Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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097
FXUS63 KOAX 151746
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1246 PM CDT FRI MAY 15 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 349 AM CDT FRI MAY 15 2015

CONVECTIVE CHANCES AND THEIR ASSOCIATED SEVERITY ARE THE MAIN
FORECAST CONCERNS THROUGH THE SHORT TERM.

00Z UPPER AIR ANALYSIS INDICATED A WELL-DEFINED SHORTWAVE TROUGH
FM NM INTO WESTERN TX. THIS IS EXPECTED TO LIFT NEWD THROUGH THE
CWA BY MID AFTN TODAY. AHEAD OF THIS WAVE A STRONG MCS WAS
OCCURRING OVER THE SOUTHERN PLAINS. ADDITIONAL TSRA WERE
DEVELOPING IN AN AREA OF WAA OVER WRN NEB INTO NRN KS WHERE THE
850 MB FRONT IS STARTING TO LIFT TO THE N. CONVECTIVE EVOLUTION
THROUGH THE EARLY PART OF THE DAY IS UNCERTAIN DUE TO THE ONGOING
CONVECTION THAT MODELS...ESPECIALLY CONVECTION ALLOWING
MODELS...ARE NOT CAPTURING WELL. CURRENT FEELING IS THAT AS THE
SHORTWAVE APPROACHES THIS MORNING...AND LARGE-SCALE FORCING
INCREASES WE WILL SEE AN INCREASE IN CONVECTIVE COVERAGE OVER THE
FA. THIS MAY HAPPEN BY THE WRN NEB/KS CONVECTIVE LIFTING NEWD
THRU THE FA...OR ADDITIONAL STORMS DEVELOPING OVER THE FA AS
850-700 THETA-E ADVECTION INCREASES AND STABILITY DECREASES.
LATEST OBJECTIVE ANALYSIS INDCS AROUND 1500-2000 J/KG OF MUCAPE
UPSTREAM OVER KS AND WE SEE NO REASON THIS WON`T SPREAD INTO THE
AREA OVER THE NEXT SEVERAL HOURS. THE WIND FIELD THROUGH MOST OF
THE DAY THOUGH IS FAIRLY WEAK WITH EFFECTIVE SHEAR AOB 30
KT. NEVERTHELESS ORGANIZED MULTI-CELLED CONVECTION APPEARS
POSSIBLE GIVEN THE INSTABILITY AND FORCING WITH A FEW ISO STRONG
TO SEVERE STORMS POSSIBLE FM LATE MRNG INTO THE EARLY AFTN. THIS
CONVECTION WILL EITHER TEND TO LIFT NEWD OUT OF THE FA...OR WEAKEN
AS LARGE-SCALE SUBSIDENCE INCREASES IN THE WAKE OF THE SHORTWAVE
TROUGH. THUS WE WILL HAVE DECREASING POPS THROUGH THE AFTERNOON.
MODELS CONT TO PROG THE WARM FRONT TO DEVELOP FM WRN NEB TO ALONG
THE KS/NEB BORDER LATE THIS AFTERNOON. SOME MODELS DO INDC CI ALONG
THIS BOUNDARY...BUT THIS APPEARS MORE LIKELY WEST OF THE FA WHERE
BETTER DYNAMICS WILL COME INTO PLAY. WILL MAINTAIN SOME SCHC POPS
INTO THE EARLY EVENING HOURS NEAR THIS BOUNDARY BUT MOST OF THE
NIGHT SHOULD BE DRY AND WARM.

