Christmas Storm IV

[GaWx]

Shoot, I'll take that in a heartbeat! And if I could get some sleet with that order, I'd be happy as a pig in mud.

But my many years of experience in Ga. say, "not so quick, Bunky, we can slap you down with 10 seconds left." So, I'll wait patiently to see what Santa brings.

How about Sav. ? Did they stay in the mix? I'd kind of like to see sticking snows two years running there. T

Sav ~1.5"..would be biggest since 1989. Nighty night.

[CAD_Wedge_NC]

I don't have any idea what data was ingested to cause this change once the system came on-shore. The models saw something tonight that abruptly changed everything. Possible bad data?? Who knows??

[Pilotwx]

Put a little salt in the wound! For us back in the west .Did just what the GFS did went a little wide right to come back left, of course for our neighbors to the North!

On a side note will have no problem flying a kite! It will even be clear!

This is from Allan's site, 978 off the VA capes. Storm sheds 30mb in 24 hours, I imagine QPF totals would be a little higher if this actually verified.

[NCSNOW]

Did you honesty expect them to hold the same solution till verification? Even this run of the EC is somewhat extreme compared to the other guidance tonight. Granted, while not as extreme as the 12z run, a widespread 5" event in the SE does not happen all that often. I stated yesterday, that for a model to be able to resolve subtle differences in the atmosphere 120hrs out is highly unlikely. The 0z runs tomorrow night (actually tonight since it is already Thursday), will be the first set outside of the dead zone, and we should begin to see a consensus start to form. But we do already see a general consensus on the ens means, which are very similar, and likely paint a more accurate picture of what is going to happen at this range.

post of the nite. Guranteed what verifies this weekend , not one model has laid out ATM. Took me a few knockdowwns and suprises (Jan/2000) to learn models are a tool, not the actual outcome of our weather. Still potential folks.

[WeatherNC]

0z 48hr WRF's are out on NCEP, huge difference between the two.

NMM

ARW

[Pilotwx]

Here is something that just doesn't make sense with the runs over the past 2 or 3 days the moisture QPF just seems so underdone. With A LOW 978 near the coast it still is just spitting out .10 for DC

[WeatherNC]

Here is something that just doesn't make sense with the runs over the past 2 or 3 days the moisture QPF just seems so underdone. With A LOW 978 near the coast it still is just spitting out .10 for DC

0z GFS ens members are coming out on Allan's site, through 90 hrs so far, none of them look bad...

http://raleighwx.americanwx.com/models/gfsensemble/members/00zf084.html

Good Night!

[WeatherNC]

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

158 AM EST THU DEC 23 2010

VALID 12Z MON DEC 27 2010 - 12Z THU DEC 30 2010

...EAST COAST CYCLONE STILL INDICATED FOR DAYS 3 THROUGH 5...

USED THE 00Z/23 ECMWF FOR THE PRELIMINARY FRONTS AND PRESSURES FOR

DAYS 3 THROUGH 5...SWITCHING TO AN EVEN BLEND WITH THE 12Z/22

ECENS MEAN THEREAFTER TO ADDRESS THE UNCERTAINTIES IN SYNOPTIC

DETAIL INHERENT TO THAT TIME RANGE IN A MORE ZONAL FLOW PATTERN.

