Deep South Winterwx Discussion 2015-2016

[Metalicwx220]

The 12z Euro valid FRIDAY morning... big upper level low swinging through MS/AL, this would likely have its own cold air and produce snow in this setup.

Does it move through Georgia?

[Jag95]

Jackson, MS...

THE CONSENSUS OF MODEL SOLUTIONS SHOW A VIGOROUS UPPER LEVEL TROUGH
PLOWING SOUTHEAST OUT OF THE PLAINS AND TOWARDS THE LOWER MS VALLEY
TUESDAY MORNING WITH SURFACE LOW PRESSURE GAINING STRENGTH JUST
SOUTH OF THE LA COAST. THEREAFTER...MODELS SHOW STRONG AGREEMENT
THAT THE UPPER TROUGH WILL "CLOSE OFF" INTO A VIGOROUS UPPER LOW
THAT WILL MOVE ACROSS THE ARKLAMISS TUESDAY AFTERNOON INTO TUESDAY
NIGHT WHILE STRENGTHENING SURFACE LOW PRESSURE NEAR THE GULF COAST
ADVANCES TO OUR EAST. WITHOUT GOING INTO DETAILS OF VARIOUS
MECHANISMS OF ATMOSPHERIC LIFT INVOLVED I WILL SUFFICE IT TO SAY
THAT THIS IS A TERRIBLY GOOD RECIPE FOR RAIN ACROSS THE REGION.
ADDITIONALLY...THE GULF LOW IN CONJUNCTION WITH A TRAILING UPPER LOW
MOVING OVERHEAD IS ALSO A PRETTY GOOD RECIPE FOR GETTING SNOW AROUND
HERE. LAST NIGHT WE ALLUDED TO THE FACT THAT DESPITE SOME FAVORABLE
FACTORS FOR WINTRY PRECIP POTENTIAL THAT MAY COME TOGETHER WE WERE
GOING TO STICK WITH A RAIN FORECAST SINCE TEMPERATURES IN THE LOWER
ATMOSPHERE JUST WERE NOT FORECAST TO BE COLD ENOUGH. TONIGHT`S MODEL
RUNS STILL INDICATE WARMISH LOW LEVEL TEMPERATURES...BUT THE
PREDICTION OF A COLD-CORE UPPER LOW GOING RIGHT THROUGH THE HEART OF
THE FORECAST AREA PROVIDES A WILD CARD NOT SUGGESTED STRONGLY LAST
NIGHT. THESE UPPER LOWS HAVE VERY COLD AIR ALOFT THAT WILL ENSURE
SNOW PRODUCTION ABOVE GROUND. THEY COULD ALSO PRODUCE HEAVY
PRECIPITATION BURSTS THAT HELP TO DYNAMICALLY CHILL THE LOWER
ATMOSPHERE AND ALLOW AT LEAST SOME SNOW TO GET THE SURFACE...DESPITE
SURFACE TEMPERATURES ABOVE FREEZING.

[Brent]

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
145 PM CST SUN JAN 23 2011

ALZ011>015-017>050-241945-
AUTAUGA-BARBOUR-BIBB-BLOUNT-BULLOCK-CALHOUN-CHAMBERS-CHEROKEE-
CHILTON-CLAY-CLEBURNE-COOSA-DALLAS-ELMORE-ETOWAH-FAYETTE-GREENE-HALE-
JEFFERSON-LAMAR-LEE-LOWNDES-MACON-MARENGO-MARION-MONTGOMERY-PERRY-
PICKENS-PIKE-RANDOLPH-RUSSELL-SHELBY-ST CLAIR-SUMTER-TALLADEGA-
TALLAPOOSA-TUSCALOOSA-WALKER-WINSTON-
145 PM CST SUN JAN 23 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE COUNTIES SERVED BY THE
NATIONAL WEATHER SERVICE OFFICE IN BIRMINGHAM.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

THERE IS A CHANCE OF MIXED WINTER WEATHER PRECIPITATION ACROSS NORTH
CENTRAL ALABAMA LATE TUESDAY NIGHT THROUGH EARLY WEDNESDAY MORNING.
ACCUMULATIONS ARE POSSIBLE...ESPECIALLY IN THE HIGHER ELEVATIONS OF
NORTHEAST ALABAMA. THIS IS A COMPLEX WEATHER SCENARIO WITH REGARDS
TO THE TRACK AND STRENGTH OF THE STORM SYSTEM...AND SLIGHT CHANGES
WILL ULTIMATELY AFFECT PRECIPITATION TYPE AND AMOUNTS. STAY TUNED
FOR FORECAST UPDATES.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT IS NOT
EXPECTED AT THIS TIME.

$$

[Brent]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
312 PM CST SUN JAN 23 2011

.DISCUSSION...

