December-Wet/Stormy New Years Eve Ahead

[srainhoutx]

potential to have wide societal impacts

What do you mean by wide societal impacts?

While we are still a couple of days out and there remains some uncertainty in the eventual track of the Storm system, there strong indications that both winter weather as well as a severe potential may well unfold across portions of E Texas extending E into the Deep South S of the I-20 Corridor. Further N into Eastern Oklahoma/Arkansas and on ENE in Mid West/Tennessee Valley within the cold sector, a variety of winter weather including snow and ice and very gusty winds and blowing snow creating the potential for a high impact event affecting travel as well as societal impacts during the busy Holiday period. The storm system is currently nearing the California Coast and should be onshore and in the RAOB network tomorrow. One concern we are following closely in the South is the Severe aspect of this dynamic Winter Storm. The SPC has outlined a Day 4 threat for severe storms in their Outlook. At this time the main threat appears to be damaging winds with a linear line of rapidly moving storms, but the tornado potential cannot be dismissed during the late Christmas Day time frameperiod beginning in SE Texas and extending overnight into Southern Louisiana/Mississippi and Alabama on the 26th. The severe potential may extend further E into GA/FL and SC on the 27th.

[srainhoutx]

I like to keep an eye on HPC's surface low track in their winter suite of products http://www.hpc.ncep.noaa.gov/wwd/winter_wx.shtml

12222012 08Z Winter Storm Track HPC lowtrack_ensembles.gif

12222012 lowtrack_circles.gif

but after reading SPC's 3 & 4 day forecasts, we might choose to grill our steaks x-mas eve instead of x-mas day... http://www.spc.noaa.gov/products/outlook/

unome, I changed the images to an attachment so it is smaller ~vs~ a hotlink image which is too large to be visible within our platform format. Also I'd caution folks that what those images are showing is a lead wave, not the Christmas Day Storm on the HPC charts. That will follow later this weekend via the HPC Winter Storm Track maps... The lead wave will play a pivotal role as to how things evolve for the Christmas Storm. A warm front will move N from the Western Gulf across Central/SE Texas into Louisiana during the day Christmas Eve setting the stage for the Severe potential outlined above. There are strong suggestions a Coastal Low/wave will develop along the Middle/Upper Texas Coast setting the stage for all the potential events that will follow. This appears to be a very dynamic storm complex with many implications for a large part of the Eastern half of the CONUS.

SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
239 AM EST SAT DEC 22 2012

VALID 12Z SAT DEC 22 2012 - 12Z MON DEC 24 2012

***STRONG LOW PRESSURE SYSTEM DEPARTING THE NORTHEAST U.S.***

***MORE BAD WEATHER FOR THE WEST COAST STATES***

***VERY COLD FOR THE NORTHERN PLAINS AND UPPER MIDWEST***


THE STRONG AREA OF LOW PRESSURE THAT AFFECTED MUCH OF THE CENTRAL
AND EASTERN U.S. OVER THE PAST COUPLE OF DAYS IS FORECAST TO MOVE
INTO EASTERN CANADA DURING THE DAY ON SATURDAY. SOME LINGERING
LIGHT SNOW SHOWERS ARE STILL POSSIBLE NEAR THE GREAT LAKES AND
INTO NORTHERN NEW ENGLAND THROUGH EARLY SUNDAY. THE HIGHER
ELEVATIONS OF THE CENTRAL APPALACHIANS WILL ALSO RECEIVE SOME
ADDITIONAL SNOWFALL. IN ADDITION, STRONG AND GUSTY WINDS ARE
LIKELY THROUGH SATURDAY WITH GUSTS UP TO 50 MPH POSSIBLE.

OVER THE WEST COAST STATES, STEADY RAIN AND HIGHER ELEVATION SNOW
IS EXPECTED TO CONTINUE AS ONSHORE FLOW CONTINUES UNABATED AHEAD
OF A FRONTAL TROUGH. THE HEAVIEST PRECIPITATION IS LIKELY FOR
CENTRAL AND NORTHERN CALIFORNIA, WITH A COUPLE INCHES OF RAIN FOR
COASTAL AREAS AND AT LEAST TWO FEET OF SNOW IN THE HIGHER
MOUNTAINS OF THE SIERRA NEVADA RANGE.

ELSEWHERE, BITTERLY COLD AIR WILL CONTINUE FOR THE NORTHERN PLAINS
AND UPPER MIDWEST THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK.
OVER THE DEEP SOUTH AND INTO TEXAS, MUCH COOLER AND CONSIDERABLY
DRIER WEATHER HAS ARRIVED BEHIND THE COLD FRONT AND IT WILL FEEL
MORE LIKE DECEMBER.

[unome]

thanks srain, the direct links will let everyone view the most recent forecast (not certain how often it's updated ?)

HPC Forecast Surface Low Positions (with ensemble clusters) http://www.hpc.ncep.noaa.gov/lowtracks/ ... embles.gif

HPC Forecast Surface Low Positions (with uncertainty circles) http://www.hpc.ncep.noaa.gov/wwd/lowtrack_circles.gif

SPC all convective forecasts http://www.spc.noaa.gov/products/outlook/

it will be more clear once x-mas time period falls in the Day 3 range and closer

still, I think we'll grill our steaks x-mas eve, as our current forecast calls for "partly sunny/72" vs "thunderstorms likely/65" on x-mas day. Santa will understand... and speaking of Santa, track his progress with NORAD with your kiddos ! http://www.noradsanta.org/

Glad we don't need to worry about travel weather this yr, for everyone that does, stay safe & happy trails to you & yours !



edited to fix the links, I had them reversed...

