Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 251713 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1213 PM CDT MON MAY 25 2015 .UPDATE...
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ISSUED AT 1215 PM CDT MON MAY 25 2015 SPOTTY SHOWERS ASSOCIATED WITH THE LEAD VORT LOBE ATTACHED TO THE UPPER LOW ACROSS THE ROCKIES HAS PUSHED OUT OF THE AREA THIS MORNING. MEANWHILE...A QUICK 17Z SURFACE ANALYSIS REVEALED THE NEARLY STATIONARY FRONT WAS LOCATED ACROSS NORTH CENTRAL NE THROUGH NORTHWEST IA. BULK OF THE FORECAST AREA WILL REMAIN IN THE WARM SECTOR TODAY WITH WARM AND HUMID CONDITIONS. BEST CHANCES FOR PRECIP WILL BE ALONG THE FRONT IN NORTHEAST NEBRASKA THIS AFTERNOON...AND PROBABLY NOT ACROSS THE REMAINDER OF THE FORECAST AREA UNTIL VERY LATE THIS AFTERNOON AND MORE LIKELY THIS EVENING AS THE UPPER SUPPORT EVENTUALLY ARRIVES. WIND SHEAR IS MARGINAL AT 25 TO 35 KNOTS... BUT INSTABILITY WILL STRONG WHICH WILL YIELD A HAIL AND HIGH WIND RISK WITH ANY STORMS THAT DEVELOP. LOW LEVEL 0-1KM SHEAR IS FORECAST TO INCREASE THIS EVENING...RESULTING IN A SMALL WINDOW OF RISK FOR AN ISOLATED TORNADO IN SOUTHEAST NEBRASKA AND SOUTHWEST IOWA.
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&& .SHORT TERM...
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(TODAY THROUGH WEDNESDAY) ISSUED AT 313 AM CDT MON MAY 25 2015 ISOLATED SHOWERS/THUNDERSTORMS ARE POPPING UP IN THE CWA BETWEEN BROADER AREAS OF SHOWERS AND/OR THUNDERSTORMS. SUBJECTIVE 00Z UPPER AIR ANALYSIS INDICATES BROAD UPPER-LEVEL LOW CENTERED IN EASTERN WY...WITH 500MB HEIGHT FALLS UP TO 40M ACROSS THE MO RIVER VALLEY. ABUNDANT MOISTURE WAS NOTED AT MOST LEVELS...INCLUDING 8C+ DEWPOINTS AT 850MB STRETCHING FROM THE GULF COAST INTO EASTERN NEB/SD/SOUTHERN MN. SURFACE LOW AT 07Z WAS CENTERED IN SOUTHWEST KS/OK-TX PANHANDLES...WITH SECONDARY LOW IN SOUTH CENTRAL MN/NORTH CENTRAL IA. IN BETWEEN...WEAK TROUGH AXIS ACROSS EASTERN NEB WAS NOTED BY LIGHT WINDS...AND FOG HAD FORMED NEAR THE TROUGH AXIS ACROSS NORTHEAST TO CENTRAL NEB. MAIN FORECAST CONCERN IS CONVECTIVE POTENTIAL TODAY/TONIGHT...AS WELL AS ONGOING SHOWER/THUNDERSTORM POTENTIAL THROUGHOUT THE FORECAST. CONFIDENCE IS LOW IN EVOLUTION OF CONVECTION TODAY/TONIGHT...AND REALLY THROUGHOUT THE REST OF THE FORECAST AS WELL...AS MURKY PATTERN CONTINUES. MORNING SHOWERS/THUNDER SHOULD CLEAR FOR AT LEAST A LITTLE WHILE FROM LATE MORNING INTO THE AFTERNOON...ESPECIALLY IN THE SOUTHERN 2/3 OF THE CWA. THIS WOULD ALLOW SOME HEATING AND DESTABILIZATION...WHICH IS INDICATED BY SHORT- TERM MODELS. MID-LEVEL LAPSE RATES ARE CURRENTLY WEAK ACROSS