Thanksgiving Snowstorm?

[Guest]

The GGEM and the EC both show a Turkey day storm with a track from OK/TX ne to just east of Detroit. Most IMO will all see rain changing to a heavy snow from, N.MO, IL ( at and near the lake) into southern MI (At and near the lake Kalamazoo/Grand Rapids west in sw MI and as well over by Detroit), IN and OH. To the nw of there in WI and IA and areas away from the lake in N.IL and MI it should be mainly snow however it still should start off as a little rain before quickly changing over.

Below is the EC for Turkey Day!





And below here is the GGEM (Canadian)


BTW of all things the 06z gfs has picked up on it as well.

Any other coments are more then welcome!

[PurdueWx80]

Yes, people have been talking about it in the other post labeled white thanksgiving.

We are too far out for any model to pick up on the amount of low-level cold air that will be involved with this system. GFS numbers are almost always much too high more than a week out, and we all know predicted storm tracks this far out leave much to be desired. I'm fairly confident a storm will go up west of the mountains, but it's the minor details that will dictate exactly where the snow falls. The orientation of the 500 mb flow, if correct, leads me to believe a polar and/or arctic air mass will come in just in time. See the other post for where I think the heaviest snow may fall.

[Guest]

Thats kewl Purdue. I cant say or nor was i trying to say who would get what. Amounts wise. The colder air would be nice because as it stands right now from them model runs if there is colder air to work with it would bode very well for this area ESPECIALLY with a track such as the GGEM is showing above!

[PurdueWx80]

This morning's GEM is also one big tease, at 144 hours it shows a possibly developing low over the Gulf states (TX/LA) and MUCH colder air across the Lakes and Midwest...just in time for Thanksgiving.

[CaptinCrunch]

EXTENDED (AFTER THANKSGIVING)....

LONG RANGE TRENDS REMAIN UNCERTAIN AS TELECONNECTIONS AND MODEL
SOLUTIONS ARE NOT IN AGREEMENT. BOTH THE GFS AND ECMWF SHOW A BROAD
BASED...BUT SOMEWHAT FLAT...TROUGH OVER THE EASTERN UNITED STATES
FOR NEXT WEEKEND. THE PSEUDO-ZONAL FLOW DURING THIS PERIOD WILL BE
MAINLY PACIFIC IN ORIGIN...SO WHILE IT MAY BE A BIT COOLER THAN
NORMAL...TRUE COLD AIR IN THE 6 TO 10 AND 8 TO 14 DAY PERIODS IS NOT
LIKELY.

LOOKING AT TELECONNECTION INDICES...THE CPC ENSEMBLE NAO MODEL SHOWS
ALL MEMBERS POINTING TO A NEGATIVE NAO EVENT FROM THANKSGIVING INTO
EARLY DECEMBER. A LOOK AT THIS INDEX ALONE MAY LEAD ONE TO THINK
THAT A COLD PERIOD WILL BE ON TAP...BUT A CLOSER LOOK SHOWS THAT THE
POINT INDEX IS PROBABLY BEING SKEWED BY WEAK RIDING OVER GREENLAND
INSTEAD OF CAPTURING THE WHOLE PICTURE. A CLOSER LOOK AT THE GFS
REVEALS THE TRADEMARK GREENLAND BLOCK...BUT THE UPSTREAM CANADIAN
VORTEX IS FORECAST TO BE NORTH AND WEST OF HUDSONS BAY RATHER THAN
OVER...OR EAST OF IT. AS A RESULT...THE OVERALL FLOW IS ZONAL
BENEATH THE VORTEX KEEPING THE REAL COLD AIR TO OUR NORTH.

MEANWHILE...THE ENSEMBLE PNA MODEL INDICATES A NEGATIVE PHASE
BETWEEN THANKSGIVING AND EARLY DECEMBER. THIS IS MORE TYPICAL OF A
RIDGE IN THE EASTERN U.S. BUT AS ALREADY POINTED OUT...BOTH THE GFS
AND ECMWF SHOW A BROAD AND SOMEWHAT FLAT TROUGH.

THE CPC PROGNOSTIC DISCUSSION ONCE AGAIN SUGGESTS LOW CONFIDENCE IN
THE 6 TO 10 AND 8 TO 14 GRAPHICS...THIS TIME DUE TO DISAGREEMENT
BETWEEN TELECONNECTIONS/MODEL FORECASTS...POOR CONTINUITY AND A
ZONAL FLOW WITH WEAK ANOMALIES.

[aggiecutter]

Model error is even more common in a changing pattern like the one we are heading into. Next week, winter fires it's first warning shot into the plains. By mid-month it will be very cold between the Rockies and the Appalachains.

Capncrunch, I bet we have a couple wintry events in North Texas before the first of the year. The pattern is setting up just right for it. GOM lows and arctic highs coming down from the plains.

[CaptinCrunch]

I wont be suprised if we see winter weather between Dec 13 and the 21. By then the pattern change should be well seen for the central plains and deep south.

[PurdueWx80]

Thanksgiving COLD storm is more like it. I know I said the GFS's numbers are crap this far out, but looking at the 12Z's prognostication of 850 T, I would say Thanksgiving day will be one to remember, temperature wise. For several runs now it has basically broken off a mini-"polar vortex" across the Midwest and Ohio Valley for Turkey Day. Temps at 850 of -15 would surely mean lake effect snow to boot, and surface temps struggling through the 30's all the way to TN.



The snowstorm is still on to the west of the surface low track, and with several models taking this into the 980's (or even to 980 mb), blizzard conditions seem possible at times, particularly further north in the event. Thursday will also be very brisk, with wind advisories likely across much of the east. Hope no one planned a Thanksgiving Day picnic!

[nystate]

Any chance for snow in upstate NY/PA? I have relatives driving up from Philly to Watertown and would like to know if they can expect adverse weather.

[PurdueWx80]

There will definitely be some lake effect in Upstate NY and PA on Thanksgiving, and probably on Friday as well.

[PurdueWx80]

There will definitely be some lake effect in Upstate NY and PA on Thanksgiving, and probably on Friday as well. Roads are still warm so I don't see it as being a huge driving headache.