000
FXUS64 KTSA 042344
AFDTSA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
544 PM CST WED DEC 4 2013

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
ONGOING LOCALIZED IFR CEILINGS ACROSS FAR NW AR ARE LIKELY TO
CONTINUE WELL INTO THE EVENING HOURS...WITH GENERALLY MVFR/VFR
CONDITIONS ELSEWHERE. CONDITIONS WILL BEGING TO DETERIORATE ACROSS
SE OK LATE TONIGHT...AND SPREAD EASTWARD INTO WESTERN AR AROUND
SUNRISE. THE BAND OF PRECIP WILL INTENSIFY ACROSS THE REGION
DURING THE MORNING INTO EARLY AFTERNOON...WITH NE OK SITES ON THE
NORTHERN PERIPHERY OF THE HEAVIEST PRECIP. FREEZING RAIN WILL
LIKELY IMPACT THE KMLC/KFSM ZONE...WITH SLEET MORE LIKELY ACROSS
FAR NW AR. GENERALLY LIGHT SLEET OR SNOW ACROSS NE OK SITES.

&&

.PREV DISCUSSION... /ISSUED 428 PM CST WED DEC 4 2013/

DISCUSSION...

***SIGNIFICANT WINTER WEATHER IMPACTS ARE LIKELY ACROSS MUCH OF
 EASTERN OKLAHOMA AND NORTHWEST ARKANSAS OVER THE NEXT 24 TO 36
 HOURS***

ANOTHER DIFFICULT FORECAST TODAY. THE INITIAL SURGE OF ARCTIC AIR
IS MAKING ITS WAY ACROSS THE FORECAST AREA TODAY...AND COLDER AIR
WILL CONTINUE TO FILTER INTO THE REGION THROUGH THE END OF THE
WEEK. THIS IS ALL IN RESPONSE TO MAJOR AMPLIFICATION OF THE UPPER
FLOW PATTERN OVER THE WESTERN 2/3RDS OF NORTH AMERICA. A DEEP
POSITIVE TILT UPPER TROUGH IS DIGGING OVER THE WESTERN CONUS AS I
TYPE...WITH A FETCH OF CROSS-POLAR UPPER FLOW CLEAR FROM SIBERIA
DOWN INTO NORTH AMERICA. THIS PATTERN IS FORECAST TO PERSIST UNTIL
ABOUT THE MIDDLE OF NEXT WEEK...WHEN FINALLY THE PATTERN
DEAMPLIFIES AND WE CAN THAW OUT. UNTIL THEN...WE WILL BE IN THE
DEEP FREEZE FOR ABOUT A WEEK...WHERE TEMPERATURES WILL NOT CLIMB
ABOVE FREEZING.

SINCE IN THIS TYPE OF PATTERN THE ARCTIC AIR WILL BE UNDERCUTTING
A STRONG SOUTHWESTERLY JET ALOFT OVER THE SOUTHERN TIER OF
STATES...WINTER PRECIPITATION WILL BE THE RESULT...WITH
SIGNIFICANT IMPACTS TO THE PUBLIC LIKELY. SEVERAL ROUNDS OF WINTRY
PRECIP ARE EXPECTED...AND I WILL GO INTO FURTHER DETAIL BELOW.

THE FIRST ROUND OF PRECIP WILL BEGIN THURSDAY MORNING AND WILL
CONTINUE THROUGH THURSDAY EVENING AS ONE OR MORE BANDS OF MODERATE
PRECIP SET UP FROM SOUTHEAST AND EAST CENTRAL OKLAHOMA UP INTO
WEST CENTRAL AND NORTHWEST ARKANSAS DUE TO INCREASING LOW-MID LVL
FRONTOGENESIS AND ISENTROPIC LIFT IN THE RIGHT ENTRANCE REGION OF
THE STRONG SOUTHWESTERLY UPPER JET. THERE WILL BE A SHARP GRADIENT TO
THE NORTHWEST OF WHERE THIS MAIN BAND SETS UP...SUCH THAT AREAS
ALONG AND NORTHWEST OF I-44 MAY NOT SEE MUCH OF ANY PRECIP DURING
THE DAY ON THURSDAY. TEMP PROFILES FROM THE NAM/GFS SUGGEST THAT
PRECIP WILL START OFF AS RAIN IN SE OK AND W CNTRL
AR...TRANSITIONING TO FZRA DURING THE DAY AS THE SUB- FREEZING AIR
WORKS ITS WAY INTO THIS AREA. SOME LIGHT ICING IS POSSIBLE BY THE
END OF THE DAY ACROSS EAST CNTRL AND SOUTHEAST OK OVER INTO WEST
CNTRL AR TO THE NORTHWEST OF HERE...I.E...E CNTRL AND NE OK AND NW
AR...A FREEZING RAIN AND SLEET MIX TO START...BECOMING
PREDOMINANTLY SLEET. IF LIGHT PRECIP DOES INDEED FALL TO THE NORTH
OF I-44...THAT SHOULD BE MAINLY SNOW IF ANYTHING...ESPECIALLY NEAR
THE KS BORDER.