THE PLAINS...THOUGH THEY ARE FORECAST TO INCREASE TODAY...PROVIDING A MORE UNSTABLE PROFILE. MODELS INITIATE CONVECTION SOMEWHERE AROUND NORTH CENTRAL KS TO SOUTHEAST NEB SOMETIME IN THE VERY LATE AFTERNOON OR EARLY EVENING AS UPPER LOW EJECTS ONTO THE PLAINS AND OPENS INTO A TROUGH. BULK SHEAR IS PROGGED ON THE WEAK SIDE...AT 30- 40KT...BUT LOW-LEVEL SHEAR IS ADEQUATE. ANOTHER POINT OF UNCERTAINTY IS WHETHER THE TIMING OF THE SHORTWAVE WILL ALIGN WITH BEST AVAILABLE INSTABILITY. ALL IN ALL...PLENTY OF CAVEATS...WITH A SPECTRUM OF POTENTIAL THAT RANGES FROM A COUPLE OF EVENING THUNDERSTORMS TO A HANDFUL OF SEVERE STORMS. IF LAPSE RATES DID INCREASE AS PROGGED...THREAT WOULD EXIST FOR HAIL AND WIND...AND GIVEN SOME CURVE IN FORECAST HODOGRAPHS...ALSO A THREAT FOR TORNADOES AS LONG AS STORMS CAN REMAIN SURFACE-BASED. PRECIPITATION SHOULD SLOWLY WORK ITS WAY OUT OF THE CWA THROUGH THE DAY ON TUESDAY...WITH LINGERING SLIGHT CHANCE POPS ON THE EASTERN/SOUTHERN FRINGES OF THE CWA THROUGH THE DAY AND INTO THE EVENING. IN ITS WAKE...WEATHER SHOULD BE FAIRLY QUIET ON TUESDAY NIGHT AND WEDNESDAY. .LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY) ISSUED AT 313 AM CDT MON MAY 25 2015 NEXT SHORTWAVE BRINGS A CHANCE OF THUNDERSTORMS WEDNESDAY EVENING/NIGHT...WITH HIGHEST CHANCES IN THE NORTHERN CWA. PATTERN BECOMES MORE ACTIVE FROM THERE INTO THE WEEKEND AS ANOTHER TROUGH DIGS INTO THE ROCKIES BEFORE EJECTING ACROSS THE PLAINS. AS HAS BEEN THE CASE SO FAR THIS SPRING...CONFIDENCE IN WHETHER PERIODS OF RAIN WILL BE ACCOMPANIED BY THUNDER...AND WHETHER ANY STORMS WILL BE SEVERE...IS QUITE LOW. ABUNDANT MOISTURE BUT WEAK CAPPING AND WEAK FOCUS FOR THUNDERSTORM DEVELOPMENT COULD MEAN THAT CLOUDS AND/OR CONVECTIVE COMPLEXES COULD AGAIN IMPEDE DESTABILIZATION...WITH THE POTENTIAL FOR INGREDIENTS TO COME TOGETHER FOR STRONG TO SEVERE STORMS SOMEWHERE ON THE PLAINS.
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&& .AVIATION...
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(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1215 PM CDT MON MAY 25 2015 VFR CONDITIONS THROUGH MOST OF THE PERIOD. SOUTHWEST WINDS AROUND 12 KNOTS INITIALLY...COULD SEE OCCASIONAL GUSTS UP TO 18 KNOTS THROUGH 00Z. CONVECTIVE DEVELOPMENT SHOULD HOLD OFF UNTIL 23Z AT KOFK...AND NOT UNTIL 02-03Z AT KLNK/KOMA. WILL HAVE ABOUT A 4-5 HOUR WINDOW OF THUNDERSTORM OPPORTUNITY...THEN A SHOWER CHANCE AFTER THAT.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ UPDATE...DEWALD SHORT TERM...MAYES LONG TERM...MAYES AVIATION...DEWALD

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