Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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359 FXUS63 KOAX 060922 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 322 AM CST SAT FEB 6 2016 .SHORT TERM...
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(TODAY THROUGH MONDAY) ISSUED AT 322 AM CST SAT FEB 6 2016 THE PRIMARY FORECAST CONCERN IS THE POTENTIAL FOR STRONG WINDS SUNDAY INTO MONDAY. A POSITIVELY TILTED SHORT-WAVE TROUGH STRETCHING FROM AN UPPER LOW JUST SOUTH OF HUDSON BAY INTO THE SRN PLAINS WILL QUICKLY SHIFT EAST IN ADVANCE OF A POTENT UPSTREAM SHORT-WAVE TROUGH WHICH WILL TRANSLATE ALONG THE INTERNATIONAL BORDER FROM THE NRN ROCKIES TO UPPER GREAT LAKES TODAY INTO TONIGHT. TEMPORARY SUBSIDENCE/RIDGING ON THE BACKSIDE OF THE FORMER AND AHEAD OF THE LATTER WILL PROMOTE DOWNSLOPE WARMING TODAY WITH TEMPERATURES REBOUNDING TO NEAR OR SLIGHTLY ABOVE SEASONAL NORMALS. SOME PATCHY FOG WILL BE REMAIN POSSIBLE INTO MID MORNING...PRIOR TO THE ONSET OF DEEP BOUNDARY- LAYER MIXING. A MID TO UPPER-LEVEL JET STREAK FOLLOWING ON THE HEELS OF THE INTERNATIONAL-BORDER IMPULSE WILL PROGRESS FROM THE NRN HIGH PLAINS INTO THE OZARK PLATEAU SATURDAY NIGHT INTO SUNDAY...CONTRIBUTING TO THE FORMATION OF A CLOSED UPPER LOW OVER THE GREAT LAKES AND THE RAPID AMPLIFICATION OF A BROADER-SCALE TROUGH CENTERED OVER THE MS VALLEY. THIS UPPER-AIR PATTERN EVOLUTION WILL DRIVE A SURFACE COLD FRONT SEWD THROUGH THE FORECAST AREA BY DAYBREAK SUNDAY. WHILE SOME RAIN OR SNOW SHOWERS WILL BECOME POSSIBLE SUNDAY AFTERNOON OVER PORTIONS OF NERN NEB INTO W-CNTRL IA...THE AIR MASS IN THE WAKE OF THE FRONT WILL INITIALLY BE RELATIVELY DRY WITH ONLY SOME INCREASE IN CLOUDS EXPECTED. THE PRIMARY IMPACT OF THE EVOLVING GREAT LAKES SYSTEM WILL BE NORTHWEST WINDS WHICH WILL STRENGTHEN THROUGH THE DAY /SUNDAY/ OWING TO STEEPENING LAPSE RATES IN THE LOWEST 1-2 KM AGL...AND RESULTANT DOWNWARD TRANSFER OF HIGHER-MOMENTUM FLOW ALOFT. AT THIS POINT...IT APPEARS THAT WINDS WILL REMAIN BELOW HIGH WIND WARNING CRITERIA...THOUGH AN ADVISORY MAY BE NECESSARY AT SOME POINT DURING THE SUNDAY INTO MONDAY TIME PERIOD. SUNDAY NIGHT INTO MONDAY...CONTINUED MID-TROPOSPHERIC COLD ADVECTION AND WEAK FORCING FOR ASCENT ON THE PERIPHERY OF THE GREAT LAKES CYCLONE WILL YIELD A LOW-PROBABILITY CHANCE FOR SNOW SHOWERS...MAINLY ALONG AND EAST OF THE MISSOURI RIVER. GRADIENT FLOW ON THE BACKSIDE OF THE LARGE-SCALE TROUGH WILL REMAIN STRONG WITH GUSTY NORTH OR NORTHWEST WINDS CONTINUING INTO MONDAY AFTERNOON. THIS COULD LEAD TO AREAS OF BLOWING SNOW...PARTICULARLY SUNDAY NIGHT THROUGH MONDAY MORNING. .LONG TERM...(MONDAY NIGHT THROUGH FRIDAY) ISSUED AT 322 AM CST SAT FEB 6 2016 LATEST MEDIUM-RANGE GUIDANCE /E.G. GEFS AND DETERMINISTIC ECMWF AND GFS/ IS IN REASONABLY GOOD AGREEMENT IN DEPICTING THE GRADUAL EWD SHIFT OF THE UPPER TROUGH THIS UPCOMING WEEK WITH MID-LEVEL FLOW BECOMING MORE NWLY FROM THE NRN ROCKIES INTO MID-MS VALLEY. THE MEAN LOW-LEVEL BAROCLINIC ZONE WILL SUBSEQUENTLY ORIENT IN SIMILAR FASHION...GENERALLY BISECTING THE MID-MO VALLEY FOR SEVERAL DAYS. THE UPSHOT IS THAT ANY SMALL PERTURBATIONS MOVING THROUGH THIS FLOW PATTERN WILL CAUSE LATITUDINAL OSCILLATIONS IN THE BAROCLINIC ZONE...INTRODUCING CONSIDERABLE UNCERTAINTY IN TEMPERATURE AND PRECIPITATION FORECASTS. WE WILL MAINTAIN THE NOTION OF A GRADUAL WARM UP FROM EARLY THROUGH MID WEEK WITH A DRY FORECAST...BUT THIS WILL BE SUBJECT TO CHANGE.
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&& .AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1133 PM CST FRI FEB 5 2016 BATCH OF MVFR CIGS SHOULD CLEAR KLNK AND KOMA TAF SITES BY 10Z. MVFR VSBYS IN FOG ARE LIKELY THROUGH 16Z OR SO AT KOMA AND PERHAPS KLNK...BUT SOME LOWER VSBYS AT OR BELOW 1SM ARE POSSIBLE AT KOMA. ALL AREAS SHOULD BECOME VFR BY 18Z AND REMAIN THAT WAY THROUGH THE END OF THE TAF PERIOD. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...MEAD LONG TERM...MEAD AVIATION...DERGAN

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