Deep South Winterwx Discussion 2015-2016

[Brent]

My guess is it will be too warm for significant snow on Saturday on the coast, but it bears watching, maybe a few flakes mixed in with rain at the end.

As for the Monday/Tuesday storm, all options still on the table. The models are all over the map today. Could be a blizzard or a cold rain, who knows.

[Stormcenter]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
341 PM CST THU FEB 25 2010

.SHORT TERM...

A VIGOROUS SHORT WAVE TROUGH WILL DESCEND FROM THE PLAINS STATES
INTO THE GULF SOUTH STARTING TOMORROW INTO SATURDAY. THIS CLIPPER
LIKE SYSTEM WILL BRING INCREASING CLOUD COVER THE AREA TONIGHT.
A DECENT COLD POOL WILL ALSO REMAIN IN PLACE ACROSS THE REGION
TONIGHT AS A DEEP LONG WAVE TROUGH DOMINATES THE EASTERN THIRD
NATION. AS THE SHORT WAVE DIVES INTO TEXAS A REGION OF ENHANCED
LIFT ON THE LEE SIDE OF THE UPPER LEVEL TROUGH ALONG WITH A STRONG
THERMAL GRADIENT ACROSS TEXAS WILL ALLOW FOR A DEVELOPMENT OF
SURFACE LOW LATE TONIGHT INTO EARLY TOMORROW. THIS LOW WILL TRACK
TO THE SOUTHEAST THROUGHOUT TOMORROW...ALLOWING FOR SOUTHEAST
WINDS AND AN ONSHORE FLOW TO SET UP ACROSS THE CWA. STRONG LOW
LEVEL MOISTURE ADVECTION WILL TAKE PLACE TONIGHT INTO TOMORROW
MORNING...WITH SHOWERS DEVELOPING BY THE AFTERNOON ACROSS THE
FORECAST AREA. THESE SHOWERS WILL BE DRIVEN BY A REGION OF
ENHANCED PVA AND LIFT ACROSS THE GULF SOUTH.

HEADING INTO TOMORROW NIGHT...THE SHORT WAVE TROUGH WILL SWING
THROUGH THE GULF SOUTH...WITH THE SURFACE LOW TRACKING ACROSS THE
NORTHERN GULF OF MEXICO. INITIALLY...RAIN IS EXPECTED ACROSS THE
FORECAST AREA...BUT A CHANGE OVER TO A WINTRY MIX OF
RAIN...SLEET...AND SNOW IS EXPECTED AFTER MIDNIGHT OVER THE
NORTHERN HALF OF THE CWA. AFTER REVIEWING MODEL SOUNDINGS A DEEP
COLD POOL ASSOCIATED WITH THE MAIN UPPER LEVEL SYSTEM WILL TRACK
ACROSS THE REGION. THIS WILL DROP THE TEMPERATURES ALOFT INTO A
FAVORABLE RANGE FOR SNOW FORMATION. IN ADDITION...THE LOW LEVELS
WILL SEE SOME COLD AIR ADVECTION TAKE HOLD ON THE BACK SIDE OF THE
LOW. THIS COLDER AIRMASS WILL ALLOW FOR A QUICK CHANGE OVER TO
SNOW AND SLEET OVER SOUTHWEST MISSISSIPPI AND FAR NORTHERN
SECTIONS OF THE FLORIDA PARISHES. ALONG THE I-12 CORRIDOR...A MIX
OF RAIN AND SNOW IS EXPECTED. FOR AREAS SOUTH OF
I-12...TEMPERATURES WILL BE FAR TOO WARM FOR ANY WINTRY
PRECIPITATION. FORTUNATELY...ALL OF THE PRECIPITATION WILL BE
LIGHT...WITH LITTLE IF ANY ACCUMULATION EXPECTED OVER NORTHERN
ZONES. THE MIX SHOULD COME TO AN END BY NOON...AS STRONG NEGATIVE
VORTICITY ADVECTION AND SUBSIDENCE TAKES HOLD. DEEP LAYER
RIDGING WILL DOMINATE THE AREA ON SUNDAY...WITH CLEAR SKIES AND
COOLER THAN NORMAL TEMPERATURES EXPECTED.

