Deep South Winterwx Discussion 2015-2016

[TigerCraig]

New Orleans AFD:

LONG TERM...
CUT-OFF LOW WEST OF THE SOUTHERN CALIFORNIA COAST HAS STOPPED
RETROGRADING AND SHOULD BECOMING PROGRESSIVE AS ONE SHORT-WAVE
ROUNDS THE BASE OF THE TROUGH TONIGHT AND THE PIN-WHEEL SYSTEM
STARTS FEELING THE AFFECTS OF STRONG SUB-TROPICAL FLOW ON THE
EQUATOR SIDE OF THE CIRCULATION. MODEL JET PROGS INDICATE
100-120KT JET MAX ON DOWNWIND SIDE OF THE CIRCULATION DEVELOPING
THURSDAY WHICH SHOULD MAINTAIN ABOUT A 40KT SYSTEM SPEED AROUND
30N LATITUDE. THIS WOULD PUT IT IN THE CENTRAL GULF STATES AREA ON
SUNDAY. GFS SHOWS A WELL DEVELOPED NORTH GULF LOW WITH THIS SYSTEM
PASSAGE WHICH KEEPS MUCH OF THE FORECAST AREA IN THE COLD SECTOR
AND MARGINAL CONDITIONS FOR WINTRY PRECIPITATION PROSPECTS MAINLY
IN SOUTHWEST MISSISSIPPI NORTHWARD DURING THE DAY SUNDAY. THE
ECMWF IS FARTHER NORTH WITH SIMILAR FEATURE AND SLOWER...COMING
THROUGH SUNDAY NIGHT. GIVEN THE PERFORMANCE OF ECMWF LATELY...AND
IN COORDINATION WITH KJAN...OPTED TO GO CLOSER TO ECMWF TIMING
WITH A SLIGHT HEDGE TO COMPROMISE ON LOCATION OF SURFACE
LOW...THEREBY LEANING TOWARDS A SLEET AND POSSIBLY FREEZING RAIN
POTENTIAL ONSETTING SUNDAY EVENING INTO THE OVERNIGHT HOURS BEFORE
ENDING MONDAY MORNING. GFS SOUNDINGS ARE MORE SUPPORTIVE OF A MORE
COMPLEX WEATHER PICTURE AT MCCOMB AREA WITH A COLD RAIN
TRANSITIONING TO WET SNOW ON WET-BULB EFFECT...THEN TRANSITIONING
TO SLEET FOR QUITE A WHILE BEFORE WARM LAYER ALOFT LOWERS DUE TO
LATENT HEAT RELEASE TO SHRINK THE SUB-FREEZING LAYER ENOUGH TO
REDUCE TO EITHER A VERY COLD RAIN OR A PERIOD OF FREEZING
RAIN...DEPENDING ON SURFACE TEMPERATURE AT THE TIME OF PRECIP. AT
THIS TIME...SHOWED DOMINANT WEATHER SUNDAY NIGHT TO BE SLEET BUT
THIS IS USUALLY NOT THE CASE...OFTEN WITH SOME TRANSITIONAL
PRECIPITATION INVOLVED DURING THESE DYNAMIC SYSTEM PASSAGES. IN
LOUISIANA AND MISSISSIPPI COASTAL COUNTIES...TEMPERATURE PROFILES
LOOK TO STAY ABOVE FREEZING THE ENTIRE TIME TO PRETTY MUCH
MAINTAIN A COLD RAIN PROCESS THAT MAY BREIFLY TURN OVER TO SLEET
FOR A VERY SHORT DURATION PRIOR TO PRECIPITATION ENDING. MODEL
TRENDS WILL HAVE TO BE WATCHED...PARTICULARLY FOR TIMING AND
DEGREE OF COLDNESS...BUT CAUSATIVE SYSTEM IS CLEARLY TRACKABLE ON
SATELLITE IMAGERY IN EASTERN PACIFIC. AFTER THIS EVENT...MODELS
SHOW SOME STEADY MODIFICATION THROUGH NEXT WEEK AND SEEM TO HAVE
BACKED OFF ON INTENSITY OF ARCTIC AIRMASS INDICATED IN THE DAY7-10
PERIOD...THOUGH PATTERN IS STILL INDICATED AND FAVORED...BUT
INTENSITY OF SURFACE SURGE WAS UNDERCUT BY ABOUT 10MB OVER NW
CANADA LATE NEXT WEEK. MORE ON THIS IN FUTURE DISCUSSIONS. 24/RR

[Ntxw]

Hey now! I'm just the messenger, repeating what I see! Don't hold me accountable . Yeah it shows snowcover in Gulf coast including FL panhandle.