THE GULF LOW SYSTEM MON THRU WED CONTINUES TO BE THE ONLY SYSTEM OF
INTEREST OVER THE NEXT 7 DAYS SO LET`S GET RIGHT TO IT.

THE OVERALL SYNOPTIC SET UP REMAINS THE SAME AS EACH FORECAST MODEL
CONTINUES TO SHOW A DIGGING UPPER TROF AND A DEVELOPING GULF LOW.
THE 12Z GFS AND ECMWF SOLUTIONS APPEAR PRETTY CONSISTENT WITH EACH
OTHER IN THE TIMING AND TRACK OF THE SFC LOW...BUT THERE ARE SOME
DIFFERENCES. WILL CONTINUE TO GO WITH MORE OF A GFS/ECMWF BLEND FOR
THE PERIOD MON THRU WED.

THE SFC LOW DEVELOPS IN THE NW GULF ON MON AND THEN SLIDES ENE INTO S
GA BY WED MRNG. PRECIPITATION COULD BEGIN AS EARLY AS MON EVENING
IN THE WEST AND THE OVERSPREAD THE ENTIRE CWA ON TUE. LOW LEVEL
TEMPS WILL BE TOO WARM FOR ANY FROZEN PRECIP THRU TUE AFTN. THE
REALLY TRICKY PART COMES TUE EVNG INTO WED MRNG. AT FIRST GLANCE
THIS LOOKS LIKE A CLASSIC SNOW SET UP FOR NORTH AND CENTRAL
ALABAMA...AS FAR AS THE LOCATION AND INTENSITY OF THE SFC LOW...BUT
THINGS JUST AREN`T ADDING UP TO MUCH SNOW JUST YET. HOWEVER THIS
COULD CHANGE SIGNIFICANTLY WITH EVEN THE SLIGHTEST BIT OF CHANGE IN
SFC TEMPS AND/OR THE TRACK OF THE SFC LOW.

AFTER LOOKING AT THE 12Z GFS...WE HAVE VERY LITTLE ROOM FOR ERROR
WHEN IT COMES TO GETTING ALL RAIN OR SEVERAL INCHES OF SNOW. THE GFS
IS SPITTING OUT LARGE AMOUNTS OF QPF AND FAIRLY HIGH PRECIP RATES
TUE NIGHT INTO WED MRNG. THESE HIGH RATES ARE MOST LIKELY DUE TO THE
DEVELOPMENT OF A TROWAL AND PRETTY DECENT FRONTOGENETICAL FORCING.
THE QUESTION WILL BE WHETHER OR NOT THESE PRECIP RATES WILL BE HIGH
ENOUGH FOR DYNAMIC COOLING TO BRING COOLER TEMPS DOWN TO THE SFC.
GFS PROFILE TEMPS AT THE SFC (AND UP TO AROUND 850 MB) ARE A FEW
DEGREES ABOVE FREEZING...WITH PLENTY OF MOISTURE UP TO 300 MB.
THEREFORE ALL IT WILL TAKE IS COOLING THE SFC TEMPS DOWN BY A DEGREE
OR TWO FOR US TO SEE RAIN SWITCH OVER TO ALL SNOW ACROSS THE NRN
PORTION OF THE CWA. IF YOU TAKE THE GFS SOUNDING AT 12Z WED FOR
ANYWHERE IN NORTH CENTRAL AL AND COOL THE LOWEST LEVELS BY LET`S SAY
2 DEGREES THEN YOU COULD HAVE SOME PRETTY SIGNIFICANT SNOWFALL. THE
ECMWF IS A LITTLE COOLER THAN THE GFS BUT EVEN IT IS STILL
QUESTIONABLE. FOR NOW...FEEL MOST COMFORTABLE LEAVING RAIN OR SNOW
WORDING IN FOR THE NRN HALF OF THE CWA TUE NIGHT/WED MRNG...WITH ALL
RAIN TO THE SOUTH AS TEMPS ARE JUST TOO WARM THERE. WILL WAIT AND
SEE IF MODELS TREND SFC TEMPS COOLER...IF THAT HAPPENS THEN WILL
HAVE TO MAKE SOME MAJOR ADJUSTMENTS TO THE WX GRIDS AND INTRODUCE
SOME SNOW AMOUNTS. MOISTURE EXITS THE AREA BY WED AFTN AS THE SFC
LOW SLIDES OFF THE ATLANTIC COAST...THUS ENDING PRECIP CHANCES.