THE 00Z/23 NAM AND GFS WERE LOW PROBABILITY OUTLIERS AT THE END OF

THE SHORT RANGE...OUT OF SYNC WITH THE GEM

GLOBAL...UKMET...ECMWF...AND GEFS MEAN. THE NAM AND GFS INDICATED

A MORE RAPID PROGRESSION THE BIG SYNOPTIC WAVE HEADED FOR THE EAST

COAST VIA EARLIER INTERACTION WITH THE NORTHERN STREAM OVER THE

PLAINS STATES. THE CURRENT DETERMINISTIC ECMWF RUN HAS COME EAST

INTO THE MOST RECENT ECENS MEAN SLOT OFF THE EAST COAST...AND THE

GEFS MEAN HAS COME WEST TO MEET IT...INSTILLING MORE CONFIDENCE

WITH THE TRACK OF THIS LOW THAN PREVIOUS FORECAST PACKAGES. THE

CLOSING OFF OF THE MID LEVEL VORTEX ALONG THE EAST COAST EARLY IN

THE PERIOD WILL ACT AS A STONE TO THE UPSTREAM FLOW...WITH SPLIT

ENERGY OVER THE WEST NOODLING ACROSS SOUTHERN CANADA AND INTO THE

DESERT SOUTHWEST. AFTER THE VORTEX DISLODGES...MUCH OF THE NATION

WILL BE AWASH IN PACIFIC AIR FOR THE FIRST TIME SINCE

NOVEMBER...WITH THE TIMING AND TRACK OF SHORTWAVE FEATURES LENDING

THEMSELVES TO MORE RELIANCE ON ENSEMBLE MEANS.

CISCO

NCEP HPC and SPC SREF (MODEL) DERIVED WINTER WEATHER IMPACT GRAPHICS Prob

http://www.hpc.ncep.noaa.gov/wwd/impactgraphics/

[HKY18]

6z nam is way different than the 0z H5 LOL looks better through 30

MUCH slower than the 0z run with the southern s/w now to see where this ends up!

[lilj4425]

Wow...closed off still at hr42. Slowed down too. Major differences compared to last run.

[lilj4425]

Still closed off at hr51. NAM is bringing a resurrection.

[HKY18]

northern stream is much more consolidate and stronger than 00z nam as well. this look like 2 different models LMAO

[WeatherNC]

Wow...closed off still at hr42. Slowed down too. Major differences compared to last run.

[HKY18]

amazing the amount of difference no matter the outcome good god that is one of the biggest change in one run i have seen in a long time!

[HKY18]

s/w moving into gulf at hr60 northern stream is trying great ridge out west as well. this is a trend in the right direction for sure

[WeatherNC]

Going to go BOOM this run, guaranteed!

[HKY18]

phase beginning at hr 63

[lilj4425]

That northern stream is really digging at hr69. Shortwave too far south?

[WeatherNC]

this might be a nuclear bomb not even dynamite LOL

I don't know, may have spoken to soon, the sw is in the central gulf, and I am not sure the northern stream will be able to catch it in time.

[HKY18]

06z nam:

0z NAM

[HKY18]

at 72hrs its dampening the s/w wth lol i might not do it this run

[HKY18]

NAM just digs the thing too far south if we could get an in between track of the 00z and 6z run then this thing would explode.

[DLI4SCwx]

Willing to bet 12z will give us what we want. Or close to it at least.

[WeatherNC]

[lilj4425]

Another excellent GSP AFD:

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.

BEING THAT IT WOULD BE AT LEAST AN INCH OF SNOW ON CHRISTMAS DAY IF

THE FORECAST WORKS OUT...WE WOULD TECHNICALLY HAVE A WHITE

CHRISTMAS. THAT WOULD MAKE IT A HISTORIC EVENT FOR THIS AREA BECAUSE

IT HAS BEEN MORE THAN 50 TO 60 YEARS OR SO SINCE THE LAST WHITE

CHRISTMAS OVER THE PIEDMONT. TAKEN IN THE CONTEXT OF HAVING A WHITE

CHRISTMAS...EVEN ONE INCH OF SNOW WOULD MAKE IT A MEMORABLE EVENT

BECAUSE OF THE DAY...EVEN IF THE TOTAL ACCUMULATION FROM THE STORM

IS WELL BELOW THE AMOUNTS SEEN IN OTHER HISTORICAL WINTER STORMS.

[lilj4425]

GFS a little slower with our s/w at hr24.

[crossthread]

KILM AFD...

3:30 am this morning..

Short term /Friday through Saturday night/...

as of 3 am Thursday...high pressure and Delaware-amplifying upper pattern

in place on Friday. Flow remains northerly with weak warm advection not

starting until late Friday night. Limited air mass modification on

Friday...hindered by increasing high cloud later in the afternoon.

Highs on Friday will be very similar if not slightly cooler than Thursday

given temperatures starting out 5 to 10 degrees Friday morning.

Aforementioned high cloud continues to thicken up Friday night.

