Christmas Storm IV

[POWERSTROKE]

As I have said I was not getting exited until Thursday as I remember this so many times. Especially this one because the Euro was due for a flop. I won't give up until after today's runs of the euro as we have all seen it shift late in the game. Got to go fire up the smoker to cook Boston Butts all day for my employees. The wind outside is terrible. I was thinking the wind was only going to be a factor west of me but it is here too. Hopefully we will get a shift to at least get something on Christmas Day. Great job by all the mets and the others that are really involved in passing the information.

[DaculaWeather]

Birmingham having a hard time with it

HERE'S THE SET UP...A LARGE TROF WILL KICK OFF A SURFACE BASED LOW

PRESSURE SYSTEM. DEPENDING ON WHICH MODEL YOU LOOK AT...THE

SURFACE LOW WILL EITHER EXPERIENCE RAPID INTENSIFICATION ALONG THE

NORTHERN GULF OF MEXICO...OR IT WOULD JUST SLOWLY DEVELOP AND

MEANDER AROUND BEFORE IT GATHERS STRENGTH OVER THE ATLANTIC. IN

SIMPLE TERMS...PORTIONS OF CENTRAL ALABAMA COULD EITHER SEE MAYBE

1 TO 2 INCHES OR NOTHING AT ALL.

NORMALLY...WE LIKE TO SEE SOME AGREEMENT BETWEEN THE MODELS AS

THAT WILL INCREASE MY CONFIDENCE IN THE FORECAST. AS STATED...THIS

IS NOT THE CASE...AT LEAST NOT YET. IT IS IMPORTANT TO NOTE THAT

THE ECMWF HAS BEEN STICKING TO ITS GUN AND HAS NOT CHANGED MUCH

OVER THE LAST SEVERAL RUNS. IT DEVELOPS A STRONG SURFACE LOW

PRESSURE ALONG THE NORTHERN GULF OF MEXICO...ALONG THE SWEET SPOT

SO TO SPEAK...WITH PLENTY OF COLD AIR TO WORK WITH. AS A MATTER OF

FACT...IT SHOWS THE HEAVIER SNOW AMOUNTS ALONG THE SOUTHERN ZONES

WHEN MOISTURE IS DEEPER ALONG THE FREEZING COLUMN. ALTHOUGH

TEMPERATURES ARE COLDER NORTHWARD...THERE IS A SIGNIFICANT DROP IN

MOISTURE ALONG THE LOW LEVELS AND THUS LIMITED SNOW AMOUNTS.

THE 06Z NAM AND 00Z GEM ARE NOT STARTING TO TREND CLOSER TO THE

ECMWF AS FAR AS THE TIMING AND PLACEMENT OF THE SYSTEM.

HOWEVER...BOTH OF THESE MODELS SHOW A MUCH WEAKER SURFACE LOW

PRESSURE. WITH THE NAM AND GEM TRENDING CLOSER TO THE ECMWF...THAT

LEAVES THE GFS AS THE OUTLIER MODEL.

THE 00Z RUN OF THE GFS IS BY FAR THE FASTEST SOLUTION COMPARED TO

THE REST OF THE MODELS AS IT MOVES THE SYSTEM THROUGH 12 HOURS

AHEAD. BUT HOLD YOUR HORSES THOUGH...THE 06Z IS NOW STARTING TO

COME IN AS IT IS NOW STARTING TO TREND CLOSER TO THE ECMWF.

SO...MAYBE THE MODELS ARE NOW STARTING TO KEY OFF ON SOMETHING

THAT THEY ALL AGREE. BASED ON THE FACT THAT THEY HAVE BEEN ALL

OVER THE PLACE THE LAST SEVERAL DAYS...IT WOULD BE PRUDENT TO WAIT

AT LEAST THE NEXT RUN TO SEE IF CONSISTENCY INCREASES.

SO...AFTER TAKING ALL OF THIS INTO ACCOUNT...THE CURRENT THINKING

IS THAT PRECIPITATION WILL REMAIN ALL LIQUID SATURDAY MORNING

SINCE THAT IS WHEN THE WARMEST TEMPERATURES ARE EXPECTED TO OCCUR.

THEN SWITCHING TO A MIX OF RAIN AND SNOW SATURDAY AFTERNOON WHEN

THE COLD AIR BEGINS TO SPILL IN FROM THE NORTHWEST. IF ENOUGH

MOISTURE REMAINS BY SATURDAY NIGHT...THEN EXPECT PRECIPITATION TO

BE ALL SNOW.

