Severe Thunderstorm Warning 122, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
300 PM CDT THU JUN 6 2002

.SYNOPSIS...SFC RIDGE HAS SHIFTED WELL TO THE SOUTHEAST OF THE
FORECAST AREA THIS AFTERNOON WHILE STRONG LOW PRESSURE MOVES ACROSS
THE CANADIAN PRAIRIE PROVINCES.  SURFACE BOUNDARY CURRENTLY EXTENDS
FROM THE CNTRL DAKOTAS AND THEN SWWD BACK INTO WRN NEB AND ERN CO.

.FOREAST...FRONTAL BOUNDARY EXPECTED TO SAG FURTHER SEWD TONIGHT AND
HANG UP OVR NRN NEB/SRN SD AS SFC LO DEVELOPS OVR ERN WY/ERN CO.
MODELS ARE GENERATING SOME QPF IN NRN ZONES ALONG FRONTAL BOUNDARY
AND IN ASSOCIATION WITH NRN STREAM SHORTWAVE. SOME CONVECTION HAS
ALREADY BEGUN OVR S CNTRL SD THIS AFTERNOON. MOISTURE IS LACKING
LOOKING AT RH CROSS SECTIONS AND FORECAST SOUNDINGS ACROSS CWA. WITH
SOME SLIGHT QG FORCING INDICATED...AND STEEP MID LEVEL LAPSE RATES
AND ONGOING CONVECTION...HAVE OPTED TO CONTINUE WITH 20 POPS FOR NRN
AREAS TNT.

FRONTAL BOUNDARY STAYS ACROSS NRN ZONES ON FRIDAY.  WITH HIGH
PRESSURE SHIFTING FURTHER EWD...MOISTURE WILL RETURN INTO THE
REGION.  850MB SWRLY FLOW INCREASES AND NOSE OF THIS JET WILL
INTERACT W/ SFC BOUNDARY OVER NERN NEB TOMORROW NIGHT.  MID LEVEL
LAPSE RATES STEEPEN AND 850MB MOISTURE INCREASES.  THINKING IS THAT
SFC HEATING AND LIFT OVER FRONTAL BOUNDARY WL WEAKEN AFTERNOON CAP
TO START CONVECTION BY LATE AFTERNOON/EARLY EVENING.  HAVE BOOSTED
HIGHS TOMORROW OVR NRN ZONES BECAUSE LOOKS LIKE FRONT HAS SLOWED
DOWN AND WL STAY N OF AREAS DURING MAX HEATING. ALSO HAVE BUMPED UP
OVER REST OF AREA AS FORECAST THICKNESSES CONT TO INCREASE.

SFC LO CONTINUES TO DEVELOP OVER ERN CO ON SUNDAY WITH BIG UPPER
LEVEL TROF DIGGING OVER WRN US.  SHORTWAVE EJECTS OUT OF FLOW ON
SUNDAY AND SO WL CONT WITH TSTM CHANCE INTO MONDAY WHEN SFC LO MOVES
OVERHEAD AND UPPER LOW MOVES NEWD.  HIGH PRESSURE THEN BEGINS TO
MOVE IN FROM THE WEST AS WEAK UPPER RIDGING TAKES HOLD FOR THE END
OF THE PERIOD.

.OMA...NONE.

GRIFFIS

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-070600-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
525 PM CDT THU JUN 6 2002

THERE IS A SLIGHT CHANCE THAT STORM SPOTTERS WILL BE NEEDED THIS
EVENING OVER PART OF NORTHEAST NEBRASKA...MAINLY NORTHWEST OF A
LINE FROM DAVID CITY NEBRASKA TO ONAWA IOWA.  STORM SPOTTER
ACTIVATION IS NOT EXPECTED OVER THE REST OF EASTERN NEBRASKA AND
SOUTHWEST IOWA THROUGH TONIGHT... NOR OVER NORTHEAST NEBRASKA
AFTER MIDNIGHT.

DAYTIME HEATING HAS RESULTED IN UNSTABLE CONDITIONS FROM CENTRAL
NEBRASKA INTO SOUTHEAST SOUTH DAKOTA.  IN ADDITION...A DRY LINE
EXTENDED ACROSS THAT REGION.  DEVELOPING THUNDERSTORMS ALONG THIS
BOUNDARY COULD MOVE INTO NORTHEAST NEBRASKA THIS EVENING.  IF
THEY DO...LARGE HAIL WOULD BE THE PRIMARY SEVERE WEATHER THREAT.
ALTHOUGH GUSTY WINDS ARE ALSO POSSIBLE.  A MORE STABLE AIRMASS
FARTHER TO THE SOUTHEAST GREATLY LIMITS THE CHANCES THAT
THUNDERSTORMS WILL MAKE IT INTO SOUTHEAST NEBRASKA OR SOUTHWEST
IOWA TONIGHT.

ALTHOUGH THERE STILL IS A THREAT OF THUNDERSTORMS OVER NORTHEAST
NEBRASKA AFTER MIDNIGHT...AND MARGINALLY SEVERE HAIL COULD STILL
FALL FROM THE STRONGER STORMS...WIDESPREAD ORGANIZED ACTIVITY IS
NOT LIKELY. THUS SPOTTER ACTIVATION IS ALSO NOT LIKELY.

INSTABILITY WILL BE INCREASING ACROSS A LARGER PART OF THE AREA
FRIDAY AFTERNOON AND EVENING AS TEMPERATURES AGAIN WARM WELL INTO
THE 80S AND DEWPOINTS INCREASE.  IN ADDITION...A FRONT IS
EXPECTED TO STALL NEAR THE NEBRASKA AND SOUTH DAKOTA BORDER.
STRONG TO SEVERE THUNDERSTORMS COULD AGAIN DEVELOP ALONG THIS
FRONT LATE FRIDAY AFTERNOON AND MOVE INTO PARTS OF EASTERN
NEBRASKA AND WEST CENTRAL IOWA FRIDAY NIGHT.  THE AREA WITH THE
GREATEST RISK APPEARS TO BE NORTH OF A LINE FROM SEWARD TO THE
OMAHA AND COUNCIL BLUFFS AREA.	SUPERCELLS ARE POSSIBLE...WITH
HAIL AND DAMAGING WINDS THE MAIN SEVERE WEATHER HAZARDS.

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).

CHERMOK