DEEP SOUTH SNEAUX 1/9/11-1/11/11

[ROLLTIDE]

Good one from Jackson,MS NWS

LONG TERM...THERE WILL BE TWO MAIN FORECAST ELEMENTS TO FOCUS ON
IN THE LONG TERM. FIRST WILL BE THE SYSTEM FOR EARLY SUN INTO SUN
NIGHT AND THE POTENTIAL FOR SNOW OR LOCALLY HEAVY RAIN. SECOND WILL
BE ON TEMPS AS A SOUTHWARD PUSH OF ARCTIC AIR LOOKS TO ARRIVE BY TUE
AND POTENTIALLY BRING SOME OF THE COLDEST AIR OF THE SEASON. I
MENTION THESE AS THE PRIMARY FOCUS OF THE FORECAST...BUT MUCH
UNCERTAINTY EXISTS FOR ANY OF THIS TO OCCUR...ESPECIALLY THE SNOW.

FOR THE LATE WEEKEND SYSTEM...I WOULD HAVE TO SAY THAT THE GLOBAL
MODEL OUTPUT IS NOT TOO BAD FOR OUR AREA. THE REASON IS THEY ALL
SHOW A SYSTEM MOVING THROUGH AND BRINGING PRECIP TO THE AREA FROM
EARLY SUN-SUN NIGHT. THE DIFFERENCES COME IN THE DETAILS AND THE
TRACK/INTENSITY OF THE UPPER S/WV AND SFC LOW. IN THIS CASE...SMALL
DIFFERENCES IN 50 TO 150 MILES WILL HAVE HUGE IMPACTS ON PRECIP TYPE
AND OVERALL IMPACT TO THE FORECAST AREA. THE RECENT TRENDS FROM THE
GEM/EURO ARE FOR A POTENT UPPER SYSTEM AND FAIRLY STRONG SFC LOW
WITH THE TRACK OF THE SFC LOW FURTHER NORTH NOW AND MORE OF THE CWA
TOO WARM FOR SNOW. THE EXCEPTION WITH THESE MODELS WOULD BE ACROSS
THE FAR NW DELTA WHERE IT REMAINS COLD ENOUGH FOR SNOW OR SOME SORT
OF MIX. AS FOR THE GFS...THE 00Z RUN HAS TRENDED A TAD COLDER...MORE
TOWARD THE PREV EURO...AND OFFERS MORE SNOW/MIX PRECIP POTENTIAL FOR
A GREATER PORTION OF THE CWA. AS YOU CAN SEE...SMALL DIFFERENCES
WILL PLAY A MAJOR ROLE IN PRECIP TYPE AND LOCATION.
ADDITIONALLY...THE S/WV (UPPER LOW) RESPONSIBLE FOR THIS POTENTIAL
IS STILL OFF THE COAST OF SW CA AND LOCATED UNDER A UPPER RIDGE
AXIS. WITH THIS SYSTEM STILL OUT OF THE OBS NETWORK...THERE REMAINS
MULTIPLE SCENARIOS AND MUCH UNCERTAINTY IN JUST HOW THE FEATURE WILL
EVOLVE AS IT MOVES INTO THE WEST AND PUSHES EAST OVER THE NEXT 60-90
HRS.

AN IMPORTANT THING TO MENTION IS HOW ALL THE GUID AT THIS POINT
SHOWS FAIRLY STRONG AGREEMENT ON LIQUID EQUIVALENT TOTALS BETWEEN
1-2 INCHES. THAT IS A DECENT AMOUNT OF RAIN JUST FALLING AS
LIQUID...ESPECIALLY AFTER A GOOD PORTION OF THE CWA RECEIVED 2-4
INCHES LAST WEEKEND. THUS THE POTENTIAL FOR LOCALLY HEAVY RAIN. THE
BIG PROBLEM WILL BE IF SOME OR ALL OF THIS LIQUID WOULD FALL AS SNOW
OR SOME SORT OF MIX. IF SO...THEN A MAJOR WINTER STORM WOULD BE IN
ORDER WITH SNOW TOTALS OF 5-15 INCHES AND SLEET/ICE ACCUMS OF .5 TO
1 INCH. FOR THE WINTRY STUFF TO OCCUR THE COLDER SOLUTIONS WOULD
HAVE TO PAN OUT AND BASED OFF THE MOST RECENT MODEL RUNS...THIS RISK
IS STILL ON THE LOW SIDE BUT DEFINITELY POSSIBLE. HOWEVER...IT WOULD
NOT TAKE MUCH OF A SWING TO THE COLDER SIDE TO MAKE THAT RISK MUCH
HIGHER.

