Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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000
FXUS64 KOUN 210506
AFDOUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
1106 PM CST SAT DEC 20 2014

.DISCUSSION...
AVIATION DISCUSSION FOR THE 06Z TAFS IS BELOW.

&&

.AVIATION...
HAVE LOW CONFIDENCE IN THE TAFS.

OVERALL...THINK WORSENING CONDITIONS WILL OCCUR AT ALL SITES WITH
WIDESPREAD IFR OR LOWER CONDITIONS DEVELOPING BY 15Z...THOUGH
EXACTLY WHEN AND HOW BAD CONDITIONS GET REMAIN UNCERTAIN.
CONDITIONS WILL BE CLOSE TO AIRPORT MINIMUMS NEAR KCSM...KWWR...
AND KGAG THROUGH 17Z. IMPROVING CONDITIONS WILL LIKELY OCCUR WEST
OF KEND-KDUC AFTER 15Z. IFR AND LOWER CONDITIONS MAY REDEVELOP
OVER WESTERN OKLAHOMA AFTER 00Z.

PATCHES/AREAS OF -DZ WILL DEVELOP AFTER 08Z...THEN SPREAD
SOUTHWEST TO NORTHEAST...AFFECTING ALL SITES EXCEPT KGAG
AND KWWR.

MBS

&&

.PREV DISCUSSION... /ISSUED 950 PM CST SAT DEC 20 2014/

UPDATE...
ONLY MINOR UPDATES TO THE FORECAST THIS EVENING. THE PRIMARY
CHANGE IS TO REMOVE THE MENTION OF DENSE FOG IN THE WEST THIS
EVENING. IT IS NOT COMPLETELY OUT OF THE QUESTION TO SEE SOME VERY
ISOLATED AREAS OF DENSE FOG OVERNIGHT... BUT THE TRENDS IN THE
HIGH- RESOLUTION MODEL OUTPUT ARE TO BE LESS AGGRESSIVE WITH THE
DENSE FOG FORMATION IN OUR FORECAST AREA AND GENERALLY CONFINE THE
DENSE FOG TO HIGHER ELEVATIONS /SUCH AS THE WICHITA MOUNTAINS OR
SOME OF THE HIGHER ELEVATIONS OF ROGER MILLS AND ELLIS COUNTIES/.
WILL CONTINUE TO MENTION GENERAL FOG AND DRIZZLE OVERNIGHT.

PREV DISCUSSION... /ISSUED 308 PM CST SAT DEC 20 2014/

DISCUSSION...
MOISTURE BOUNDED BY STRONG INVERSION IS NOT EXPECTED TO GO
ANYWHERE UNTIL COLD FRONT SURGES IN LATE MONDAY. MIXING ON HIGHER
TERRAIN HAS PROGRESSED INTO WESTERN OKLAHOMA AND ADJACENT PARTS OF
NORTHERN TEXAS...BUT THIS IS NOT EXPECTED TO MAKE IT VERY FAR EAST
THIS EVENING. BACKING/INCREASING FLOW AHEAD OF INCOMING S/WV
EXPECTED TO ALLOW STRATUS AND FOG TO REDEVELOP TONIGHT. WITH THE
CLEARING ACROSS FAR WESTERN/NORTHWEST OKLAHOMA THIS
EVENING...COULD SEE TEMPS FALL WELL DOWN INTO THE 30S BEFORE
HIGHER DEWPOINTS BEGIN TO SURGE NORTHWARD. THIS COULD LEAD TO A
FAIR AMOUNT OF DENSE FOG LATE TONIGHT AND WILL MENTION THIS IN THE
GRIDS. FOG EXPECTED ELSEWHERE...BUT NOT AS DENSE. PATCHY DRIZZLE
ALSO EXPECTED OVERNIGHT AND SUNDAY MORNING AS TROUGH APPROACHES.
CANNOT RULE OUT SOME LIGHT SHOWERS AS WELL BUT WILL NOT MENTION IN
THIS ISSUANCE.

IN ASSOCIATION WITH THE MENTIONED COLD FRONT...DEEP AND VERY COLD
TROUGH WILL EVOLVE OVER THE SOUTHERN PLAINS AND POINTS EAST LATE
MONDAY THROUGH TUESDAY. MODELS ARE COMING INTO BETTER AGREEMENT
WITH DEVELOPMENT OF POST-FRONTAL PRECIPITATION. BASED SOLELY ON
THICKNESS PROGS AND HISTORICAL H7-H5 THERMAL THRESHOLDS...ONE
MIGHT EXPECT SNOW ACROSS WESTERN/SOUTHERN OKLAHOMA ON TUESDAY.
HOWEVER...WITH LOWER LEVEL DETERMINISTIC PROGS AND FORECAST
SOUNDINGS...LOWER LEVELS APPEARS TO STAY TOO WARM FOR TOO LONG FOR
ANYTHING MORE THAN A POSSIBLE RAIN/SNOW MIX BEFORE ENDING NEAR THE
RED RIVER. THIS SCENARIO WILL BE MONITORED BUT AT THIS TIME NO
MENTION OF SNOW IN LATEST FORECAST ISSUANCE.

COOL DOWN WILL NOT LAST LONG AS SOUTHWEST FLOW COMMENCES LATE
WEDNESDAY INTO CHRISTMAS DAY AHEAD OF NEXT WEATHER SYSTEM. ANOTHER
COLD FRONT STILL EXPECTED CHRISTMAS NIGHT AND FRIDAY. THIS FROPA
APPEARS TO BE DRY AND WILL BRING TEMPERATURES DOWN CLOSER TO
AVERAGE INTO NEXT WEEKEND.

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&

$$

26/17/17


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