[srainhoutx]

The 12Z Euro/Canadian/Ukmet are a tad further S than the operational GFS/NAM solution with the upper trough/5H low. The non American guidance suggest snow across portions of Oklahoma and along or just S of the Red River Valley with impressive totals for Arkansas and points ENE along with some potential ice as well across Tennessee and Northern Mississippi. In the warm sector, a severe weather event potential appears to be growing from E Texas and on E into Louisiana and the Deep South.

12222012 12Z Euro 12zeuro500mbHeightAnomalyNA072.gif

12222012 12Z Euro 12zeuro500mbHeightAnomalyNA096.gif

12222012 12Z Euro 12zeurohourly850mbTempAnomalyNA072.gif

12222012 12Z Euro 12zeurohourly850mbTempAnomalyNA096.gif

[srainhoutx]

HPC Model Diagnostic Discussion for the 12Z suite of guidance:

...SFC LOW IMPACTING THE WEST COAST ON SUN...

PREFERENCE: 12Z NAM / 12Z ECMWF
CONFIDENCE: AVERAGE

REGARDING THE SFC LOW REACHING THE WEST COAST ON SUN...THE GFS
LOOKS FAST...AND THE 12Z ECMWF HAS SPED UP CLOSER TO THE CONSENSUS
BUT THE 12Z NAM AND 00Z EC MEAN ARE STILL A BIT BACK TOWARD THE
ENSEMBLE CONSENSUS...SLIGHTLY BEHIND THE 12Z ECMWF. GIVEN
DOWNSTREAM PREFERENCES...A 12Z NAM/ECMWF BLEND IS LIKELY BEST WITH
THE SFC LOW COMING INTO THE WEST COAST ON SUN GIVEN PLACEMENT IN
THE MIDDLE OF THE SPREAD...WITH CONSIDERATION OF SOME OF THE
FASTER GUIDANCE.

...SHRTWV ENERGY AMPLIFYING THROUGH THE INTERMOUNTAIN WEST ON MON
AND REACHING THE CNTRL/SRN PLAINS TUE...

PREFERENCE: 12Z ECMWF / 12Z UKMET
CONFIDENCE: BELOW AVERAGE

THE NAM IS ON THE WEAKER AND NRN SIDE OF THE MODEL SPREAD WITH
BOTH THE SHORTWAVE AND SFC LOW BY THE TIME THE SYSTEM REACHES THE
PLAINS. THE GFS HAS TRENDED QUICKER WITH THE SHORTWAVE EJECTING
OUT INTO THE PLAINS ON TUE AND IS ON THE FASTER SIDE OF THE
SPREAD. GIVEN THE 12Z CMC IS A BIT OUTSIDE OF THE
CONSENSUS...BLENDING THE 12Z ECMWF AND 12Z UKMET APPEAR THE BEST
WAY TO GO AND FALL RIGHT IN THE MIDDLE OF THE CONVERGING ENSEMBLE
SPAGHETTI LOW PLOTS...LOOKING OVER THE PAST 5 RUNS. THE 12Z ECMWF
LOOKS MOSTLY UNCHANGED FROM ITS 00Z RUN WITH THIS SYSTEM.

[srainhoutx]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NORMAN OK
340 PM CST SAT DEC 22 2012

OKZ004>048-050>052-TXZ083>090-231200-
HARPER-WOODS-ALFALFA-GRANT-KAY-ELLIS-WOODWARD-MAJOR-GARFIELD-
NOBLE-ROGER MILLS-DEWEY-CUSTER-BLAINE-KINGFISHER-LOGAN-PAYNE-
BECKHAM-WASHITA-CADDO-CANADIAN-OKLAHOMA-LINCOLN-GRADY-MCCLAIN-
CLEVELAND-POTTAWATOMIE-SEMINOLE-HUGHES-HARMON-GREER-KIOWA-JACKSON-
TILLMAN-COMANCHE-STEPHENS-GARVIN-MURRAY-PONTOTOC-COAL-COTTON-
JEFFERSON-CARTER-JOHNSTON-ATOKA-LOVE-MARSHALL-BRYAN-HARDEMAN-
FOARD-WILBARGER-WICHITA-KNOX-BAYLOR-ARCHER-CLAY-
INCLUDING THE CITIES OF...BUFFALO...ALVA...CHEROKEE...MEDFORD...
PONCA CITY...ARNETT...WOODWARD...FAIRVIEW...ENID...PERRY...
CHEYENNE...TALOGA...WEATHERFORD...CLINTON...WATONGA...
KINGFISHER...GUTHRIE...STILLWATER...ELK CITY...SAYRE...CORDELL...
ANADARKO...YUKON...EL RENO...MUSTANG...OKLAHOMA CITY...CHANDLER...
CHICKASHA...PURCELL...NORMAN...MOORE...SHAWNEE...SEMINOLE...
HOLDENVILLE...HOLLIS...MANGUM...HOBART...ALTUS...FREDERICK...
LAWTON...DUNCAN...PAULS VALLEY...SULPHUR...ADA...COALGATE...
WALTERS...WAURIKA...ARDMORE...TISHOMINGO...ATOKA...MARIETTA...
MADILL...DURANT...QUANAH...CHILLICOTHE...CROWELL...VERNON...
WICHITA FALLS...MUNDAY...KNOX CITY...SEYMOUR...ARCHER CITY...
HOLLIDAY...LAKESIDE CITY...HENRIETTA
340 PM CST SAT DEC 22 2012

...WINTER PRECIPITATION REMAINS POSSIBLE CHRISTMAS DAY...

