Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 192021
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
321 PM CDT SAT APR 19 2014

.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 309 PM CDT SAT APR 19 2014

RAIN/THUNDERSTORM CHANCES THROUGH MONDAY MORNING ARE THE PRIMARY
FORECAST CONCERNS.

FRONTAL BOUNDARY HAS SLIPPED INTO NORTHEAST NEBRASKA THIS AFTERNOON.
AHEAD OF THE FRONT...TEMPERATURES HAVE CLIMBED WELL INTO THE 70S ON
BRISK SOUTH TO SOUTHWEST WINDS...HOWEVER MOISTURE HAS BEEN SLOW TO
RETURN. DEW POINTS WERE GENERALLY IN THE MID AND UPPER 40S...WITH
LOWER 50S READINGS WELL SOUTH IN CENTRAL KANSAS AND OKLAHOMA. A
WEAK MID LEVEL WAVE AS SEEN IN WATER VAPOR IMAGERY AND RAP HEIGHT
FIELDS WAS MOVING THROUGH NORTHEAST NEBRASKA...AND WAS TRIGGERING
MID LEVEL RETURNS ON RADAR ACROSS NORTHEAST NEBRASKA AND EASTERN
SOUTH DAKOTA. HOWEVER ONLY VIRGA IS EXPECTED THERE AS LOW
HUMIDITIES EXIST BELOW MID LEVEL CLOUD LAYER. CONGESTUS CLOUDS
WERE ALSO NOTED IN SOUTH CENTRAL NEBRASKA IN AREA OF INCREASING
BUT STILL WEAK INSTABILITY.

MEANWHILE...UPPER TROUGH DRIFTING EAST THROUGH ARIZONA WILL
GRADUALLY WORK TOWARD THE PLAINS OVERNIGHT AND EVENTUALLY EAST OF
THE AREA MONDAY. AHEAD OF THIS TROUGH...A COUPLE OF MID LEVEL WAVES
WILL RIPPLE NORTHEAST ACROSS NEBRASKA...AND SHOULD TRIGGER
SCATTERED SHOWERS OR STORMS FOCUSED NEAR SURFACE FRONT. BEST
CHANCE FOR THUNDERSTORMS APPEARS TO COME LATER THIS EVENING AND
OVERNIGHT AS CONVECTION EXPECTED TO DEVELOP IN NORTH CENTRAL
KANSAS OR SOUTH CENTRAL NEBRASKA MOVES INTO OUR AREA. THE SLOW
MOISTURE RETURN WAS HOLDING INSTABILITY IN CHECK THIS AFTERNOON
BUT IS EXPECTED TO INCREASE LATE IN THE DAY OR EARLY EVENING. MID
LEVEL LAPSE RATES OF 8.5-9 C/KM WERE ALREADY IN PLACE IN WESTERN
KANSAS/NEBRASKA OVER TOP OF INCREASING LOW LEVEL CONVERGENCE
NORTHEAST OF SURFACE LOW IN EASTERN COLORADO. VARIOUS SYNOPTIC AND
MESO SCALE MODELS (NAM/GFS/RAP/HRRR/HOPWRF) INDICATE CONVECTION
POPPING IN NORTH CENTRAL KANSAS AND SOUTH CENTRAL NEBRASKA
SOMETIME IN THE 23Z TO 02Z TIMEFRAME...AND DEVELOP/SPREAD THIS
NORTHEAST ALONG FRONTAL ZONE DURING THE EVENING. SEVERE PARAMETERS
ARE NOT IMPRESSIVE WHEN STORMS ARRIVE OVERNIGHT...ELEVATED CAPE
800 J/KG AND 0-6KM SHEAR NEAR 25KT...SO NOT EXPECTING MORE THAN
SMALL HAIL AND GUSTY WINDS. CHANCES WILL DECREASE FROM SOUTHWEST
TO NORTHEAST AFTER MIDNIGHT AS THIS COMPLEX ROLLS OUT OF OUR AREA.