CONVECTIVE EVOLUTION IS ALSO UNCLEAR FOR SAT AS WELL...WITH THE
CONCERNS FROM LAST NIGHTS FORECAST STILL IN PLAY TONIGHT. AS
ASCENT/HEIGHT FALLS SPREAD INTO THE PLAINS LATE TONIGHT WE SHOULD
SEE AN INCREASE IN SHOWERS AND THUNDERSTORMS OVER THE SOUTHERN
PLAINS AGAIN WITH WEAK CAPPING. AS THE WIND FIELD ASSOCIATED WITH
THE TROUGH SPREADS EWD THESE SHOULD ADVANCE FAIRLY RAPIDLY
NORTHEASTWARD THROUGH THE NIGHT...POTENTIALLY MAKING IT VERY NEAR
OUR FA BY 12Z ON SAT. CONVECTIVE CHANCES WILL CONTINUE TO INCREASE
THROUGH THE DAY ON SAT WITH FAIRLY STRONG FORCING SPREADING
THROUGH WITH GOOD MOISTURE IN PLACE. THE PRESENCE OF THIS EARLY
CONVECTION AND LACK OF A WELL-ESTABLISHED ELEVATED MIXED LAYER
OVER THE PLAINS SIGNIFICANTLY LIMITS THE INSTABILITY OVER THE FA
DURING THE DAY ON SAT. THUS WE STILL FEEL WE WILL SEE A GOOD DEAL
OF CONVECTION ON SAT...MUCH OF THIS WILL LIKELY BE NON-SEVERE. WE
MAY SEE A BETTER CHANCE OF SOME STRONGER THUNDERSTORMS ON SAT
EVENING AS SVR CONVECTION THAT DEVELOPS OVER WRN KS SPREADS NEWD
ASSOCIATED WITH THE 100 KT H3 JET MAX. WITH A UNIDIRECTIONAL WIND
FIELD WE WOULD LIKELY SEE WIND AND MAYBE SOME HAIL AS A THREATS.

SUNDAY THE UPPER LEVEL LOW MOVES INTO THE NORTHERN PLAINS AND THE
SURFACE TROUGH SHIFTS E OF THE FA TAKING MOST OF THE MOISTURE WITH
IT. BEHIND THE TROUGH AND AHEAD OF THE COLD FRONT WE SHOULD HAVE A
CHANCE TO WARM FAIRLY WELL ON SUNDAY WITH GOOD MIXING AND
DECREASING CLOUDS. HAVE INCREASED HIGHS MOST AREAS WITH LOWER 80S
SOUTH AND 70S NORTH. THE COLD FRONT DOES MOVE THROUGH LATE ON
SUNDAY THOUGH AND WILL USHER IN MUCH COOLER AIR.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 349 AM CDT FRI MAY 15 2015

THIS PERIOD WILL BE DOMINATED BY WELL BELOW NORMAL TEMPERATURES.
LONG RANGE MODELS ARE IN BETTER AGREEMENT THIS MORNING IN THE
LARGE-SCALE PLACEMENT OF FEATURES. IN THE WAKE OF THE SHORT TERM
SYSTEM WE SHOULD SEE COOL CANADIAN HIGH PRESSURE BUILD INTO THE
NORTHERN PLAINS AND CONTINUE TO PROVIDE THE FA WITH A COOL NE FLOW
THROUGH THE EXTENDED. A SYSTEM MOVES THROUGH THE PLAINS ON TUE
NIGHT AND WED MAY SPREAD SOME SHOWERS INTO THE AREA WITH DRY
WEATHER RETURNING FOR THU.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1236 PM CDT FRI MAY 15 2015

MESSY AVIATION WEATHER WILL CONTINUE THROUGH THIS FORECAST PERIOD
WITH WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IMPACTING ALL
THREE TAF SITES. THE INITIAL LINE OF THUNDERSTORMS MOVING ACROSS
THE KLNK AND KOMA SITES AS OF 18Z WILL MOVE TO THE EAST AND
PROVIDE A BREAK UNTIL AROUND 23Z WHEN NEW CONVECTION WILL BE
POSSIBLE. THUNDERSTORMS HAD ALREADY MOVED NORTHEAST OF KOFK AND
EXPECT THEM TO REMAIN MVFR TO VFR THROUGH 06Z.

&&

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

$$

SHORT TERM...BOUSTEAD
LONG TERM...BOUSTEAD
AVIATION...MEYER



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