WEATHER FORECAST MODELS CONTINUE TO DEPICT THE POTENTIAL FOR A
WINTER STORM TO AFFECT OKLAHOMA AND NORTHERN TEXAS CHRISTMAS EVE
NIGHT THROUGH CHRISTMAS NIGHT...WITH THE BEST CHANCES FOR
PRECIPITATION ON CHRISTMAS DAY. A BRIEF PERIOD OF A VERY LIGHT
WINTRY MIX WILL BE POSSIBLE CHRISTMAS EVE NIGHT ACROSS WESTERN
OKLAHOMA...WITH LIGHT RAIN POSSIBLE ACROSS SOUTHERN OKLAHOMA AND
WESTERN NORTH TEXAS. THE PRECIPITATION WILL THEN CHANGE OVER TO
SNOW ON CHRISTMAS. MODERATE TO STRONG WINDS COULD ALSO LEAD TO
SOME BLOWING AND DRIFTING OF THE SNOW IN SOME AREAS BUT BLIZZARD
CONDITIONS APPEAR UNLIKELY. THE SNOW IS EXPECTED TO END FROM WEST
TO EAST CHRISTMAS NIGHT.

THE AMOUNT OF SNOW AND WHERE THE HEAVIEST SNOWFALL WILL OCCUR
REMAINS UNCERTAIN...AS DIFFERENCES REMAIN BETWEEN THE SOLUTIONS
FROM THE COMPUTER MODELS. SOME MODELS CONTINUE THE TRACK OF HEAVIEST
SNOW ACROSS NORTHERN PORTIONS OF OKLAHOMA...WHILE OTHERS TAKE IT
ACROSS SOUTHERN OKLAHOMA INTO NORTHERN TEXAS. CONTINUING WITH A
CONSENSUS APPROACH...THE HIGHEST SNOW TOTALS ARE EXPECTED FROM WEST
CENTRAL OKLAHOMA INTO CENTRAL AND SOUTHEAST OKLAHOMA WHERE AMOUNTS
COULD AVERAGE THREE TO SIX INCHES.

WITH THE VARIATION IN FORECAST TRACKS AND SNOW AMOUNTS...EVERYONE
ACROSS THE STATE OF OKLAHOMA AND THOSE ACROSS NORTHERN TEXAS
SHOULD PAY CLOSE ATTENTION TO REFINED FORECASTS OVER THE WEEKEND.
IF YOU ARE PLANNING TO TRAVEL ACROSS THE SOUTHERN PLAINS FOR THE
UPCOMING HOLIDAY WEEK...HAVE A CONTINGENCY PLAN IN PLACE AND
PREPARE FOR WEATHER-RELATED DELAYS AND CANCELLATIONS.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TULSA OK
339 PM CST SAT DEC 22 2012

ARZ001-002-010-011-019-020-029-OKZ049-053>076-230945-
BENTON-CARROLL-WASHINGTON AR-MADISON-CRAWFORD-FRANKLIN-SEBASTIAN-
PUSHMATAHA-CHOCTAW-OSAGE-WASHINGTON OK-NOWATA-CRAIG-OTTAWA-PAWNEE-
TULSA-ROGERS-MAYES-DELAWARE-CREEK-OKFUSKEE-OKMULGEE-WAGONER-
CHEROKEE-ADAIR-MUSKOGEE-MCINTOSH-SEQUOYAH-PITTSBURG-HASKELL-
LATIMER-LE FLORE-
INCLUDING THE CITIES OF...ROGERS...BENTONVILLE...BERRYVILLE...
EUREKA SPRINGS...FAYETTEVILLE...SPRINGDALE...HUNTSVILLE...
VAN BUREN...OZARK...CHARLESTON...FORT SMITH...ANTLERS...CLAYTON...
HUGO...PAWHUSKA...BARTLESVILLE...NOWATA...VINITA...MIAMI...
PAWNEE...TULSA...CLAREMORE...PRYOR...JAY...BRISTOW...OKEMAH...
OKMULGEE...WAGONER...TAHLEQUAH...STILWELL...MUSKOGEE...EUFAULA...
SALLISAW...MCALESTER...STIGLER...WILBURTON...POTEAU
339 PM CST SAT DEC 22 2012

...CHRISTMAS DAY/NIGHT WINTER WEATHER POTENTIAL ACROSS EASTERN
OKLAHOMA AND NORTHWEST ARKANSAS...

A WINTER STORM WILL DEVELOP OVER THE SOUTHERN PLAINS CHRISTMAS DAY
WITH THE POTENTIAL FOR ACCUMULATING SNOW ACROSS MUCH OF EASTERN
OKLAHOMA AND NORTHWESTERN ARKANSAS. ALTHOUGH THE EXACT TRACK
REMAINS SOMEWHAT UNCERTAIN...MOST OF THE REGION WILL LIKELY RECEIVE
AT LEAST AN INCH OR TWO FROM THIS SYSTEM. THE STORM WILL LIKELY
LAY DOWN A HEAVIER BAND OF SNOW ACROSS A PORTION OF THE REGION.
LATEST DATA SUGGEST THE GREATEST SNOW POTENTIAL WILL OCCUR ALONG
AND SOUTH OF A EUFAULA TO EUREKA SPRINGS LINE. PEOPLE TRAVELING
ACROSS THE REGION CHRISTMAS DAY SHOULD CONTINUE TO MONITOR THE
LATEST FORECAST.

