we had the Alaskan Vortex in place (same as last winter) . Again this is NOT something that was accounted on by the majority of your weather outlets. Many of them bought into the CFSv2 which was showing a colder then normal January across the east. Thru 14 days this has been wrong.
Besides the reason mentioned above another reason is the Madden Julian Oscillation.
The MJO has traveled thru unfavorable phases for below normal temperatures and snowfall across the east because the MJO has been going thru the warmer phases. Current MJO is in phase 6 and has slowed down its progression some. Where does the MJO go from here?
NCEP GFES shows going into phase 7 and then looping back into phase 6 before re emerging in phase 7..
NCEP GEFS_BC shows a loop in Phase 6 with a brief stint in phase 7..
NCEP GFSOP shows a brief stint in phase 7 back into phase 6 before reemerging back in phase 7
UKMET shows phase 6 into phase 7
Canadian shows phase 6
ECM shows phase 6 and then phase 7 and then heading back towards phase 6 but kind of ending around the border of 6 to 7
So as you can see there has not been much change in the MJO since the last update and it will either be phase 7 ,,phase 6 or into 7 before back to 6 before re emerging in 7..
A reminder of what the different phases look like for Phase 6 and 7 in January..
Phase 6
Phase 7
One is warmer outlook and one is colder outlook and it helps to explain why the models are oscillating back and forth between warmer and colder because the MJO is quite uncertain as the different models above show the picture.
So we turn to the teleconnections and we look to the NAO and we look at tonights guidance for starters..
Well for those that may not know the red is positive and the blues is negative so the ECM is forecasting the NAO to go positive while the GFS also forecasts to go positive but at the end of the run takes it negative again. A positive NAO is NOT a cold signal so we need to look elsewhere for the cold. And these images from the GFS/ECM make sense considering we see this:
NAO is forecasted to go positive above as well. So we look to the EPO.
This is what is going to be responsible for delivering the colder weather into the lower 48 states and that is the EPO. We see the EPO negative but we also see that at the end of the runs the EPO is anticipated to go to positive. This could signal a return to what we been experiencing since Dec 1st ..this is something we have to watch.
From the PNA you can see that the models are showing and in agreement on a period of about 4 days where the PNA is going to go positive but then it spikes back to the negative.
Now none of this information we have provided to this point has been made up. It is clearly shown by the graphics and charts.
So what happens from here? With the MJO still being in phase 6 we are still going to continue with temperatures to be above normal but they are not going to be as above normal as what they been. Kind of like a step down process. First shot of colder air arrives in about 72 hrs ..However this will just be a transient shot of colder air as the guidance shows a moderation before the next shot comes south and east.
This is something we have been discussing on our facebook page quite frequently.
So the question becomes for going forwarded and getting a sustained locked in colder then normal weather pattern is does the teleconnections cooperate? If the NAO goes positive and the PNA goes negative then we will revert back into a warmer pattern and we may end up with a shorter time period of colder air.
People want answers to these questions but these are questions that need to be watched to see what happens with the teleconnections.
Right now our best guess is that we will turn colder in about 72 hrs and we will moderate for a short time again before turning colder once again. The brunt of this cold air will probably be centered over the midwest and the Northern New England area while the rest of us do get colder but nothing historically cold. How long does it last? That all depends on those teleconnections.
We are going to be keeping temperatures over 3 cities for the next two weeks to see whether or not we end up with a pattern change or not..
Half of winter is gone and we have half to go and the question that remains to be seen and answered is if we can salvage it. Will it get colder ...yes...will it be historically cold in the east? Likely not...
Stay tuned..
Let us start off by taking a look at where we have been for the first 9 days of the month of January
Majority of the region has been above normal...some areas are still somewhat below normal but these are confined to Northern New England and over western PA to ohio and WV where it is seasonal to slightly below but keep in mind that this is BEFORE the real warm up occurs...
To give you an example here is Day 3 Max temperatures from HPC as of this morning update
These will spike the departures to the positive side even more then what they should be and keep in mind that majority of your weather outlets were calling for a change to colder weather come January based off the CFS showing a colder January. This has not been the case and the reason why is quite simple..
The PNA is shown to be extremely negative .This in combination with the MJO being into phase 5.
Leads to this type of look..
