Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 202012 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 312 PM CDT SUN APR 20 2014 .SHORT TERM...
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(TONIGHT THROUGH WEDNESDAY) ISSUED AT 254 PM CDT SUN APR 20 2014 MAIN FORECAST CHALLENGE WILL BE POPS TONIGHT/OVERNIGHT AND AGAIN WEDNESDAY/WEDNESDAY NIGHT. THE REGION REMAINS IN BETWEEN TWO MID/UPPER LEVEL SYSTEMS. THE FIRST OF WHICH IS A SHORTWAVE TROUGH MOVING THROUGH NEARLY ZONAL FLOW ALONG THE INTERNATIONAL/MONTANA BORDER. THE SECOND SYSTEM IS A SHORTWAVE TROUGH LOCATED OVER THE OKLAHOMA PANHANDLE. 12Z UPPER AIR ANALYSIS SHOWS 850MB DEWPOINTS IN THE 5-8C RANGE OVER THE CENTRAL PLAINS AHEAD OF THE SOUTHERN SYSTEM. AT THE SURFACE...THE STATIONARY BOUNDARY THAT HAD EXTENDED ACROSS NORTHEASTERN NEB HAS WASHED OUT FOR THE MOST PART. SFC DEWPOINTS RANGE ANYWHERE FROM THE UPPER 40S TO THE LOWER 50S ACROSS THE FORECAST AREA THIS AFTERNOON. INSTABILITY CONTINUES TO INCREASE ACROSS NORTHEASTERN KANSAS AS TEMPERATURES INCREASE INTO THE LOWER 80S. BY 20Z...MUCAPE ACROSS SOUTHEAST NEB/SOUTHWEST IOWA WAS AROUND 500J/KG. A WEAK IMPULSE MOVING NORTHEAST OUT OF THE MAIN SOUTHERN SHORTWAVE WILL CONTINUE TO MOVE INTO NORTHWEST KANSAS PROVIDING SUPPORT FOR SCATTERED SHOWERS AND THUNDERSTORMS. SHORT RANGE MODELS INCLUDING THE RAP/HOPWRF/HRRR CONTINUE TO GENERATE CONVECTION LATE THIS AFTERNOON OVER NORTH CENTRAL KANSAS/SOUTHEAST NEBRASKA AND SPREAD THIS ACTIVITY NORTHEAST ACROSS EASTERN NEBRASKA AND INTO SOUTHWESTERN IOWA THIS EVENING. IN ADDITION TO THIS AREA...A NARROW BAND OF HIGH BASED CONVECTION ALONG THE WASHED OUT FRONTAL BOUNDARY MAY GENERATE SOME LIGHT RAIN SHOWERS WITH A FEW ISOLATED RUMBLES OF THUNDER. IN EITHER AREA...BULK SHEAR VALUES WILL REMAIN QUITE WEAK AND INSTABILITY IS MARGINAL SO NOT ANTICIPATING ANY SEVERE STORMS. THE NORTHERN PLAINS SHORTWAVE TROUGH WILL ALLOW A COLD FRONT CURRENTLY OVER THE WESTERN DAKOTAS TO SLIDE SOUTH INTO THE FORECAST AREA BY 10-12Z. WILL INCLUDE POPS ALONG THIS BOUNDARY AS IT SLIDES SOUTH THROUGH THE REGION INTO MONDAY MORNING AND LINGER IN OUR SOUTHEAST TOWARD 18Z. SFC HIGH PRESSURE BUILDS OVERHEAD TUESDAY ALONG WITH UPPER LEVEL RIDGING. LOW LEVEL WARM/MOIST ADVECTION WILL BE UNDERWAY TUESDAY EVENING AS STRENGTHENING LOW LEVEL JET DRAWS +10C 850MB DEWPOINTS TOWARD THE AREA. OVERNIGHT CONVECTION LOOKS LIKELY TUE NIGHT/WED MORNING IN ADVANCE OF APPROACHING WESTERN TROUGH ALONG WITH STRONG LOW LEVEL JET. A DAYTIME LULL IS LIKELY IN ACTIVITY BUT WEDNESDAY AFTERNOON/EVENING LOOKS QUITE ACTIVE WITH THE APPROACH OF DEEPENING UPPER TROUGH AND ASSOCIATED SFC COLD FRONT. SEVERE WEATHER POTENTIAL HAS BEEN OUTLOOKED BY SPC. .LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY) ISSUED AT 254 PM CDT SUN APR 20 2014 UPPER TROUGH AXIS WILL SWING THROUGH THE CWA BY THURSDAY MORNING ALLOWING ACTIVE WEATHER TO SHIFT OFF TO THE EAST. THE MAIN WEATHER IN THE EXTENDED WILL BE INTO THE WEEKEND AS A STRENGTHENING TROUGH DIGS ACROSS THE WESTERN CONUS BRINGING ANOTHER ROUND OF ACTIVE WEATHER TO US LATE IN THE WEEKEND/EARLY NEXT WEEK. TIMING AND POSITION OF THE LARGE SCALE FEATURES IS UNCERTAIN...BUT IT CERTAINLY COULD BE ACTIVE FOR A LARGE CHUNK OF THE REGION.
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&& .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1208 PM CDT SUN APR 20 2014 GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MONDAY MORNING. WEAK COLD FRONT ACROSS NORTHEAST NEBRASKA WILL EVENTUALLY MOVE SOUTHEAST LATER TONIGHT...WITH NORTH WINDS BEHIND THE FRONT REACHING KOFK BEFORE 12Z AND KOMA/KLNK SLIGHTLY AFTER. A FEW SHOWERS COULD AFFECT TAF SITES THIS AFTERNOON AND EVENING...WITH AN ISOLATED THUNDER ALSO POSSIBLE BUT NOT MENTIONED IN TAFS AS CHANCES ARE RELATIVELY SMALL. BETTER CHANCES FOR SHOWERS OR STORMS WILL COME WITH THE COLD FRONT OVERNIGHT. STILL LOW LEVEL MOISTURE IS LIMITED SO GENERALLY VFR CIGS/VSBYS ARE EXPECTED EXCEPT RIGHT UNDER THE STRONGER STORMS. CLEARING SKIES AND 15 TO 25KT NORTH WINDS ARE EXPECTED BY 18Z MONDAY. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...KERN LONG TERM...KERN AVIATION...DERGAN

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