midwest folks -- update on event / some changes

[PurdueWx80]

Memphis would have nasty ice (.25 to locally 0.5") with 2-4" of snow on top of that by Thursday morning, according to the 00Z Eta. I imagine Memphis will issue a warning by 3-4 a.m. - if they see things differently it may end up being a winter wx advisory or freezing rain advisory, but a winter storm warning seems most appropriate.

1000-850 and 1000-700 critical thicknesses are south of Ohio river by 12Z tomorrow and stay that way through the event (although they do back up ever so slightly as the low travels up and a trough of warm air aloft (TROWAL) develops. Wxguy's predictions of up to 20" are very much possible according to the Eta just north of the Ohio river. If a layer of warm air can sneak in (w/o the models seeing it) a significant icing event may occur on either side of the Ohio. Projected soundings so far indicate mostly snow north of the river with QPF values progged to be as high as 2" in this region. The convective potential mentioned is hard to forecast, but certainly seems plausible w/ this event, and if realized, VERY isolated locales will see 2 feet of snow. The Eta shows temperatues of -10 to -15F across the snow area Friday morning, with the coldest of the air yet to reach the region.

UPDATE - 2m temps forecast by Eta for Christmas morning range from -20 to approximately -28 over the snow!!!!!!!!

[jkt21787]

The GFS is in and it seems even stronger for this area as far as ice, so a warning will likely be issued in the morning.

[PurdueWx80]

Precip has broken out slightly earlier than expected - raining moderately at my parent's and the winds have shifted to the NW as the front has just come through...temp near 39 and falling! Guess I'll keep posting every few hours or when things change!

Edit - Guessing parts of Louisville Forecast area will be upgraded to ice storm warning looking at 00Z models - warm layer aloft just above freezing (near 850 mb, no warmer than 34F at Louisville) with surface temps falling through the 20's by evening tomorrow and into the teens tomorrow night. Very tough call tonight, somewhat further west track per models, stronger surface and low-level circulations, high PW's to work with and surface temps falling off rapidly behind front. I'd really not want to be the person making decisions at any office in the TN/OH Valley tonight/tomorrow.

[TazzyD]

WISH-TV 8 out of Indy just said parts of south-south central Indiana could get around 15" of snow in some parts of southern IN. YOWSA! I'm impressed. They're starting to agree more with what you all have been saying. They keep slowly keep increasing the amount predicted. Can't say I'm really looking forward to it.

[wxguy25]

I still think CLE is going to see 8-12” even w/ a changeover since 0.75” of liquid will have already fallen (as all snow) prior to it. w/ the SLP and 850h low tracks further west, the WAA will be stronger and more likely to bring a few layers above freezing as ETA soundings would suggest.

The WAA is strong and probably will be sufficient enough to offset the adiabatic cooling ensuing from the high UVM so there will be a changeover to ZRA and IP for a short time until the low passes by and CAA kicks in.

http://vortex.plymouth.edu/gifs/041222041425.gif

Notice the small layer above 0C…this is a CLASSIC ZRA sounding.

As far as convective processes are concerned, the BEST chance for someone to see 24” will be under CSI bands which form with the intensifying frontogenesis

[Brent]

UPDATE - 2m temps forecast by Eta for Christmas morning range from -20 to approximately -28 over the snow!!!!!!!!

Is that -28 degrees FAHRENHEIT? SURFACE TEMPS? What's the all time records up there?

[beachbummer]

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE LOUISVILLE KY
10 PM EST TUE DEC 21 2004
...FIRST WINTER STORM OF THE SEASON TO AFFECT MUCH OF THE LOWER OHIO
VALLEY...
.A DEVELOPING LOW PRESSURE SYSTEM OVER EASTERN TEXAS IS FORECAST TO
STRENGTHEN AND MOVE NORTHEAST TOWARD THE OHIO VALLEY LATER TONIGHT
AND WEDNESDAY. THE COMBINATION OF INCREASING GULF MOISTURE ALONG
WITH COLD AIR DIVING SOUTH FROM CANADA WILL PROVIDE THE NECESSARY
INGREDIENTS FOR A MAJOR WINTER STORM ACROSS PORTIONS OF THE LOWER
OHIO VALLEY. THIS INCLUDES HEAVY SNOW...SLEET AND FREEZING RAIN.
.THE NATIONAL WEATHER SERVICE IN LOUISVILLE UPGRADED THE NORTHERN
PORTIONS OF THE WINTER STORM WATCH AREA TO A WINTER STORM WARNING.
THE WINTER STORM WARNING COVERS SOUTH CENTRAL INDIANA AND
PORTIONS OF NORTH CENTRAL KENTUCKY.
.IT SHOULD BE NOTED THAT A SLIGHT CHANGE IN THE TRACK OF THIS LOW
PRESSURE SYSTEM WILL ALTER WHERE THE HEAVIEST PRECIPITATION WILL
OCCUR...AS WELL AS WHERE THE MAIN BRUNT OF THE WINTERY MIX OF
FREEZING RAIN...SLEET AND SNOW WILL OCCUR.
INZ076>079-083-084-089-221000-
CRAWFORD-DUBOIS-JEFFERSON-ORANGE-PERRY-SCOTT-WASHINGTON-
INCLUDING THE CITIES OF...JASPER
10 PM EST TUE DEC 21 2004
...WINTER STORM WARNING IN EFFECT FROM 3 AM WEDNESDAY TO 6 AM EST
THURSDAY...
THE NATIONAL WEATHER SERVICE IN LOUISVILLE KY HAS ISSUED A WINTER
STORM WARNING. LIGHT RAIN WILL QUICKLY OVERSPREAD THE ENTIRE AREA.
THE RAIN IS FORECAST TO CHANGE TO ALL SNOW BEFORE SUNRISE. THE SNOW
MAY BECOME HEAVY AT TIMES WITH ACCUMULATIONS OF 6 TO 10 INCHES
POSSIBLE. AREAS THAT WILL BE IMPACTED WITH THIS ACCUMULATION OF
SNOW INCLUDE THE CITIES OF JASPER...PAOLI...SCOTTSBURG AND MADISON.
TRAVEL WILL BECOME EXTREMELY HAZARDOUS LATE TONIGHT AND DURING THE
DAY ON WEDNESDAY. THOSE WITH HOLIDAY TRAVEL PLANS IN THE WARNED AREA
ARE ADVISED TO MONITOR THE LATEST FORECASTS AND ADJUST TRAVEL PLANS
AS NEEDED. IF THIS IS NOT POSSIBLE...USE EXTREME CAUTION IF TRAVEL
IS UNAVOIDABLE.
STAY TUNED TO NOAA ALL HAZARDS RADIO...COMMERCIAL MEDIA OUTLETS OR
YOUR CABLE TELEVISION PROVIDER FOR THE LATEST INFORMATION CONCERNING
THIS POTENTIALLY DEADLY WINTER WEATHER SITUATION.
THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGICAL AND CLIMATE
INFORMATION...IS AVAILABLE ON THE WEB AT HTTP://WWW.CRH.NOAA.GOV/LMK
OR AT HTTP://WEATHER.GOV.
$$

[wx247]

Some interesting changes have taken place over the last 12 hours via the models. Places like Memphis, Murray, KY... watch out! Yowzers! Ice, Ice Baby!

[wxguy25]

Some interesting changes have taken place over the last 12 hours via the models. Places like Memphis, Murray, KY... watch out! Yowzers! Ice, Ice Baby!

Its not a good thing for you though, Garrett. I said 2-4" for you earlier, however now it appears as if MOST of the snow should stay off to your south. 1-3" tops IMO.