Severe Thunderstorm Warning 331, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
325 AM CDT WED AUG 28 2002

AT 06Z SFC RIDGE EXTENDED FROM GREAT LAKES REGION INTO ERN NEBRASKA
WITH WEAK TROF OVER THE WESTERN DAKOTAS. COUPLE OF OUTFLOW BOUNDRIES
SHOW UP ON SFC MAP WITH ONGOING CONVECTION. ONE FROM THE WESTERN
PANHANDLE OF NEBRASKA INTO NORTH CENTRAL COLORADO AND ANOTHER OVER
NORTH CENTRAL KANSAS. UPPER LOW REMAINS ANCHORED OVER SWRN ID IN TROF
OVER THE WESTERN U.S. WITH RIDGING INTO THE CENTRAL PLAINS.  CONVECTION
HAS BEEN OCCURRING ON PERIPHERY OF THE UPPER RIDGE THIS MORNING.

LITTLE CHANGE TO THIS PATTERN INDICATED BY MODELS THROUGH THURSDAY
WITH H85 MOISTURE AXIS IN PLACE OVER THE WESTERN HIGH PLAINS ALONG
WITH STEEPER MID LEVEL LAPSE RATES AND STRONGER H85 FLOW.  SPOTTY
AFTERNOON AND EVENING THUNDERSTORMS POSSIBLE ACROSS THE CWFA DURING
THE PERIOD BUT MAIN CONVECTION EXPECTED TO FIRE OVER THE WESTERN
HIGH PLAINS.  QUESTION THEN BECOMES HOW FAR EAST SYSTEMS MAY TRACK
DURING THE OVERNIGHT PERIOD.

WILL CONTINUE WITH PERSISTENCE FORECAST THROUGH THE SHORT TERM BASED
ON LIMITED CHANGE TO PATTERN.

IN THE EXTENDED...AVN AND ECMWF INDICATE UPPER RIDGE FLATTENS EARLY
IN THE PERIOD AS A PIECE OF THE WESTERN WAVE BEGINS TO MOVE INTO THE
NORTHERN PLAINS FRIDAY WITH SECOND AND MORE AMPLIFIED TROF COMING
ACROSS OVER THE WEEKEND. THE SECOND WAVE PUSHES A COLD FRONT INTO
THE REGION SUNDAY INTO MONDAY WITH SOUTHWARD EXTENT OF FRONT IN
QUESTION AT THIS TIME.  WITH FASTER FLOW DEVELOPING DURING THE PERIOD
TIMING OF EVENTS BECOME A PROBLEM.  HAVE INTRODUCED SOME CHANCE POPS
FOR NRN PARTS OF THE CWFA FOR SUNDAY AND SUNDAY NIGHT WITH EXPECTED
ARRIVAL OF SURFACE FRONT BUT OTHERWISE LITTLE ELSE CHANGED AT THIS
TIME DUE TO UNCERTAINTY OF MODEL TIMING.

.OMA...NONE.
FOBERT

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-282300-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1200 PM CDT WED AUG 28 2002

STORM SPOTTER ACTIVATION IS NOT EXPECTED ACROSS EASTERN NEBRASKA
OR SOUTHWEST IOWA THIS AFTERNOON OR TONIGHT.

A CLUSTER OF THUNDERSTORMS OVER CENTRAL NEBRASKA HAS PRODUCED AN
OUTFLOW BOUNDARY THAT WILL MOVE ACROSS EASTERN NEBRASKA THIS
AFTERNOON.  UNSTABLE AIR WILL AGAIN BE IN PLACE BY LATE
AFTERNOON...SO A FEW THUNDERSTORMS MAY DEVELOP ALONG THE OUTFLOW
BOUNDARY...MAINLY OVER EAST CENTRAL AND NORTHEAST NEBRASKA.
HOWEVER THERE IS VERY LITTLE WIND SHEAR...SO THE STORMS SHOULD BE
SHORT-LIVED AND MAINLY JUST CONTAIN BRIEF PERIODS OF HEAVY RAIN.

THERE WILL BE A CONTINUED CHANCE FOR STORMS INTO THE
WEEKEND...BUT ORGANIZED SEVERE WEATHER DOES NOT APPEAR LIKELY AT
THIS TIME.

THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC AND CLIMATIC
INFORMATION IS AVAILABLE ON THE INTERNET AT
WWW.CRH.NOAA.GOV/OAX OR AT WEATHER.GOV (LOWER CASE)

DDN