Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 231726 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1226 PM CDT SAT MAY 23 2015 .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 311 AM CDT SAT MAY 23 2015 ...MAIN CHALLENGE IS TIMING THE MORE LIKELY PERIODS OF RAIN... THE FORECAST AREA WILL REMAIN IN AN ACTIVE PATTERN THROUGH MONDAY NIGHT AS A LARGE UPPER LOW CONTINUES TO SPIN OVER THE ROCKIES. EARLY MORNING WATER VAPOR LOOP WAS TELLING...IMPRESSIVE AMOUNT OF SUBTROPICAL MOISTURE WAS BEING PULLED INTO THE PLAINS AND ROCKIES REGIONS AS SLOW MOVING UPPER LOW CHURNS NEAR FOUR CORNERS. BLENDED TOTAL PRECIPITABLE WATER PRODUCT SHOWED MOST OF THE PLAINS AND ROCKIES OVER 100 PERCENT OF NORMAL AT 06Z. LARGE SURFACE HIGH PRESSURE MOVED FROM EASTERN NEBRASKA TO PENNSYLVANIA IN THE PAST 24 HOURS...WITH WEAK LEE SIDE CYCLOGENESIS TAKING SHAPE ALONG THE FRONT RANGE. SOUTHERLY LOW LEVEL FLOW HAS BECOME ESTABLISHED OVER THE PLAINS EARLY THIS MORNING...ALBEIT WEAK. MOISTURE RETURN HAS BEEN STEADY...WITH SURFACE DEWPOINTS IN THE LOW 50S OVER MUCH OF THE FORECAST AREA AND LOW 60S TO THE SOUTH ALONG THE RED RIVER. THIS PATTERN WILL BE CONDUCIVE TO THE DEVELOPMENT OF SHOWERS GIVEN THE INCREASINGLY MOIST PROFILE AND NUMEROUS SOURCES OF VERTICAL MOTION. THE BIG UPPER LOW TO THE WEST WILL PROVIDE DIFFLUENT FLOW AT THE JET LEVEL AS IT MEANDERS NORTHEAST THROUGH MONDAY NIGHT. SHORTWAVES ROTATING AROUND THE LOW WILL PROVIDE ADDITIONAL LIFT. THIS HAS RESULTED IN A FAIRLY LARGE AREA OF SHOWERS CURRENTLY OVER SOUTHWEST NEBRASKA INTO COLORADO...BUT THIS AREA SHOULD MOVE QUITE SLOWLY NORTHEAST. MUCH OF THE FORECAST REGION SHOULD REMAIN DRY TODAY...WAITING FOR THE SHOWERS TO THE WEST TO ARRIVE AND TRACK NORTHEAST ACROSS THE REGION. INSTABILITY IS LIMITED DUE TO THE RELATIVELY COOL AIRMASS...THEREFORE THUNDERSTORMS ARE NOT EXPECTED TO BE WIDESPREAD WITH THIS RAIN TODAY. TONIGHT THE RAIN WILL OVERSPREAD THE AREA AND WILL BE AIDED BY A 30-35 KNOT LOW LEVEL JET AND WEAK ISENTROPIC LIFT. A SLIGHT INCREASE IN INSTABILITY IS EXPECTED WITH INCREASING LOW LEVEL MOISTURE. RAIN CHANCES TONIGHT LOOK HIGH...IN THE 70-90 PERCENT RANGE. DURING THE DAY ON SUNDAY A WARM FRONT WILL MOVE NORTH THROUGH THE REGION...HOWEVER MOST MODELS STILL PULL A DRY SLOT NORTH THROUGH NEBRASKA DURING THE AFTERNOON. THIS WILL LIMIT CONVECTION IN WESTERN COUNTIES BUT THE WARM FRONT MAY SUSTAIN THE CONVECTION IN EASTERN COUNTIES. POPS ARE TAPERED FROM SLIGHT CHANCE IN THE WEST TO LIKELY EAST SUNDAY. SUNDAY NIGHT INTO MONDAY CONFIDENCE IS LOW WITH THE POP FORECAST. THE PRIMARY UPPER CIRCULATION IS EXPECTED TO MOVE INTO MINNESOTA MONDAY...HOWEVER THE AIRMASS WILL REMAIN MOIST AND UNSTABLE WITH THE POTENTIAL FOR ADDITIONAL SHORTWAVES MOVING THROUGH THE SOUTHWEST UPPER FLOW. WE CONTINUED THE CHANCE POPS FOR THUNDERSTORMS IN THE SUNDAY NIGHT - MONDAY NIGHT PERIOD. .LONG TERM...(MONDAY NIGHT THROUGH FRIDAY) ISSUED AT 311 AM CDT SAT MAY 23 2015 WE FINALLY HAVE SOME CONFIDENCE IN A DRY PERIOD TUESDAY INTO WEDNESDAY AS WEAK UPPER RIDGING MOVES IN AND MORE IMPORTANTLY...SURFACE HIGH PRESSURE BUILDS IN FROM THE NORTH. BUT THIS IS SHORT LIVED AS YET ANOTHER SOMEWHAT IMPRESSIVE TROF MOVES THROUGH THE WESTERN US WEDNESDAY NIGHT THROUGH FRIDAY. SURFACE CYCLOGENESIS AND RETURNING MOISTURE IS CAUSE FOR CHANCE POPS DURING THE SECOND HALF OF THE UPCOMING WEEK. && .AVIATION...
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(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1218 PM CDT SAT MAY 23 2015 REGIONAL RADAR SHOWING TSRA/IFR CONDITIONS CURRENTLY LIFTING THRU KS AND INTO S-CNTRL NEB. EXPECT THE PCPN ACTIVITY TO REACH ERN NEB LATE THIS AFTN WITH IFR CONDITIONS SETTLING IN AT ALL TAF SITES. AT THIS POINT...APPEARS LIKELY THAT COMBINATION OF IFR/LIFR CONDITIONS WILL PREVAIL THRU ABOUT 12Z SUN MORNING...THEN POSSIBLE IMPROVEMENT TO MVFR TWD 18Z SUN.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...NIETFELD LONG TERM...NIETFELD AVIATION...DEE

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