Area Forecast Discussion
Issued by NWS Tulsa, OK

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000
FXUS64 KTSA 271112
AFDTSA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
512 AM CST THU NOV 27 2014

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.

A FEW SC WILL BE POSSIBLE AT KROG THIS MORNING AS A MVFR CIG DECK
CONTINUES TO MOVE EAST...OTHERWISE VFR CONDITIONS WILL PREVAIL AT ALL
SITES THROUGH THE TAF PERIOD.



&&

.PREV DISCUSSION... /ISSUED 306 AM CST THU NOV 27 2014/

DISCUSSION...

HAPPY THANKSGIVING EVERYONE. COOL SURFACE HIGH PRESSURE IN THE
WAKE OF YESTERDAY`S FRONT WILL SLIDE EAST OVER THE REGION ON THIS
TURKEY DAY...AND THUS EXPECT HIGHS 5 TO 10 DEGREES COOLER THAN
YESTERDAY. A DE-AMPLIFICATION OF THE CURRENT POSITIVE PNA PATTERN
WILL OCCUR IN THE NEXT COUPLE DAYS...AND THE RESULTING DOWNSLOPE
FLOW REGIME OVER THE PLAINS WILL RESULT IN A RATHER QUICK WARM UP
TO CLOSE OUT THE WEEK. HIGHS WILL TOUCH OR EXCEED 70 DEGREES THIS
UPCOMING WEEKEND IN MANY AREAS.

THEN THE BOTTOM FALLS OUT. A STRONG SHORTWAVE TROUGH IS STILL
FORECAST BY THE MODELS TO DIVE OUT OF WESTERN CANADA AND THEN
ACROSS THE NORTHERN TIER OF STATES BY LATE IN THE WEEKEND. THIS
WILL SEND A SURGE OF SHALLOW ARCTIC AIR OOZING SOUTH OVER THE
PLAINS LIKE SPILLED MILK. THERE IS GOOD AGREEMENT ON FRONTAL
TIMING...WHICH INCREASES CONFIDENCE THAT IT WILL BE TOO LATE TO
STOP THE WARM UP ON SUNDAY AND THAT IT WILL BE MUCH COLDER ON
MONDAY. THE FORECAST FOR SUNDAY AND MONDAY WAS WEIGHTED TOWARD THE
NEW 00Z ECMWF...WHICH SHOWS A SHARPER WARM UP AHEAD OF THE FRONT
AND A SHARPER COOL DOWN BEHIND IT. WILL FOLLOW THE PREVIOUS
SHIFTS LEAD AND CONTINUE LOW POPS IN THE EAST SUNDAY NIGHT INTO
MONDAY...WHERE MODELS CONTINUE TO BREAK OUT LIGHT QPF. THIS IS
LIKELY GOING TO BE A DRIZZLE OR VERY LIGHT RAIN AS THE SHALLOW
FRONT LIFTS RETURNING LOW LEVEL MOISTURE. SURFACE TEMPS ON THE
NORTHERN FRINGE /FAR NE OK AND NW AR/ MAY SUPPORT SOME VERY LIGHT
ICING SO THIS WILL NEED TO BE WATCHED.

SOME ENERGY PUNCHES INTO THE WESTERN CONUS FROM THE PACIFIC EARLY
NEXT WEEK...AND THE RESULTING LOWER PRESSURES OVER THE HIGH PLAINS
WILL HELP TO DRAW THE SHALLOW COLD WEDGE OUT...THOUGH THERE IS
SOME UNCERTAINTY AS TO HOW QUICK THIS WILL OCCUR. ONCE
AGAIN...USED A WEIGHTED BLEND OF THE COOLER ECMWF FOR HIGHS
TUESDAY.

THE GFS AND ECMWF DIVERGE LATER ON NEXT WEEK WITH THE ECMWF
RETURNING US TO THE POSITIVE PNA PATTERN WE`RE IN NOW...WHILE THE
GFS MAINTAINS A MORE PROGRESSIVE SPLIT FLOW REGIME. THUS...WILL NOT GO
ANY HIGHER THAN SLIGHT CHANCE POPS AND WILL STAY WITH A BLEND OF
THE SOLUTIONS FOR TEMPS GIVEN THE UNCERTAINTY.

LACY

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&

$$

AVIATION...23



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