AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 608 AM CST WED NOV 20 2013 .DISCUSSION... PLEASE SEE THE 12Z AVIATION DISCUSSION BELOW. && .AVIATION... EXPECT MVFR CIGS THROUGH TODAY AND TONIGHT FOR MOST TERMINALS. WINDS WILL ACTUALLY DECREASE THIS AFTERNOON TO AROUND 10 TO 15 KT FROM THE SOUTH. LATER TONIGHT THUNDERSTORMS APPEAR POSSIBLE INITIALLY NEAR LAW/HBR JUST AFTER 00Z...AND THEN NEAR OKC/OUN AND PNC CLOSER TO 06 TO 10Z. CONFIDENCE IS FAIRLY HIGH WITH AT LEAST SOME PRECIPITATION OCCURRING AT THESE TERMINALS...ALTHOUGH THUNDERSTORMS MAY BECOME MORE ISOLATED CLOSER TO 06Z ACROSS CENTRAL OK. FLIGHT CONDITIONS WILL DETERIORATE OVERNIGHT AS IFR CIGS DEVELOP. && .PREV DISCUSSION... /ISSUED 520 AM CST WED NOV 20 2013/ DISCUSSION... SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO MOVE NORTHEAST ACROSS NE OK EARLY THIS MORNING ALONG LLJ AND WITHIN ZONE OF ISENTROPIC ASCENT AHEAD OF A MID LEVEL SHORTWAVE TROUGH AND NEAR THE LER OF UPPER JET MOVING OUT OF THE ROCKIES. ACROSS OUR AREA...STRATUS OVER WESTERN OK/N TX WILL SLOWLY SHIFT EASTWARD DURING THE DAY TODAY AS THE 850MB FLOW VEERS SLIGHTLY. THIS CLOUD CLOVER WILL INHIBIT HEATING A BIT ESPECIALLY ACROSS THE EAST SO EXPECT COOLER TEMPS ALONG AND EAST OF I35 TODAY. LATE TODAY THROUGH TONIGHT...ANOTHER SHORTWAVE TROUGH WILL TRAVERSE THE PANHANDLE AND A LLJ WILL DEVELOP ALONG THE I44 CORRIDOR. AN ELEVATED INSTABILITY AXIS WILL ALSO ACCOMPANY THE LOW LEVEL MOISTURE ADVECTION FROM W N TX THROUGH CENTRAL OK. SOME STRONG STORMS COULD DEVELOP DURING THE OVERNIGHT HOURS NEAR THE PREVIOUSLY MENTIONED AREAS WITH SUFFICIENT DEEP SHEAR IN PLACE...BUT MODEST MID LEVEL LAPSE RATES SHOULD KEEP HAIL SIZES BELOW SEVERE LIMITS. THIS FIRST ROUND OF MOIST CONVECTION WILL SHIFT NORTHEASTWARD DURING THURS MORNING. ATTENTION THEN TURNS TO THE APPROACHING ARCTIC COLD FRONT MOVING INTO NW OK AS EARLY AS THURSDAY AFTERNOON...AND SOMEWHERE NEAR THE I44 CORRIDOR AROUND 00Z FRI. EXPECT THE SECOND ROUND OF MOIST CONVECTION TO DEVELOP WITH THIS FRONT ALONG AND SOUTH OF I44 THURSDAY EVENING. AGAIN...SOME ELEVATED INSTABILITY AND SUFFICIENT DEEP LAYER SHEAR MAY SUPPORT SOME MARGINAL HAIL SPECIFICALLY ACROSS SW OK/W N TX. TEMPS WILL DROP RAPIDLY BEHIND THE FRONT TO BELOW FREEZING ALONG AND NORTH OF I44 BY FRI 12Z. POST-FRONTAL PRECIP TYPE FOR MOST AREAS WILL BE RAIN OR FREEZING RAIN...WITH SOME SLEET/SNOW PERHAPS SNEAKING INTO EXTREME NORTHWESTERN OK WHERE ICE WILL ACTUALLY BE PRESENT IN THE DENDRITIC ZONE. ITS DIFFICULT TO DETERMINE HOW MUCH ACCUMULATION WILL OCCUR THROUGH LATE FRIDAY NIGHT BEHIND THE FRONT...BUT SUSPECT AN ADVISORY WILL MOST BE NECESSARY IN THE NEAR FUTURE TO ACCOUNT FOR AT LEAST LIGHT ACCUMULATION ON BRIDGES/OVERPASSES...TREES...AND POWERLINES. THE MOST SIGNFICANT PRECIPITATION WILL LIKELY COME TO AN END BY MIDDAY FRIDAY AS SOME DRIER MID LEVEL AIR NUDGES IN AND ISENTROPIC DESCENT TAKES OVER...BUT EXPECT SOME LIGHT FREEZING RAIN THROUGH FRIDAY NIGHT MAINLY ALONG AND SOUTH OF I40 ALONG 700MB DEFORMATION ZONE. TEMPS WILL STRUGGLE TO CLIMB INTO THE 40S THROUGH THIS WEEKEND...WITH THE COLDEST MORNING LOWS EXPECTED SUNDAY UNDER A SFC RIDGE. THE NEXT CHANCE FOR WINTRY PRECIP WILL BE LATE MONDAY THROUGH TUESDAY AS A CUTOFF LOW FINALLY MAKES IT OUT OF THE SW AND SOME WHERE OVER THE SOUTHERN PLAINS. WILL CONTINUE TO SLOWLY INCREASE POPS WITH THIS FEATURE WITH CURRENT PRECIP TYPES APPEARING TO BE SNOW AND SLEET. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 63 58 64 32 / 10 60 60 80 HOBART OK 65 59 67 30 / 20 50 50 60 WICHITA FALLS TX 70 60 73 36 / 10 40 40 70 GAGE OK 66 53 59 24 / 10 30 30 40 PONCA CITY OK 62 55 59 31 / 20 80 80 70 DURANT OK 68 58 68 45 / 0 40 40 80 &&
Posted on: Wed, 20 Nov 2013 12:26:00 +0000
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