TOO EARLY TO TELL YET ON AMOUNTS. NOTHING IN THE MODELS SO FAR

SUGGESTS ANYTHING OTHER THAN ADVISORY CRITERIA WHICH ONE QUARTER

UP TO TWO INCHES.

[DaculaWeather]

Huntsville still uncertain, calling for a coupe of inches.

THIS IS WHERE THE MODELS DIVERGE IN TERMS OF TIMING. SFC

CYCLOGENESIS BEGINS AROUND THE LA COASTLINE AND THE SFC LOW MOVES

OFF TO THE EAST AND THEN NORTHEAST AS IT ROUNDS THE PANHANDLE OF

FLORIDA AND PROCEEDS OFF THE COAST OF GA. THE ECMWF STRENGTHENS THIS

LOW TO A GREATER EXTENT THAN THE OTHER MODELS. THIS SCENARIO WOULD

MEAN A STRONGER PULL OF COLD FREEZING AIR OVER THE TN VALLEY (AND

THE SOUTHEAST IN GENERAL) WHICH WOULD INCREASE THE LIKELIHOOD OF

SNOW. THE DIVERGENCE IN THE MODELS IS ACTUALLY ON THE TIMING AS

OPPOSED TO THE TRACK (THOUGH THE ECMWF TRACK IS PROBABLY MORE TO THE

SOUTH AMONG THE MODELS' DEPICTION). GIVEN THE UNCERTAINTY WITH THE

SOLUTIONS...AM INCLINED TO KEEP LIKELY POPS FOR SNOW IN THE FORECAST

FOR SATURDAY MORNING/AFTERNOON. ANOTHER THING TO CONSIDER IS THAT

THE GFS HAS DRIED OUT THE DENDRITIC GROWTH ZONE (-10 TO -20 DEGREES

CELSIUS) WHEN THE SFC COLD AIR ARRIVES, WHICH IS STARKLY DIFFERENT

FROM PREVIOUS MODEL RUNS.

HOWEVER...DID NOT MAKE MUCH IN THE WAY OF ADJUSTMENTS TO THE SLOWER

TIMING OF THE ECMWF (AT THIS POINT ANYWAY) GIVEN THE IDIOSYNCRASIES

OF THE MODELS WITH THIS TYPE OF SCENARIO AND THE FACT THAT ANY

WOBBLE NORTH WOULD MEAN MORE SNOWFALL. WITH THE UNCERTAINTY FACTOR

STILL THERE, WILL GO WITH A CONSERVATIVE ESTIMATE OF GENERALLY LESS

THAN AN INCH OF ACCUMULATION WITH MORE ACCUMULATIONS OVER SOUTHERN

MIDDLE TN.

[DaculaWeather]

New RAH AFD

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...

AS OF 300 AM THURSDAY...

THE OVERALL SYNOPTIC PATTERN CONTINUES TO TAKE AN UPPER TROUGH

CURRENTLY IN THE VICINITY OF SOUTHERN CA AND THEN MOVES THE WAVE

EAST ACROSS THE SOUTH CENTRAL UNITED STATES WHERE IT THEN PHASES

WITH NORTHERN STREAM ENERGY DIVING OUT OF CANADA FRIDAY INTO

SATURDAY. RESULTANT SURFACE CYCLOGENESIS OVER THE NORTHERN GULF

COAST WILL THEN LIFT NORTHEAST SATURDAY INTO SUNDAY ALONG THE

SOUTHEAST COAST AND EVENTUALLY NORTH ALONG THE EAST COAST.

UNCERTAINTY AND MODEL DIFFERENCES STILL REVOLVE AROUND THE EXACT

TRACK OF THE SURFACE LOW. THE ECMWF HAS BEEN VERY CONSISTENT IN

BEING THE SLOWEST AND FURTHEST WEST (VERY CLOSE TO THE COAST) AS IT

TRACKS THE SURFACE LOW ACROSS THE NORTHERN GULF OF MEXICO BEFORE

BOMBING OFF THE CAROLINA COAST ON SUNDAY. THIS SOLUTION WOULD RESULT

IN A SIGNIFICANT SNOW EVENT FOR ALL OF CENTRAL NORTH CAROLINA.