WE ARE CURRENTLY POSTING PRELIMINARY SNOW AMOUNT INFORMATION TO OUR
DECISION SUPPORT PAGE AT WWW.WEATHER.GOV/TULSA/DSP/DSP.PHP. THE
LOCATION AND MAGNITUDE OF ANY WINTER WEATHER IMPACTS WILL CONTINUE
TO BE REFINED AS THIS SYSTEM APPROACHES. GIVEN THE SYSTEM IS STILL
OFF THE NORTHWEST PACIFIC COAST...ANY SMALL DEVIATION IN THE STORM
TRACK COULD RESULT IN SIGNIFICANT FORECAST CHANGES EARLY NEXT
WEEK. THEREFORE...SNOW AMOUNTS WILL CONTINUE TO BE ADJUSTED AND
THE LOCATION OF THE HEAVIEST SNOW SWATH COULD SHIFT SEVERAL COUNTIES
IN ANY DIRECTION. PERSONS ACROSS SOUTHEAST OKLAHOMA AND NORTHWEST
ARKANSAS SHOULD BE PREPARED FOR ACCUMULATING SNOW CHRISTMAS DAY
INTO CHRISTMAS NIGHT. ROADS MAY BECOME SLICK AND HAZARDOUS CAUSING
TRAVEL DELAYS.




SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
205 PM CST SAT DEC 22 2012

TXZ091>095-100>107-116>123-231200-
MONTAGUE-COOKE-GRAYSON-FANNIN-LAMAR-YOUNG-JACK-WISE-DENTON-COLLIN-
HUNT-DELTA-HOPKINS-PALO PINTO-PARKER-TARRANT-DALLAS-ROCKWALL-
KAUFMAN-VAN ZANDT-RAINS-
205 PM CST SAT DEC 22 2012

...WINTER WEATHER OUTLOOK FOR DECEMBER 25TH...

A STRONG STORM SYSTEM IS EXPECTED TO MOVE ACROSS THE REGION ON
CHRISTMAS DAY. BASED ON THE LATEST FORECAST DATA...THERE WILL BE A
GOOD CHANCE OF A COLD RAIN ON CHRISTMAS DAY ACROSS NORTH AND
CENTRAL TEXAS. ALONG AND TO THE NORTH OF I-20...ATMOSPHERIC
PROFILES WILL BECOME COLD ENOUGH FOR THE RAIN TO MIX WITH OR
CHANGE OVER TO SNOW DURING THE AFTERNOON AND EVENING HOURS. THE
LATEST MODEL GUIDANCE SUGGESTS SNOWFALL ACCUMULATIONS UP TO 2
INCHES ARE POSSIBLE CHRISTMAS AFTERNOON AND EVENING ALONG AND
NORTH OF A BOWIE TO EMORY LINE. SOUTH OF THIS LINE...LIGHT
ACCUMULATIONS OF SNOW ARE POSSIBLE.

AS THE CHANGE OVER TO SNOW OCCURS...NORTHWEST WINDS ARE EXPECTED
TO INCREASE IN SPEED TO 20 TO 30 MPH. ANY SNOW ACCUMULATIONS
WILL BLOW AROUND IN THESE WINDS...WHICH MAY REDUCE VISIBILITY IF
TRAVELING AFTER SUNSET ON CHRISTMAS DAY.

AS OF THIS AFTERNOON...THE UPPER LEVEL STORM SYSTEM WAS ENTERING
THE PACIFIC NORTHWEST. AT THIS TIME...THERE STILL REMAINS A GREAT
DEAL OF UNCERTAINTY REGARDING THE EXACT TRACK AND ANY ASSOCIATED
WINTRY PRECIPITATION FALLING OVER NORTH TEXAS ON CHRISTMAS DAY. IF
THE TRACK OF THE SYSTEM WERE TO SHIFT FARTHER SOUTH...THE
POTENTIAL FOR HIGHER SNOWFALL ACCUMULATIONS ACROSS THE REGION
WOULD INCREASE AND THE RAIN/SNOW LINE WOULD SHIFT FARTHER TO THE
SOUTH.

IN ADDITION TO THE WINTER PRECIPITATION POTENTIAL...THERE IS ALSO
A THREAT FOR SOME SEVERE STORMS EARLY CHRISTMAS MORNING AND
POSSIBLY INTO THE DAY ON THE 25TH. THE THREAT FOR SEVERE WEATHER
AT THIS TIME IS MAINLY SOUTH OF I-20 AND EAST OF I-35. THE
DETAILS OF THE SEVERE WEATHER POTENTIAL ARE JUST NOW COMING TO
FRUITION AND WILL ALSO BE REFINED OVER THE NEXT FEW DAYS.

BOTTOM LINE...WINTRY PRECIPITATION IS POSSIBLE MAINLY ALONG AND
NORTH OF THE I-20 CORRIDOR FOR THE AFTERNOON AND EVENING HOURS OF
CHRISTMAS DAY. SOME SNOW ACCUMULATIONS UP TO 2 INCHES ARE POSSIBLE
ALONG AND NORTH OF A BOWIE TO EMORY LINE. CHECK BACK FOR THE
LATEST FORECAST UPDATES IN THE COMING DAYS AS THESE DETAILS ARE
VERY LIKELY TO CHANGE WITH FUTURE FORECASTS.


SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SHREVEPORT LA
156 PM CST SAT DEC 22 2012

ARZ050-051-059>061-070>073-LAZ001>006-OKZ077-TXZ096-097-108>112-
124>126-136>138-231200-
BOSSIER-BOWIE-CADDO-CAMP-CASS-CLAIBORNE-COLUMBIA-FRANKLIN-GREGG-
HARRISON-HEMPSTEAD-HOWARD-LAFAYETTE-LINCOLN-LITTLE RIVER-MARION-
MCCURTAIN-MILLER-MORRIS-NEVADA-RED RIVER TX-SEVIER-SMITH-TITUS-
UNION AR-UNION LA-UPSHUR-WEBSTER-WOOD-
156 PM CST SAT DEC 22 2012

...WINTER WEATHER WILL BE POSSIBLE CHRISTMAS AFTERNOON AND NIGHT
MAINLY NORTH OF THE INTERSTATE 20 CORRIDOR...

