Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 251138
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
638 AM CDT MON MAY 25 2015

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 313 AM CDT MON MAY 25 2015

ISOLATED SHOWERS/THUNDERSTORMS ARE POPPING UP IN THE CWA BETWEEN
BROADER AREAS OF SHOWERS AND/OR THUNDERSTORMS. SUBJECTIVE 00Z UPPER
AIR ANALYISS INDICATES BROAD UPPER-LEVEL LOW CENTERED IN EASTERN
WY...WITH 500MB HEIGHT FALLS UP TO 40M ACROSS THE MO RIVER VALLEY.
ABUNDANT MOISTURE WAS NOTED AT MOST LEVELS...INCLUDING 8C+ DEWPOINTS
AT 850MB STRETCHING FROM THE GULF COAST INTO EASTERN NEB/SD/SOUTHERN
MN. SURFACE LOW AT 07Z WAS CENTERED IN SOUTHWEST KS/OK-TX
PANHANDLES...WITH SECONDARY LOW IN SOUTH CENTRAL MN/NORTH CENTRAL
IA.  IN BETWEEN...WEAK TROUGH AXIS ACROSS EASTERN NEB WAS NOTED BY
LIGHT WINDS...AND FOG HAD FORMED NEAR THE TROUGH AXIS ACROSS
NORTHEAST TO CENTRAL NEB.

MAIN FORECAST CONCERN IS CONVECTIVE POTENTIAL TODAY/TONIGHT...AS
WELL AS ONGOING SHOWER/THUNDERSTORM POTENTIAL THROUGHOUT THE
FORECAST.  CONFIDENCE IS LOW IN EVOLUTION OF CONVECTION
TODAY/TONIGHT...AND REALLY THROUGHOUT THE REST OF THE FORECAST AS
WELL...AS MURKY PATTERN CONTINUES. MORNING SHOWERS/THUNDER SHOULD
CLEAR FOR AT LEAST A LITTLE WHILE FROM LATE MORNING INTO THE
AFTERNOON...ESPECIALLY IN THE SOUTHERN 2/3 OF THE CWA.  THIS WOULD
ALLOW SOME HEATING AND DESTABILIZATION...WHICH IS INDICATED BY SHORT-
TERM MODELS.  MID-LEVEL LAPSE RATES ARE CURRENTLY WEAK ACROSS THE
PLAINS...THOUGH THEY ARE FORECAST TO INCREASE TODAY...PROVIDING A
MORE UNSTABLE PROFILE.  MODELS INITIATE CONVECTION SOMEWHERE AROUND
NORTH CENTRAL KS TO SOUTHEAST NEB SOMETIME IN THE VERY LATE
AFTERNOON OR EARLY EVENING AS UPPER LOW EJECTS ONTO THE PLAINS AND
OPENS INTO A TROUGH.  BULK SHEAR IS PROGGED ON THE WEAK SIDE...AT 30-
40KT...BUT LOW-LEVEL SHEAR IS ADEQUATE.  ANOTHER POINT OF
UNCERTAINTY IS WHETHER THE TIMING OF THE SHORTWAVE WILL ALIGN WITH
BEST AVAILABLE INSTABILITY.  ALL IN ALL...PLENTY OF CAVEATS...WITH A
SPECTRUM OF POTENTIAL THAT RANGES FROM A COUPLE OF EVENING
THUNDERSTORMS TO A HANDFUL OF SEVERE STORMS. IF LAPSE RATES DID
INCREASE AS PROGGED...THREAT WOULD EXIST FOR HAIL AND WIND...AND
GIVEN SOME CURVE IN FORECAST HODOGRAPHS...ALSO A THREAT FOR
TORNADOES AS LONG AS STORMS CAN REMAIN SURFACE-BASED.

PRECIPITATION SHOULD SLOWLY WORK ITS WAY OUT OF THE CWA THROUGH THE
DAY ON TUESDAY...WITH LINGERING SLIGHT CHANCE POPS ON THE
EASTERN/SOUTHERN FRINGES OF THE CWA THROUGH THE DAY AND INTO THE
EVENING.  IN ITS WAKE...WEATHER SHOULD BE FAIRLY QUIET ON TUESDAY
NIGHT AND WEDNESDAY.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 313 AM CDT MON MAY 25 2015

NEXT SHORTWAVE BRINGS A CHANCE OF THUNDERSTORMS WEDNESDAY
EVENING/NIGHT...WITH HIGHEST CHANCES IN THE NORTHERN CWA. PATTERN
BECOMES MORE ACTIVE FROM THERE INTO THE WEEKEND AS ANOTHER TROUGH
DIGS INTO THE ROCKIES BEFORE EJECTING ACROSS THE PLAINS. AS HAS BEEN
THE CASE SO FAR THIS SPRING...CONFIDENCE IN WHETHER PERIODS OF RAIN
WILL BE ACCOMPANIED BY THUNDER...AND WHETHER ANY STORMS WILL BE
SEVERE...IS QUITE LOW.  ABUNDANT MOISTURE BUT WEAK CAPPING AND WEAK
FOCUS FOR THUNDERSTORM DEVELOPMENT COULD MEAN THAT CLOUDS AND/OR
CONVECTIVE COMPLEXES COULD AGAIN IMPEDE DESTABILIZATION...WITH THE
POTENTIAL FOR INGREDIENTS TO COME TOGETHER FOR STRONG TO SEVERE
STORMS SOMEWHERE ON THE PLAINS.

&&

.AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 635 AM CDT MON MAY 25 2015

THROUGH THE LATE MORNING HOURS...KOFK AND KOMA WILL BE IMPACTED BY
IFR AND LIFR CONDITIONS DUE TO MOISTURE BEING TRAPPED IN AN AREA
WITH LITTLE WIND. THIS IS DUE TO AN AREA OF LOW PRESSURE THAT
EXTENDS FROM WESTERN KANSAS THROUGH NORTHEAST NEBRASKA INTO
MINNESOTA...AND A MOIST AIRMASS. KLNK SHOULD REMAIN SOUTH OF THE
IFR CIGS/VSBYS.

AS THE LOW SLOWLY MOVES EAST...CONDITIONS SHOULD IMPROVE TO MVFR
AND VFR BY EARLY AFTERNOON. HOWEVER...SCATTERED THUNDERSTORMS ARE
EXPECTED TO DEVELOP DURING THE LATE AFTERNOON AND EVENING HOURS. A
FEW STORMS COULD BE QUITE STRONG...ESPECIALLY NEAR THE KOMA AND
KLNK TAF SITES.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$

SHORT TERM...MAYES
LONG TERM...MAYES
AVIATION...NIETFELD



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