THE SECOND WAVE OF PRECIP WILL BEGIN AFTER MIDNIGHT THURSDAY NIGHT
AS A STRONG WAVE EJECTS NORTHEAST ACROSS THE PLAINS. THE MODELS
CONTINUE TO SHOW A NICE MID LVL DEFORMATION ZONE SETTING UP IN
ADVANCE OF THE WAVE...SHOWING UP NICELY AS A BAND OF HIGHER QPF
FROM EAST CENTRAL OK INTO NORTHWEST AR. BY THIS TIME...TEMP
PROFILES FAVOR SLEET AND SNOW WITH SIGNIFICANT ACCUMULATIONS
POSSIBLE. FARTHER TO THE SOUTH OVER SOUTHEAST OK AND WEST CENTRAL
AR...THE NAM/GFS/ECMWF ARE IN UNANIMOUS AGREEMENT THAT A BAND OF
MODERATE TO POSSIBLY HEAVY PRECIPITATION WILL ORGANIZE FROM
NORTHERN TX UP INTO WEST CENTRAL AR. TEMP PROFILES FROM THE
NAM/GFS SUGGEST THAT THE WARM LAYER WILL BE STRONG ENOUGH TO
SUPPORT ICE FOR MOST IF NOT ALL OF THE NIGHT...WITH A CHANGE OVER
TO SLEET LATE FROM NORTH TO SOUTH AS THE COLDER AIR FINALLY GETS
DEEP ENOUGH. SIGNIFICANT ICE ACCUMULATIONS ARE EXPECTED THURSDAY
NIGHT...WITH MAJOR IMPACTS TO TRAVEL AND EVEN THE POWER GRID. FOR
THIS REASON...THE WINTER STORM WARNING HAS BEEN CHANGED OR
UPGRADED TO AN ICE STORM WARNING FROM NOON THURSDAY TO 6 PM
FRIDAY. BY FRIDAY MORNING...SNOW OR SLEET WILL BE THE PREDOMINANT
WEATHER TYPES...AND THE ICE STORM WARNING CAN BE CHANGED BACK TO A
WINTER STORM WARNING IF NEEDED AT THAT TIME. THE QG LIFT SHUTS OFF
RAPIDLY BY MIDDAY FRIDAY...AND PRECIP CHANCES WILL ACCORDINGLY END
AS WELL FOR THE MOST PART FRIDAY AFTERNOON.

THE FINAL ROUND OF PRECIP WILL GET GOING THIS WEEKEND. ANOTHER
WAVE WILL LIFT OUT OF THE WESTERN CONUS TROUGH AND ACROSS THE
PLAINS. INCREASING WARM/POSITIVE PV ADVECTION WILL DRAW MOISTURE
NORTH AND INCREASE LIFT OVER THE ARCTIC COLD DOME AT THE SURFACE.
THIS WILL ONCE AGAIN PRODUCE WINTRY PRECIPITATION OVER THE REGION.
TEMP PROFILES SUGGEST SNOW ACROSS THE NORTH AND ICE DOWN
SOUTH...WITH SLEET IN BETWEEN. HOWEVER...SINCE THE SURFACE FRONT
AND BEST MOISTURE WILL BE SHUNTED WELL TO OUR SOUTH AND EAST BY
THIS TIME...THERE WILL NOT BE AS MUCH MOISTURE FOR THIS SYSTEM TO
WORK WITH. PRECIP AMOUNTS WILL BE LIGHT OVERALL COMPARED TO THE
FIRST SYSTEM. ALSO...MODEL SOUNDINGS SUGGEST DRYING IN THE CRUCIAL
-10 TO -15C LAYER ALOFT...AND THUS PERIODS OF FREEZING DRIZZLE ARE
ALSO POSSIBLE. THE LIFT FROM THIS SYSTEM SHOULD LIFT NORTHEAST BY
SUNDAY NIGHT...WITH PRECIP CHANCES ENDING THEN.

THE WESTERN CONUS LONGWAVE TROUGH WILL FINALLY LIFT OUT ACROSS THE
PLAINS EARLY NEXT WEEK. HOWEVER...BY THIS TIME THERE WILL NOT BE
ENOUGH MOISTURE TO SQUEEZE OUT PRECIPITATION...AND HAVE THUS KEPT
THE FORECAST DRY. WITH THE TROUGH LIFTING OUT...WE WILL FINALLY
GET A CHANCE TO THAW OUT TOWARD THE END OF NEXT WEEK.

THE COLD OVER THE UPCOMING WEEK WILL BECOME A CONCERN...ESPECIALLY
IF AREAS LOSE POWER AND FOR AN EXTENDED TIME. LOWS ON SATURDAY AND
TUESDAY EVEN WEDNESDAY MORNINGS COULD DROP TO NEAR ZERO OR EVEN
BELOW ZERO OVER A SNOWPACK...WITH WIND CHILLS WELL BELOW THAT. GET
READY FOLKS.

LACY

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   26  27  21  23 /  10  50  90  80
FSM   36  37  25  27 /  40 100 100 100
MLC   31  32  22  25 /  20 100 100  80
BVO   25  26  20  23 /  10  40  60  70
FYV   29  30  20  22 /  20 100  90 100
BYV   28  29  20  21 /  20 100  90  90
MKO   29  30  22  24 /  10 100  90  80
MIO   25  27  19  22 /  10  50  70  70
F10   28  28  21  23 /  10  90  90  80
HHW   37  38  27  28 /  40 100 100  80

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...ICE STORM WARNING FROM NOON THURSDAY TO 6 PM FRIDAY FOR OKZ049-
     OKZ053-OKZ072-OKZ076.

     WINTER STORM WARNING FROM 6 AM THURSDAY TO 6 PM FRIDAY FOR
     OKZ054-OKZ055-OKZ056-OKZ057-OKZ058-OKZ059-OKZ060-OKZ061-
     OKZ062-OKZ063-OKZ064-OKZ065-OKZ066-OKZ067-OKZ068-OKZ069-
     OKZ070-OKZ071-OKZ073-OKZ074-OKZ075.

AR...WINTER STORM WARNING FROM 6 AM THURSDAY TO 6 PM FRIDAY FOR
     ARZ001-ARZ002-ARZ010-ARZ011.

     ICE STORM WARNING FROM NOON THURSDAY TO 6 PM FRIDAY FOR ARZ019-
     ARZ020-ARZ029.

&&

$$

AVIATION...07