FXUS63 KOAX 080823
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
323 AM CDT SUN MAY 8 2011
.DISCUSSION...
THUNDERSTORM CHANCES THROUGH MONDAY MORNING...TEMPERATURES MONDAY
AND TUESDAY...THEN HANDLING EVOLUTION OF UPPER FLOW AND THE EFFECT
ON SENSIBLE WEATHER AT MID WEEK...ARE THE PRIMARY FORECAST CONCERNS.
WEAK SHORTWAVE WAS TRIGGERING ISOLATED TO SCATTERED SHOWERS ACROSS
SOUTH DAKOTA THIS MORNING...WITH A FEW RETURNS NOTED FROM TIME TO
TIME IN NORTHERN NEBRASKA. PRESENT TRENDS SUGGEST MOST OF THIS
ACTIVITY WILL REMAIN NORTH OF THE CWA THIS MORNING...BUT WILL
MAINTAIN A SMALL CHANCE FOR STORMS IN OUR FAR NORTH.
ATTENTION THEN TURNS TO POTENTIAL SEVERE WEATHER LATE THIS AFTERNOON
AND OVERNIGHT. AS A PREFACE...SPC HAS PLACED ALL OF EASTERN NEBRASKA
AND WESTERN IOWA IN A SLIGHT RISK AREA THROUGH 12Z MONDAY. UPPER
FLOW REGIME WILL CONTINUE TO UNDERGO THE TRANSITION TO A WESTERN
TROUGH WITH SOUTHWEST FLOW INTO THE PLAINS. MORNING WATER VAPOR
LOOPS AND RUC ANALYSIS SHOW INCREASING MID LEVEL FLOW INTO THE
NORTHERN ROCKIES WITH A SHORTWAVE TROUGH BEING LIFTED NORTHEAST
THROUGH EASTERN NEW MEXICO. THIS SHORTWAVE COULD PROVIDE NECESSARY
MINOR COOLING ALOFT TO ALLOW STORMS TO FIRE LATER THIS AFTERNOON. AT
THE SURFACE...LOWERING PRESSURES IN THE HIGH PLAINS IN RESPONSE TO
INCREASING FLOW ALOFT WILL ACCELERATE LOW LEVEL SOUTHEASTERLY FLOW
THROUGH THE PLAINS. CURRENT DEW POINTS IN THE CWA ARE IN THE UPPER
30S TO UPPER 40S...BUT RICHER 50S ARE JUST SOUTH OF THE AREA IN
EASTERN KANSAS...AND 60S DEW POINTS WERE NOTED IN OKLAHOMA. LOW
LEVEL TRAJECTORIES ARE NOT FAVORABLE FOR THIS MOISTURE TO SURGE INTO
OUR AREA...BUT CERTAINLY CENTRAL NEBRASKA IS IN LINE TO SEE 60S DEW
POINTS THIS AFTERNOON. HOWEVER NAM AND GFS MODELS BOTH PAINT 60 TO
65F SURFACE DEW POINTS INTO SOUTHEAST NEBRASKA BY LATE AFTERNOON.
PLENTY OF SUNSHINE TODAY ALONG WITH RELATIVELY MILD START SHOULD
PUSH TEMPS INTO THE 80S FOR MUCH OF THE CWA WITH THE WARMEST IN THE
SOUTH WHERE MOISTURE RETURN IS MOST LIKELY. FORECAST SOUNDINGS SHOW
OVER 3000 J/KG OF CAPE IN SOUTHEAST NEBRASKA THIS AFTERNOON...BUT
ALSO SHOW WARM MID LEVEL TEMPERATURES PROVIDING FAIRLY DECENT CINH
ON THE ORDER OF 100 J/KG. GIVEN FAIRLY STRONG CAP AND SUSPECT
MOISTURE RETURN...AM THINKING STORMS WILL HAVE A TOUGH TIME
FIRING IN OUR CWA THROUGH SUNSET. BUT IF THEY DO...0-6KM BULK
SHEAR OF 30KTS WILL BE SUFFICIENT FOR SEVERE STORMS WITH LARGE
HAIL. LOW LEVEL SHEAR WILL ALSO BE MAXIMIZED IN SOUTH CENTRAL OR
SOUTHEAST NEBRASKA WHERE DEVELOPING WARM FRONT WILL RESIDE. THUS
TORNADOES ARE ALSO POSSIBLE.
MORE LIKELY SEVERE THREAT WILL HOLD OFF UNTIL MID TO LATE EVENING
AND CONTINUING OVERNIGHT AS WARM FRONT LIFTS NORTH THROUGH EASTERN
NEBRASKA AND WESTERN IOWA. SOUTHERLY LOW LEVEL JET NEAR 50KTS WILL
TRANSPORT MID TEENS 850 DEWPOINTS NORTH THROUGH THE CWA...WITH
PARCEL LIFTED FROM 850MB PRODUCING CAPE OVER 2500 J/KG AND ONLY
SMALL CINH. THESE STORMS SHOULD REMAIN MOSTLY ELEVATED WITH LARGE
HAIL THE PRIMARY THREAT AS THE NIGHT WEARS ON.
STORMS WILL GRADUALLY LIFT NORTH OF THE CWA ON MONDAY...LEAVING THE
REST OF THE DAY DRY AND WARM. HAVE HIGHS WELL INTO THE 80S THEN.
MUCH OF THE SAME TUESDAY...BUT SOUTHWESTERLY COMPONENT TO LOW LEVEL
WIND WILL HELP PUSH TEMPERATURES OVER 90 IN A GOOD PART OF OUR AREA.
THE WESTERN UPPER TROUGH WILL GRADUALLY PUSH INTO THE PLAINS AT MID
WEEK. MODELS ARE NOW SUGGESTING THIS WILL OCCUR IN PIECES AS AN
UPPER LOW BREAKS OFF AND MOVES EAST THROUGH THE NORTHERN PLAINS
WHILE POTENT SHORTWAVE ENERGY LIFTS NORTHEAST FROM THE BASE OF THE
TROUGH. AN ASSOCIATED COLD FRONT WILL PUSH INTO THE CWA TUESDAY
NIGHT OR WEDNESDAY...PROVIDING A FOCUS FOR RAIN/CONVECTION AT ANY
TIME TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. MODELS ARE STILL TRYING
TO CONVERGE ON A TIMING SOLUTION...SO WILL NOT TAMPER WITH FORECAST
AT THIS TIME. CURRENT HIGH CHANCES FOR SHOWERS AND THUNDERSTORMS FOR
MUCH OF THE CWA LOOKS OKAY.
DERGAN
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
SFC LOW PRESSURE WILL STRENGTHEN OVER ERN CO THIS AFTN RESULTING IN
SE WIND GUSTS AROUND 25KT AT ALL TERMINALS. EXPECT WINDS TO SUBSIDE
TWD 09/00Z. ALSO...HAVE OPTED TO INCLUDE PROB30 GROUP AT KOFK BTWN
09/01Z-05Z FOR POSSIBLE TSRA. UNCERTAINTY THOUGH FORCE PRECLUDING OF
PROB30 GROUPS AT KOMA/KLNK.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$