Just for Kicks...12zGFS shows a Thanksgiving Noreaster

[RNS]

you bring up a good point about FRZRN...if theres strong thermal inversion aloft (say between H95 and H8), in which temps in those layers are well above frrezing (say +3 to +5C or more) as the rain falls into the cooler layer at the SFC, it will transfer the heat downward through the colder layer and temperatures will rise.

this can make a big difference in situations where temperatures in the layers closest to the surface are between 30 and 32. below 30, it would take a significant warm layer aloft to transfer enough heat dowanward through precipitation processes to bring temperatures up above freezing.

or this can also be the rule in the case of strong shallow layer CAD, or cold air advection, which because the colder air is more dense it sinks below the more bouyant warmer layer...resulting in a change to freezing rain even in spite of temperatures above H95 that may not be supportive.

the best freezing rain events are those that occur in the face of strong CAD east of the mountains, with high perssure to the north helping to keep the cold air in place near the surface.

Icing events in the face of strong warm air advection normally occur as the result of over running, and quickly change to rain once the cold air at the surface is mixed out.

with snow...the opposite occurs.

also as far as analogs are concerned...notice how the north pacific patterns this fall (on average) have been very reminicent of the winter patterns in 1969/70, and 1964/65. both years featuteed a weaker than average alleutian low, and tendency for troughing along the west coast. the key to those winters however was the strong high latitude blocking.

when the pacific jet duels with a -NAO, theres plenty of winter wx fun for everyone in the east.

[Stormsfury]

Interesting ...

I created some reanalysis maps from the January 7th-8th, 1988 winter storm and this was a pure classic overrunning storm with only a weak surface low associated with this overrunning event but very strong CAD ...

Temperature maps at 850mb - notice in 12 hours the 0ºC line strattled CHS, more seen on the Closeup SE view below and quickly rose almost 6ºC!! Meanwhile, SFC temperatures remained below FRZ but up from the 21ºF during the day with light to moderate sleet (with accum. of 1") mixing with ZR during the afternoon ...

500mb Geopotential Heights January 7th, 12z

500mb Geopotential Heights Jan 8th, 1988 - 00z
January 7th at 12z 850mb Temperatures

January 8th at 00z 850mb Temperatures

January 7th at 12z 850mb Temps. Southeast View

January 8th at 00z 850mb Temperatures Southeast View

RNS, you hit the nail on the hit perfectly about temperatures at 850mb were indeed even WARMER than 5ºC during that overrunning event ... while SFC temperatures continued below FRZ (29º-30ºC) ... by evening, the precipiation was entirely in the form of +ZR.

Acrobat PDF file regarding the 1988 Storm which was a record setting snowfall (GSP) in the absence of a rapidly deepening cyclone.
http://www.erh.noaa.gov/gsp/localdat/ta2001-02.pdf

SF

[SacrydDreamz]

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _300.shtml

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _312.shtml

Hmmm...

[Anonymous]

Ji,

Before you fall in love with the GFS, please know that she loves to flirt with snow geese. Once snow lovers succumb to her seductive charts, she has a bad habit of breaking their hearts. Not always, but many times.

Seriously, there does appear to be a reasonable chance of an important storm around Thanksgiving Day. However, odds do not favor a coastal snowstorm:

1) The GFS' south and east bias.
2) November weather that has started in similar fashion to November 2003.

Total November snowfall amounts follow:

Boston: 0.0"-1.0" (Extremes in dataset: 0.0"/2.8"; Years with T or more: 11/12)
New York City: 0.0"-0.6" (Extremes in dataset: 0.0"/1.1"; Years with T or more: 8/12)
Washington, DC: 0.0"-0.8" (Extremes in dataset: 0.0"/1.6"; Years with T or more: 8/12)

What this data seems to suggest is that there is the possibility that at the very end of the storm, there might be a brief period of snow or flurries. Still, one should really wait until the event draws closer to try to identify the details, so the above sentence should be seen as a mere possibility at this time and little more. Colder air will likely follow the storm and the month should close on a cold note. But, it does appear that this cold could be of the transient variety (Pacific Jet, SOI, etc.).

For those living and dying with each development in the "analog wars," the November 8-10 cold spell coincided well with a similar shot of cold in 1960. Ok, the GFS isn't the only one who can tease winter weather lovers around here.

Hey Donald...

Ive been around long enough to realize the The GFS 3 days out yet alone 13 days out isnt very reliable. I just posted the link cause it showed a Noreaster on the holiday knowing full well it was probably BS. Certainly i wouldnt expect a noreaster with snow in the big cities in November...its very rare....I watch the GFS for pattern not neccesairly for the fine details. IT did really well on the closed low idea as all the models have it now.

I believe Thankgiving day will be seasonable in the Mid atlantic with cold air not far away.

[Anonymous]

Well...there was a pretty good Thankgiving storm after all...not a noreaster but still a pretty important event. I think the GFS does great 10-16 days out with at least identifying potential. it showed the March 2001 Noreaster back in Middle February....now for details...thats another story. lol

[JCT777]

Ji - agreed that the GFS did see the storm potential correctly.

Let's see in 10 days what the day 14 GFS shows for Christmas.