That's why I hate the free version. It didn't look like snow that far south, but I guess it did. I'll take it !

Well, the free version doesn't show surface temperatures. The euro is betting that the surface temps will be colder (I see mid 30s approaching the coast) while 850 temps are a bit warmer except for the areas you see on the free site that you think is snow most likely will be, hence a hunch that not all of this would be snow, perhaps sleet etc the further south you go. I'm sure the details will be clear the coming days.

[Ivanhater]

NWS Mobile/Pensacola AFD..usually skeptical being on the coast but interesting tidbit

PLACEMENT OF THE SURFACE LOW OVER THE NORTHERN GULF IS INDICATED BY
THE GFS BEING MUCH FURTHER SOUTH THAN THE ECMWF...WHICH HAS IT RIGHT
OVER BUY 42007 BY 12Z MONDAY MORNING. LOWS IN THE MID AND UPPER 30S
MONDAY MORNING MEANING PRECIP WOULD BE LIQUID BUT THE TRENDS WILL
CONTINUE BEING MONITORED FOR THE DOWNWARD DRIFT WE FREQUENTLY SEE IN
MOS RUN-TO-RUN. NONETHELESS SUNDAY AND SUNDAY NIGHT LOOK LIKE A
WINDY AND RAINY 24 HOURS. /77

[Ntxw]

GFS is showing an ice storm for the mid south.

Freezing near the surface


Warmer Aloft

[northjaxpro]

[quote="Brent"]BMX:

THE BIGGEST QUESTION REMAINS THIS WEEKEND`S SYSTEM. MODELS SEEM TO
BE COMING TOGETHER...A LITTLE. THE 12Z GFS HAS A GULF LOW AGAIN...
BUT NOW ITS MUCH FURTHER SOUTH...WHICH ANY FURTHER SOUTH AND THERE
WOULDN`T BE ANY MOISTURE TO PLAY WITH. ...THE 12Z EURO ON THE OTHER
HAND...HAS THE MOISTURE...AND HAS THE COLD...AND HAS THE
ACCUMULATIONS. THIS IS WITHOUT A DOUBT THE MOST AGGRESSIVE IN THE
WAY OF SNOW THAT WE HAVE SEEN. IF THE 12Z EURO TODAY VERIFIED...4 TO
6 INCHES OF SNOW COULD FALL IN SOME PART OF THE CWA ON
SUNDAY/MONDAY. YES I SAID SNOW. NOW I`M NOT QUITE READY TO BUY INTO
THAT MUCH SNOW JUST YET...BUT LIKE WE HAVE BEEN SAYING...EXPECT TO
SEE SOME TYPE AND SOME AMOUNT OF WINTRY PRECIPITATION IN THE THE
SUNDAY/MONDAY TIMEFRAME. SO WILL RUN WITH THIS CONSIDERATION OF RAIN
OR SNOW IN THE GRIDS...AND ADD THE HIGHLIGHT FOR THE POTENTIAL OF
WINTER WEATHER ON MONDAY AS WELL AS SUNDAY.

IN FACT...NORTHERN COUNTIES COULD CONTINUE TO SEE FLAKES AS LATE AS
TUESDAY...SO WILL HAVE TO MONITOR FOR MORE WHITE STUFF.

Good grief!

Sunday: A chance of rain and snow. Mostly cloudy, with a high near 40. Chance of precipitation is 40%.

Sunday Night: A chance of rain and snow. Cloudy, with a low around 30. Chance of precipitation is 50%.

Monday: A chance of rain and snow. Cloudy, with a high near 40. Chance of precipitation is 40%.

Monday Night: A slight chance of rain and snow. Mostly cloudy, with a low around 28. Chance of precipitation is 20%.

