FXUS63 KOAX 220813
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
313 AM CDT SUN MAY 22 2011
.DISCUSSION...
SMALL PRECIPITATION CHANCES OVER THE NEXT COUPLE OF DAYS...THEN
INCREASING CHANCES AT MID WEEK WITH EJECTING UPPER LOW...ARE THE
PRIMARY FORECAST CONCERNS.
UPPER LOW WAS CENTERED OVER CENTRAL SOUTH DAKOTA AT 06Z...AND WAS
DRIFTING TO THE EAST-NORTHEAST. SHORTWAVE TROUGH THAT HELPED TRIGGER
SEVERE STORMS OVER THE CWA SATURDAY EVENING WAS PUSHING THROUGH IOWA
AND MINNESOTA THIS MORNING...BUT ANOTHER VORT MAX WAS CLEARLY
DEFINED ON WATER VAPOR LOOPS SPINNING INTO NORTH CENTRAL NEBRASKA.
THIS VORT WAS SPARKING SCATTERED SHOWERS OVER WESTERN AND CENTRAL
NEBRASKA...WHICH WILL MOVE OVER AT LEAST NORTHEAST NEBRASKA DURING
THE MORNING.
THEN THIS AFTERNOON...A COUPLE OF POCKETS OF INSTABILITY COULD
BUBBLE UP SHOWERS OR STORMS THIS AFTERNOON. STEEP LAPSE RATES NEAR
EXITING UPPER LOW AND IN CORE OF ELONGATED SHORTWAVE TROUGH WILL
RESIDE IN OUR NORTHERN CWA THIS AFTERNOON. AND LINGERING SURFACE DEW
POINTS NEAR 60F IN OUR SOUTH WITH TEMPS NEAR 80 WILL YIELD
SURFACE-BASED CAPES NEAR 1500 J/KG IN OUR SOUTH. BOTH AREAS MAY SEE
SCATTERED SHOWERS OR STORMS POPPING DURING AFTERNOON PEAK HEATING
WITH ACTIVITY DIMINISHING QUICKLY BY SUNSET.
AS UPPER LOW MOVES INTO THE GREAT LAKES ON MONDAY...ATTENTION THEN
TURNS TO NEXT UPPER TROUGH/LOW MOVING OUT OF THE SOUTHWEST CONUS.
SUBTROPICAL JET IN THE SOUTHERN PLAINS WILL PROMOTE SURFACE LOW
DEVELOPMENT IN OKLAHOMA/TEXAS PANHANDLE REGION WITH SHARPENING
BAROCLINIC ZONE INTO NORTHERN MISSOURI. THIS AREA WILL BE THE FOCUS
FOR AFTERNOON CONVECTION MONDAY. ALSO...ANOTHER SHORTWAVE DROPPING
SOUTHEAST FROM THE NORTHERN PLAINS MAY SKIRT NORTHEAST NEBRASKA.
WILL MAINTAIN HIGHEST POPS IN OUR SOUTH NEAR SURFACE FRONTAL
BOUNDARY...AND IN THE NORTH NEAR SHORTWAVE. HOWEVER CAN NOT RULE OUT
AN ISOLATED AFTERNOON SHOWER OR STORM ANYWHERE IN THE CWA GIVEN COOL
TEMPERATURES ALOFT.
PRECIPITATION CHANCES WILL GRADUALLY INCREASE TUESDAY AND WEDNESDAY
AS UPPER TROUGH/LOW EJECTS INTO THE PLAINS. MODELS PLACE NEARLY
STACKED LOW PRESSURE SYSTEM IN EASTERN KANSAS BY WEDNESDAY MORNING.
WARM AND MOIST ADVECTION AHEAD OF APPROACHING SYSTEM WILL PLACE
LIKELY POPS IN SOUTHERN NEBRASKA AND SOUTHWEST IOWA TUESDAY NIGHT
INTO WEDNESDAY MORNING...WITH DECREASING CHANCES WEDNESDAY NIGHT AS
UPPER LOW MOVES OFF TO THE EAST. CURRENT FORECAST HAS THIS WELL IN
HAND...SO NO MAJOR CHANGES WERE NECESSARY.
THURSDAY SHOULD BE DRY...BUT WILL MAINTAIN A CHANCE FOR
THUNDERSTORMS ON FRIDAY AS GFS/ECMWF BRING A SIGNIFICANT SHORTWAVE
THROUGH THE PLAINS. GFS SWEEPS THIS FEATURE TROUGH THE CWA WHILE THE
ECMWF IS FARTHER NORTH. HOWEVER BOTH MODELS PAINT A DECENT STRIPE OF
QPF ACROSS OUR AREA ON FRIDAY.
TEMPERATURES SUNDAY AND MONDAY SHOULD CLIMB INTO THE 70S TO NEAR 80
WITH SOME SUNSHINE HELPING THE WARMING. COOLER HIGHS IN THE 60S OR
LOWER 70S ARE EXPECTED TUESDAY THROUGH FRIDAY WITH CLOUDS/PRECIP AND
PERSISTENT NORTHERLY LOW LEVEL WIND COMPONENT HINDERING WARMUP.
DERGAN
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
LOW PRESSURE OVER SOUTH CENTRAL SOUTH DAKOTA WILL TRACK SLOWLY EAST
INTO CENTRAL MINNESOTA BY THE END OF THE PERIOD. SURFACE TROF
ASSOCIATED WITH THE LOW WILL MOVE THROUGH EASTERN NEBRASKA BY 00Z.
PERIOD OF MVFR CIGS AND VSBY IN SHOWERS POSSIBLE THIS AFTERNOON AT
KOFK WITH GENERALLY VFR CIGS AT BOTH KLNK AND KOMA DURING THE
PERIOD.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$