THEN CHANCES BEGIN TO INCREASE AGAIN SUNDAY MORNING WITH THE
APPROACH OF UPPER TROUGH. SURFACE DEW POINTS WILL CONTINUE TO
RISE...LIKELY INTO THE MID TO UPPER 50S BY AFTERNOON...WITH COLD
FRONT BRIDGING NORTH TOWARD THE SOUTH DAKOTA BORDER. AFTERNOON
SURFACE CAPES SHOULD APPROACH 1500 J/KG BUT SHEAR IS LIMITED. SO
AGAIN SEVERE CHANCES ARE SMALL...BUT CONTINUED DEVELOPMENT OF
SHOWERS/STORMS APPEARS LIKELY THROUGH THE AFTERNOON AND EVENING
GIVEN COOLING ALOFT FROM UPPER TROUGH. WILL HAVE FAIRLY HIGH PRECIP
CHANCES SUNDAY AFTERNOON AND NIGHT FOR MUCH OF THE SOUTHERN TWO-
THIRDS OF THE CWA BEFORE FRONT FINALLY BEGINS MOVING SOUTHEAST LATE
SUNDAY NIGHT. LINGERING SHOWERS/STORMS NEAR I-80 AND SOUTH WILL
REMAIN IN THE FORECAST MONDAY MORNING...THEN CLEARING SKIES WITH
SURFACE HIGH PRESSURE AND RIDGING ALOFT BUILDING IN WILL RULE THE
FORECAST INTO TUESDAY.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 309 PM CDT SAT APR 19 2014

THE LONGER TERM PERIOD WILL BEGIN WITH UPPER RIDGE AXIS SHIFTING OFF
TO THE EAST WITH THE APPROACH OF ANOTHER TROUGH SLIDING INTO THE
ROCKIES. THAT TROUGH WILL WORK THROUGH THE PLAINS WEDNESDAY AND
THURSDAY BEFORE LIFTING THROUGH THE GREAT LAKES FRIDAY AND SATURDAY.
WILL HAVE PRECIPITATION CHANCES IN THE FORECAST UNTIL THAT PASSES
BY...WITH A CHANCE FOR SEVERE STORMS AT MID WEEK.

THUNDERSTORMS ARE POSSIBLE TUESDAY NIGHT AS WARM ADVECTION COMMENCES
UNDER DIFFLUENT MID LEVEL FLOW AHEAD OF WESTERN TROUGH. MID LEVEL
INSTABILITY IS NOT THAT STRONG THEN...BUT SCATTERED SHOWERS/STORMS
ARE CERTAINLY POSSIBLE. ON WEDNESDAY...SURFACE LOW PRESSURE WILL
INTENSIFY IN THE HIGH PLAINS WITH DRYLINE SETTING UP IN WESTERN
NEBRASKA. WARM ADVECTION CONTINUES OVER OUR AREA LEADING TO
LINGERING CHANCE FOR SHOWERS/STORMS. BUT BETTER CHANCES COME
WEDNESDAY NIGHT AS LOW/FRONT/DRYLINE MOVE INTO EASTERN NEBRASKA
UNDER DYNAMIC MID LEVEL FLOW AND 60KT LOW LEVEL JET. TIMING AND
MAGNITUDE OF THESE FEATURES WILL STILL HAVE TO BE FINE-TUNED WITH
LATER FORECASTS...BUT THIS CERTAINLY BEARS WATCHING.

MOST OF THE THUNDERSTORM ACTIVITY WILL BE EXITING THURSDAY
MORNING...BUT COULD SEE SOME REDEVELOPMENT OF SHOWERS ESPECIALLY IN
OUR NORTH AND EAST DURING THE AFTERNOON AS MID LEVEL COLD POOL
ROTATES THROUGH THE REGION. COOLER AIR WILL FOLLOW WITH HIGHS
GENERALLY IN THE 60S TO END THE WEEK.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1246 PM CDT SAT APR 19 2014

VFR CONDITIONS ARE EXPECTED THROUGH THIS AFTERNOON. A COLD FRONT
WILL CONTINUE TO SLOWLY MOVE SOUTHEAST ACROSS THE AREA. MVFR CIGS
AND VISIBILITIES ARE POSSIBLE FOR THE REMAINDER OF THE TAF PERIOD
AS THE COLD FRONT BEGINS TO STALL. THE FRONT WILL BE THE FOCUS FOR
SHOWERS...ESPECIALLY FROM NEAR 02-10Z AND AGAIN AT KOFK FROM
12-18Z SUN. MORE SHOWERS AND POTENTIAL THUNDERSTORMS ARE POSSIBLE
FOR KLNK AND KOMA AFTER 18Z SUNDAY.


&&

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

$$

SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...KERN



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