HOWEVER...THE PAST COUPLE OF RUNS OF THE GFS/GEM MODELS HAVE PLACED

THE TRACK OF THE SURFACE LOW FURTHER OFFSHORE...RESULTING IN LESS IN

THE WAY OF QPF AMOUNTS. IT SHOULD BE NOTED THAT THE LATEST RUN OF

THE ECMWF (23/00Z) HAS SHIFTED SLIGHTLY TO THE EAST AND THIS TREND

WILL HAVE TO BE MONITORED CLOSELY OVER THE NEXT COUPLE OF RUNS.

NEVERTHELESS...MOST OF THE PRECIP IS STILL EXPECTED LATE CHRISTMAS

DAY/NIGHT...BUT WILL LEAVE A SLIGHT CHANCE IN FOR THE NORTHWEST

EARLY SATURDAY DUE TO THE TIMING UNCERTAINTIES. WILL THEN GRADUALLY

TREND POPS OUT OF THE REGION FROM SOUTHWEST TO NORTHEAST ON SUNDAY

AND INTO THE OVERNIGHT HOURS. THE PREDOMINANT P-TYPE NOMOGRAM PLOTS

CONTINUE TO INDICATE ALL SNOW ACROSS CENTRAL NC...WITH ONLY A SMALL

WINDOW OF RAIN AND/OR SNOW ACROSS THE SOUTHEAST AT THE ONSET OF THE

PRECIP. THEREFORE...THE GREATEST FORECAST CHALLENGE CONTINUES TO BE

JUST HOW MUCH SNOW WE WILL RECEIVE...AS THIS HAS THE POTENTIAL OF

BECOMING A SIGNIFICANT SNOW EVENT.

[strongwxnc]

This place died last night...

06NAM is real light with the qpf for NC. GFS was better and little wetter than the nam.

GSP continues to favor the euro and the new HPC guidance.

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC

606 AM EST THU DEC 23 2010

.SHORT TERM /FRIDAY THROUGH SUNDAY/...

AS OF 330 AM THURSDAY...THE UPPER WAVE THAT WILL EVENTUALLY IMPACT

THE SOUTHEAST ON CHRISTMAS DAY HAS MOVED ONSHORE OVER SRN CA...SO

HOPEFULLY THE NUMERICAL MODELS WILL COME INTO BETTER AGREEMENT NOW

THAT WE ARE 72 HOURS OUT. AT THIS TIME...THOUGH...THERE REMAINS

ENOUGH DISAGREEMENT AMONG THE VARIOUS MODEL SOLUTIONS TO KEEP

CONFIDENCE IN CHECK AND UNCERTAINTY IN THE DETAILS ABOUT HOW THIS

ONE WILL PLAY OUT. THE 00Z RUNS OF THE GFS AND NAM HAVE A MUCH

FARTHER NORTH LOW TRACK AND ARE STILL RELATIVELY FAST. THE GEM IS

WEAK AND FARTHER SOUTH. MEANWHILE...THE 00Z ECMWF CONTINUES TO SHOW

DECENT CONSISTENCY FROM ONE RUN TO THE NEXT IN TERMS OF MOVING THE

LOW ALONG THE NORTHERN GULF COAST SATURDAY AND THEN DEEPENING THE

LOW OVER THE GULF STREAM OFF THE SOUTHEAST COAST SUNDAY MORNING. I

WILL CONTINUE TO MORE OR LESS HANG MY HAT ON THE ECMWF RUN BECAUSE

OF ITS CONSISTENCY...WITH A NOD TOWARD THE FASTER MODELS FOR THE

TIMING. EITHER WAY...IT LOOKS LIKE FRIDAY WILL REMAIN DRY WITH TEMPS

BELOW NORMAL AS THE COOL AIR CONTINUES TO MOVE IN AHEAD OF THE LOW.

ISENTROPIC UPGLIDE SHOULD SPREAD IN FROM THE WEST AFTER SUNSET WITH

PRECIP DEVELOPING ALOFT FROM WEST TO EAST AND FROM THE MID LEVELS

DOWNWARD AFTER SUNSET. IT SHOULD TAKE AWHILE FOR THE PRECIP TO WORK

DOWN THROUGH THE DRY AIR AT LOW LEVELS...SO BY SUNRISE ON CHRISTMAS

DAY THE LEADING EDGE OF THE PRECIP WILL PROBABLY REMAIN OVER THE

MTNS. CONTINUED UPGLIDE AND FRONTOGENESIS ALOFT AND AHEAD OF THE LOW

WILL STEADILY BRING THE PRECIP EASTWARD ACROSS THE FORECAST AREA. IN

THESE SITUATIONS...A DEFORMATION ZONE TYPICALLY SETS UP TO THE NORTH

AND WEST OF THE DEVELOPING LOW...AND WOULD FORCE THE BEST PRECIP.