.LONG TERM...

THE DEEP LAYER RIDGING WILL QUICKLY SLIDE TO THE EAST SUNDAY
NIGHT...AS ANOTHER STRONG UPPER LEVEL LOW MOVES INTO THE SOUTHERN
PLAINS. STRONG ASCENT ON THE SOUTHEAST SIDE OF THE SYSTEM IN A
REGION OF ENHANCED DIFLUENCE...COMBINED WITH A SHARP THERMAL
GRADIENT OVER THE WESTERN GULF OF MEXICO WILL ALLOW FOR A VERY
STRONG GULF LOW TO FORM IN THE WESTERN GULF SUNDAY NIGHT. AT THE
SAME TIME...A POOL OF COLD AIR WILL REMAIN ACROSS THE FORECAST
AREA. INCREASING CLOUD COVER IS EXPECTED SUNDAY NIGHT AS THE
STRONG UPPER LEVEL LOW APPROACHES FROM THE WEST AND SOUTHWEST FLOW
IN THE MID-LEVELS RIDES UP AND OVER A MORE STABLE AND COLDER
AIRMASS AT THE SURFACE. WITH STRONG ISENTROPIC FORCING IN THE MID-
LEVELS AND HIGH OMEGA VALUES ALOFT...EXPECT RAIN TO OVERSPREAD THE
ENTIRE FORECAST AREA ON MONDAY. THIS BROAD PRECIP FIELD WILL
CONTINUE INTO MONDAY NIGHT AS THE LOW TRACKS THROUGH THE NORTHERN
GULF OF MEXICO AND BEGINS TO DEEPEN RAPIDLY OVER THE NORTHEAST
GULF AND THE SOUTHEASTERN ATLANTIC SEABOARD. AS THE LOW
DEEPENS...COLDER AIR WILL BE DRAWN SOUTH INTO THE REGION LATE
MONDAY NIGHT INTO EARLY TUESDAY MORNING. ADDITIONALLY...THE MAIN
COLD POOL ASSOCIATED WITH THE UPPER LEVEL LOW WILL BE PASSING
THROUGH. IT APPEARS THAT A CHANGE OVER TO WINTRY PRECIP COULD TAKE
PLACE MONDAY NIGHT INTO TUESDAY. IT IS FAR TOO EARLY TO DETERMINE
THE EXACT TIMING AND TYPE OF PRECIP ALONG WITH ANY ACCUMULATION
AMOUNTS. THIS NEXT SYSTEM WILL HAVE TO BE MONITORED CAREFULLY
THROUGH THE WEEKEND.
STRONG SUBSIDENCE AND DRY AIR ADVECTION WILL TAKE HOLD OF THE CWA
TUESDAY NIGHT WITH RAPIDLY CLEARING SKIES AND COLD TEMPERATURES
EXPECTED. COLDER THAN NORMAL READINGS AND DRY CONDITIONS WILL
THROUGH THE END OF THE WEEK AS UPPER LEVEL RIDGING REMAINS OVER
THE AREA.

&&

[Ivanhater]

18z GFS Snowfall map...check it out North Central Gulfcoast!

[Lane]

It looks like in this run, the low moves much farther north. If this were to pan out, does that mean the snow line moves farther north as well?

[Ntxw]

If that were to pan out, there would be a lot of snow in the deep south.

[attallaman]

18z GFS Snowfall map...check it out North Central Gulfcoast!

Does that map show up to 1" of snow along the MS Gulf Coast over into AL? A NOLA TV met was posting on Twitter that my area could possible see snow this weekend, no accumulation.

[Brent]

It looks like in this run, the low moves much farther north. If this were to pan out, does that mean the snow line moves farther north as well?

That model is a HUGE hit for the deep south, it's showing about 8 inches of snow here. It's the best model for snow for us.

I'm still very uncertain what will happen Tuesday, the models today have been a mess. I'm hoping the GFS will come north soon, the others range from pretty good to awesome for snow, but it is still 4 days away.

