Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 210829 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 329 AM CDT SUN SEP 21 2014 .SHORT TERM...
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(TODAY THROUGH TUESDAY) ISSUED AT 311 AM CDT SUN SEP 21 2014 ...RAIN CHANCES MON NT AND TUE CONTINUE TO BE THE PRIMARY FORECAST CONCERNS... A UNIQUE UPPER FLOW PATTERN WILL DETERMINE THE WEATHER...AND SPECIFICALLY THE RAIN CHANCES...THROUGH THE NEXT SEVERAL DAYS OVER THE FORECAST AREA. WATER VAPOR LOOP AND UPPER AIR DATA INDICATES THIS PATTERN CONSISTS OF AN UPPER RIDGE THAT CURRENTLY EXTENDS FROM THE SOUTHERN ROCKIES INTO BRITISH COLUMBIA...AND A SLOW-MOVING CUTOFF UPPER LOW THAT HAS BEEN LINGERING ON THE WEST SIDE OF THE UPPER RIDGE AXIS...CURRENTLY SITTING OVER CALIFORNIA. THE SURFACE REFLECTION OF THE UPPER RIDGE WAS A 1026 MB SURFACE HIGH CENTERED OVER EASTERN MONTANA...REPRESENTING A DRY AIRMASS THAT HAS WORKED INTO THE FORECAST AREA. THIS DRY AIRMASS AND SURFACE HIGH WILL KEEP QUIET AND DRY WEATHER IN PLACE THROUGH MONDAY. HOWEVER BY MONDAY EVENING THE UPPER LOW OVER CALIFORNIA IS EXPECTED TO DRIFT INTO THE UPPER RIDGE AND MAKE ITS WAY INTO THE NORTHERN HIGH PLAINS OF WYOMING AND MONTANA. THERE IS VERY GOOD MODEL AGREEMENT WITH THE POSITION OF THIS LOW...AND THE RUN-RUN CONSISTENCY IS ALSO HIGH. MODEL TRENDS ARE TOWARD SLIGHTLY HIGHER HEIGHTS WITH THE UPPER LOW...BUT GENERALLY THE CONSISTENCY IS QUITE GOOD. WITH SIMILAR MODEL AGREEMENT...CYCLOGENESIS OVER THE NORTHERN HIGH PLAINS IS PROGGED MONDAY NIGHT WITH THE SURFACE HIGH MOVING EAST OF THE MISSISSIPPI RIVER AND STRONG SOUTH FLOW SETTING UP OVER THE PLAINS. EXPECT ANY RAIN MONDAY NIGHT TO BE CONFINED TO CENTRAL NEBRASKA...WITH PERHAPS A FEW LIGHT SHOWERS TRYING TO OVERCOME THE DRY AIR AND MOVE AS FAR EAST AS COLUMBUS AND NORFOLK LATE MONDAY NIGHT. ON TUESDAY THE UPPER LOW MOVES INTO THE DAKOTAS WITH ASSOCIATED UPPER TROUGH EXTENDING INTO THE SOUTHERN PLAINS...THE SURFACE LOW DEEPENS TO OUR WEST...AND ENOUGH MOISTURE RETURNS TO SUPPORT PRECIPITATION OVER ALL OF OUR FORECAST AREA. INSTABILITY SHOULD BE LIMITED SO WE MAINLY EXPECT RAIN SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS. POPS RANGE FROM CHANCE IN THE EAST TO LIKELY IN OUR WESTERN COUNTIES. TEMPERATURES WILL BE HELD DOWN A FEW DEGREES ON TUESDAY FROM THE RAIN/CLOUDS...WITH UPPER 60S - LOW 70S COMMON. .LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY) ISSUED AT 311 AM CDT SUN SEP 21 2014 THE PATTERN ON TUESDAY GENERALLY REMAINS IN PLACE INTO WEDNESDAY...BUT MODEL SOLUTIONS QUICKLY DIVERGE AFTER WEDNESDAY NIGHT. IN ADDITION...SUBSIDENCE FROM THE UPPER RIDGE SHOULD BE OVERTAKING THE UPPER LOW WITH AN OVERALL WEAKENING OF THE VERTICAL MOTION ASSOCIATED WITH IT. MODELS SHOW 500 MB HEIGHTS AT OR ABOVE 5880 METERS IN THE UPPER RIDGE...WITH WEAK UPPER FLOW AND WARMING ALOFT. THIS SHOULD SUPPRESS CONVECTION MOST AREAS. THEREFORE KEPT POPS TUESDAY NIGHT INTO WEDNESDAY NIGHT...BUT HAVE A DRY FORECAST FOR THURSDAY THROUGH SATURDAY. TEMPERATURES UNDER THE UPPER RIDGE SHOULD RETURN TO NEAR OR SLIGHTLY ABOVE NORMAL VALUES IN THE UPPER 70S BY THE END OF THE WEEK.
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&& .AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1218 AM CDT SUN SEP 21 2014 VFR CONDITIONS THROUGH THE PERIOD AS HIGH PRESSURE BUILDS INTO THE REGION. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...NIETFELD LONG TERM...NIETFELD AVIATION...FOBERT

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