THIS WILL PROBABLY HAPPEN SOMEWHERE OVER THE WESTERN HALF OF THE

CAROLINAS SATURDAY NIGHT...BUT WHERE IS TOO DIFFICULT TO PIN DOWN AT

THIS POINT. AS THE LOW MOVES UP THE COAST ON SUNDAY MORNING THIS

DEFORMATION ZONE WOULD PIVOT...PROBABLY TO OUR EAST...AND MOVE OUT

OF THE AREA...ENDING THE PRECIP. IF THE TIMING OF THE FASTER MODELS

IS CORRECT THEN PRECIP WOULD END SATURDAY EVENING...WHILE IF THE

ECMWF IS ULTIMATELY CORRECT THEN PRECIP WOULD LINGER OVER THE

WESTERN PIEDMONT OF NC INTO SUNDAY MORNING. AT THIS POINT...THERE IS

TOO MUCH UNCERTAINTY TO SAY IF THE MAIN PRECIP WILL BE SATURDAY

AFTERNOON OR SATURDAY NIGHT...SO THE PROBABILITY WILL BE HELD IN THE

LIKELY CATEGORY FOR BOTH PERIODS. AS THE LOW MOVES OUT SOME TIME ON

SUNDAY WE SHOULD TRANSITION TO A NW FLOW SNOW EVENT OVER THE MTNS

ALONG THE TN BORDER. AS FOR PRECIPITATION TYPE...MODEL FORECAST

SOUNDINGS STILL SUGGEST IT SHOULD BE A RAIN VS SNOW CONCERN.

BOUNDARY LAYER TEMPS WILL BE THE KEY. THE NUMERICAL GUIDANCE STILL

LOOKS TOO WARM FOR HIGH TEMPS SATURDAY AND THE FORECAST CONTINUES TO

UNDERCUT THE GUIDANCE BY SEVERAL CATEGORIES WITH THE EXPECTATION

THAT DENSE CLOUD COVER AND PRECIP FALLING ALOFT IN THE MORNING WILL

DRASTICALLY INHIBIT HEATING BEFORE THE PRECIP MAKES IT TO THE

GROUND. WHEN IT DOES...IT COULD BEGIN AS A BRIEF PERIOD OF RAIN AND

SLEET...BEFORE IT CHANGES OVER TO SNOW AS THE LOW LEVEL ATMOSPHERE

COOLS ACROSS ALL BUT THE AREA TO THE SOUTH OF A LINE ROUGHLY FROM

CARNESVILLE TO HARTWELL... ANDERSON...AND LAURENS. TO THE NORTH OF

THAT LINE...THE BULK OF THE PRECIP WILL BE SNOW THROUGH THE EVENT.

AS FOR HOW MUCH...THAT IS EVEN MORE UNCERTAIN...AND AT THIS TIME THE

BEST CALL IS FOR SOMETHING IN THE RANGE FROM ONE TO FIVE INCHES

BASED ON AN AVERAGE OF THE MODEL GUIDANCE. THERE IS STILL SOME

POTENTIAL FOR SOME LOCATIONS TO GET HEAVY SNOW. BOTTOM LINE...IT

STILL LOOKS FAVORABLE FOR SNOW TO FALL ON CHRISTMAS DAY...MAINLY

AFTER NOON...ACROSS MOST OF THE WESTERN CAROLINAS AND EXTREME

NORTHEAST GEORGIA.

[DaculaWeather]

CAE still calling for snow

BASED ON LATEST GUIDANCE LITTLE CHANGE MADE TO EXTENDED

FORECAST...

CONTINUED HIGH UNCERTAINTY REGARDING TRACK AND EVOLUTION OF

CAROLINA STORM LATE SATURDAY AND SUNDAY. 00Z GFS/NAM MODELS

FURTHER NORTH WITH SURFACE LOW TRACK ACROSS GULF COAST...AND

FASTER/WEAKER THAN ECMWF/GEM. ECMWF TRACK STILL MORE FAVORABLE FOR

WINTRY PRECIPITATION THAN GFS...WHICH IS ACROSS NORTH CENTRAL

FLORIDA THEN NORTHEAST OFF THE SOUTH CAROLINA COAST BY EARLY SUNDAY.

