Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 182030 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 330 PM CDT FRI APR 18 2014 .SHORT TERM...
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(TONIGHT THROUGH MONDAY) ISSUED AT 324 PM CDT FRI APR 18 2014 THUNDERSTORM CHANCES BEGINNING SATURDAY INTO SUNDAY NIGHT ARE THE PRIMARY FORECAST CONCERNS. FLAT UPPER RIDGING WAS OVER THE PLAINS THIS MORNING...AHEAD OF MEAN TROUGH EXTENDING FROM SOUTHERN BRITISH COLUMBIA INTO THE NORTHERN BAJA. UPPER LOW EJECTING FROM NORTHERN IDAHO THIS AFTERNOON WILL TRACK ALONG THE CANADIAN BORDER THROUGH SATURDAY MORNING BEFORE LIFTING TOWARD HUNDSON BAY ON SUNDAY. THIS FEATURE WILL NUDGE A SURFACE COLD FRONT INTO THE PLAINS...REACHING NORTHEAST NEBRASKA BY SATURDAY AFTERNOON. MEANWHILE...SOUTHERN PART OF WESTERN TROUGH WILL PUSH THROUGH THE SOUTHERN ROCKIES SATURDAY NIGHT AND EVENTUALLY EAST OF THE CENTRAL AND SOUTHERN PLAINS BY MONDAY. SO NET RESULT OF THESE FEATURES WILL BE FOR SATURDAY COLD FRONT TO STALL OVER OUR AREA SATURDAY AND REMAIN QUASI-STATIONARY UNTIL SOUTHERN PART OF THE TROUGH MOVES EAST LATE SUNDAY NIGHT OR MONDAY. THUS CONTINUED CHANCES FOR THUNDERSTORMS WILL REMAIN IN THE FORECAST. SURFACE WINDS WERE BEGINNING TO KICK UP THIS AFTERNOON AS HIGH PRESSURE SLIDES EAST AND PRESSURES LOWER IN THE HIGH PLAINS. WINDS SHOULD HELP MIX OUT SOME OF THE HIGHER PARTICULATE CONCENTRATIONS FROM SMOKE AND DUST THAT WERE TRAPPED UNDER STRONG MORNING INVERSION. THOSE WINDS WILL CONTINUE OVERNIGHT AND SATURDAY UNTIL COLD FRONT APPROACHES SATURDAY AFTERNOON. LOW LEVEL MOISTURE IS RELATIVELY LOW THIS AFTERNOON...WITH DEW POINTS ONLY IN THE 40S FROM CENTRAL NEBRASKA TO THE RED RIVER. HOWEVER A PLUME OF 50S DEW POINTS IS FORECAST TO SURGE NORTH FROM CENTRAL TEXAS INTO EASTERN NEBRASKA BY LATE SATURDAY AFTERNOON. TEMPERATURES AHEAD OF THE FRONT WILL LIKELY APPROACH 80...BUT RELATIVELY MILD AIR ALOFT WILL KEEP SURFACE BASED CAPES WELL BELOW 1000 J/KG. 0-6KM BULK SHEAR IS ALSO LIMITED TO 20-25KT LATE SATURDAY AFTERNOON. BUT CONVERGENCE ALONG FRONT COMBINED WITH SUBTLE COOLING ALOFT FROM WEAK SHORTWAVE EJECTING FROM THE SOUTHWEST SUGGESTS SHOWERS AND THUNDERSTORMS WILL BE LIKELY SATURDAY NIGHT...BUT SEVERE THREAT APPEARS LIMITED AT BEST. THIS WAVE WILL EJECT TO OUR NORTHEAST SUNDAY MORNING...SO IT LOOKS LIKE A LULL IN ACTIVITY THEN. ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED SUNDAY AFTERNOON WITH APPROACH OF SOUTHERN UPPER WAVE. COLD FRONT SHOULD SET UP NORTHWEST OF INTERSTATE 80 IN THE AFTERNOON...WITH CONTINUED INFLUX OF LOW LEVEL MOISTURE PUSHING SURFACE DEW POINTS TOWARD 60F. TEMPERATURES ALOFT WILL ALSO BE COOLER AS TROUGH APPROACHES...AND WITH SURFACE TEMPERATURES IN THE 70S...SURFACE- BASED CAPES SHOULD TOP OUT IN THE 1500-2000 J/KG RANGE. UPPER FLOW IS RELATIVELY WEAK...SO AGAIN SHEAR IS MINIMAL WITH 0-6KM BULK SHEAR NEAR 20KT. SEVERE THREAT AGAIN LOOKS MINIMAL...BUT MAYBE A LITTLE BETTER THAN SATURDAY. PRECIPITATION CHANCES WILL CONTINUE INTO SUNDAY NIGHT...ENDING FROM NORTHWEST TO SOUTHEAST WITH TIME...AND ONLY IN SOUTHEAST NEBRASKA AND SOUTHWEST IOWA WILL THERE BE LINGERING CHANCES MONDAY MORNING. NORTHWEST FLOW THEN WILL CLEAR SKIES AND COOL TEMPERATURES SLIGHTLY...BUT SHOULD STILL SEE HIGHS WELL INTO THE 60S MONDAY AFTERNOON. .LONG TERM...(MONDAY NIGHT THROUGH FRIDAY) ISSUED AT 324 PM CDT FRI APR 18 2014 MID LEVEL RIDGING WILL BUILD INTO THE REGION MONDAY NIGHT AND TUESDAY AS STRONG MID LEVEL TROUGH DEVELOPS OVER THE PACIFIC NORTHWEST. BY WEDNESDAY...UPPER LOW WILL MOVE INTO THE NORTHERN ROCKIES AND EVENTUALLY TRACK ACROSS THE NORTHERN PLAINS THURSDAY AND FRIDAY. WARMER TEMPERATURES SHOULD RESULT TUESDAY INTO WEDNESDAY WHEN HIGHS IN THE 70S IF NOT SOME 80S WILL RULE. UPPER LEVEL DIFFLUENCE WILL INCREASE MARKEDLY ON WEDNESDAY...IN CONCERT WITH STRONG WARM ADVECTION REGIME IN THE LOWER HALF OF THE ATMOSPHERE. COULD SEE ELEVATED WARM ADVECTION CONVECTION LATE TUESDAY NIGHT AND DURING THE DAY WEDNESDAY...HOWEVER BETTER CHANCES SHOULD COME WEDNESDAY NIGHT WHEN UPPER TROUGH BEGINS TO MOVE INTO THE PLAINS AND SHOVES SURFACE LOW/COLD FRONT/DRYLINE INTO EASTERN NEBRASKA. SURFACE DEW POINTS AGAIN SHOULD APPROACH 60 WITH COOLING ALOFT. STRONG SHEAR IS FORECAST AS LOW LEVEL JET KICKS UP...WITH GFS FORECASTING 50KT OF 0-6KM BULK SHEAR. INSTABILITY AND SHEAR CERTAINLY LOOK SUFFICIENT FOR SEVERE HAIL WEDNESDAY NIGHT...WITH TIMING AND POSITION OF SURFACE FEATURES STILL IN QUESTION FOR LOCATION OF POTENTIALLY STRONGER SEVERE MODE. STORMS WILL LIKELY LINGER INTO THURSDAY MORNING BEFORE FRONT SWEEPS TO THE EAST. SOMEWHAT COOLER TEMPERATURES BEHIND THIS SYSTEM THURSDAY...AND EVEN COOLER FRIDAY AS CORE OF COLD AIR SETTLES SOUTH.
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&& .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1241 PM CDT FRI APR 18 2014 VFR CONDITIONS WILL CONTINUE THROUGHOUT THE TAF CYCLE. MORNING SMOKE AND HAZE HAS MIXED OUT AND VISIBILITIES CONTINUE TO IMPROVE EARLY THIS AFTERNOON AS SOUTHERLY SFC WINDS INCREASE AND GUST TO NEAR 30 KTS. PASSING HIGH CLOUDS ARE EXPECTED OVERNIGHT. HAVE INTRODUCED LOW LEVEL WIND SHEAR FROM NEAR 06Z THROUGH 15Z OR SO AS A SOUTHWESTERLY LOW LEVEL JET INCREASES. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...DERGAN LONG TERM...DERGAN AVIATION...KERN

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