Increase in clouds and weak warm advection after midnight will hold

lows in the upper 20s to around 30.

Second half of the forecast continues to be problematic. Very little

agreement between the NAM/GFS/ECMWF/Canadian solutions...some of

which also lack run to run consistency. Have decided to lean in

favor of a NAM/European model (ecmwf) blend...which his close to but slightly faster

than yesterdays HPC solution. Additionally...a portion of the GFS

ensembles support a similar solution. As a side note...the 00z

operational GFS is one of the fastest solutions when compared to its

ensemble members and is being discounted at this time.

Feel fairly confident precipitation will not be an issue Christmas day and

that highs will range from close to 50 near to the coast to around

40 far inland. Combination of Arctic air mass and expected slow

evolution of storm system will probably delay the onset of precipitation

until Sat evening. Track/timing/strength of the system will

determine what happens and so far do not have a good handle on this.

Current forecast calls for rain changing to rain snow or all snow

Sat night.This is not much of a change from previous forecast.

Still way to early to start talking about potential snowfall

amounts..especially as this will be highly dependent on track. Lows

will be near to just below freezing Sat night.

Despite all the uncertainty there is some good news.The feature

that is ultimately responsible for developing the storm has moved

over the southwestern US and will be sampled by 12z radiosonde observations. By this

time tomorrow this should help provide a clearer picture as to what

impact the storm will have on the Carolinas.

&&

Long term /Sunday through Wednesday/...

as of 3 am Thursday...beginning of the period will be dominated by

storm system affecting the southeastern US. Still a lot of

uncertainty with respect to the storm...but it seems likely that a

large portion of the area will see some snow as the low passes

offshore. Still unsure as to how much and exactly when...but these

are details that should become clearer within the next 24 hours.

Solution between the faster GFS and slower European model (ecmwf) is favored...with

low pressure deepening off the southeast coast at the start of the

period. Latest European model (ecmwf) is a little faster...especially from Sun night

on and only hints at some lingering flurries for Monday.

Another shot of Arctic air will spread over the southeast as strong

500 mb trough pushes south. Latest European model (ecmwf)/GFS are quicker to move the

Arctic air mass out than previous runs and is not favored. Expect

the cold air will hang on into Tuesday night or Wednesday before building 500 mb

ridge and westerly low level flow is able to start a warm up.

Temperatures will continue below climatology with highs around or below 40

and lows in the upper teens to around 20.

[lilj4425]

GFS has closed low at hr42 over Dallas. More qpf over Texas. Slower than last run. Still closed off near Texas/Louisiana border at hr51.

Edit: closed off over Baton Rouge at hr54

Edit: 1012 low over Panhandle of Florida at hr66. Northern stream is trying.

[DaculaWeather]

FFC

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...

MAJOR DIFFERENCES CONTINUE BETWEEN THE GFS AND ECMWF IN THE LONG

TERM. WHILE THE GFS HAS THE CHRISTMAS DAY STORM MOVING UP THE MID

ATLANTIC COAST ON SUNDAY...THE ECMWF HAS THE SURFACE LOW JUST

EMERGING OFF THE COAST OF JACKSONVILLE KEEPING MOISTURE OVER THE

CWA. THE LATTER BEING THE CASE...SNOW WOULD CONTINUE TO FALL OVER

MUCH OF THE CWA. WILL GO WITH A COMPROMISE LEANING HEAVILY TOWARD

THE GFS SOLUTION. ARCTIC AIR MOVES INTO THE CWA SUNDAY THROUGH

TUESDAY. THE GFS IS QUICKER TO WARM US UP BUT BY WEDNESDAY BOTH

MODELS HAVE THE CWA IN A ZONAL FLOW...THIS THEY DO AGREE ON. GFS HAS

A SHORT WAVE MOVING INTO THE CWA WEDNESDAY NIGHT AND THURSDAY AND

THE ECMWF KEEPS US DRY. AT THIS TIME WILL GO WITH THE DRY CONDITIONS

AS GFS DOES HAVE A DIFFICULT TIME WITH SHORT WAVES IN THE LONG TERM.

[DaculaWeather]

And GSP

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.