A STRONG UPPER LEVEL STORM SYSTEM IS EXPECTED TO DEVELOP
CHRISTMAS DAY OVER OKLAHOMA...AS VERY COLD AIR DEEPENS AND BEGINS
TO PUSH SOUTHEAST BEHIND A COLD FRONT INTO SOUTHEAST OKLAHOMA
AND SOUTHWEST ARKANSAS CHRISTMAS AFTERNOON AND EVENING. SCATTERED TO
NUMEROUS SHOWERS AND A FEW THUNDERSTORMS WILL QUICKLY DEVELOP EARLY
CHRISTMAS MORNING ACROSS THE REGION AHEAD OF THE FRONT...AND PERSIST
THROUGH AT LEAST MIDDAY AS AN UPPER LEVEL DISTURBANCE LIFTS NORTHEAST
THROUGH THE AREA. TO THE NORTH OF THE AREA OVER CENTRAL AND EASTERN
OKLAHOMA WHERE THE SUBFREEZING TEMPERATURES ARE EXPECTED...AREAS OF
SNOW WILL DEVELOP AND GRADUALLY SPREAD EAST NEAR THE COLD CORE CENTER
OF THIS STORM SYSTEM. THE RAIN IS EXPECTED TO CHANGE OVER TO A RAIN
SNOW MIX BEFORE TRANSITIONING OVER TO ALL SNOW CHRISTMAS AFTERNOON
AND EVENING OVER PORTIONS OF EXTREME NORTHEAST TEXAS...SOUTHEAST
OKLAHOMA...AND SOUTHWEST ARKANSAS...MAINLY NORTH OF THE INTERSTATE 30
CORRIDOR AS THE COLDER AIR DEEPENS OVER THESE AREAS.

SOME SNOW ACCUMULATIONS WILL BE POSSIBLE CHRISTMAS AFTERNOON AND
EVENING MAINLY NORTH OF A MOUNT VERNON AND NEW BOSTON TEXAS...TO
HOPE ARKANSAS LINE. THESE POTENTIAL ACCUMULATIONS WILL BE
DEPENDENT ON THE TRACK OF THIS STORM SYSTEM...AND HOW QUICKLY THE
COLDER SUBFREEZING AIR IS ABLE TO PENETRATE SOUTHEAST INTO THE
AREA. A MORE SOUTHWARD STORM TRACK WOULD RESULT IN A POTENTIAL
INCREASE IN SNOW ACCUMULATIONS FARTHER SOUTH ACROSS THE AREA
CHRISTMAS AFTERNOON AND NIGHT.

AT THIS TIME...AREAS ALONG THE INTERSTATE 20 CORRIDOR OF NORTHEAST
TEXAS AND NORTH LOUISIANA MAY SEE A LIGHT RAIN SNOW MIX CHRISTMAS
NIGHT AS THIS STORM SYSTEM BEGINS TO PULL AWAY FROM THE AREA. NO SNOW
OR ICE ACCUMULATIONS ARE EXPECTED...AS SURFACE TEMPERATURES SHOULD
REMAIN ABOVE FREEZING.

UNCERTAINTIES STILL REMAIN AS TO THE TRACK...TIMING...AND DEPTH OF
THE COLDER SUBFREEZING AIR OF THIS STORM SYSTEM. RESIDENTS ACROSS
THESE AREAS SHOULD STAY TUNED TO THE LATEST STATEMENTS AND FORECASTS
IN THE FEW DAYS FROM THE NATIONAL WEATHER SERVICE IN SHREVEPORT
CONCERNING THIS POTENTIAL WINTER STORM.


SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LITTLE ROCK AR
243 PM CST SAT DEC 22 2012

ARZ003>007-012>016-021>025-030>034-037>047-052>057-062>069-231200-
ARKANSAS-BAXTER-BOONE-BRADLEY-CALHOUN-CLARK-CLEBURNE-CLEVELAND-
CONWAY-DALLAS-DESHA-DREW-FAULKNER-FULTON-GARLAND-GRANT-HOT SPRING-
INDEPENDENCE-IZARD-JACKSON-JEFFERSON-JOHNSON-LINCOLN-LOGAN-LONOKE-
MARION-MONROE-MONTGOMERY-NEWTON-OUACHITA-PERRY-PIKE-POLK-POPE-
PRAIRIE-PULASKI-SALINE-SCOTT-SEARCY-SHARP-STONE-VAN BUREN-WHITE-
WOODRUFF-YELL-
243 PM CST SAT DEC 22 2012

...WINTER WEATHER POTENTIAL ACROSS MUCH OF ARKANSAS CHRISTMAS DAY
AND CHRISTMAS NIGHT...

AN UPPER LEVEL STORM SYSTEM IS FORECAST TO TRACK INTO THE SOUTHERN
PLAINS STATES CHRISTMAS DAY. PRECIPITATION WILL BEGIN TO OVERSPREAD
THE STATE FROM THE SOUTH STARTING LATER MONDAY NIGHT AND CONTINUING
CHRISTMAS DAY.

AT THIS TIME...THE POTENTIAL FOR WINTER WEATHER EXISTS FOR MUCH OF
ARKANSAS. THE PRECIPITATION WILL START OFF MAINLY AS RAIN ACROSS
SOUTHERN AND CENTRAL PARTS OF THE STATE CHRISTMAS MORNING. WITH
COLDER AIR IN PLACE AT THE SURFACE...SOME SLEET OR SNOW COULD MIX
WITH THE RAIN AT THE ONSET AS IT ADVANCES NORTHWARD. OVER NORTHERN
ARKANSAS...IT APPEARS THAT MAINLY SNOW OR A PERIOD OF RAIN AND SNOW
WILL OCCUR TUESDAY.