[zippity]

NATIONAL WEATHER SERVICE HUNTSVILLE AL
350 PM CST SUN JAN 23 2011

.DISCUSSION...
IN SUMMARY...DISCREPANCIES AMONGST MED RANGE GUIDANCE MEMBERS AND
RUN TO RUN INCONSISTENCY IS CONTINUING TO CREATE LOW CONFIDENCE IN
EVOLVING FORECAST SCENARIO FOR EARLY THIS WEEK. THE TREND FAVORS A
SLIGHTLY MORE NORTHWARD/WESTWARD TRACK OF THE SFC LOW...AND KEEPS
THE MAIN CORE OF THE UPR LOW JUST TO OUR SOUTH. HVY SNOWFALL IS
LOOKING LESS LIKELY AREAWIDE...BUT THE THREAT FOR SOME SNOWFALL
REMAINS. WILL HAMMER OUT DETAILS BELOW.

AFTERNOON ANALYSIS SHOWS A HIGHLY SHEARED UPR SHORT WAVE STRETCHING
FROM THE CENTRAL PLAINS DEEP INTO THE DESERT SOUTHWEST. CONVERGENT
SFC FLOW AND COUPLING WITH AN ASSOCIATED COLD FRONT HAS GENERATED A
NARROW BAND OF MAINLY LGT RAIN FROM NEAR THE DFW METROPLEX INTO THE
OZARK REGION. FORWARD PROGRESS WITH THE LOW-LVL FRONTAL BOUNDARY IS
EXPECTED TO BE VERY SLOW HOWEVER...AS THE UPR WAVE WEAKENS FURTHER
AND PUSHES SOUTHEAST. WHILE BETTER FORCING FOR ASCENT WILL REMAIN TO
OUR WEST...ISENTROPIC LIFT/MOISTURE ADVECTION AHEAD OF THE UPR WAVE
MAY STILL MANAGE TO GENERATE SOME LGT PRECIP TONIGHT. THE MAIN
OBSTACLE FOR ANY SFC PRECIP WILL BE A DRY LYR UP THRU ABOUT 4-7KFT
WHERE DEW POINT DEPRESSIONS ON THE ORDER OF ABOUT -10C ARE
PLAUSIBLE. IF THE LIFT BECOMES SUFFICIENTLY ROBUST...A LITTLE LIGHT
PRECIP MAY BE ABLE TO PENETRATE THIS LAYER...BUT AM NOT COUNTING ON
MUCH. IN FACT...THE FORECAST WILL FEATURE NO QPF IN THE AREA. AS FOR
PRECIP TYPE...TEMPS SHOULD BE WARM ENOUGH FOR ANY PRECIP TO BE IN
THE FORM OF -RA THIS EVENING. HOWEVER...WITH THE POTENTIAL FOR DRY
AIR ADVECTION IN THE LOW LEVELS AND EVAPORATIVE COOLING...TEMPS MAY
BE COLD ENOUGH TO SUPPORT SOME -LGT SNOW OR FLURRIES LATE. FCST
SOUNDINGS SHOW A TEMP STRUCTURE THAT COULD SUPPORT EITHER
-RA/-FZRA/-SN...SO ALL WERE INCLUDED BTWN 09-15Z. IMPORTANTLY...TO
STRESS AGAIN...LOOKS LIKE A LGT PRECIP EVENT IF ANY OCCURS AT ALL.

THE SFC FRONT WILL MOVE SLOWLY TOWARDS OUR AREA BUT REMAIN TO OUR
WEST THROUGH TUESDAY. SMALL CHANCES FOR PRECIP WILL CONTINUE INTO
MONDAY MORNING AS THE UPR WAVE MOVES EASTWARD. HOWEVER...BARELY ANY
FORCING FOR ASCENT AND ONLY SHALLOW MOISTURE REMAIN FOR MONDAY.
THUS...THE WX MENTION FOR MONDAY IS FOR CONDITIONS MAINLY IN THE
MORNING. THE POSSIBILITY EVEN EXISTS THAT SOME PARTIAL CLEARING
COULD OCCUR IN THE AREA ON MONDAY AFTERNOON. WAA SHOULD HELP TO
PROPEL TEMPS INTO THE LOW 50S IN MOST AREAS...BUT IF MORE SUN BREAKS
OUT...THEN THESE VALUES WILL BE HIGHER.

NOW FOR THE MAIN LOW TO TRACK ACROSS THE SOUTHEAST...
AN UPR WAVE DIGGING QUICKLY SOUTHWARD TOWARDS THE NRN ROCKIES WILL
CARVE OUT A DEEPER TROUGH IN THE PLAINS BY LATE MONDAY. HEIGHT FALLS
AHEAD OF THE DIGGING TROUGH WILL LEAD TO CYCLOGENESIS ALONG THE
STALLED FRONTAL BOUNDARY IN THE NW GULF. THE SUBSEQUENT TRACK OF
THIS SFC LOW HAS BEEN A POINT OF FOCUS FOR THIS FCST AND PREVIOUS
ONES...AND CONTINUES TO BE A BIT OF A PROBLEM...AS IT OFTEN IS WITH
THESE SITUATIONS. IN TANDEM WITH THE TRACK OF THE CORE OF THE UPR
TROUGH...WINTRY PRECIPITATION STILL APPEARS POSSIBLE ACROSS THE
AREA. HOWEVER...IT SHOULD BE NOTED THAT GUIDANCE CONTINUES TO TREND
THE SFC LOW MORE INLAND...AND BRINGS MILDER AIR INTO THE REGION. 12Z
SOUNDINGS WOULD INDICATE LITTLE CHANCE FOR ANY SNOW WITH LOW-LVLS
SIMPLY TOO WARM FOR SN TO REACH THE SFC. HOWEVER...WITH THE
POTENTIAL FOR THE CORE OF THE UPR LOW TO TRACK DIRECTLY ACROSS THE
AREA...STRONG UVM AND COLUMN COOLING MAY OCCUR AND BE SUFFICIENT TO
DROP LOWER LAYER TEMPS NEAR/BELOW FREEZING. AT THIS TIME...THE TRACK
OF THE UPR LOW IS PROGGED BY THE CONSENSUS OF GUIDANCE TO TAKE PLACE
JUST TO OUR SOUTH...BUT IS CLOSE ENOUGH TO CAUSE SOME LINGERING
UNCERTAINTY. WILL CONTINUE TO ADVERTISE A CHANGE OVER FROM RAIN TO
SNOW DURING THE NIGHTTIME HOURS...BUT THE INFLUX OF WARMER HIGHER
THETA-E AIR IN THE LOWER LEVELS AND THE TREND TOWARDS A MILDER
AIRMASS AT THIS POINT IS DIFFICULT TO IGNORE. WITH THIS IN
MIND...AND CONSIDERING THAT TRENDS FOR MID-LVL FORCING/FRONTOGENESIS
MAINLY LINE UP ACROSS OUR SOUTHERN/EASTERN AREAS...HAVE DECREASED
SNOWFALL AMOUNTS AND RELOCATED THE SWATH OF GREATER SNOWFALL TO THE
SOUTH AND EAST. REMAINING AMOUNTS ARE ON THE ORDER OF ABOUT TWO
INCHES OR LESS. BUT IT IS IMPORTANT TO REITERATE...A LOT OF
UNCERTAINTY REMAINS WITH THE FORECAST FOR ANY SNOWFALL AMOUNTS...AND
EVEN PRECIP TYPE.

AS THE UPR LOW TRAVERSES TO THE EAST...ANY PRECIP WILL QUICKLY TAPER
OFF FROM WEST TO EAST DURING THE MORNING ON WEDNESDAY. WITH ONLY
MILD CAA...TEMPS MAY ACTUALLY REACH THE LOW/MID 40S ON WED AS
SUNSHINE POTENTIALLY RETURNS DURING THE AFTERNOON. THUS...ANY SNOW
COULD BEGIN MELTING QUICKLY.

ANOTHER QUICK MOVING SHORT WAVE IS EXPECTED TO CROSS THE AREA ON
THURS/FRI...BUT CONTINUES TO LOOK RATHER MOISTURE-STARVED. SO...NO
PRECIP ADDED IN AT THIS TIME.

A BROAD TROUGH BUT AMPLIFIED TROUGH WILL DEVELOP IN THE EASTERN
CONUS BY SAT...ALLOWING ANOTHER COLD FRONT TO MOVE ACROSS THE AREA
PERHAPS BY LATE SATURDAY. OTHERWISE...MEAN RIDGING IN THE WESTERN
CONUS AND TROUGHING IN THE EAST WILL ENSURE A CONTINUATION OF BELOW
NORMAL TEMPS FROM NEXT WEEKEND AND LIKELY BEYOND.

[Metalicwx220]

Hey, close to Baton Rouge, bring it a little further West please. 9 days out, not in quite the worst fantasy land but still too far off for any comfort.

[Ivanhater]

We all know details don't' mean jack at this range so there is no point discussing snow totals or exact location, but you gotta love the set up that has been consistently shown.

A very strong high around 1040mb settling into the central U.S and a Gulf low

[Dean4Storms]

Going to be all in the details. If that ridge doesn't push any further southward then enough moisture could make it up our way. Have to like what we keep seeing though.

[Ivanhater]

60 hour Nam

[Metalicwx220]

60 hour Nam

IS it starting a cooler trend?

[Ntxw]

^ Lower levels are even warmer. Only N Miss/AL/TN (even here surface temps are 40-50ish) stand a good chance a brief changeover outside of the mountains.

[BigB0882]

Too warm at the surface or it is too warm higher up. It will eventually come together for someone!

[Ivanhater]

^ Lower levels are even warmer. Only N Miss/AL/TN stand a good chance a brief changeover outside of the mountains.

I still don't trust it. I think if the surface temps are in range, some dynamic cooling will do the rest. Nice trends today anyway.

Whatever happens with this storm, my attention is on the February 1st one

[BigB0882]

Would anyone be willing to explain what has to line up for the Gulf to get a big snow fall? I have always wondered why it is so rare. I mean, we get to freezing quite often although usually only at night. Why is it that we never have systems moving through with moisture when it is cold? What is the most important elements to getting Gulf coast snowfalls?

[Brent]

Would anyone be willing to explain what has to line up for the Gulf to get a big snow fall? I have always wondered why it is so rare. I mean, we get to freezing quite often although usually only at night. Why is it that we never have systems moving through with moisture when it is cold? What is the most important elements to getting Gulf coast snowfalls?

Basically... because when it's cold it's dry. Usually a weaker storm system(which 99% of the time is what you get to your south) brings in warm air(along with moisture). You need a very strong storm system to draw in cold air on the north side.

Also the jet stream... the jet stream very very rarely goes south of you to allow a storm to track in a favorable position. It's much more common to track near or over you which dooms you from snow... or over me even(more classically, for big storms in the Ohio Valley).

[Brent]

^ Lower levels are even warmer. Only N Miss/AL/TN (even here surface temps are 40-50ish) stand a good chance a brief changeover outside of the mountains.

Yeah... surface temps are dooming us here. The only hope I see is a slight chance with the ULL to cause some dynamic cooling but it may be too late by then. *shrugs*

[BigB0882]

Looks like the 0z GFS takes it all away. Hopefully just a hiccup, I want someone to have some fun!

