Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 302322
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
622 PM CDT THU APR 30 2015

.SHORT TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 319 PM CDT THU APR 30 2015

RAIN CHANCES BEGINNING LATER TONIGHT INTO FRIDAY...AND WHEN BEST
CHANCES ARE OVER THE WEEKEND...REMAIN THE PRIMARY FORECAST CONCERNS.

MID LEVEL SHORTWAVE EXTENDING FROM EASTERN SASKATCHEWAN INTO MONTANA
WILL CONTINUE ITS TREK EASTWARD THIS AFTERNOON AND WEAKEN LATER
TONIGHT AS IT MOVES TOWARD THE GREAT LAKES. ATTENDANT COLD FRONT NOW
IN THE HIGH PLAINS OF THE DAKOTAS WILL BE PUSHED SOUTHEAST INTO
NORTHEAST NEBRASKA AFTER MIDNIGHT...BUT WILL ONLY LIMP FARTHER
SOUTHEAST AS UPPER SUPPORT WEAKENS. CURRENT AND FORECAST MOISTURE
PROFILES ARE RELATIVELY DRY...ALONG WITH LIMITED UPPER SUPPORT. SO
WHILE AM EXPECTING SHOWERS AND ISOLATED THUNDER TO OCCUR ALONG
FRONTAL BOUNDARY...COVERAGE SHOULD BE WIDELY SCATTERED IN NATURE.
WILL INTRODUCE PRECIP ALONG FRONT BEGINNING IN NORTHEAST NEBRASKA
AFTER 06Z...THEN APPROACHING INTERSTATE 80 BY MID FRIDAY MORNING.
GIVEN LESSENING AFFECTS OF FORCING ALOFT AND ALONG FRONTAL
ZONE...HAVE GRADUALLY DECREASING CHANCES FOR PRECIPITATION FRIDAY
AFTERNOON AND EVENING.

FOR SATURDAY...ISOLATED SHOWERS COULD LINGER IN SOUTHWEST IOWA OR
SOUTHEAST NEBRASKA IN THE MORNING...BUT MOST OF THE REST OF THE DAY
SHOULD BE DRY. MODEL OUTPUT IS BASICALLY DRY SATURDAY
AFTERNOON...AND CAN NOT REALLY PIN DOWN RESIDUAL FRONTAL
BOUNDARY...AND UPPER SUPPORT IS NON EXISTENT. HOWEVER GFS IS
PAINTING AN AREA OF 1000-1500 J/KG OF SURFACE-BASED CAPE SATURDAY
AFTERNOON IN EASTERN NEBRASKA WITH LIMITED CINH. SO CAN NOT RULE
OUT AN ISOLATED STORM FIRING AT SOME POINT...BUT AREAL COVERAGE
LOOKS MINIMAL.

THEN ATTENTION TURNS TO WARMER TEMPERATURES SUNDAY AHEAD OF ANOTHER
APPROACHING COLD FRONT. MID LEVEL WAVE TRACKING ACROSS SOUTHERN
CANADA AND THE NORTHERN PLAINS WILL AGAIN PUSH A COLD FRONT INTO
NORTHEAST NEBRASKA LATER SUNDAY AFTERNOON. WARM MID LEVEL
TEMPERATURES SHOULD CAP MOST CONVECTION AT THAT TIME...AND WILL ALSO
ALLOW TEMPERATURES AHEAD OF THE FRONT TO WARM WELL INTO THE 80S.
THERMAL TROUGH AT 850MB POINTS DIRECTLY INTO NORTHEAST NEBRASKA
WHERE HIGHS IN THE MID 80S OR HIGHER SHOULD OCCUR...WITH AT LEAST
LOWER 80S ACROSS THE REST OF EASTERN NEBRASKA AND SOUTHWEST IOWA.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 319 PM CDT THU APR 30 2015

BETTER SHOWER/THUNDER CHANCES ARE IN THE OFFING FOR MUCH OF THE WEEK
AS SUNDAY COLD FRONT SLIPS INTO THE CWA AND REMAINS CLOSE TO OUR
AREA UNTIL LATER IN THE WEEK AS AN UPPER LOW/TROUGH APPROACHES.
INSTABILITY SHOULD BE AT LEAST MODERATELY HIGH SUNDAY EVENING GIVEN
WARM AFTERNOON TEMPERATURES AND INCREASING LOW LEVEL MOISTURE. AS
ATMOSPHERE COOLS IN THE EVENING...EXPECT SCATTERED STORMS ALONG COLD
FRONT AS IT MOVES TOWARD INTERSTATE 80 AND BEYOND. SOME HAIL
POTENTIAL GIVEN DEGREE OF INSTABILITY...BUT SHEAR IS RATHER WEAK AT
THIS TIME.

THERE IS SOME MODEL CONSISTENCY IN STALLING FRONT IN SOUTHEAST
NEBRASKA ON MONDAY...THE SHOVING IT BACK NORTH INTO NORTHEAST
NEBRASKA ON TUESDAY. THE POTENTIAL WILL EXIST FOR STORMS ALONG THIS
BOUNDARY BOTH DAYS...AND THE EXACT LOCATION WILL BE TOUGH TO NAIL
DOWN RIGHT NOW. HOWEVER IT SEEMS LOGICAL THAT AFTERNOON HEATING WILL
PLAY A ROLE IN TIMING OF HIGHEST PRECIP CHANCES...FAVORING THE
AFTERNOON AND EVENING BOTH MONDAY AND TUESDAY. BY WEDNESDAY...UPPER
TROUGH WILL BE ROTATING INTO THE PLAINS...BRINGING COOLER MID LEVEL
TEMPERATURES OVER GRADUALLY MOISTENING LOW LEVELS. THUS
INSTABILITY AND POTENTIAL FOR SEVERE ARE FORECAST TO INCREASE
BOTH WEDNESDAY AND THURSDAY...WITH GFS SUGGESTING 3000 J/KG OF
SURFACE-BASED CAPE THURSDAY AFTERNOON.

&&

.AVIATION...(00Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 619 PM CDT THU APR 30 2015

VFR CONDITIONS ARE EXPECTED THROUGH THE TAF CYCLE. ISOLATED TO
SCATTERED SHOWERS...WITH A FEW LIGHTNING STRIKES...ARE POSSIBLE IN
THE VICINITY OF KOFK BEGINNING AROUND 09-12Z...AND IN THE
VICINITY OF KOMA/KLNK BEGINNING AROUND 12-15Z. CEILINGS SHOULD
REMAIN VFR IN ANY SHOWERS...WITH VFR VISIBILITY MOST LIKELY AS
WELL. HAVE LEFT MENTION OUT FOR NOW GIVEN UNCERTAINTY IN COVERAGE.
WINDS WILL VEER FROM SOUTHEASTERLY TO SOUTHWESTERLY THROUGH THE
TAF CYCLE...BUT SPEEDS SHOULD LARGELY REMAIN NEAR 10KT OR LESS.

&&

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

$$

SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...MAYES



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