AS THE STORM SYSTEM BEGINS TO MOVE EAST OF THE AREA CHRISTMAS
NIGHT...THE PRECIPITATION WILL TRANSITION TO ALL SNOW AS COLDER AIR
MOVES BACK INTO THE AREA. SIGNIFICANT ACCUMULATIONS OF SNOWFALL WILL
BE POSSIBLE ACROSS PARTS OF ARKANSAS. HOWEVER...WITH THE UNCERTAINTY
OF THE TRACK...THE LOCATIONS THAT WILL SEE THE MOST SIGNIFICANT
ACCUMULATIONS ARE UNKNOWN AT THIS TIME. PLEASE CONTINUE TO MONITOR
THE LATEST FORECAST AND STATEMENTS FROM YOUR NATIONAL WEATHER
SERVICE.

[srainhoutx]

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0205 AM CST SAT DEC 22 2012

VALID 241200Z - 251200Z

...NO SVR TSTM AREAS FORECAST...

...TX COASTAL PLAINS/LOWER MS VALLEY...
A PROGRESSIVE UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD ACROSS THE
INTERMOUNTAIN WEST ON MONDAY AND INTO THE ROCKIES. AHEAD OF THE
SYSTEM...MOISTURE WILL RETURN ACROSS THE TX COASTAL PLAINS AND LOWER
MS VALLEY. AS THE UPPER-LEVEL TROUGH MOVES INTO THE SRN PLAINS
MONDAY NIGHT AND LARGE-SCALE ASCENT INCREASES IN THE SRN
PLAINS...THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE ACROSS THE SERN
THIRD OF TX EXTENDING EWD ACROSS SRN LA. AT THIS POINT...MODEL
FORECASTS SHOW SFC DEWPOINTS IN SE TX IN THE LOWER TO MID 60S F WITH
ABOUT 50 KT OF DEEP LAYER SHEAR. THIS ENVIRONMENT SHOULD SUPPORT A
SEVERE THREAT LATE MONDAY NIGHT AND ROTATING STORMS WILL BE POSSIBLE
ACROSS THE TX COASTAL PLAINS AFTER MIDNIGHT. IF THE UPPER-LEVEL
TROUGH IS A BIT SLOWER THAN FORECAST...THE BRUNT OF THE THUNDERSTORM
DEVELOPMENT COULD BE DELAYED UNTIL TUESDAY AFTER DAYBREAK. FOR THIS
REASON...WILL GO WITH A SEE TEXT FOR MONDAY NIGHT WITH THE POTENTIAL
TO UPGRADE TO SLIGHT RISK IN LATER OUTLOOKS.

..BROYLES.. 12/22/2012

[cisa]

We lost our power from Thursday at 2am to Friday at 4pm with the last storm. Thursday night was a cold one in our house. I really hope that doesn't repeat itself.

[Ptarmigan]

Interesting the NWS calls for rain on Sunday and on Christmas Eve, it is sunny. Christmas Eve night and Christmas Day gets stormy as Santa Claus comes. Looks like Santa is going to be giving us rain again. Thirds Christmas in a row to see rain. It is not unprecedented to see three Christmas in a row be rainy. There was four rainy Christmas in a row from 1938 to 1941. 1938 and 1939 had over 1 inches of rain.

[unome]

yep, but since we need more rain I'll bet most of us will love the rain

[Ptarmigan]

yep, but since we need more rain I'll bet most of us will love the rain

I would be happy with the rain. It would be a great Christmas gift for us.

[unome]

I would be happy with that also Ptarmigan

[srainhoutx]

Neutral trending to negative troughs/upper air disturbances along with a potent upper jet raise an eyebrow for severe potential in the warm sector. Stay weather wise gang...

[ticka1]

i know folks will be busy christmas eve and christmas day with family and festivities -will there be folks monitering the weather situation and alerting us to bad weather if it develop??

[srainhoutx]

From NWS Dallas/Ft Worth tonight...

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
958 PM CST SAT DEC 22 2012

.UPDATE...
EVENING SURFACE OBSERVATIONS AND FORT WORTH SOUNDING INDICATE A
STEADY MOISTENING OF THE LOWER PARTS OF THE ATMOSPHERE OVER THE
LAST 24 HOURS. THIS IS IN RESPONSE TO INCREASING SOUTHERLY FLOW
AHEAD OF A WEAK DISTURBANCE WHICH WILL MOVE THROUGH THE PLAINS
LATE TOMORROW. A WEAK SURFACE LOW CURRENTLY OVER THE TX PANHANDLE
WILL MOVE EAST WITH THIS DISTURBANCE ON SUNDAY ALLOWING A COLD
FRONT FRONT TO APPROACH THE AREA. LATEST HIGH RESOLUTION GUIDANCE
INDICATES THAT THE FRONT WILL ACTUALLY ENTER OUR NORTHWEST
COUNTIES BY MIDDAY SUNDAY...SO HAVE LOWERED HIGH TEMPERATURES BY
SEVERAL DEGREES ACROSS THOSE AREAS. THIS COLD FRONT WILL CONTINUE
SOUTH SUNDAY EVENING WITH LOWS IN THE UPPER 20S AND LOWER 30S
ACROSS THE NORTHERN HALF OF THE AREA SUNDAY NIGHT.