AS FOR NOW...I WILL STAY CONSERVATIVE AND LEAN TO MORE OF THE
CONSENSUS AND STAY WITH THE SLIGHTLY WARMER SOLUTIONS. I WILL
CONTINUE TO MENTION RAIN OR SNOW OR SLEET FOR MOSTLY THE N HALF
WHERE THE POTENTIAL IS A BIT HIGHER FOR WINTRY PRECIP TO BE REALIZED
IN THOSE LOCATIONS. AS FOR POPS...GUID VALUES LOOKED GOOD AND ONLY
SOME SMALL ADJ WERE MADE. THESE NEW POPS ARE A DECENT INCREASE TO
THE PREV FORECAST...ESPECIALLY FOR THE SUN-SUN NIGHT PERIODS. TEMPS
ARE TOUGH AND STAYED PRETTY CLOSE TO GUID. GUID VALUES LOOK GOOD ON
SAT...BUT OPTED TO RAISE SAT NIGHT SOME AND STAY CLOSE TO THE
ENSEMBLE MEAN AS THE MAJORITY OF THE OPS GUID AND ENSEMBLE MEMBERS
FAVORED THE WARMER LOWS. AS FOR SUN HIGHS...GUID VALUES WERE USED
WITH THE EXCEPTION BEING ACROSS THE NW WHERE COOLER READINGS ARE
EXPECTED.

ONE IMPORTANT THING ON DEALING WITH THE FORECAST FOR THIS SYSTEM
IS...EXPECT CHANGES! THE POTENTIAL EXISTS FOR SOME SORT OF BIG
WINTER WEATHER EVENT. HOWEVER...IT IS VERY CLOSE TO BEING JUST RAIN
AND NOT A MAJOR DEAL. FORECASTS SHOULD BE MONITORED OVER THE COMING
DAYS AS I AM SURE CHANGES WILL BE IN STORE.

AS FOR THE SECOND FORECAST ELEMENT OF CONCERN...COLD TEMPS FROM
TUE-THU. THE NICE THING ABOUT THIS IS...MODELS ARE IN DECENT
AGREEMENT ON BUILDING VERY COLD AIR OVER CANADA AND PUSHING IT SOUTH
FOR MID WEEK. JUST HOW MUCH OF THE CORE OF THIS AIRMASS GETS
DELIVERED SOUTH WILL DETERMINE HOW COLD WE WILL ULTIMATELY GET...BUT
INDICATIONS ARE THAT WE WILL BE QUITE CHILLY AND HAVE THE POTENTIAL
TO SEE THE COLDEST CONDITIONS OF THE SEASON. OVERALL...HIGH TEMPS
FOR THIS PERIOD WERE TRIMMED COLDER WITH ONLY SOME SMALL ADJ TO LOWS
FOR WED-THU. AT THIS TIME...DO NOT WANT TO GET TOO AGGRESSIVE AND
WOULD LIKE TO SEE THE MODELS REALLY PUSH THE CORE OF THE COLD INTO
THE REGION BEFORE JUMPING ON THE TEENS FOR LOWS AND STAYING BELOW
FREEZING FOR HIGHS. STAY TUNED FOR WHAT LOOKS TO BE A RETURN TO
WINTER FOR THE SOUTH. /CME/

[ROLLTIDE]

[Joe-Nathan]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
521 AM CST THU JAN 6 2011

OUTLOOK...
THE EUROPEAN MEDIAN RANGE FORECAST MODEL AND THE GFS MODEL ARE IN
BETTER AGREEMENT ON THE 00 UTC CYCLE RUN...DEPICTING THE BIG BEND
LOW EXITING THE MIDDLE TEXAS COASTAL WATERS BY EARLY MORNING SUNDAY.

MUCH COLDER AIR WILL SPILL THROUGH THE FORECAST AREA FOR MONDAY
THROUGH THURSDAY.

THE FIRST PROBLEM ENCOUNTERED IS THE POSSIBILITY OF LIGHT FREEZING RAIN
BY EARLY MORNING MONDAY...ACROSS THE PINEY HILLS AND LAKES REGION.
THE GFS DEPICTS NO ACCUMULATION.

THE SECOND PROBLEM ENCOUNTERED IS THE POSSIBILITY OF THE RETURN OF
FREEZING RAIN BY EARLY MORNING THURSDAY...ONCE AGAIN ACROSS THE
PINEY HILLS AND LAKES REGION. THE GFS DEPICTS SOME ICE ACCUMULATION.

[ROLLTIDE]

...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
1008 AM EST THU JAN 6 2011

.DISCUSSION...
AWIPS PROBLEMS SOLVED AND MRX TAKING BACK FORECASTING FROM OHX AT
THIS TIME. WILL UPDATE MORNING PACKAGE AND TURN ATTENTION TOWARD
WINTER WEATHER POTENTIAL WITH SYSTEM LATE TONIGHT INTO SATURDAY.
MODEL SOUNDINGS LOOK QUITE COLD FOR FRIDAY AND SUPPORT GOOD SNOW
CRYSTAL GROWTH...SO MAY NEED WINTER WEATHER ADVISORIES AS FAR SOUTH
AS CHA AREA...WITH POTENTIAL FOR WARNING AMOUNTS OF SNOW OVER PARTS
OF SW VA AND OUR EASTERN MTNS...AS UPSLOPE SNOW SHOWERS LINGER INTO
SATURDAY.

