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The Culprit? Look no further than The NAO.
Last weekend several runs of the ECMWF indicated the development of a STRONG rex-blocking set-up/MAJOR split flow over the North ATL as the system which is currently dumping snow on the Midwest lifted NE toward Newfoundland and became the new 50-50 low. At the same time a similar strong trough was PROGGED to develop over SCANDINAVIA-- this would shorten the wavelengths over the North Atlantic and allow the ridge to build over Greenland, thereby initiating a powerfully –NAO. Some of the data developed a large omega block which retrograded westward into Canada.
The idea was that a s/w sliding down the ridge off the west coast into the 4-corners region lift northeast into the plain on SUN and MON, but b/c of the 50-50 low and block—the s/w would be forced to stay south (having to around the 50-50 low instead of being able to run northward into the lakes w/o resistance IF the 50-50 low and block were not there). The SLP would have developed in the central/NWRN GOM and headed NE into the OV before transferring to the MA coast setting the stage for a MILLER TYPE B significant east coast snowstorm.
Supporting the idea were also a few runs of the UKMET and GGEM. BUT, by now you are probably aware this scenario is NOT going to happen.
INSTEAD the NE, MA and Eastern Lakes will miss out on this one. For the Midwest and Lakes however it looks like another winter storm for NOV 27-29.
What should happen is the event today lifts northeastward into SE Canada—BUT instead of becoming the new 50-50 low, sharpening the wavelengths and pumping the ridge over Greenland-- it will simply continue to lift northeastward to Greenland resulting in a +NAO.
So w/ NO 50-50 low, a +NAO and the PV off the playing field in NW Canada this will be a MIDWEST and LAKES event snow and winter wise. The basic line of thinking here is simple the s/w kicks out of the 4-corners region FRI and out into AR/LA/TX region by SAT where it lifts northeastward into the lakes SUN and phases w/ another s/w coming through the upper Midwest meanwhile The SLP will develop on D3 over Eastern OK and head NNE to a position over the NW portion of SRN MI.
500mb hgt/vort
http://vortex.plymouth.edu/cgi-bin/gen_ ... ge=800x630
http://vortex.plymouth.edu/cgi-bin/gen_ ... ge=800x630
MSLP
http://vortex.plymouth.edu/cgi-bin/gen_ ... &cu=latest
http://vortex.plymouth.edu/cgi-bin/gen_ ... &cu=latest
Ahead of it in the warm sector there will be yet another severe wx episode not dissimilar to what we just dealt with over TN, MS, LA, and AR as the s/w approaches from the west. There appears to be a favorable upper level jet structure w/ the region being in the exit region of a 116 KT jet streak which would promote upper level divergence and upward motion aided by increasing DPVA ahead of the vortmax. Furthermore, there appears to be a decent 50-55 KT low level moisture transporting jet directed at the region which would help to aid Storm-relative inflow.
Nevertheless, MOST signs seem to point to a rather BIG svr wx event in the same place as there was yesterday. As if they really need it.
http://vortex.plymouth.edu/cgi-bin/gen_ ... &cu=latest
It also means MORE heavy rain for the NE except for perhaps northern Maine initially where there might be enough cold air in place for P-type problems at the start but we have a few days to work on the details.
More important to note is the potential for real BIG flooding problems in the NE as well as perhaps some SVR wx. There appears to be a similar strong low level Southeasterly jet on the order of 50+ KT directed at the northeast at the same time as the region falls under the influence of the left exit region of a potent upper jet to the south. There should be VEERING of the flow w/ height that could help tornadic potential near the warm front.
http://vortex.plymouth.edu/cgi-bin/gen_ ... &cu=latest
http://vortex.plymouth.edu/cgi-bin/gen_ ... &cu=latest
IF I had to make a guess on where the snow would fall I would say a bit further NW of where it is today based on the track of the s/w and SLP. This includes anyone from NW MO, IA, and NW IL into WI and eventually the UP of Michigan.
NOW this is where it gets fun for the NE and MA!
As the ridge begins to amplify off the west coast on D3 a new and STRONGER s/w will slide SE into the four corners region but will NOT be allowed to cutoff from the flow since there is a Kicker upstream off of BC on D5 that come onshore the PAC NW on D6.
http://vortex.plymouth.edu/cgi-bin/gen_ ... ge=800x630
At the same time the PV will intensify and begin to push southeastward toward the NW shore of Hudson Bay by D7 as the s/w comes out into the plains.
http://vortex.plymouth.edu/cgi-bin/gen_ ... ge=800x630
This is a GOOD position for an east coast event, since the PV is not off the playing field but at the same rate, NOT suppressing the flow and shearing everything apart. It will be in the right position as to preclude the s/w from moving northeastward into the lakes like the past two have, but instead keep it on basically and eastward track.
The fact that the PV is sliding southward into the aforesaid position would open the door once again for the NAO to turn negative since the PV would pump the ridge quit a bit downstream.
What i THINK will happen here is you will get a SFC low to develop in the WRN GOM and ride NE into the Lower OV before being forced to go to the coast. This has the POTENTIAL to be the first reputable winter storm for the NE DEC 1-3.