So the question becomes where are we going? There is no doubt that over the next 4-5 days we are going to continue to be above normal and that takes us thru the first half of the month of January. So can January be salvaged? Is there a pattern change on the way?
This is all going to be dependent on what happens with the MJO and the skill of the models forecasting the MJO is not to reliable and can change from day to day but as of right now they are mainly suggesting that after a stint in Phase 7
The MJO could be heading back into or at least looping thru Phase 6 which would show the following:
So lets look at the MJO forecasts but before we do lets just take a look at the skill of the forecasts via the verification of the MJO
So with that in mind lets look at the forecasts...
The full plume of the NCEP GEFS loops the MJO thru Phase 6 and stays in Phase 6.
And even looking at this image of the NCEP GEFS it shows a brief stint in phase 7 before moving back into phase 6. This would indicate a shot of colder air followed by moderation in temps before perhaps heading back to phase 7 for a shot of colder air again...
UKMET takes the MJO into phase 7 which would definitely represent a colder temperature regime.
ECM takes it into and thru Phase 6 (warmer) and then briefly into phase 7 (colder) and then back into Phase 6 (warmer) ..
ECM ensembles more or less take it between phases 6 and 7 straddling the border and do a loop into 6 before going back into 7 ..in other words a return to colder weather ..then briefly moderating before back to colder weather..
GGEM shows the MJO staying in phase 6. Which would indicate solely on the MJO more in the way of milder weather.
So as you can see the verification of the MJO forecasts has not been great and they are basically either saying Phase 7 or phase 7 before heading back to phase 6.
So now lets look at the actual teleconnections and then we will take a look at the actual model guidance..
As we noted the PNA is currently negative or forecasted to go negative if using CPC
The AO is slightly positive right now but anticipated to go negative but then the members are kind of divided on whether it stays negative or goes back positive..
Most members show it staying negative and a couple quite negative.
And essentially the same thing can be said about the NAO with it being slightly positive right now but heading into the negative territory. However a few members show going back positive. And then we have the EPO which according to this graph
Is more of a neutral negative then going completely negative ..and then is more of a neutral positive.
Remember to really get sustained cold weather into the east you want to see the following:
A negative AO (check)
A negative NAO (check)
A negative EPO (somewhat check)
And a positive PNA (not checked)
MJO into Phases 7 ,8 or 1 with 8 or 1 being the best for East Coast storms. (somewhat uncertain)
So lets look at the guidance...
This is the 12 Z European Computer guidance and it brings the coldest of the air into the Mid Atlantic and the Northeast at 216 hrs out and then lifts the coldest of the air into New England by 240 hours out.
This run is actually warmer over the midwest then last nights 00z ECM run as this image will show..
The GFS shows the coldest of the air actually over the Midwest region during the same time as the ECM above.. except at 192 hours out when it is in the NE region..
But by the 11-15 day range it begins to warm up.. on the operational and looking at the ensembles..
And if you look at the ensembles from the past three runs you can see this as well..
Here was 00z
Here was 6 Z
So are we heading into a Major pattern change or are we looking at a transient shot of colder air? With the PNA remaining strongly negative and the MJO moving thru the warm phases and looking to go into phase 7 briefly before heading back towards phase 6.. the most logical conclusion based on teleconnections would be to expect a return to colder weather (but transient) before moderating once again to more seasonal temperatures to perhaps slightly above seasonal to end out the month of January.
If we were to get the PNA to go positive while the NAO is negative and the AO is negative with a negative EPO we could then be talking about a more sustained shot of colder weather. Its all dependent on the PNA and the MJO and we will continue to monitor this and update this .
Presently looks like a transient shot of colder air followed by moderation (notice this does not mean warm it just means not as cold as it will be at around 216 hrs out)...so we can not at this point and time call this a pattern change until we see what the PNA and the MJO actually do. If the MJO makes it into phase 7 and progresses thru to 8 and 1 then we could have a Major pattern change but right now none of the guidance is suggesting that so we can not be forecasting that to occur.
Meanwhile it will be warm with temperatures into the 50s and maybe near 60 which is well above normal for this time of the year as much as 20 degrees above normal and a rain event early next week before the colder air arrives. The only frozen could be North of NYC ...other wise New England region.
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