Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 051128 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 628 AM CDT TUE MAY 5 2015 .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 333 AM CDT TUE MAY 5 2015 ACTIVE WEATHER PATTERN CONTINUES ACROSS THE PLAINS THIS WEEK WITH EPISODIC PERIODS OF SEVERE WEATHER/CHANCES FOR RAIN. THE 00Z H3 JET WAS STRONGEST OVER THE PACIFIC NORTHWEST AND ACROSS MEXICO. THE H5 PATTERN HAD CLOSED LOW PRESSURE OFF THE PACIFIC NORTHWEST AND ANOTHER AREA OF CLOSED LOW PRESSURE OVER THE SOUTHWEST U.S. AHEAD OF THE SOUTHWEST SYSTEM...INTO THE PLAINS THERE WERE WEAK RIPPLES OF EMBEDDED SHORTWAVE TROFS IN THE FLOW. H85 FLOW WAS NOT REAL STRONG...25 TO 30KTS ACROSS PARTS OF KANSAS/OKLAHOMA/TEXAS...WITH POOLING OF MOISTURE +10-12DEG C FROM KANSAS. THE OAX SOUNDING WAS +10 AT H85 AND WITH 1.30 INCHES PWAT...NEARLY 200% NORMAL. THE SURFACE FRONT EARLY THIS MORNING WAS LOCATED OVER SOUTHEAST NEBRASKA AND SOUTHERN IOWA...WITH ANOTHER BOUNDARY SOUTH OVER CENTRAL KANSAS. WARM FRONT WAS MAKING STEADY PROGRESS NORTHWARD EARLY THIS MORNING...AND HAD MOVED NORTH OF A LINCOLN TO RED OAK LINE AS OF 3AM. ISENTROPIC UPGLIDE OVER FRONTAL ZONE CONTINUED TO GENERATE SCATTERED SHOWERS ABOUT 40 MILES NORTH OF THE FRONT...AND EXPECT THIS TREND TO PERSIST DURING THE MORNING AS BOUNDARY LIFTS INTO NORTHEAST NEBRASKA. IN ITS WAKE...JUICY ATMOSPHERE WILL REMAIN IN PLACE GIVE RELATIVELY HIGH PRECIPITABLE WATER VALUES AND SURFACE DEW POINTS APPROACHING 60F...BUT UPPER SUPPORT WILL WANE AS WEAK WAVE CURRENTLY OVER EASTERN NEBRASKA LIFTS NORTHEAST. WHILE WE WAIT FOR BETTER UPPER SUPPORT LATER TONIGHT...CAN NOT RULE OUT ISOLATED TO SCATTERED SHOWERS DEVELOPING IN THE HEAT OF THE AFTERNOON. SHORT RANGE MESOSCALE MODELS ARE HINTING AT THIS SCENARIO WITH SURFACE- BASED CAPES REACHING THE 500-1000 J/KG RANGE IF TEMPERATURES REACH THE MID AND UPPER 70S AS EXPECTED. THIS SHOULD BE ACHIEVABLE IF BREAKS IN CLOUDS ARE REALIZED...ESPECIALLY IN SOUTHEAST NEBRASKA AND SOUTHWEST IOWA...AS PER A MAJORITY OF SHORT RANGE MODEL FORECASTS. TONIGHT...THE CLOSED LOW OVER THE SOUTHWEST U.S. WILL LIFT ACROSS COLORADO AND BY 12Z...STRETCHES FROM WYOMING TO NORTHEAST COLORADO...INTO CENTRAL KANSAS. THE 30 TO 35KT JET OVER CENTRAL KANSAS AND OKLAHOMA INCREASES TO 45 TO 50KTS BY 06Z. THE SURFACE FRONT SHOULD BE IN NORTHEAST NEBRASKA...LIFTING NORTH OF THE AREA BY 12Z. THIS PATTERN WILL PROMOTE SHOWERS AND THUNDERSTORMS OVER THE WESTERN PLAINS...SHIFTING