TRACK OF THE STORM DEPENDS CONSIDERABLY ON NORTHERN STREAM

SHORT WAVE DETAILS ROTATING THROUGH DEVELOPING LONG WAVE UPPER

TROUGH IN THE EASTERN STATES SATURDAY/SUNDAY. THE KEY TO THIS

EVENT WILL BE HOW WELL THE NORTHERN STREAM ENERGY PHASES WITH THE

POTENT CLOSED LOW CURRENTLY OFF THE CALIFORNIA COAST...AS IT MOVES

EAST ACROSS THE SOUTHERN PART OF THE COUNTRY. THIS WILL DETERMINE

THE EVENTUAL TRACK OF THE SURFACE LOW AND THE DEGREE TO WHICH IS

DEEPENS AS IT MOVES UP THE COAST. LATEST GFS/NAM SUPPORT MAINLY

RAIN THROUGH AT LEAST 00Z SUNDAY...AND RAIN/SNOW MIXING NORTHERN

MIDLANDS. ECMWF SUPPORTS MORE WINTRY PRECIPITATION...FOR A LONGER

PERIOD SATURDAY NIGHT INTO SUNDAY. GIVING SPECIFIC SNOW AMOUNTS

THIS FAR OUT IN THE FORECAST IS RELATIVELY MEANINGLESS GIVEN THE

UNCERTAINTY AND THE RANGE OF POSSIBLE SCENARIOS.

HOWEVER...SNOWFALL OVER THE FORECAST AREA COULD RANGE FROM A

DUSTING OR LIGHT ACCUMULATION TO SEVERAL INCHES IF EVERYTHING

COMES TOGETHER AND A DEFORMATION ZONE SETS UP NORTHWEST OF THE

LOW. THERE IS INCREASING CONFIDENCE THAT THERE WILL BE SOME

SNOWFALL IN THE FORECAST AREA THOUGH...BUT AGAIN OTHER FACTORS

SUCH AS GROUND TEMPERATURES WILL ALSO HAVE A NEGATIVE IMPACT ON

ANY ACCUMULATIONS.

GIVEN THE CONTINUED UNCERTAINTY WITH AN EVENT STILL 3-4 DAYS

AWAY...ELECTED TO MAKE ONLY MINOR CHANGES TO THE WEATHER

GRIDS...CONTINUING TO ADVERTISE MAINLY LOW CHANCES OF RAIN

SATURDAY AFTERNOON WITH POSSIBLE MIXING WITH OR CHANGING TO SNOW

ACROSS THE NORTHERN MIDLANDS. THE BEST CHANCES FOR ALL

PRECIPITATION...LIQUID OR FROZEN LOOKS TO BE DURING THE PERIOD

FROM SATURDAY NIGHT INTO EARLY SUNDAY. TEMPERATURES SHOULD REMAIN

WELL BELOW NORMAL SATURDAY AND SUNDAY STRUGGLING INTO THE 40S.

[DaculaWeather]

Reading the AFD's, it sounds like the gfs is coming more in line with the euro's. Not much to look at on radar out west right now.

[strongwxnc]

I agree. I did miss all the disco from last night...I see the euro trended faster and east. However, at least KGSP continues to paint the same picture (with the addition of P-types issues) that they were yesterday.

Reading the AFD's, it sounds like the gfs is coming more in line with the euro's. Not much to look at on radar out west right now.

[DaculaWeather]

Amazing how quiet it is right now. I feel like I have to type quieter so I don't wake everyone up.

I missed most of last night too. Sounded like some discouraged people though.

[Lowpressure]

Sure, hopes seemed crushed for some. When level heads kept warning, be careful this may be too good to be true. Models are still having a hard time figuring this out. ECMWF has been remarkably consistant and may still pan out. I have felt the whole time that something in the middle with end up as the result. Low track through the deep south, but not the bomb the ECMWF depicted. We will see.

[Cold Rain]

Good morning, all! New thread is up:

[eyes2theskies]

Sure, hopes seemed crushed for some. When level heads kept warning, be careful this may be too good to be true. Models are still having a hard time figuring this out. ECMWF has been remarkably consistant and may still pan out. I have felt the whole time that something in the middle with end up as the result. Low track through the deep south, but not the bomb the ECMWF depicted. We will see.

If I had to be anywhere right now it would be here though. Kinda in the middle

[strongwxnc]

Yep. I think the euro train is arriving at it stops to early and with a few less passengers.

However, As I showen above HPC issues its 3 day map. We are just inside the window....

Amazing how quiet it is right now. I feel like I have to type quieter so I don't wake everyone up.

I missed most of last night too. Sounded like some discouraged people though.