Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 060510
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1210 AM CDT WED MAY 6 2015

.SHORT TERM...(TONIGHT)
ISSUED AT 251 PM CDT TUE MAY 5 2015

A WARM FRONT REMAINS DRAPED ACROSS EASTERN NEBRASKA AND WESTERN IOWA
THIS AFTERNOON WITH A FEW ISOLATED SHOWERS AROUND THE BOUNDARY
ACROSS NORTHEAST NEBRASKA. OTHER ISOLATED SHOWERS HAVE POPPED UP
WHERE AGITATED CU FIELD HAS DEVELOPED DUE TO DIURNAL AFTERNOON
HEATING BUT THESE STRUGGLE TO HOLD ON. DO EXPECT THESE TO DIMINISH
ONCE WE LOSE HEATING THIS EVENING. ALOFT...A MID LEVEL NEGATIVELY
TILTED TROUGH AXIS EXTENDS ACROSS THE FOUR CORNERS AREA INTO
NORTHEASTERN NEW MEXICO. THIS WAVE WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT BRINGING INCREASING SHOWERS AND THUNDERSTORMS TO THE
HIGH PLAINS. AS THE WAVE CONTINUES TO TRACK NORTHEAST...EXPECT
SHOWERS AND THUNDERSTORMS TO SPREAD EAST INTO OUR AREA WHERE
WIDESPREAD RAINSHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED
THROUGH THE OVERNIGHT AND INTO THE MORNING.

KERN

SHORT TERM...(WEDNESDAY THROUGH FRIDAY)

ISENTROPIC LIFT WILL CONTINUE ACROSS THE REGION WEDNESDAY WHICH
WILL RESULT IN NUMEROUS SHOWERS AND THUNDERSTORMS THROUGH THE DAY
WEDNESDAY...THUS WILL MAINTAIN HIGH LIKELY POPS AS THE LEAD WAVE
CONTINUES TO MOVE THROUGH THE AREA. BELIEVE GFS MOS MAY BE TOO
OPTIMISTIC GIVEN THE EXPECTED CLOUD COVER...THUS BLENDED HIGHS
CLOSER TO THE MET GUIDANCE FOR NOW.

AS THE FIRST ROUND OF PRECIPITATION MOVES OFF THE NORTHEAST...THE
SECOND ROUND OF PRECIP WILL LIKELY DEVELOP ACROSS THE CENTRAL
PORTIONS OF NE/KS WHERE THEY HAVE A BETTER CHANCE OF BEING
SEVERE...THEN PUSHING EASTWARD INTO OUR ARE WEDNESDAY EVENING...
INITIALLY INTO EASTERN NEBRASKA AND EVENTUALLY INTO WESTERN IOWA.
STILL APPEARS TO BE A MARGINAL RISK FOR SEVERE STORMS ACROSS
EASTERN NEBRASKA GIVEN STRENGTHENING LOW LEVEL JET INTO THE 50 TO
60 KNOT RANGE...BUT MAY LOSE A LITTLE BIT OF PUNCH AS THEY MOVE
INTO WESTERN IOWA.

WHATEVER DEVELOPS WEDNESDAY NIGHT COULD BE LINGERING ALONG/EAST OF
THE MISSOURI RIVER THURSDAY MORNING AS THE SECONDARY WAVE
CONTINUES TO TO MOVE EAST EAST. WHILE THE FRONT REMAINS IN THE
AREA...THERE COULD BE A SEVERAL HOUR BREAK IN PRECIP BY LATE
THURSDAY MORNING TO EARLY THURSDAY AFTERNOON. HOWEVER...WITH
FRONT SETTLING SOUTHWARD AND STILL WITHIN THE FORECAST AREA DURING
PEAK HEATING...SHOULD SEE THUNDERSTORMS REDEVELOP ALONG THE FRONT
IN SOUTHEAST NEBRASKA AND SOUTHWEST IOWA BY THURSDAY
EVENING...WITH STRONGEST STORMS PUSHING INTO KS/MO BY MIDNIGHT.
FURTHER NORTH...THERE COULD BE A FEW SHOWERS ALONG THE NE/SD
BORDER THURSDAY NIGHT...AND AREAS IN BETWEEN COULD REMAIN DRY.

FRIDAY COULD ACTUALLY BE MOSTLY DRY AS WELL. MODELS ARE HAVING A
SOMEWHAT DIFFICULT TIME AGREEING ON HOW FAR SOUTH THE FRONT
SETTLES. THE NAM/GFS ARE GENERALLY DRY DURING THE DAY FRIDAY...BUT
ECMWF/SREF REMAIN OVERLY WET. STARTED TRIMMING POPS DOWNWARD AND
GUT FEELING TELLS ME IT MIGHT BE A PRETTY DECENT DAY.

DEWALD

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 251 PM CDT TUE MAY 5 2015

THE NEXT TROUGH BEGINS TO MOVE INTO THE FOUR CORNERS REGION FRIDAY
NIGHT THROUGH SATURDAY WITH A PERSISTENT EASTERLY FLOW IN OUR
AREA. THIS IS TYPICALLY A DRYING FLOW FOR US...THUS STARTED
TRIMMING POPS DOWN EARLY IN THE PERIOD...WITH BETTER FOCUS AND
DYNAMICS DEVELOPING ACROSS THE WESTERN HIGH PLAINS WITHIN THE
UPSLOPE REGIME. STORM CHANCES INCREASE AGAIN SATURDAY NIGHT AS
ISENTROPIC LIFT OVERSPREAD THE REGION ONCE AGAIN. WILL LIKELY HAVE
TO WATCH FOR ELEVATED HAILERS AS INSTABILITY INCREASES.

THE EVOLUTION OF THE SURFACE LOW OFF THE FRONT RANGE IS THE KEY TO
THE FORECAST FOR SUNDAY AND MONDAY. ECMWF/GFS ARE SIGNIFICANTLY
DIFFERENT IN THEIR SOLUTIONS AND OVERALL TIMING. THUS OVERALL
CONFIDENCE IN THE DETAILS IS LOW AT THIS TIME. USED MODEL
BLENDS FOR NOW WITH GENERIC THUNDERSTORM CHANCES...BUT GIVEN
STRONG DYNAMICS MOVING ONTO THE PLAINS...WILL ALSO BE INCREASINGLY
CONCERNED FOR SEVERE WEATHER POTENTIAL. HOWEVER DUE TO WIDE MODEL
SPREADS...IT`S TOO SOON TO PINPOINT ANY SPECIFIC MODES OR DETAILS
SINCE A LOT DEPENDS ON POSITIONING OF FRONTS AND SURFACE LOW
CIRCULATIONS. WEATHER UNCERTAINTY FOR MONDAY HINGES ON WHAT
HAPPENS ON SUNDAY. WENT DRY FOR TUESDAY.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1143 PM CDT TUE MAY 5 2015

REGIONAL RADAR SHOWING LARGE AREA OF SHRA/ISOLD TS LIFTING NWD
OVER ERN NEB. MODELS IN AGREEMENT CONDITIONS DETERIORATING TO MVFR
AT ALL TAF SITES WITH ONSET OF PCPN ACTIVITY WHICH SHOULD CONTINUE
THRU ABOUT 14Z THIS MORNING. IN ADDITION...HAVE ADDED PROB30
GROUP TO ALL TERMINALS FOR POSSIBLE TSRA DEVELOPMENT LATER THIS
AFTN.

&&

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

$$

SHORT TERM...KERN/DEWALD
LONG TERM...DEWALD
AVIATION...DEE



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