EASTWARD OVERNIGHT AS THE LOW LEVEL JET VEERS AND STRENGTHENS. WEDNESDAY MORNING...SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS THE AREAS...SHIFTING INTO IOWA. DURING THE AFTERNOON...DESTABILIZATION WILL OCCUR FROM OKLAHOMA NORTH INTO KANSAS AND CENTRAL NEBRASKA ALONG WITH INCREASING 0-6KM BULK SHEAR OVER KANSAS. THIS COMBINED WITH AN H7 SPEED MAX/H5 SUPPORT IS LIKELY WHY THERE IS A SLIGHT RISK FOR SEVERE STORMS IN THIS REGION. THURSDAY...AS THE H5 TROF SLOWLY LIFTS NORTH...BUT GENERALLY LINGERS OVER THE NORTHERN PLAINS WITH A COLD FRONT OVER THE CWA...WITH PLENTY OF MOISTURE AHEAD OF THE FRONT...MODERATE INSTABILITY DEVELOPS WITH 35KTS OF 0-6KM BULK SHEAR. SHOWERS AND THUNDERSTORMS SHOULD STRENGTHEN WITH AFTERNOON HEATING. CURRENTLY IN THE MARGINAL SEVERE RISK...BUT MAY SEE THIS INCREASE DUE TO HIGHER INSTABILITY. .LONG TERM...(THURSDAY NIGHT THROUGH MONDAY) ISSUED AT 333 AM CDT TUE MAY 5 2015 WITH CLOSED H5 LOW PRESSURE OVER CALIFORNIA/NEVADA AND SOUTHWEST FLOW ALOFT...MOISTURE REMAINS IN PLACE OVER THE CENTRAL AND SOUTHERN PLAINS. THIS SYSTEM LIFTS NORTHEAST INTO COLORADO SATURDAY NIGHT AND SUNDAY. THERE WILL BE SHOWERS AND THUNDERSTORM CHANCES ESPECIALLY ACROSS THE SOUTHERN PART OF THE FORECAST AREA CLOSER TO THE SURFACE FRONT. STORMS BECOME LIKELY ACROSS THE ENTIRE FORECAST AREA SATURDAY NIGHT WITH THE PROGRESS OF THE MID TROPOSPHERIC TROF. THERE AREA SOME TIMING DIFFERENCES SUNDAY THROUGH MONDAY AS TO HOW LONG THE PRECIPITATION WILL LINGER. TEMPERATURES SHOULD BE BELOW OR NEAR NORMAL. && .AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 628 AM CDT TUE MAY 5 2015 MVFR AND IFR CIGS/VSBYS WILL OCCASIONALLY AFFECT TAF SITES THROUGH THE MORNING AS ISOLATED SHOWERS WANDER THROUGH EASTERN NEBRASKA. AS A WARM FRONT LIFTS NORTH OF THE TAF SITES BY 18Z...SOUTHEAST WINDS AND VFR CIGS ARE FORECAST. HOWEVER ISOLATED SHOWERS AND MAYBE A THUNDERSTORM COULD DEVELOP AT JUST ABOUT ANY TIME BETWEEN 20Z AND 02Z IN A MOIST AND UNSTABLE ATMOSPHERE...AND COULD BRING MVFR CONDITIONS WITH THEM. THE CHANCE FOR MORE WIDESPREAD SHOWERS WITH MVFR TO IFR CIGS/VSBYS WILL COME AFTER 04Z AS ANOTHER WAVE OF MID LEVEL ENERGY EJECTS INTO THE PLAINS. THUNDERSTORMS ARE ALSO POSSIBLE WITH THIS SYSTEM...BUT EXPECTED LIMITED COVERAGE WILL PRECLUDE MENTION IN TAFS AT THIS TIME. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...DERGAN/ZAPOTOCNY LONG TERM...ZAPOTOCNY AVIATION...DERGAN

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