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[ROLLTIDE]

12Z GFS run

http://wxcaster.com/gis-gfs-snow-ove...?STATIONID=MOB

[Joe-Nathan]

FROM KLFY TV10 Wx BLOG:

Wet Weather This Weekend…

We’re tracking a large, spinning area of low pressure in the mid to upper levels of the atmosphere over the Pacific Ocean, off the coast of California. This disturbance will take a track across Northern Mexico, then across the Deep South thru the weekend. As the energy aloft nears the Gulf of Mexico, a surface low pressure system will begin forming over South Texas/Northern Mexico, then really deepen over the Western Gulf. At this point, the actual surface low looks to track over the Gulf waters, keeping a cool northeast wind blowing across South Louisiana as a soaking rainfall begins Saturday night and lasts well into Sunday.



In this scenario, we may only see temps in the 40s Sunday. If the surface low moves inland, then we could jump well into the 60s. We’ll keep tracking this system but bottom line: wet weather looks to be a near certainty for the weekend.

What looks far from certain is getting some wintry precip in the area later next week. The latest couple runs of the GFS model bring the cold air in for the middle of next week, but then produce a low pressure system across the Central US for the end of the week, allowing us to warm up. A second blast of cold air moves into the US for the following weekend, but may stay to the north of us. So, as we’ve been stating, there is much uncertainty regarding the evolution of next week’s Arctic invasion. It’s always fun to think about snow 10 days out when the models are showing such an event, but reality is oftentimes much different. The latest model runs show no chance of snow for us. We’ll keep you posted!

By David Paul, January 5, 2011, 7:03 pm o'clock

[Joe-Nathan]

FROM TwisterData: Monday Morning Jan 10ish

[Joe-Nathan]

LOOK AT THE SNOW COVER FOR THE 12th: hello GA MTN!!!

The south LA duck hunter in me really likes this kind of snow coverage!

[ROLLTIDE]

If you want snow make the drive to Memphis,TN

LATE SATURDAY NIGHT INTO MONDAY...A DEVELOPING LOW PRESSURE SYSTEM
WILL TRACK SOMEWHERE NEAR THE GULF COAST INTO THE SOUTHEAST UNITED
STATES. MODELS HAVE COME INTO CLOSER AGREEMENT WITH THE TRACK AND
TIMING BUT THERE ARE STILL MINOR DIFFERENCES WHICH COULD PLAY A HUGE
ROLE IN WHERE AND HOW MUCH. THE 00Z GFS IS THE FURTHEST SOUTH WITH
THE SFC LOW OF THE MODELS...TRACKING THE LOW JUST SOUTH OF THE GULF
COAST BUT IS FARTHER NORTH THAN LAST NIGHTS RUN. THE MAJOR
DIFFERENCE BETWEEN THE ECMWF/CANADIAN AND THE GFS IS THAT BOTH THE
00Z ECMWF AND 00Z CANADIAN CLOSE OFF A 500 MB LOW AND TRACK IT
OVER THE MIDSOUTH. THE GFS IS JUST A 500MB WAVE. THE GFS KEEPS BULK OF
THE PRECIPITATION TO THE SOUTH WITH NORTH MISSISSIPPI HAVING THE
BEST CHANCE OF SEEING WINTER WEATHER. HOWEVER IF A 500MB LOW WERE
TO DEVELOP...IT COULD ENHANCE SNOWFALL WHERE IT TRACKS. THE
CANADIAN AND ECMWF SEEM TO BE CONSISTENT WITH A CLOSED 500 MB LOW
DEVELOPING. THE BIG DIFFERENCE BETWEEN THOSE TWO MODELS IS THAT
THE CANADIAN SEEMS TO BE A TAD FARTHER NORTH THAN THE ECMWF WITH
THE SFC LOW TRACK. IF THE CANADIAN IS RIGHT...PRECIP TYPE ISSUES
COULD OCCUR ACROSS THE SOUTHERN PORTIONS OF THE CWA AS SLIGHTLY
WARMER AIR MOVES IN AHEAD OF THE SFC LOW. HOWEVER MOST OF THE CWA
WOULD STAY ENTRENCHED IN THE ARCTIC AIR...KEEPING PRECIP TYPE ALL
SNOW. BOTH MODELS SEEM TO INDICATE THAT SIGNIFICANT SNOWFALL COULD
OCCUR ACROSS THE CWA. A LOT WILL DEPEND WHERE THE DEFORMATION ZONE
SETS UP AND WHERE THE 500 MB LOW TRACKS. LOOKING AT THE LATEST
ECMWF AND CANADIAN...THE MEMPHIS METRO AREA MAY HAVE A BETTER CHANCE AT
SEEING ACCUMULATING SNOW THAN NORTH MISSISSIPPI WHICH THE GFS
SHOWS. WITH THAT BEING SAID...WE ARE STILL A LONG WAY OUT AND
MODELS COULD STILL CHANGE. FOR THIS FORECAST WILL LEAN TOWARD THE
00Z ECMWF AS IT IS THE SOLUTION IN THE MIDDLE. PRECIPITATION
SHOULD BEGIN TO SPREAD IN FROM THE SOUTH LATE SATURDAY NIGHT WITH
THE BULK OF THE PRECIPITATION OCCURRING SUNDAY NIGHT INTO EARLY
MONDAY.