[Ivanhater]

[Brent]

GFS COMES AROUND!

[Ivanhater]

00z GFS

[Lane]

[Brent]

Euro is an epic storm, PHASE:

[Ivanhater]

06z GFS

[srainhoutx]

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
733 AM EST FRI FEB 26 2010

VALID 12Z TUE MAR 02 2010 - 12Z FRI MAR 05 2010

...WINTER CONTINUES WITH ANOTHER SNOW THREAT ACROSS THE INTERIOR
SOUTHEAST AND LOWER MID ALANTIC NEXT WEEK WITH AN ADDITIONAL
WIDESPREAD SNOW THREAT FROM THE SIERRAS INTO THE ROCKIES AND
REACHING THE CENTRAL PLAINS LATE NEXT WEEK...

MEDIUM RANGE GUIDANCE MAINTAINS A FAIRLY ENERGETIC PATTERN WITH
BUNDLES OF ERN PAC TROF ENERGY SEPARATING NEAR THE WEST COAST AS
THEY RUN INTO A PERSISTENT MEAN RIDGE OVER CANADA AND W-CNTRL
CONUS. THE LEADING SRN STREAM SYSTEM OF INTEREST IS FCST TO
TRAVEL FROM THE SRN PLAINS/WRN GULF COAST TO JUST OFF THE EAST
COAST IN THE MON-WED TIME FRAME. WHILE THERE IS SOME SPREAD WITH
THIS FEATURE... THE 00Z GFS AND GEFS MEAN ARE ON THE PROGRESSIVE
SIDE OF THE SPECTRUM WITH THE ECMWF/CMC/UKMET/NOGAPS AND 12Z ECMWF
ENSEMBLE MEAN ALL HOLDING THE SYSTEM CLOSER TO THE COAST BY LATE
DAY 5 WED. THIS SLOWER/WRN CLUSTER IS LIKELY BEST IN LIGHT OF THE
TENDENCY THIS SEASON FOR MODELS TO VERIFY TOO FAR SEWD SEVERAL
DAYS IN ADVANCE. ONE SIGNIFICANT WILD CARD IN THE EVOLUTION OF
THIS SYSTEM IS A BUNDLE OF ENERGY EXPECTED TO TRACK SEWD FROM THE
UPR MS VALLEY MON ONWARD. THUS FAR GUIDANCE HAS NOT BEEN
EXTREMELY AGREEABLE AMONG EACH OTHER AND COMPARED TO SUCCESSIVE
RUNS... BUT AT THE VERY LEAST THE LATEST ENSEMBLE GUIDANCE OFFERS
MORE SUPPORT FOR THE 00Z ECMWF WITH THIS FEATURE VERSUS THE
SLOW/DEEP OUTLIER SOLN OF THE 00Z GFS. MEANWHILE THE GFS/GEFS
MEAN MAY ALSO BE A LITTLE TOO FAST IN BRINGING THE NEXT ERN PAC
TROF TO THE WEST COAST DURING THE FIRST HALF OF NEXT WEEK. THE
GFS/ECMWF ACHIEVE SIMILAR TIMING BY DAY 6 THU THOUGH... AND BY DAY
7 FRI THERE IS MODERATE AGREEMENT UPON A WAVE REACHING THE SRN
PLAINS. FINALLY THE 00Z GFS IS ON THE SRN EDGE OF THE SOLN
ENVELOPE WITH THE CORE OF MID LVL ENERGY AND ASSOC SFC LOW NEARING
THE WEST COAST LATE NEXT WEEK BUT LATEST ENSEMBLE MEANS INDICATE
THE DAY 7 TROF ALOFT MAY BE A LITTLE MORE AMPLIFIED THAN THE 00Z
ECMWF. OVERALL BETTER COMPARISON TO THE FULL RANGE OF GUIDANCE
FAVORS USE OF A 50/50 BLEND OF THE 00Z ECMWFAND GFS AS THE
STARTING POINT FOR THE DAYS 3-7 FCST AN INCREASING PERCENTAGE OF
00Z ECMWF ENS MEAN CONCURRED BY USE OF GFS/EC LAGGED AVERAGE
FORECASTS.

THE SHORTWAVE WITH A STRONG NEG HT ANOMALY MOVING ACROSS TX AND
THE GULF COAST WILL INDUCE HVY RAINS ALONG THE GULF COAST MON AND
TUES AND EWD ACROSS FL INTO GA AND SC. DEEP TROF WITH WELL BELOW
NORMAL HTS/MID/LOW LEVEL TEMPS APPEAR LIKELY TO BRING SNOW ACROSS
THE NRN EDGE OF THE PCPN SHIELD ACROSS NRN AL/GA/SRN AND ERN TN.
AS THE TROF TAKES A MORE NEG TILTED ORIENTATION HEAVIER SNOW FALL
IS POSSIBLE ACROSS THE MTNS OF SC/NC/SWRN VA AND SRN WV. HVY
COASTAL RAINS AND ONSHORE GALE FORCE WINDS WITH HIGH SURF AND
BEACH EROSION/COASTAL FLOODING THREAT CAN BE EXPECTED TUES INTO
THURSDAY ALONG THE SOUTHEASTERN SEABOARD. AS THE MOVES UP EWD
ALONG THE COAST LOW DEEPENS LOWERING 1000-500 MB THICKNESS VALUES
AND H850 TEMPS IMPLY A SIG SNOW VERY POSSIBLY HVY SNOW THREAT FROM
THE NC MTNS AND FOOTHILLS INTO THE PIEDMONT AND NEWD INTO THE
LOWER VA PIEDMONT/TIDEWATER AREAS OF VA AND POSSIBLY LOWER SRN MD
AND LOWER DELMARVA. STRONG N-NE WINDS WILL EXTEND WELL FROM THE
MID ATLC REGION NWD ALONG THE NEW ENG COAST. DETAILS OF PCPN
TYPE/AMOUNTS AND COVERAGE WILL BECOME BETTER DEFINED AS THE EVENT
CLOSES TO WITHIN A 72 HR OR LESS TIMEFRAME.

WESTWARD...NEXT MID LEVEL COLD PAC TROF AND FRONT WILL COME INTO
THE PAC NORTHWEST AND
CA COAST TUES BRINGING MDT/HVY RAINS WITH SNOW AT HIGHER
ELEVATIONS. THE PCPN WILL EXTEND WELL INLAND BY WED AND THURS INTO
ROCKIES MAINLY AS SNOW FROM MT SWD TO NRN AZ AND NM. AS THIS
SHORTWAVE MOVES OUT INTO THE SRN HIGH PLAINS MID TO LATE WEEK
ADDITIONAL RAINFALL WILL BREAK OUT ACROSS THE SRN PLAINS WITH
INCREASING LOW LEVEL UPSLOPE GLFMEX INFLOW. A SIGNIFICANT SNOW
THREAT EWD FROM THE CO PLAINS INTO KS AND MO.
RAUSCH/ROSENSTEIN

[Lane]

Can someone translate this please? What does the "wild card" mean for snow?


ONE SIGNIFICANT WILD CARD IN THE EVOLUTION OF
THIS SYSTEM IS A BUNDLE OF ENERGY EXPECTED TO TRACK SEWD FROM THE
UPR MS VALLEY MON ONWARD. THUS FAR GUIDANCE HAS NOT BEEN
EXTREMELY AGREEABLE AMONG EACH OTHER AND COMPARED TO SUCCESSIVE
RUNS... BUT AT THE VERY LEAST THE LATEST ENSEMBLE GUIDANCE OFFERS
MORE SUPPORT FOR THE 00Z ECMWF WITH THIS FEATURE VERSUS THE
SLOW/DEEP OUTLIER SOLN OF THE 00Z GFS. MEANWHILE THE GFS/GEFS
MEAN MAY ALSO BE A LITTLE TOO FAST IN BRINGING THE NEXT ERN PAC
TROF TO THE WEST COAST DURING THE FIRST HALF OF NEXT WEEK.

[Ivanhater]

12z GFS...been consistent in bringing snow to the Gulfcoast..

[Brent]

Can someone translate this please? What does the "wild card" mean for snow?


ONE SIGNIFICANT WILD CARD IN THE EVOLUTION OF
THIS SYSTEM IS A BUNDLE OF ENERGY EXPECTED TO TRACK SEWD FROM THE
UPR MS VALLEY MON ONWARD. THUS FAR GUIDANCE HAS NOT BEEN
EXTREMELY AGREEABLE AMONG EACH OTHER AND COMPARED TO SUCCESSIVE
RUNS... BUT AT THE VERY LEAST THE LATEST ENSEMBLE GUIDANCE OFFERS
MORE SUPPORT FOR THE 00Z ECMWF WITH THIS FEATURE VERSUS THE
SLOW/DEEP OUTLIER SOLN OF THE 00Z GFS. MEANWHILE THE GFS/GEFS
MEAN MAY ALSO BE A LITTLE TOO FAST IN BRINGING THE NEXT ERN PAC
TROF TO THE WEST COAST DURING THE FIRST HALF OF NEXT WEEK.

There is a lot of wild cards with this storm, if it phases too early, it goes too far north and we get rain vs. snow.

My biggest concern with this storm remains warm air, not limited moisture.

[Lane]

That is my concern now as well; looks like the moisture will be here. But will the temperatures be cold enough.

[Brent]

It's certainly gonna be close, this from Atlanta just now:

.LONG TERM /MONDAY THROUGH FRIDAY/...
THE GFS AND ECMWF DEPICT THE SYSTEM MOVING ONSHORE ON THE WEST COAST
QUITE WELL AND PUSH IT EASTWARD MOVING INTO THE SOUTHERN PLAINS
SUNDAY NIGHT AND INTO THE SOUTHEAST U.S. MONDAY. AS IT MOVES INTO
THE SOUTHEAST IT WILL DEEPEN A TROUGH OVER THE EASTERN U.S. BRINGING
ANOTHER SURGE OF COLD AIR. THE SURFACE LOW STAYS SOUTH OF
GEORGIA...CROSSING NORTH FLORIDA MONDAY NIGHT/EARLY TUESDAY...AND TO
THE NORTH CAROLINA COAST BY TUESDAY NIGHT. PRECIP WILL SPREAD INTO
THE CWA MONDAY NIGHT AND TUESDAY. IT WILL BE COLD ENOUGH FOR SOME
ACCUMULATING SNOW TO FALL ACROSS MUCH OF THE WESTERN AND NORTHERN
PART OF THE CWA TUESDAY. THE SYSTEM PULLS OUT TUESDAY NIGHT AND
WEDNESDAY ALTHOUGH THERE APPEARS TO BE ENOUGH MOISTURE FOR SOME
RESIDUAL FLURRIES ACROSS NORTH GEORGIA WEDNESDAY. CURRENT MAX TEMPS
ON TUESDAY AND WEDNESDAY MAY BE TOO WARM BUT AT THIS POINT DO NOT
WANT TO GET INTO A FLIP FLOP SITUATION IN CASE THE NEXT RUNS COME IN
WARMER. CURRENT FORECAST IS HANDLING THE SITUATION WELL AND WILL NOT
MAKE ANY CHANGES.

[wxman57]

12z GFS...been consistent in bringing snow to the Gulfcoast..

http://www.twisterdata.com/data/models/ ... URFACE.png

http://www.twisterdata.com/data/models/ ... URFACE.png

Those charts look MIGHTY suspicious as far as snow on the Gulf Coast from MS to FL Panhandle, even north of the FL Panhandle into southern Alabama. Look at the accumulation chart THEN look at the same model's sounding for when the snow is supposed to be falling. The soundings show a layer of warm air a few thousand feet thick at the surface in those areas. That would mean cold rain, not snow. GFS was forecasting a similar 1" (or more) snow with Tuesday's system and the actual accumulation area was north of the 1" projected area.