Tuesday: A slight chance of rain and snow. Mostly cloudy, with a high near 42. Chance of precipitation is 20%.[/quote



This next shortwave that will come through the Deep South during the Sunday-Tuesday timeframe looks to be a very potent one indeed. It makes you wonder if the developing surface Low which will emerge out of the. Northern GOM will be stronger than what the current model guidance is depicting at this time.

[Brent]

7 inches of snow followed by ice on top of it?

[Stormcenter]

This is from the N.O. NWS afternoon discussion for 1/5/11

LONG TERM...
CUT-OFF LOW WEST OF THE SOUTHERN CALIFORNIA COAST HAS STOPPED
RETROGRADING AND SHOULD BECOMING PROGRESSIVE AS ONE SHORT-WAVE
ROUNDS THE BASE OF THE TROUGH TONIGHT AND THE PIN-WHEEL SYSTEM
STARTS FEELING THE AFFECTS OF STRONG SUB-TROPICAL FLOW ON THE
EQUATOR SIDE OF THE CIRCULATION. MODEL JET PROGS INDICATE
100-120KT JET MAX ON DOWNWIND SIDE OF THE CIRCULATION DEVELOPING
THURSDAY WHICH SHOULD MAINTAIN ABOUT A 40KT SYSTEM SPEED AROUND
30N LATITUDE. THIS WOULD PUT IT IN THE CENTRAL GULF STATES AREA ON
SUNDAY. GFS SHOWS A WELL DEVELOPED NORTH GULF LOW WITH THIS SYSTEM
PASSAGE WHICH KEEPS MUCH OF THE FORECAST AREA IN THE COLD SECTOR
AND MARGINAL CONDITIONS FOR WINTRY PRECIPITATION PROSPECTS MAINLY
IN SOUTHWEST MISSISSIPPI NORTHWARD DURING THE DAY SUNDAY. THE
ECMWF IS FARTHER NORTH WITH SIMILAR FEATURE AND SLOWER...COMING
THROUGH SUNDAY NIGHT. GIVEN THE PERFORMANCE OF ECMWF LATELY...AND
IN COORDINATION WITH KJAN...OPTED TO GO CLOSER TO ECMWF TIMING
WITH A SLIGHT HEDGE TO COMPROMISE ON LOCATION OF SURFACE
LOW...THEREBY LEANING TOWARDS A SLEET AND POSSIBLY FREEZING RAIN
POTENTIAL ONSETTING SUNDAY EVENING INTO THE OVERNIGHT HOURS BEFORE
ENDING MONDAY MORNING. GFS SOUNDINGS ARE MORE SUPPORTIVE OF A MORE
COMPLEX WEATHER PICTURE AT MCCOMB AREA WITH A COLD RAIN
TRANSITIONING TO WET SNOW ON WET-BULB EFFECT...THEN TRANSITIONING
TO SLEET FOR QUITE A WHILE BEFORE WARM LAYER ALOFT LOWERS DUE TO
LATENT HEAT RELEASE TO SHRINK THE SUB-FREEZING LAYER ENOUGH TO
REDUCE TO EITHER A VERY COLD RAIN OR A PERIOD OF FREEZING
RAIN...DEPENDING ON SURFACE TEMPERATURE AT THE TIME OF PRECIP. AT
THIS TIME...SHOWED DOMINANT WEATHER SUNDAY NIGHT TO BE SLEET BUT
THIS IS USUALLY NOT THE CASE...OFTEN WITH SOME TRANSITIONAL
PRECIPITATION INVOLVED DURING THESE DYNAMIC SYSTEM PASSAGES. IN
LOUISIANA AND MISSISSIPPI COASTAL COUNTIES...TEMPERATURE PROFILES
LOOK TO STAY ABOVE FREEZING THE ENTIRE TIME TO PRETTY MUCH
MAINTAIN A COLD RAIN PROCESS THAT MAY BREIFLY TURN OVER TO SLEET
FOR A VERY SHORT DURATION PRIOR TO PRECIPITATION ENDING. MODEL
TRENDS WILL HAVE TO BE WATCHED...PARTICULARLY FOR TIMING AND
DEGREE OF COLDNESS...BUT CAUSATIVE SYSTEM IS CLEARLY TRACKABLE ON
SATELLITE IMAGERY IN EASTERN PACIFIC. AFTER THIS EVENT...MODELS
SHOW SOME STEADY MODIFICATION THROUGH NEXT WEEK AND SEEM TO HAVE
BACKED OFF ON INTENSITY OF ARCTIC AIRMASS INDICATED IN THE DAY7-10
PERIOD...THOUGH PATTERN IS STILL INDICATED AND FAVORED...BUT
INTENSITY OF SURFACE SURGE WAS UNDERCUT BY ABOUT 10MB OVER NW
CANADA LATE NEXT WEEK. MORE ON THIS IN FUTURE DISCUSSIONS. 24/RR