MONDAY NIGHT INTO TUESDAY...A COUPLE OF SHORTWAVES WILL CONTINUE TO
PRODUCE SNOW SHOWERS OVER THE AREA. LITTLE TO NO ACCUMULATIONS ARE
EXPECTED WITH THE SNOW SHOWERS. WITH SNOW COVER ON THE GROUND IN
MANY PLACES...TEMPERATURES WILL BE VERY COLD ON TUESDAY. HIGHS
WILL ONLY BE IN THE UPPER 20S TO MID 30S.

TUESDAY NIGHT INTO WEDNESDAY...ARCTIC HIGH PRESSURE WILL GRADUALLY
BUILD INTO THE MIDSOUTH. THE 00Z GFS IS QUICKER AT MOVING THE HIGH IN
THAN THE ECMWF THUS IF THE ECMWF IS CORRECT FLURRIES COULD
CONTINUE INTO TUESDAY NIGHT POSSIBLY INTO WEDNESDAY.
REGARDLESS...TEMPERATURES WILL REMAIN FRIGID. LOWS WILL NOT BE AS
LOW AS THEY COULD BE THANKS TO CLOUD COVER. READINGS WILL BE IN
THE UPPER TEENS TO MID 20S. HIGHS WILL REMAIN IN THE UPPER 20S TO
LOWER 30S.

[ROLLTIDE]

Tim C

Quick wintry update – 1050 am

Dr. Tim Coleman | 10:57 am January 6, 2011 | Comments (26)
…Large uncertainty with possible winter storm Sunday and Monday…
…Ice storm possible…

(500 mb height, wind, and vorticity)

Cold, dry air will start moving into Alabama at low levels Saturday afternoon, as north winds pick up. Temperatures by Sunday morning will likely be in the mid to upper 20s in central Alabama. At the same time, an upper-level storm will move out of the SW US into Texas by Sunday morning.
As this upper-level storm approaches the Gulf Coast, a low pressure area will form somewhere in Louisiana or off the Louisiana Coast Sunday, depending on how far south the cold air pushes Saturday night and Sunday morning. This low pressure area will then move along or near the Gulf Coast Sunday night and Monday.
Precipitation is not a question with this system. It will begin to move into west Alabama Sunday, and overspread the state by Sunday night. As a matter of fact, the precipitation may be heavy, with 0.5 to 1 inch of water equivalent falling. The key to what type of precipitation falls will be the thermal profiles in the atmosphere Sunday night and Monday. Generally, the farther south the low tracks, the colder the air is in central Alabama, since we don’t get any southerly flow ahead of it if it stays near or off the coast.
For snow to form aloft, the temperature in the precipitation formation region usually needs to be 23 degrees F or colder, ideally around 14 F. Clouds are made of water droplets even at temperatures in the teens aloft, and most of these don’t start to freeze until they drop to near 20 degrees. However, once a snowflake forms, any cloud water droplets it comes in contact with will freeze onto it, making it bigger. Bottom line…if it is too warm aloft, even if it is a little below freezing, precip can fall to the ground as rain.
The worst case scenario is that southerly flow at mid-levels, or 4,000 to 10,000 feet) brings in enough warm air there to keep temperatures too warm for snow formation. Then, the precipitation would fall mainly as rain. But, if there is enough cold, dry air at the surface such that the cold raindrops evaporating as they fall cool surface temperatures to freezing, causing freezing rain (rain that freezes on contact), we could have some ice accumulation. Right now, this scenario is what is shown by the latest GFS model run.
Another possibility is that there is just enough cold air aloft for the precipitation to fall as snow. This is more likely in north Alabama (HSV), but could occur in BHM too. In this case, 2-3 inches of snow could fall Sunday night.
The third possibility is that the low moves north of the coast, warm air flows in from the Gulf, and we just get a cold rain, with temperatures in the mid to upper 30s. (Even though lows tend to like to stay near fronts and areas of large temperature changes over short distances like the coast, this inland low was shown by last night’s European model, the one that handled the snow on Christmas so well.)
My gut feeling right now (and I’m not Gibbs on NCIS nor Jack Bauer on 24, so I’m not always right) is that snow is likely from Cullman north. In central Alabama, freezing rain and snow, with ice accumulations Sunday afternoon, are possible. I’d give it a 33/33/33 shot (snow/ice/rain). Farther south, there could be a little freezing rain in Montgomery if the cold temperatures push far enough south, but that seems unlikely.
As is usually the case in Alabama, the potential winter storm system coming in on Sunday and Monday is very complicated, and to jump out and make a bold prediction 3 days out would be inappropriate. Also, don’t hang on the subtle changes in every model run, either. The models are solving very complex equations involving many variables, and some flip-flops are going to occur in what they predict. We have to sit back and take all this in and give it our best shot, accentuating the uncertainties in the forecast.