THIS COLD AIR WILL NOT BE VERY DEEP ON MONDAY AND IS LIKELY TO BE
MIXED OUT TO SOME DEGREE IN RESPONSE TO INCREASING SOUTHERLY
WINDS AHEAD OF OUR NEXT SYSTEM OF INTEREST...WHICH WILL BE THE
CHRISTMAS DAY STORM. THERE IS SIGNIFICANT INTEREST IN THIS SYSTEM
FOR ITS POTENTIAL TO PRODUCE SOME HEAVY WINTRY PRECIP TOTALS
ACROSS PARTS OF THE SOUTHERN PLAINS AND MID SOUTH. AS IS OFTEN THE
CASE IN NORTH TEXAS HOWEVER...THE EXACT TRACK HAS MAJOR IMPACTS TO
PRECIPITATION TYPE ACROSS OUR AREA. A LOOK AT SEVERAL ANALOGS TO
THE CONSENSUS FORECAST FOR EARLY TUESDAY MORNING YIELDED A HANDFUL
OF EVENTS WITH SIMILAR SYNOPTIC SETUPS. ONE EVENT IN PARTICULAR
STANDS OUT FOR ITS STRIKING SIMILARITIES TO THE CURRENT FORECAST
PATTERN. IN EARLY DECEMBER 1989 A STRONG DISTURBANCE ENTERED THE
PACIFIC NORTHWEST MOVED SOUTHEAST ACROSS THE GREAT BASIN BEFORE
DIGGING ACROSS WEST TEXAS AND EVENTUALLY MOVING OVER NORTH TEXAS.
THIS SYSTEM DUG SLIGHTLY FARTHER SOUTH THAN THE CURRENT SYSTEM IS
FORECAST...HOWEVER SIMILAR SURFACE FEATURES DEVELOPED ACROSS
SOUTHEAST TEXAS BEFORE QUICKLY MOVING TO THE NORTHEAST. THE BULK
OF THE PRECIPITATION WAS LOCATED ACROSS EAST TEXAS AND LOUISIANA
WITH WRAP AROUND WINTRY PRECIP PRIMARILY ACROSS OKLAHOMA. THE ONE
DIFFERENCE WITH THIS SYSTEM...WAS SURFACE TEMPERATURES WERE
SEVERAL DEGREES WARMER THAN CURRENTLY FORECAST. SEVERAL OF THE
OTHER ANALOGS WITH SLIGHT DIFFERENCES IN TRACKS OF THE MAIN UPPER
TROUGHS YIELDED SIMILAR RESULTS. THIS INCREASES CONFIDENCE IN THE
CURRENT FORECAST OF PRIMARILY RAIN DEVELOPING INITIALLY AND MOVING
NORTHEAST WITH THE MAIN SURFACE LOW...AND A CHANGEOVER TO SOME
SNOW ON THE BACK SIDE OF THE SYSTEM. THE CURRENT FORECAST HANDLES
THIS WELL...AND FORECAST SOUNDINGS STILL SUPPORT A CHANGEOVER TO
SNOW ON CHRISTMAS AFTERNOON/EVENING AS THE COLDER AIR FILTERS IN.
WITH SUCH A FAST MOVING SYSTEM...AND STRONG WESTERLY WINDS ALOFT...
A SIGNIFICANT DRY SLOT WILL ADVANCE EASTWARD ON CHRISTMAS DAY AS
THE SYSTEM DEEPENS. THIS SHOULD ALLOW FOR A SHARP PRECIPITATION
GRADIENT ON THE BACK SIDE OF THE LOW AND FROM NORTH TO SOUTH WHERE
ANY WINTRY PRECIPITATION SHOULD OCCUR. THE CURRENT MENTION OF
NORTH OF THE I-20 CORRIDOR LOOKS GOOD FOR ANY POSSIBLE SNOW DURING
THE DAY ON TUESDAY.

[unome]

latest HGX briefing http://www.srh.noaa.gov/hgx/?n=briefing

[Andrew]

Euro did look like it had a little stronger trough extending south compared to previous runs but that could be due to the different time frames. Really looks like based on moisture levels that Dallas really could get some good precipitation levels as the colder air races south. What really is interesting to me is the next trough that develops on the Euro. The Euro has trended towards a more potent trough around hour 144 and this run showed a trough that digs a lot farther south and isn't sheared out nearly as much. But that will be something to talk about as we get closer to the event. In the meantime lets look at the Christmas event. Looking at the GFS Skew T for hour 60 shows a low Level of Free Convection Height along with a relatively decent KI value of 25.6 and LI value of -5.8. CAPE is around 1600 (J/KG) with best CAPE almost reaching 2K (J/Kg). Also Cape looks to be extended pretty evenly throughout the vertical profile which will help the severe weather chances. PW values from around hour 60 and 66 aren't overall impressive at 1.2in but decent enough for the event. Looking at shear and the SWEAT index shows pretty good shear levels from 850mb to 500mb and presents a good presence of instability. Overall it looks like there is a pretty decent shot of at least some scattered stronger storms as the trough becomes neutral to negative tilted and we have a 110+kt jet on top of us. It is interesting that when I looked just a little farther west towards College Station the chance of severe weather looks a lot less favorable. It shows how delicate the situation is and the placement of severe weather can easily be affected.

After the Christmas system we should have a day or two of colder weather before we begin to see moisture levels return as winds come from the south. It's interesting to note after the fropa passes we have a pretty strong temperature gradient just off the coast and how fast the warmer air starts advecting back in from the south. While earlier indications showed a slightly slower progression of systems, the latest runs from global models indicate that we will remain very progressive with one system moving through after another. Good for rain, bad for cold weather & winter lovers. Then looking towards the end of the month the next system should approach from the NW but there are noticeable differences between the GFS and EURO. The GFS remains weaker while the EURO has stepped up the intensity and a further south track. Something to keep an eye on for New Years.

SKEW T from GFS:

skew t.png

GFS Hour 144:

00zgfs500mbHGHTNA144.gif

Euro Hour 144:

00zeuro500mbHGHTNA144.gif

[srainhoutx]

Folks in Central/SE Texas need to monitor Christmas Eve and into the early morning hours of Christmas Day. The SPC has issued a Slight Risk for Day 2 (Christmas Eve) for portions of Central/SE Texas with a possible stronger threat on Day 3 (Christmas Day) during the early morning hours where the SPC currently has a Slight Risk outline from SE Teas on E into Southern Louisiana and Southern Mississippi. There is a potential that a Moderate Risk may be issued Christmas Morning/day in future SPC updates. This is a very dynamic Winter Storm with both Winter and Severe weather. Stay Tuned and Keep Informed!

