Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 271107 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 507 AM CST FRI FEB 27 2015 .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 226 AM CST FRI FEB 27 2015 LARGE-SCALE PATTERN EXHIBITED A LARGE POSITIVELY TITLED UPPER LEVEL TROUGH FROM THE GREAT LAKES INTO THE DESERT SOUTHWEST. A NUMBER OF SHORTWAVE TROUGHS WERE ROTATING THROUGH THIS PATTERN. WITHIN THE NORTHERN STREAM A SHRTWV WAS SEEN OVER WY /THIS WILL LIKELY SPREAD SOME HIGH CI TO THE SRN CWA TODAY/...AND IN THE SOUTHERN STREAM ONE WAS LOCATED OVER AZ...WITH AN UPSTREAM SYSTEM MOVING INTO THE PAC NW. AT THE SURFACE ARCTIC HIGH PRESSURE WAS CENTERED RIGHT OVER THE MID MO RIVER VALLEY WITH LIGHT WINDS ACROSS THE CWA AND VERY COLD TEMPERATURES. THIS HIGH WILL START TO SHIFT SEWD TODAY...BUT WE WILL SEE VERY LIMITED MIXING...ESPECIALLY ACRS NEW SNOW AREAS OF W-CNTRL IA. HAVE TRIMMED HIGHS A TOUCH MOST AREAS...BUT ESPECIALLY IN THE FAR NE CWA. AS THE HIGH MOVES EAST TONIGHT WINDS WILL INCREASE FM THE SE...AND THIS ALONG WITH INCREASING HIGH CLOUDS WILL KEEP TEMPERATURES MUCH WARMER THAN TONIGHT. HEIGHT RISES OF 40 TO 60 M AT H5 ARE EXPECTED TONIGHT INTO SAT AS THE PREVIOUSLY MENTIONED PAC NW SHRTWV TROF DIVES INTO THE SW US. THIS WILL PROMOTE STRONG LOW TO MID LEVEL WAA CROSS THE CNTRL PLAINS AS THE REGION BECOMES LOCATED IN THE RIGHT REAR ENTRANCE REGION OF A 120 KT H25 JET. THIS PATTERN SHOULD BE FAVORABLE FOR INCREASING PRECIP OVER PARTS OF THE SRN PLAINS INTO THE DAY ON SAT LIFTING TO THE NORTHEAST. LATEST SHRT TERM MODELS ARE IN FAIR AGREEMENT IN THIS EVOLUTION THOUGH DIFFER ON SOME OF THE DETAILS. WE FEEL THE EC LIFTS PRECIP INTO THE AREA TO QUICKLY DURING THE DAY ON SAT PREFERRING A SLOWER ONSET TO -SN. THE GFS SEEMS TO STRONG WITH A NORTHERN STREAM SHRTWV TROUGH THAT SWINGS THROUGH THE DAKOTAS/MN ON SAT NIGHT AND LEADS TO ENHANCED H8 FRONTOGENESIS AND LIFT BY SUN MRNG...THUS OVER-DEVELOPS QPF. IT APPEARS THE MOST LIKELY SCENARIO IS FOR LIGHT SNOW TO SPREAD INTO SE NEB/SW IA LATE SAT AFTN/EARLY EVNG WITH OCCASIONAL -SN THROUGH SUN MRNG BEFORE THE CDFNT MOVS THRU AND PRECIP SHIFTS EWD. AS FAR AS AMOUNTS WILL GO WITH 2-3 INCHES RIGHT ALONG THE KS/MO BORDER WITH 1 INCH ALONG I80 AND LITTLE IF ANY IN NE NEB. .LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY) ISSUED AT 226 AM CST FRI FEB 27 2015 OVER OVER-ALL PATTERN WILL REMAIN ACTIVE INTO THE EXTENDED PERIOD AS THE SW US SHRTWV TROUGH CLOSES OFF LATE THIS WEEKEND BEFORE EJECTING EARLY NEXT WEEK AS AN OPEN TROUGH FOR MON/TUE/WED. MODELS CONT TO SHOW SIGNIFICANT DIFFERENCE IN THE EVOLUTION OF INDIVIDUAL SHRTWV TROUGHS WITHIN THE FAST FLOW AND CONFIDENCE IS VERY LOW FOR THE FIRST PART OF THIS PERIOD. IT APPEARS THAT MOST OF MON SHOULD BE DRY ALTHOUGH MODELS DO INCREASE ISENTROPIC LIFT BY AFTN OVER CNTRL TO NE NEB...AND WE WILL MAINTAIN SOME SCHC POPS. WE SHOULD SEE AN INCREASE IN CHCS FOR PRECIP ON MON NIGHT THOUGH AS STRONG LOW TO MID LEVEL WAA DEVELOPS OVER THE CTNRL PLAINS AND LEADS TO GOOD NET ISENTROPIC VERTICAL MOTION. ALTHOUGH MODELS DIFFER AS TO THE EXACT THERMAL PROFILE...ALL DO INDICATE THAT A MIX OF PRECIP TYPE WILL BE AN ISSUE FOR MON NIGHT AND TUE. WE WILL CONT WITH A MENTION OF RA/FZRA IN THE SOUTH...FZRA/IP IN THE CNTRL AND IP/SN IN THE NORTH...BUT PLACEMENT OF THESE TYPES WILL LIKELY CHANGE AS THE EVENT NEARS. AS THE SURFACE LIFTS SHIFTS E ON TUE WE SHOULD SEE COLDER AIR RUSH IN SWITCHING THINGS OVER TO SN TO END AT LEAST. WE WILL LINGER SOME POPS INTO TUE NIGHT AND WED ACTUALLY AS THE 00Z EC IS MUCH SLOWER THAN OTHER GUIDANCE SHIFTING THE TROUGH TO THE EAST. && .AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 506 AM CST FRI FEB 27 2015 VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. LIGHT WINDS THIS MORNING WILL BECOME SOUTHEAST THROUGH THE DAY...BUT REMAIN LIGHT. WE WILL SEE AN INCREASE IN MID AND HIGH LEVEL CLOUDS TONIGHT. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...BOUSTEAD LONG TERM...BOUSTEAD AVIATION...

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