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...

New Event for Benton County and Calhoun County and Chickasaw County and Coahoma County and DeSoto County and Itawamba County and Lee County and Lafayette County and Marshall County and Monroe County and Quitman County and Tallahatchie County and Tate County and Tippah County and Tishomingo County and Tunica County and Union County and Yalobusha County
SPS valid from Jan 6 2:05 PM to Jan 7 4:30 AM CST
Sent to SMS at Jan 6 2:05 PM CST

Radar Time: Jan 6 2011 2:30 PM CST

000
WWUS84 KMEG 062005
SPSMEG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
205 PM CST THU JAN 6 2011

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>021-048>055-088>092-071030-
ALCORN-BENTON MS-CALHOUN-CARROLL-CHESTER-CHICKASAW-CLAY-COAHOMA-
CRAIGHEAD-CRITTENDEN-CROCKETT-CROSS-DESOTO-DECATUR-DUNKLIN-DYER-
FAYETTE-GIBSON-GREENE-HARDEMAN-HARDIN-HAYWOOD-HENDERSON-HENRY-
ITAWAMBA-LAFAYETTE-LAKE-LAUDERDALE-LAWRENCE-LEE AR-LEE MS-MADISON-
MARSHALL-MCNAIRY-MISSISSIPPI-MONROE-OBION-PANOLA-PEMISCOT-
PHILLIPS-POINSETT-PONTOTOC-PRENTISS-QUITMAN-RANDOLPH-SHELBY-
ST. FRANCIS-TALLAHATCHIE-TATE-TIPPAH-TIPTON-TISHOMINGO-TUNICA-
UNION-WEAKLEY-YALOBUSHA-
INCLUDING THE CITIES OF...ABERDEEN...AMORY...BARTLETT...
BATESVILLE...BLYTHEVILLE...BOLIVAR...BOONEVILLE...
CARUTHERSVILLE...CLARKSDALE...COLLIERVILLE...CORIN TH...
COVINGTON...DRESDEN...DYERSBURG...FORREST CITY...GERMANTOWN...
HARRISBURG...HELENA...HUMBOLDT...HUNTINGDON...IUKA ...JACKSON...
JONESBORO...KENNETT...LEXINGTON...MARTIN...MEMPHIS ...MILAN...
MILLINGTON...NEW ALBANY...OLIVE BRANCH...OXFORD...PARAGOULD...
PARIS...SAVANNAH...SOMERVILLE...SOUTHAVEN...TUNICA ...TUPELO...
UNION CITY...WALNUT RIDGE...WEST MEMPHIS...WYNNE
205 PM CST THU JAN 6 2011

...MAJOR WINTER STORM LOOKING MORE LIKELY FOR SUNDAY AFTERNOON
AND SUNDAY NIGHT...

NUMERICAL WEATHER MODELS ARE BEGINNING TO CONVERGE ON A SOLUTION
REGARDING A WINTER SYSTEM FOR THIS WEEKEND. IT APPEARS AT THIS
TIME LOW PRESSURE WILL TRACK FROM SOUTH TEXAS SATURDAY NIGHT TO
THE LOUISIANA GULF COAST SUNDAY AND THE FLORIDA PANHANDLE SUNDAY
NIGHT.

MOISTURE IS EXPECTED TO SURGE NORTHWARD SUNDAY AND SPREAD
PRECIPITATION FROM SOUTH TO NORTH ACROSS THE MIDSOUTH BEGINNING
SUNDAY AFTERNOON. THE PRECIPITATION SHIELD WILL CONTINUE PUSHING
NORTH INTO SUNDAY EVENING...AFFECTING MUCH OF THE REGION.

HIGH PRESSURE OVER THE GREAT LAKES AND OHIO VALLEY WILL KEEP COLD
AIR IN PLACE THROUGHOUT THE WEEKEND...SO MOST OF THE PRECIPITATION
SHOULD REMAIN SNOW. THERE IS A SMALL CHANCE OF SOME SLEET MIXING
WITH THE SNOW ACROSS NORTHERN MISSISSIPPI SUNDAY AFTERNOON AS
SLIGHTLY WARMER AIR ALOFT PUSHES NORTH. ANY SLEET THAT FALLS
INITIALLY WILL QUICKLY TURN TO SNOW.

GIVEN THE TROPICAL ORIGIN OF THIS SYSTEM IN THE EAST PACIFIC AND
ITS ABILITY TO TAP INTO ADDITIONAL GULF MOISTURE...THIS SYSTEM
WILL HAVE A LOT OF MOISTURE TO WORK WITH. IN ADDITION...STRONG
DYNAMICS PRESENT WITHIN THE STORM WILL ALLOW FOR THE FORMATION OF
EMBEDDED HEAVY SNOW BANDS.