12232012 SPC day2otlk_0700.gif

12232012 SPC day3otlk_0830.gif

12232012 SPC day3prob_0830.gif

[srainhoutx]

HPC Update for the Winter Storm Track and snow potential in the cold sector:

...PTNS OF THE SRN PLAINS INTO THE LOWER MS VLY/WRN TN VLY/LOWER
OH VLY...

THE ELONGATED SHORTWAVE AFFECTING THE W COAST ON DAY ONE...THEN
THE IM REGION/ROCKIES ON DAY 2...WILL DIG SE ACROSS THE SRN PLAINS
AND EVENTUALLY LIFT ENE ACROSS THE LOWER MS VLY AND INTO THE
TN/LWR OH VLYS BY THE END OF DAY 3. HPC'S SNOW/ICE PROBABILITIES
WERE BASED ON A BLENDED APPROACH BOTH WITH THE QPF AND THERMAL
STRUCTURES...AS PER THE PMDHMD...THE ENSEMBLE WAS INITIALLY
NON-GFS BASED GIVEN THE RELATIVE FAST SPEED OF THE GFS COMPARED TO
THE OTHER MODEL CLUSTERS. THE 06Z GFS HAS ESSENTIALLY COME IN
BETTER ACCORD WITH THE LATEST NAM IN TERMS OF THE SFC LOW TRACK
FROM NRN LA TO NRN MS...CEN TN...AND ACROSS CEN KY TOWARD THE END
OF DAY 3 (12Z 12/26). THE ECMWF AND UKMET REMAIN SLOWER WITH THE
LOW TRACK...AND ESSENTIALLY FARTHER S (CEN TN) WITH THE LOW BY 12Z
12/26 OR WED MORNING. GIVEN THE TIMING DIFFS BTWN THE NECP CAMP
AND THE ECMWF/UKMET...AGAIN FOR NOW HPC USED AN ENSEMBLE APPROACH
WITH THE SFC-700 MB LOW TRACKS AND QPF...WHICH WOULD BASED ON THAT
TRACK AND ASSCD FVRBL REGION OF MAX UPPER LEVEL DIFFLUENCE/MID
LEVEL DEFORMATION AND TROWAL...
WOULD FAVOR A POTENTIAL FOR HEAVY SNOW ACROSS PTNS OF THE LWR MS
VLY TO INCLUDE CEN AR NEWRD THROUGH SERN MO/WRN KY.
OBVIOUSLY...GIVEN THE GUIDANCE SPREAD AT THIS POINT...FCST
CONFIDENCE IS AVG AT BEST (AVG FOR A DAY 3 FCST). THROW IN THE
ANOMALOUS NATURE OF THIS EVENT (500 MB HEIGHTS ~ 2 STD DEVS BELOW
NORMAL FOR THE LOWER MS VLY)...AS WELL AS THE POTENTIAL FOR SHIFTS
IN THE STORM TRACK...DRY SLOT...AND CONVECTIVELY ENHANCED REGIONS
(OR ALL OF THE ABOVE)...HPC PROBABILITIES WHERE MOST HEAVILY
WEIGHTED TOWARD THE LOWER THRESHOLDS (I.E. >4 INCHES) AT THIS
POINT. FOR NOW...THE DAY 3 FINAL PROBS DID INCLUDE A STRIPE OF 10%
OF >8 INCHES OVER PTNS OF CEN AND NERN ARK...AGAIN TAKING THE
ENSEMBLE APPROACH WITH THE STORM TRACK (EVEN THOUGH THE
ECMWF/UKMET WERE ABOUT 6 HRS SLOWER).

THE DEEPENING NATURE OF THIS SYSTEM (700-500 MB LOWS) AS THE
TROUGH AXIS BECOMES MORE NEGATIVELY TILTED WILL ALLOW FOR MATURING
CYCLOGENESIS WITH THE GOMEX WIDE OPEN AND COMMA-HEAD STRUCTURES
(CCB...MID-LEVEL TROWAL...AND DRY SLOT) COMING INTO PLAY. ALL THE
MODELS SHOW A GOOD POTENTIAL FOR CONVECTION AS WELL...ANY OF WHICH
IN THE WARM SECTOR COULD CERTAINLY DISRUPT THE MSTR TRANSPORT N-NW
OF THE LOW. HOWEVER AT THE SAME TIME...NEG 850-500 MB THETA-E
LAPSE RATES AND ARE PROGGED TO NUDGE UP INTO CEN-NRN AR INTO FAR
SW TN...WITH WEAK STATIC STABILITY JUST TO THE NORTH. THUS THE
CONCEPTUAL MODEL WOULD SUGGEST THE POTENTIAL FOR ELEVATED
CONVECTION (WHETHER UPRIGHT OR SLANTWISE) AND THUS ENHANCED
SNOWFALL RATES. AGAIN...QUITE A FEW VARYING FACTORS TO CONSIDER
WITH THIS SYSTEM...THUS EXPECT FURTHER ALTERATIONS TO THESE
PROBABILITIES AS THE EVENT DRAWS NEAR.

[wxman57]

Here's a meteogram from the latest GFS. About 0.75 to 1" of rain during the day Christmas. Cold front moves through around mid afternoon, bring an end to the rain. Temps fall rapidly after frontal passage. Light freeze Wed/Thu then a warm up.

GFS keeps the snow in OK but the Euro is farther south, dropping 3-5" snow in Dallas between noon and 6pm Christmas Day: