Great GSP discussion regarding this event...

[Stormsfury]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
300 PM EST WED FEB 11 2004

.DISCUSSION...
WINTER STORM IS LOOKING MORE LIKELY FOR PARTS OF WESTERN NORTH
CAROLINA...THOUGH AS ALWAYS THERE ARE A FEW CAVEATS.

TNGT THROUGH FRI...THE ETA AND GFS HAVE COME INTO MUCH BETTER
AGREEMENT TDA. FOR THE PAST SEVERAL RUNS THE ETA HAS BEEN
ADVERTISING THAT THE SFC LOW THAT DEVELOPS IN ASSOCIATION WITH THE
SRN STREAM SHORT WAVE (NOW RACING ACROSS TX) WOULD CROSS SRN AL AND
GA...W/H8 LOW CROSSING THE SRN PART OF THE CWA. THE GFS HAD BEEN
CONSIDERABLY FARTHER S AND THUS WAS GENERATING MUCH LESS QPF. NOW
THE GFS IS ACTUALLY THE WETTER MODEL...AND IT/S SFC AND H8 LOW
POSITIONS ARE ALMOST IDENTICAL TO THE ETA/S. SO THE QUESTION OF QPF
SEEMS TO HAVE BEEN SOLVED. IN FACT...WITH 4 TO 5 G/KG H7 MIXING
RATIOS AND ELY UPSLOPE FLOW...SOME FAIRLY IMPRESSIVE SNOWFALL TOTALS
WL BE POSSIBLE DESPITE THE SHORT DURATION OF THE EVENT. TO MAKES
EVEN MORE INTERESTING...THE CURRENT RAIN SHIELD MASSING OVER THE
DEEP SOUTH IS VERIFYING FARTHER TO THE NE THAN THE 12 UTC ETA.

NEXT QUESTION IS TEMPERATURES. THE ETA HAS BEEN TRENDING EVER SO
SLIGHTLY WARMER THE PAST FEW RUNS. HOWEVER...MODEL SOUNDINGS SHOW
THAT MOST OF THIS WARMING IS REALIZED AS A DEEP ISOTHERMAL LAYER. A
WARM NOSE DOES CROSS THE CWA FROM THE SW BETWEEN 12 AND 15 UTC TMRW.
HOWEVER...THIS IS BEHIND THE BEST FORCING...AND IT APPEARS THAT MOST
AREAS ACROSS THE NC MTNS...FOOTHILLS AND NW PIEDMONT SHOULD SEE
SEVERAL HOURS OF MODERATE TO HEAVY WET SNOW. THE ETA DOES DEVELOP
SOME COLD AIR DAMMING...BUT IT LOOKS TOO WEAK TO LOWER SFC WET BULBS
ENUF TO WORRY ABOUT FZRA IN THE ERN SLOPES OR IN THE LEE. IF/WHEN
THE WARM NOSE INVADES TMRW MORNING...THERE MAY BE A PERIOD OF
SLEET...BUT WL NOT WORRY ABOUT THAT IN THE GRIDS OR ZONES ATTM. ALSO
OF NOTE...THE BUFKIT AT AVL SHOWS A NICE CROSS HAIR SIGNATURE CIRCA
6 UTC (STRONG UVV IN THE -12 TO -16 DEG LAYER...GOOD FOR SNOW
CRYSTAL GROWTH)....AND AT HKY FROM 9 TO 12 UTC.

FARTHER TO THE SOUTH...ACROSS THE SC AND GA MTNS AND THE SRN
PIEDMONT...PLAN TO GO WITH AN ADVISORY ATTM. A LITTLE WORRIED THAT
DEEP ISOTHERMAL LAYER AT CLT COULD VERIFY AS A PERIOD OF WET SNOW
AROUND 12 UTC. THE LACK OF STRONG LLVL WAA MEANS THAT DIABATIC
COOLING EFFECTS OF SNOW CRYSTAL MELTING IN THE LLVLS MAY RESULT IN
MORE COOLING THAN THE MODELS SHOW. HOWEVER...THE ETA DOES ACCOUNT
FOR THIS. ALSO INTERESTING IS AN AREA OF NEGATIVE SATURATED EPV
VCNTY OF CLT AROUND 12 UTC. THIS EPV IS COLLOCATED WITH GOOD LLVL
FRONTOGENESIS AND GOOD LLVL OMEGA. IE...CONVECTIVE BANDING MIGHT
DEVELOP OVER THE SRN PIEDMONT. IF THIS WERE TO HAPPEN...THEN
LLVL COOLING WOULD BE MUCH STRONGER AND SNOW WOULD DEVELOP. A LOT TO
KEEP AN EYE ON.

LITTLE CHANGE TO THU NGHT AND FRI. LOWERED TEMPS A LITTLE WHERE SNOW
COVER IS SUSPECTED AND CUT BACK A LITTLE ON NW FLOW SHSN...BUT
THAT/S ABOUT IT FOR CHANGES.

GREAT COLLABORATION TDA WITH SURROUNDING OFFICES AND WITH HPC.
THANKS FOR ALL THE HELP.

SAT THROUGH WED...GFS HAS BEEN CONSISTENT WITH KEEPING THE NEXT
FRONTAL WAVE TO THE EAST OF THE FA ON SAT. HOWEVER...THE LATEST RUNS
OF THE GFS HAS DEPICTED A H5 TROF TO CLOSE OFF OVER THE FOUR CORNERS
ON FRI. THE CLOSED LOW IS EXPECTED TO DRIFT EAST BASICALLY ALONG
I-20 FROM TX TO SC BY LATE SUN. WILL ADD A SCHC FOR SHSN FROM SUN
INTO SUN NIGHT. WILL COOL TEMPS SUN THROUGH MON CLOSE TO THE LOWER
ENSEMBLE MEMBER. HIGH PRESSURE WILL REMAIN OVER THE CWA FOR THE
EARLY WORK WEEK. ANOTHER FRONTAL WAVE WILL BRUSH THE DEEP SOUTH
WED...AGAIN THIS FEATURE APPEARS TOO FAR TO THE SOUTH AND EAST TO
BRING PRECIP TO THE FA AND WILL GO DRY.