VERY EARLY ESTIMATES OF SNOWFALL ACCUMULATIONS APPEAR TO BE IN THE
2 TO 5 INCH RANGE TOWARD THE KENTUCKY/MISSOURI BORDERS TO AS MUCH
AS 5 TO 8 INCHES ALONG AND SOUTH OF I-40. THIS SNOWFALL FORECAST
IS HEAVILY DEPENDENT ON THE AMOUNT OF LIFT AND MOISTURE THIS
SYSTEM WILL PRODUCE...AND IS SUBJECT TO CHANGE.

DUE TO THE FRESHLY FALLEN SNOW...TEMPERATURES WILL REMAIN QUITE
COLD INTO MUCH OF NEXT WEEK. THIS WILL MAKE CLEARING ROADWAYS AND
SIDEWALKS DIFFICULT WITH THE SLUSH OR WET SNOW REFREEZING. DUE TO
THE INABILITY TO SUFFICIENTLY CLEAN ROADWAYS IN THIS PART OF THE
COUNTRY WHEN COMPARED TO NORTHERN STATES...TRAVEL MAY REMAIN
DIFFICULT WELL INTO NEXT WEEK.

ALL INTERESTS ACROSS THE MIDSOUTH SHOULD STAY UPDATED TO THE
LATEST FORECASTS AND FUTURE WATCHES AND WARNINGS. THIS SYSTEM HAS
THE POTENTIAL TO SIGNIFICANTLY IMPACT COMMERCE AND SOCIETY.

[ROLLTIDE]

Nashville,TN

DEPENDING ON THE EXACT TRACK OF THE LOW
AND STRENGTH OF THE MID/UPPER FEATURES...THIS PATTERN COULD
SUPPORT A SWATH OF SUBSTANTIAL (6+) SNOWFALL. AT THIS TIME...IT
APPEARS THE SOUTH HALF WILL BE TARGETED WITH THE HEAVIER AMOUNTS.
THE USUAL DISCLAIMERS APPLY...THIS IS SEVERAL DAYS OUT...MODELS
CAN CHANGE..

[ROLLTIDE]

James Spann

HEAVIEST SNOW: At this point, it looks like heavy snow is a very real possibility over the northern third of Alabama. Areas north of U.S. 278, or north of a line from Hamilton to Cullman to Gadsden, could see 4-8 inches of snow Sunday afternoon through Monday morning. The main period for this heavier snow will be from around 12:00 noon Sunday through 12:00 noon Monday.
GREATEST CHANCE OF ICE ISSUES: To the south, snow is likely over Central Alabama, but model data also suggests that warmer air in the 3,000-6,000 foot range could change the snow over to freezing rain at times. This is the most difficult part of this forecast; resolving the exact type of precipitation and potential for icing along the I-20 corridor (Tuscaloosa, Birmingham, Anniston). For now will just mention a chance of snow and freezing rain for this strip of the state Sunday night into Monday morning. There could be enough ice load for significant travel issues and maybe even some power outages, if the freezing rain lasts long enough.

[ROLLTIDE]

[ROLLTIDE]

Looking like a possible trip to Memphis :)

LONG TERM...SUNDAY THROUGH NEXT THURSDAY.

THE MAIN FORECAST FOCUS BEGINS SUNDAY AND CONTINUES INTO MONDAY.
MODELS HAVE FINALLY COME INTO MUCH BETTER AGREEMENT WITH THE
POTENTIAL FOR A MAJOR WINTER STORM IN THE SUNDAY AFTERNOON THROUGH
SUNDAY NIGHT TIME FRAME. THE CUT OFF LOW CURRENTLY OFF THE COAST OF
SOUTHERN CALIFORNIA WILL TRACK ACROSS THE DESERT SOUTHWEST AND
INTO TEXAS BY SATURDAY NIGHT. THE AFOREMENTIONED SURFACE LOW
DEVELOPING OFF THE TEXAS COAST WILL TRACK ALONG OR JUST NORTH OF
THE GULF COAST SUNDAY AND SUNDAY NIGHT WITH THE 500 MB LOW
TRACKING VERY FAVORABLY ACROSS NORTHERN OR CENTRAL MISSISSIPPI. AMPLE
AMOUNTS OF MOISTURE SURGING NORTH INTO TEXAS THIS AFTERNOON...AS
EVIDENT ON WATER VAPOR AND INFRARED SATELLITE...SHOULD PROVE
IMPORTANT FOR SNOWFALL AMOUNTS. THIS IS A LOW OF TROPICAL ORIGIN
SO IT IS LIKELY TO REMAIN MOISTURE LADEN AS IT TRACKS ACROSS THE
SOUTHERN U.S. IN ADDITION...A DECENT SOUTHERLY FLOW WILL DEVELOP
AHEAD OF THE SYSTEM AND IT SHOULD BE ABLE TO TAP INTO GULF
MOISTURE AS WELL.

DYNAMICS WITH THIS SYSTEM ARE VERY IMPRESSIVE. STRONG ISENTROPIC
LIFT COMMENCES SUNDAY AFTERNOON AND CONTINUES THROUGH SUNDAY
EVENING BEFORE TAPERING OFF AROUND 06Z MONDAY. THERE DOES APPEAR
TO BE A SMALL TROWAL SIGNATURE EVIDENT...ALLOWING FOR A LARGE SNOW
SHIELD DURING THIS TIME. CROSS SECTIONS ALSO INDICATE SOME CSI
EMBEDDED WITHIN THE DENDRITIC SNOW GROWTH REGION...WHICH IS ALSO
COINCIDENT WITH STRONG FRONTOGENESIS. THUS...BANDING OF SNOW LOOKS
LIKELY WITH HEAVY CONVECTIVE SNOW ALSO POSSIBLE WITHIN THESE BANDS
PARTICULARLY SUNDAY EVENING.

DRY AIR IN THE BOUNDARY LAYER WILL EAT AWAY AT THE FIRST FEW HOURS
OF SNOW SUNDAY AFTERNOON...BUT THE ATMOSPHERE SHOULD MOISTEN
PRETTY QUICKLY WITH ACCUMULATING SNOW BEGINNING OVER NORTHERN
MISSISSIPPI AROUND 21Z SUNDAY AND ELSEWHERE BY 00Z MONDAY.

THE STORM TOTAL QPF ON THE ECMWF RANGES FROM ABOUT 0.15 NEAR THE
KY/MO LINE TO 1/2 INCH NEAR I-40 AND NEAR 3/4 INCH ACROSS MUCH OF
NORTHERN MS. THE 12Z GFS IS A LITTLE LIGHTER AS IT HAS BEEN OVER
THE PAST FEW DAYS. THE NEW 18Z NAM IS ACTUALLY MORE THAN THE STORM
TOTAL OFF THE ECMWF THROUGH ONLY 06Z MONDAY...WITH MORE OCCURRING
AFTER THE MODEL ENDS. THE CANADIAN IS ALSO A LITTLE HEAVIER THAN
THE ECMWF. AS IMPRESSIVE AS THESE NUMBERS ALREADY ARE...I HAVE A
FEELING THE MODELS DON/T QUITE HAVE A HANDLE ON THE AMOUNT OF
MOISTURE THIS SYSTEM ACTUALLY AS YET SINCE THE SYSTEM IS STILL
OFFSHORE. THEREFORE...QPF AMOUNTS MAY RISE A BIT WITH TIME AS THE
SYSTEM MOVES OVER THE RAOB NETWORK IN THE NEXT DAY.

AT THIS POINT...THE SNOWFALL FORECAST IS VERY PRELIMINARY BUT
PUTTING THIS ALTOGETHER POINTS TOWARD 2-5 INCHES NEAR THE MO/KY
BORDERS AND 5 TO AS MUCH AS 8 OR MORE INCHES ALONG AND SOUTH OF
I-40. THIS JIVES WITH THE GARCIA METHOD OF DOUBLING THE MEAN
12-HOUR MIXING RATIO /ABOUT 3.25 G/KG OVER NORTHERN MS/ DURING THE
PERIOD OF HEAVIEST SNOW. IT IS STILL TOO EARLY FOR A WINTER STORM
WATCH...BUT IT IS LIKELY TO BE ISSUED BY FRIDAY AFTERNOON. FOR NOW
ISSUED AN SPS HIGHLIGHTING THE MAIN THREATS. THIS SYSTEM NEEDS TO
BE WATCHED VERY CLOSELY.

AFTER THE STORM PUSHES EAST...ANOTHER WEAK SHORT WAVE MAY BRING
ADDITIONAL SNOW SHOWERS TO NORTHERN AREAS MONDAY NIGHT AND
TUESDAY. AT THIS POINT ANY ACCUMULATIONS WOULD BE MINOR. THEN A
STRONG 1045-1050 MB HIGH WILL BUILD INTO THE CENTRAL PLAINS BY THE
MIDDLE OF NEXT WEEK. WITH FRESH...DEEP SNOW COVER LIKELY TO BE ON
THE GROUND TEMPERATURES SHOULD BE MUCH COLDER THAN GUIDANCE
INDICATES. SHOULD SEE LOWS APPROACH ZERO IN THE TYPICAL COLD
LOCATIONS AND SINGLE DIGITS OR LOW TEENS ELSEWHERE BY WEDNESDAY
NIGHT AS THE CENTER OF THE HIGH PUSHES OVERHEAD.

BORGHOFF

[ROLLTIDE]

