FXUS63 KOAX 272041
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
341 PM CDT WED JUL 27 2011
.SHORT TERM...TONIGHT.
MAIN CONCERN FOR TONIGHT IS TSTM POTENTIAL.
18Z SUBJECTIVE SURFACE ANALYSIS SHOWS LOW PRESSURE CENTERED OVER
SOUTHEAST NEBRASKA WITH WEAK BOUNDARY EXTENDING NEWD ACROSS EAST
CENTRAL NEBRASKA AND INTO WEST CENTRAL IOWA. COLD FRONT EXTENDED
FROM WESTERN MINNESOTA SWWD INTO CENTRAL SOUTH DAKOTA. FORECAST
MESOANALYSIS DATA SHOWS STRONG CAP IN PLACE ACROSS MUCH OF THE
FORECAST AREA THIS AFTERNOON WITH +16C 700MB BUBBLE OVER MUCH OF THE
SOUTHERN HALF OF THE FORECAST AREA. CURRENT THOUGHTS ARE THAT TSTMS
MAY BE ABLE TO INITIATE ON THE EDGE OF THE STRONG CAP ACROSS
NORTHEAST NEBRASKA...ALONG THE SD BORDER. DESPITE WEAK SFC
CONVERGENCE...STRONG INSTABILITY AND 0-6KM BULK SHEAR OF 40KTS
SHOULD BE ABLE TO SUSTAIN ANY TSTMS. UNCERTAINTY OF TORNADO THREAT
REMAINS...BUT DID INCLUDE IN HWO IN CASE A COUPLE DISCRETE CELLS
DEVELOP BEFORE COMPLEX TURNS INTO MCS AND ROLLS SEWD OVERNIGHT.
IN ADDITION TO THE SVR THREAT...HEAT ADVISORY CRITERIA IS BEING MET
ACROSS OUR SOUTHERN COUNTIES SO WILL LEAVE IN PLACE THROUGH 7 PM.
KERN
.LONG TERM...THURSDAY THROUGH WEDNESDAY.
MONSOONAL MOISTURE AND SURFACE BOUNDARIES WILL RESULT IN THE
CHANCE FOR THUNDERSTORMS THURSDAY AND THURSDAY NIGHT AND ALSO INTO
FRIDAY FARTHER SOUTH FOR SOUTHEAST NEBRASKA AND SOUTHWEST IOWA.
VERY HOT WEATHER WILL AGAIN BUILD IN FOR THE WEEKEND AND EARLY
NEXT WEEK.
THE RIDGE FLATTENS OVER THE NORTHERN PLAINS WITH TWO SURFACE
BOUNDARIES IN THE AREA. OVERNIGHT CONVECTION AND CONVECTION
THURSDAY MORNING WILL COMPLICATE THE FORECAST...HOWEVER IT SHOULD
PUSH THE SOUTHERN BOUNDARY INTO NORTHERN KANSAS TO NORTHERN
MISSOURI BY THURSDAY EVENING. MEANWHILE THE SECONDARY BOUNDARY
WITH MORE OF A WEAK H85 FOCUS SHOULD STRETCH FROM NORTHERN
NEBRASKA INTO NORTHERN IOWA. IN ADDITION A SHORTWAVE TROF WILL BE
PASSING THROUGH THE PLAINS. THE SURFACE BOUNDARIES AND BOUNDARIES
LEFT OVER FROM CONVECTION SHOULD PROVIDE A GOOD FOCUS FOR RE-
DEVELOPMENT DURING THE AFTERNOON. WITH THE MIX OF CLOUDS AND SUN
AND PRECIPITATION...THURSDAY HIGHS ARE EXPECTED TO BE IN THE 80S
TO LOWER 90S. DEEP LAYER SHEAR VALUES REMAIN IN THE 30 TO 40KT
RANGE THU AND THU NIGHT WITH MODEST INSTABILITY OF 1500 TO 2500
J/KG...SUFFICIENT TO KEEP THE POTENTIAL FOR SEVERE STORMS IN THE
FCST. THE CONVECTION WILL CONTINUE THURSDAY NIGHT INTO FRIDAY WITH
THE SURFACE BOUNDARY IN THE AREA FROM PARTS OF NEBRASKA AND IOWA
INTO KANSAS AND MISSOURI. SURFACE HIGH PRESSURE WILL BUILD INTO
THE NORTHERN PART OF THE FORECAST AREA FRIDAY. THE GFS IS FARTHER
NORTH WITH THE POOLING OF THE H7 DEWPOINTS COMPARED TO THE NAM AND
DID THIS MAY BE MORE REASONABLE. HIGHEST PRECIPITABLE WATER
VALUES ARE POOLING ALONG THE FRONT WITH PWS OF 2 INCHES OR MORE
SOUTH OF A LINE FROM SEWARD TO OMA INTO CENTRAL IOWA
THURSDAY...SHIFTING SOUTHWARD THURSDAY EVENING AND FRIDAY.
WHERE THUNDERSTORMS DEVELOP...LOCALLY HEAVY RAIN WILL BE
POSSIBLE.
FRIDAY NIGHT SURFACE LOW PRESSURE DEVELOPS OVER THE WESTERN HIGH
PLAINS WITH SOUTH FLOW INCREASING AND RISING HEIGHTS AHEAD OF A
SHORTWAVE TROF. THE ORGANIZED CONVECTION APPEARS TO BE FROM THE
WESTERN HIGH PLAINS INTO NORTH DAKOTA AND MINNESOTA. CONVECTION THAT
HOLDS TOGETHER MAY MAKE IT INTO THE FORECAST AREA AND WILL KEEP IT
ISOLATED FOR NOW FRIDAY NIGHT THRU SATURDAY NIGHT.
THE SHORTWAVE DRAGS THE FRONT TOWARD OUR AREA...HOWEVER SHOULD STILL
BE TO OUR NORTH IN SOUTH DAKOTA AND MINNESOTA SUNDAY. THE BUILDING
HEAT SHOULD INHIBIT STORMS SUNDAY AND MONDAY. THERE SHOULD BE A
BOUNDARY IN THE AREA MONDAY NIGHT AND TUESDAY.
ZAPOTOCNY
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
VFR CONDITIONS EXPECTED THRU MUCH OF THE TAF PD. HAVE PUT IN TEMPO
GROUPS AT ALL SITES FOR TSTMS EXPECTED TO ROLL THRU EARLY IN THE TAF
PD. KLNK AND KOMA CUD SEE TSTM ACTIVITY INTO THE OVERNIGHT HOURS.
MVFR CONDITIONS POSSIBLE IN TSTMS.
KERN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NEZ052-053-066>068-
078-088>093.
IA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR IAZ069-079-080-090-
091.
&&
$$