[cycloneye]

Off Topic= This post is only to let know those who live in the Southern States about the expanding drought conditions as after winter is over,the concern will be to deal with this increasing drought in the South.Go here to read the latest NOAA drought outlook.

[Ynotndalton]

I have seen this set up many times in the south... one you can't forecast until the event is underway as no one knows in what exact 30 mile track the best UL forcing and vertical cooling will take place inside the upper low, Or how long this cooling will take to happen. Will produce a very narrow swath of 2 or 3 inch wet snow in a line directly above the UL somewhere through N miss al and ga. will be the big heavy wet snowflakes.

[Ynotndalton]

HPC Winter Weather Discussion. SOUTHERN APPALACHIA/SOUTHEAST...
DEEPENING UPPER-LEVEL TROUGH AND EMBEDDED SHORTWAVE MOVES FROM
CENTRAL HIGH PLAINS INTO ARKLATEX REGION ON TUESDAY MORNING. STEEP
LAPSE RATES WITHIN THE COLD CORE LOW WILL ALLOW FOR A MIX OF
RAIN/SNOW TO DEVELOP ACROSS PORTIONS OF LOUISIANA...CENTRAL/EAST
TEXAS AND NORTHERN MISSISSIPPI. TUESDAY AFTERNOON...H5 SYSTEM
BEGINS TO CLOSE OFF...WITH ENERGETIC CIRCULATION TAPPING GULF
INFLOW. GOOD AGREEMENT BETWEEN ECMWF/GFS WITH H5 LOW TRACK AND
VERY COLD AIRMASS ALOFT ALONG THE I-20 FROM WEST CENTRAL
MISSISSIPPI TO THE TENNESSEE-ALABAMA LINE WITH H85-H7
FRONTOGENESIS AXIS SERVING AS THE REGION FOR POSSIBILITY OF
RAIN/SNOW MIX AND FORMATION OF A WELL-DEFINED DEFORMATION
PRECIPITATION SHIELD. ELEVATED CONVECTION WITHIN THE COLD-SECTOR
AND STEEP MID-LEVEL LAPSE RATES SUGGEST DYNAMIC COOLING WITHIN THE
MID-LEVEL FRONTOGENESIS AXIS...ALLOWING THE OTHERWISE MARGINAL
THERMAL PROFILE/COLUMN TO RAPIDLY COOL AND PRODUCE BURSTS OF
HEAVY/WET SNOWFALL...WITH LOCALLY 2-4 INCHES OF SNOWFALL...TO THE
NORTH OF THE H5 LOW TRACK TUESDAY NIGHT ACROSS SOUTHERN
TENNESSEE...NORTHEAST MISSISSIPPI...NORTHERN ALABAMA. BY WEDNESDAY
MORNING...SNOWFALL IS EXPECTED TO DEVELOP ACROSS NORTH
GEORGIA...SOUTHEAST TENNESSEE AND SOUTHWEST NORTH CAROLINA. THE
DEVELOPING WAVE CYCLONE AND MID- TO UPPER-LEVEL DEFORMATION CLOUD
SHIELD WILL CONTINUE TO BE THE FOCUS FOR DYNAMIC COOLING...WHILE
THE SURFACE PORTION OF THE SYSTEM STRENGTHENS/DEEPENS OVER THE
CAROLINAS. THE LOW-LEVEL INFLOW OFF THE ATLANTIC ALLOWING FOR
UPSLOPE FLOW TO COOL/LIFT INTO THE SOUTHERN APPALACHIANS.
SHELTERED VALLEYS COULD EXPERIENCE LOCALLY MODERATE FREEZING
RAIN/DRIZZLE FOR A TIME...BEFORE CHANGING OVER TO A LIGHT
RAIN/SNOW MIX BETWEEN 1000-2500 FT MSL. BASED ON THE 06Z HPC
QPFS...MANUAL GRAPHICS ANTICIPATE SOME 4+ INCH SNOWFALL
ACCUMULATIONS ABOVE 2500-3000FT MSL IN THE MOUNTAINS OF NORTH
CAROLINA...EASTERN TENNESSEE...SOUTHWEST VIRGINIA...EASTERN
KENTUCKY AND EASTERN WEST VIRGINIA.