Mobile

WILL HAVE DRY CONDITIONS CONTINUING THROUGH
SATURDAY EVENING...THEN SMALL TO LOW END CHANCE POPS OVER MUCH OF
THE AREA LATE SATURDAY NIGHT. OVERNIGHT LOWS OVER THE INTERIOR
PORTION OF THE AREA SATURDAY NIGHT WILL BE IN THE LOW THIRTIES...AND
MODEL SOUNDINGS SHOW AN ALTO DECK AND A FAIRLY DRY SUBCLOUD
LAYER...WITH THE WET BULB REMAINING SLIGHTLY BELOW ZERO BELOW THE
CLOUD DECK OVER THE NORTHWESTERN PORTION OF THE AREA...WITH A COLDER
WET BULB BUT WITH LESS MOISTURE FURTHER EAST OVER INLAND ZONES.
BOTH THE GFS AND ECMWF BRING IN LIGHT PRECIPITATION AMOUNTS LATE
SATURDAY NIGHT AND CURRENT PACKAGE HAS PRECIPITATION REMAINING
LIQUID OVER THE SOUTHERN TWO THIRDS OF THE AREA AND A MIX OF SNOW
AND RAIN OVER THE INTERIOR THIRD WHICH LOOKS GOOD AT THIS TIME
EXCEPT HAVE ALSO ADDED SLEET INTO THE MIX. AS THE OVERRUNNING
INCREASES WITH THE SURFACE LOW ADVANCING EASTWARD...POPS INCREASE TO
LIKELY OVER NEARLY ALL OF THE FORECAST AREA ON SUNDAY. OVER THE
INTERIOR PORTION OF THE AREA...GFS MODEL SOUNDINGS SHOW AN ELEVATED
LAYER ALOFT FROM ROUGHLY 675-900 MB WARMING TO A FEW DEGREES ABOVE
FREEZING DURING THE DAY WITH ABOUT A 100 MB DEEP SUBFREEZING LAYER
BENEATH...WHILE CLOSER TO THE COAST SOUNDINGS DO NOT HAVE A
SUBFREEZING LAYER ABOVE THE SURFACE. THE CURRENT FORECAST STARTS
SUNDAY MORNING WITH A MIX OF RAIN AND SNOW OVER THE INTERIOR
PORTION...INCLUDING SLEET BASED ON SOUNDINGS...WITH RAIN ELSEWHERE
THEN TRANSITIONS TO ALL RAIN BY SUNDAY AFTERNOON. THE GFS SOUNDINGS
INDICATE HIGH LIKELIHOOD OF AT LEAST MIXED PRECIPITATION CONTINUING
THROUGH THE DAY OVER THE INTERIOR PORTION WITH THE ECMWF SOUNDINGS
SHOWING GENERALLY THE SAME THING BUT ALSO SHOW A POTENTIAL SWITCH TO
ALL LIQUID OVER THE WESTERN PORTION DURING THE AFTERNOON. HAVE LEFT
THE FORECAST AS IS EXCEPT FOR ADDING SLEET IN THE MORNING AND WILL
LET MIDSHIFT REASSESS WITH 00Z ECMWF/GFS MODEL DATA. BOTH THE GFS
AND ECMWF SOUNDINGS SHOW WARMING IN THE LOWEST LAYERS...WITH THE GFS
ELIMINATING THE LOW LEVEL SUBFREEZING LAYER OVER INTERIOR ZONES
SUNDAY NIGHT WHILE THE ECMWF MAINTAINS A MODEST SUBFREEZING LAYER IN
THE LOWEST 50-100 MB OVER THE INLAND PORTION. CURRENT PACKAGE HAS
MIXED PRECIPITATION OVER NORTHERNMOST ZONES TRANSITIONING TO PURELY
LIQUID LATE SUNDAY NIGHT...BUT IF THE ECMWF PANS OUT...WILL NEED TO
STAY WITH A MIX INLAND DURING THE ENTIRE NIGHT. AT THIS TIME...AM
NOT EXPECTING ANY ACCUMULATION AS SURFACE TEMPERATURES SHOULD BE TOO
WARM WITH DAYTIME HIGHS IN THE LOWER FORTIES ON SUNDAY THEN LOWS
SUNDAY NIGHT RANGING FROM MID THIRTIES WELL INLAND TO LOWER FORTIES
NEAR THE COAST. THAT SAID...THERE IS THE POTENTIAL FOR WET BULB
EFFECTS DUE TO LOW LEVEL DEWPOINTS IN THE UPPER TWENTIES TO RESULT
IN COOLER THAN FORECAST TEMPERATURES WHICH COULD ALLOW FOR SOME
ACCRETION ON EXPOSED SURFACES AND BRIDGES. /29

[ROLLTIDE]

N.O

STRICTLY BASED ON PREFERRED
THICKNESS SCHEMES...WINTER TYPE PRECIPITATION DOES NOT SEEM
WARRANTED...HOWEVER MODEL SMOOTHING AND SHALLOWNESS OF COLD
AIR...AMONG OTHER FACTORS...MAY NOT CATCH THE FULL ESSENCE OF WHAT
CAN BE EXPECTED. SHOULD THE COLDER AIR BE MORE ENTRENCHED AND THE
TRAJECTORY OF THE SURFACE LOW PRESSURE AREA BE SLIGHTLY FARTHER
SOUTH THAN MODEL INDICATED...THEN A STRIP OF SLEET AND/OR SNOW MIX
MAY RESULT ALONG THE NORTHERN FRINGES. THERE IS A LOW NON-ZERO
PROBABILITY OF THIS OCCURRENCE...BUT DUE TO LOWER
CONFIDENCE...HAVE OPTED TO REMOVE FROM FORECAST AT THIS TIME.