0730 EST 21 NOV 2011… STARDATE 201111.21
I am sure someone like Bill Karins the morning meteorologist on MSNBC is a good guy and all but I am listening to him tell everybody that Wednesday, November 23 is going be a “really bad travel day in the northeast US ” because of all this heavy rain coming. While it is going to rain a lot on Tuesday night and early Wednesday morning ….the data clearly shows that by a Wednesday 7 0700 EST most of the heavy rain will be north of Boston up across Northern New England Montreal and Maine. I am not exactly sure what he is looking at but based on what I am seeing early this morning … that forecast is a lot of nonsense. Here is the 700 MN RH field from the 0z GFS valid at 0700 EST Wed 11/23. As you can see the heavy rain is about to pull out of Boston and is falling mostly over interior portions of New Hampshire Vermont and Maine and Montreal. This does not like a bad travel day to me up and down the I-95 corridor– perhaps some early morning delays but things should rapidly improve as skies clear out. http://mag.ncep.noaa.gov/GemPakTier/MagGemPakImages/gfs/20111121/00/gfs_namer_060_700_rh_ht.gif
The other major issue has to do with the development of a potentially large close cut off Low at the base of the trough on November 27 over the Midwest. The 0z and 6z GFS are going absolutely bonkers with the system developing a four or five closed off contoured 500 MB cut off Low over the Tennessee Valley late on the 27th into the 28th.
The European model which was showing this sort of development on Sunday has backed off of that idea. The 0z Monday 11/21 run now the shows a deep trough moving rapidly through the East Coast and does not close off a deep 500 MB Low at the base of thre trough. http://meteocentre.com/models/ecmwf_amer_00/GZ_PN_168_0000.gif
The 0z Canadian also develops this sort of feature. The development of this potentially significant deep closed cut off Low would be hard to overstate. Since the entire feature develops a negative tilt at 500 MB the downstream difluent flow along with the extremely warm temperatures … southerly winds bringing in copious moisture and the slow movement of the system …could set up a significant severe weather event for much of the Middle Atlantic states into NY and potentially into western New England lay on the 27th into the 28th. Taken verbatim both the 0z and 6z GFS development of the deep closed 500 Low argues for SNOW to fall over the mtns of TN eastern KY southwest VA western NC and southern WVA .
The 0z GFS ensemble shows almost no support for this solution. A FEW of the individual members to show a closed 500 Low over the Tennessee Valley that moves through the Middle Atlantic states at day 7. http://www.meteo.psu.edu/~gadomski/ENSHGT_0z/f168.html
The 6z GFS ENSEMBLE is much more impressive with 7 of 11 supporting the idea of a deep closed cutoff 500 Low over the TN or Ohio valleys.
on the 6z GFS ensemble … 13 of the 20 member ensemble support the idea of deep closed cutofff Low … so I cannot rule out of the GFS completely. I am however worried that this is from a 6Z run which statistically as been proven to be more unreliable than the 0z run.
More impressive is the vastly improved NOGAPS model with its 4dvar… and its 20 ensemble .As you can see here not only does this deep close 500 low show up on the ensemble mean but 18 of the 20 members as well.
The Euro ensemble does NOT support this and closely matches the operational run. By day 9-10 the model has a strong cold front sweeping through the Plains the Midwest and the Northeast. Low pressure is forming over Texarkana and it looks like is going be a significant snowstorm for the Midwest DEC 1-2.
My view is that since the European or r European ensemble is not yet on board with the idea of deep closed 500 Low over the TN Valley on the 27th and 28th …. in fact it was moved away from that scenario — I cannot go with it . I am not convinced that the European solution is correct but right now… given the overall synoptic pattern and the lack of high latitude blocking ….I remain skeptical of the extreme solution posed by the GFS the Canadian and the NOGAPS and their ensembles. If later on today the European model turns back towards a solution well I will be banging that big closed Low idea… like a cheap whore.
longer Term … It appears once again that the usual sources are jumping up and down about some sort a major pattern change coming as we move into DEC…. And clearly the data does not support that sort of excitment or hype. The data does show the pattern turning someoine colder of the central and eastern CONUS and ace and to the excessively torrential rains overt the Pacific Northwest.
Here we can see the deep 500 Low… the PV … That has been over the gulf Alaska and the Yukon… Retrograding towards the Bering sea …. Which in turn allows for some MODERATE 500 MB height rises to occur over the Pacific NW. So the pattern IS turning a bit colder and more seasonal as we move into December.
This shows up on the European ensemble as well.
Again nothing overpowering but certainly colder than it has been ( which is NOT saying Much). However if we change perspective and we look at this from the northern hemisphere view http://raleighwx.americanwx.com/models/ecmwfens/00zecmwfens500mbHGHTNH240.gif
We see that the polar vortex– 2 of them — are still on the WRONG side of the hemisphere for any sort of significant sustained colder outbreaks getting into any portion of the U.S. Or Southern Canada. The AO is very Positive as is the NAO.
the EPO is beginning to come back towards earth and near neutral conditions by day 15
One last note in this concerns the current WEAK MJO… Don’t forget to look at this link which shows other MJO models besides the CPC GFS stuff. Most of the GFS / CPC MJO plots show the current MJO impulse weakening moving into the circle of death somewhere in Phase 2. The European Briitsh Japanese and Brazilian models do NOT shows weakening actually shows the current Impulse gaining mater intensity as it moves into phase 3 and 4 in early DEC. Clearly such a development would have potentially significant impact on the idea of a cold December over the central and eastern U.S.