Hail and Damaging Wind in Nebraska, September 6 to 7, 2001

SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
213 PM CDT THU SEP 6 2001

...FORECAST CHALLENGE WILL BE PRECIP/COOL TEMPS TONITE THRU SAT...

12Z SURFACE ANALYSIS SHOWED NORTHERN EXTENT OF GULF MOISTURE
REACHING ALL THE WAY TO CANADIAN BORDER WITH 65 DEWPOINTS. FRONTAL
BOUNDARY STRETCHED FROM CENTRAL NORTH DAKOTA TO LOW OVER SOUTHWEST
WYOMING...WITH PREFRONTAL TROF STARTING TO TAKE SHAPE IN LEE OF
ROCKIES FROM KRAP TO KCOS.  BEHIND THE FRONT 3 HR PRESSURE CHANGES
OF 2+ MB NOTED OVER WRN NORTH DAKOTA.

UPPER LEVELS SHOW DYNAMIC PATTERN WITH LOW SITUATED OVER GREAT
BASIN.  AT H5 CLOSED LOW CENTERED OVER CENTRAL IDAHO WITH THERMAL
TROUGH DIPPING SOUTH INTO NRN TX.  NICE HEIGHT FALLS OF UP TO
60M/12HR ALSO NOTED AHEAD OF TROUGH AT H7 OVER CENTRAL PLAINS.

AN EARLY AUTUMN-LIKE AIRMASS WILL BEGIN TO TAKE HOLD OF THE CWFA
AFTER DARK TONIGHT WITH WIDESPREAD RAIN EXPECTED.  ISOLATED SVR ALSO
A POSSIBILITY AS SEVERAL PARAMETERS COMING TOGETHER.  SPECIFICALLY
OF INTEREST IS STRONG TEMP/MOISTURE ADVECTION IN STIFF SOUTHERLY
FLOW AHEAD OF THE FRONT.  ETA ALSO CRANKS UP 50+KT H85 LL JET AT
06Z.  KAIN-FRITCH ETA STARTS THE ACTION OVER NEB PHDL THIS EVENING
WHERE MORE SUN HAS ALLOWED DESTABILIZATION...BUT THINGS REALLY GET
GOING LATER. ETA IN AGREEMENT WITH AVN IN PLACING 1INCH+ QPF OVER US
DURING 12 HOUR PERIOD FROM 06-18Z FRI. ALTHOUGH HAIL/WIND
PROBABLISTIC MAPS INCLUDE US...WB ZERO HTS RATHER HIGH FOR LARGE
HAIL.

SYSTEM SCOOTS OUT BY FRIDAY AFTERNOON WITH COLD AIR FINALLY SLIPPING
IN BY 12Z SAT.  HAVING TROUBLE WITH AWIPS MODEL TEMP DISPLAY...BUT
TRENDS AND NUMERICAL GUIDANCE SUGGEST THAT TEMPS WILL RUN SOME 10 TO
15 DEGREES COOLER WITH NIGHTTIME LOWS IN THE 40S.  COLDEST AIR STILL
RIDING NORTH IN ERN DAKOTAS WITH 546 THICKNESS VALUES APPARENT ON
PROGS. GRADIENT ALSO REMAINS RATHER TIGHT ON SAT WITH H85 35-40KT
NORTH WIND EXPECTED TO MIX DOWN TO AT LEAST 20KT AT SURFACE WITH
SKIES PARTLY CLOUDY.

IN THE LATER PERIODS...MRF RUN TO RUN CONSISTENCY IS POOR...BUT
LATEST RUN FROM 00Z THURS IS IN GOOD AGREEMENT WITH AVN/UKMO/AND
ECMWF IN CARRYING SYSTEM OVER GREAT LAKES BY SUN.  THIS WILL BRIEFLY
RETURN NORTHWEST FLOW REGIME WITH WEAK RIDGING OVER INTERMOUNTAIN
WEST. AS PATTERN BECOMES MORE PROGRESSIVE WE WILL TRANSITION WITH
FLOW FROM SOUTHWEST BY TUES NIGHT AND ASSOCIATED WARMUP. NEXT CHANCE
FOR PRECIP IS REMOTE...BUT LOOKS LIKE POSSIBILITY WITH SHORTWAVE
COMING ACROSS NE COLO ON WED NIGHT AND THURSDAY IN ADVANCE OF
ALBERTA LOW.

.GID...NONE.

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