[Brent]

Holy crap

[Ivanhater]

After confirming from those who have access to the Euro snow map. It indeed shows Snow from New Orleans to just east of Pensacola all across the Gulf coast!

[BigB0882]

Wow at the map Brent posted. Can we just bring down the snow all the way to the coast, please? I don't need 6+ inches, 2 or 3 will do!

[tugreenie]

i live along the 1-10 corridor on the MS coast. What are my snow possibilities?

[Ivanhater]

i live along the 1-10 corridor on the MS coast. What are my snow possibilities?

I can't post the 12z Euro snowfall map on here but I made a rough (and I do mean rough ) sketch of it in paint. On the Euro the snow makes it all the way to the Gulf coast including areas from New Orleans to just east of Pensacola.

[BigB0882]

I like the map Ivan, rough or not! If it puts snow in Baton Rouge then I will take it. lol

[sherry]

What is the outlook for North Carolina (piedmont area)? Is this going to be like the last storm where the mets called on 1 inch and then last minute change it to 6 inches? Is this one more predictable?

[Brent]

0z GFS major crippling ice/snow storm across MS/AL/GA and into the Carolinas(hard to tell but I think it's mostly ice on Monday).

[Ntxw]

GFS gives ATL nearly 3/4 inch liquid, which would be ice. Ice I-20 on either side left and right, north to the Tennessee border.

Edit: If this panned out it would be a devastating ice storm for Northern MS/AL/GA/Carolinas.

[MississippiWx]

Brent-

I'm an avid model watcher, but I'm a little uneducated when it comes to determining precip type on the models. I know that normally precip north of a 0 degree isotherm is snow, but I'm not seeing where you can tell this is an ice storm. I believe you because our NWS office in Jackson is giving us a 50% chance of freezing rain and sleet here on Sunday. Have a feeling the chances of that are going to go up after this 00z run of the GFS. Thanks for your input. I'm eagerly awaiting the morning discussions! Exciting times here in the Deep South!

[Ivanhater]

Brent-

I'm an avid model watcher, but I'm a little uneducated when it comes to determining precip type on the models. I know that normally precip north of a 0 degree isotherm is snow, but I'm not seeing where you can tell this is an ice storm. I believe you because our NWS office in Jackson is giving us a 50% chance of freezing rain and sleet here on Sunday. Have a feeling the chances of that are going to go up after this 00z run of the GFS. Thanks for your input. I'm eagerly awaiting the morning discussions! Exciting times here in the Deep South!

When the blue line at the surface is further south like in the first image than the blue line at 850mb(higher up in the atmosphere) that is ice.

[Ivanhater]

By the way..the GFS has been pretty consistent in showing another Deep South winter storm later in the period...they just keep coming

[MississippiWx]

Brent-

I'm an avid model watcher, but I'm a little uneducated when it comes to determining precip type on the models. I know that normally precip north of a 0 degree isotherm is snow, but I'm not seeing where you can tell this is an ice storm. I believe you because our NWS office in Jackson is giving us a 50% chance of freezing rain and sleet here on Sunday. Have a feeling the chances of that are going to go up after this 00z run of the GFS. Thanks for your input. I'm eagerly awaiting the morning discussions! Exciting times here in the Deep South!

When the blue line at the surface is further south like in the first image than the blue line at 850mb(higher up in the atmosphere) that is ice.

Ok, thanks!

Well, in that case, the GFS isn't showing any winter precip here in South MS. Hopefully, that will change and it will come more in line with the EURO.