Flash Flooding and Hail in Nebraska, July 17, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
644 AM CDT THU JUL 17 2008

.AVIATION...06Z KGRI TAF. VFR CONDITIONS EXPECTED FOR MUCH OF THE
DAY. WINDS ARE EXPECTED TO INCREASE A BIT WITH TIME FROM THE
SOUTH. POSSIBLE THUNDERSTORMS THIS LATE AFTERNOON AS A COLD FRONT
APPROACHES FROM THE NORTH...AND BY THIS EVENING THUNDERSTORMS WILL
BE PROMINENT. THE MVFR CONDITIONS IN THE TAF THIS EVENING AND
OVERNIGHT ARE A GENERAL GUESS...BUT AT TIMES THESE CONDITIONS
COULD BE MUCH WORSE AS THE THUNDERSTORMS ARE EXPECTED TO CONTAIN
EXCEPTIONALLY HEAVY RAIN AT TIMES. LARGE HAIL AND DAMAGING WIND
WILL ALSO BE POSSIBLE WITH SOME THUNDERSTORMS. THERE COULD BE A
VERY PROLONGED PERIOD OF HEAVY RAIN...AND A VRB025KT WIND
ESTIMATION WAS GIVEN FOR THE ENTIRE NIGHT. TIMING OF COLD FRONT IS
TRICKY...AND WILL BE DIFFICULT TO NAIL DOWN A TIME WHEN WIND WILL
BECOME PREDOMINATELY NORTH AFTER THE FRONT MOVES THROUGH. THIS
WOULD PROBABLY BE VERY LATE IN THE FORECAST...WHICH WILL LIKELY BE
REFINED WITH FUTURE FORECASTS.

&&

.PREV DISCUSSION... /ISSUED 333 AM CDT THU JUL 17 2008/

DISCUSSION...MAIN FORECAST CONCERN IS THE CHANCE OF THUNDERSTORMS
THROUGH SATURDAY...INCLUDING POSSIBLY SEVERE WEATHER THIS AFTERNOON
AND EVENING AND HEAVY RAIN OVERNIGHT.

CURRENT SATELLITE AND RADAR HAVE THUNDERSTORMS TO THE WEST OF THE
FORECAST AREA. SURFACE ANALYSIS INDICATES THAT MOST OF THE
THUNDERSTORMS ARE ALONG A SURFACE FRONT DRAPED FROM THE HIGH PLAINS
INTO MINNESOTA. THE CURRENT THUNDERSTORMS ARE YET TO THE WEST OF THE
AREA AND EXPECT THAT THESE WILL MOVE THROUGH THE NORTHERN PART OF
THE FORECAST AREA THROUGH THE MORNING. THE SURFACE FRONT SHOULD GET
INTO THE FORECAST AREA LATER THIS AFTERNOON AND WILL MOVE SLOWLY
THROUGH THE FORECAST AREA THIS AFTERNOON AND TONIGHT. EXPECT THAT
THUNDERSTORMS WILL DEVELOP RAPIDLY ALONG THE FRONT THIS AFTERNOON.
AS THE FRONT MOVES TO THE EAST AN UPPER WAVE MOVES THROUGH. FOR THIS
AFTERNOON AND EVENING EXPECT THAT SOME OF THE THUNDERSTORMS COULD
BECOME SEVERE AS THE CAPE IS OVER 4000 J/KG. THE SHEAR IS ONLY 20 TO
25 KNOTS AT THE GREATEST. EXPECT THAT HAIL WILL BE THE PRIMARY
THREAT BUT COULD HAVE SOME WIND AS THE STORMS SHOULD BE LINEAR IN
NATURE. BY MID EVENING THE CAPE DIMINISHES AND EXPECT THAT THE
STORMS WILL MOSTLY JUST CAUSE RAIN. FORECAST PRECIPITABLE WATER
VALUES OF 2 TO 2.5 INCHES ARE EXPECTED ACROSS THE AREA MOSTLY
THROUGH THE NIGHT.

THE FRONT MOVES THROUGH MUCH OF THE FORECAST AREA BY FRIDAY MORNING.
ANOTHER UPPER WAVE MOVES THROUGH THE AREA ON FRIDAY. WITH THE FRONT
IN THE VICINITY THERE IS A CHANCE FOR THUNDERSTORMS. THE BETTER
CHANCES WILL BE IN THE SOUTHEAST NEARER TO THE FRONT BUT WITH THE
UPPER WAVE MOVING THROUGH THERE IS A CHANCE EVERYWHERE. YET ANOTHER
UPPER WAVE MOVES INTO THE AREA FRIDAY NIGHT BUT THE SURFACE FRONT IS
GONE AND DO NOT EXPECT AS MUCH OF A CHANCE FOR THUNDERSTORMS.
ANOTHER WAVE MOVES THROUGH SATURDAY AND SATURDAY NIGHT. THERE IS A
SURFACE FRONT THAT MOVES THROUGH THAT COULD SET OFF MORE
THUNDERSTORMS AGAIN. MADE NO CHANGES TO SUNDAY AND BEYOND.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...FLASH FLOOD WATCH FROM THIS EVENING THROUGH FRIDAY MORNING FOR
     NEZ039>041-046>049-060>064-072>077-082>087.

KS...NONE.
&&

AVIATION...HEINLEIN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HASTINGS NE
504 AM CDT THU JUL 17 2008

KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087-
181200-
PHILLIPS-SMITH-JEWELL-ROOKS-OSBORNE-MITCHELL-VALLEY-GREELEY-NANCE-
SHERMAN-HOWARD-MERRICK-POLK-DAWSON-BUFFALO-HALL-HAMILTON-YORK-
GOSPER-PHELPS-KEARNEY-ADAMS-CLAY-FILLMORE-FURNAS-HARLAN-FRANKLIN-
WEBSTER-NUCKOLLS-THAYER-
504 AM CDT THU JUL 17 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL NEBRASKA AND
PORTIONS OF NORTH CENTRAL KANSAS.

.DAY ONE...TODAY AND TONIGHT.

THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG A COLD FRONT AS IT
MOVES THROUGH THE OUTLOOK AREA TODAY AND TONIGHT. SOME OF THE
STORMS MAY BE SEVERE IN THE LATE AFTERNOON AND EVENING. THE
PRIMARY THREAT WITH THESE STORMS WILL BE HAIL TO THE SIZE OF
QUARTERS AND DAMAGING WIND GUSTS TO 60 MPH. THE THUNDERSTORMS WILL
MOVE SLOWLY ACROSS THE AREA TONIGHT. VERY HEAVY RAIN IS POSSIBLE
WITH THESE THUNDERSTORMS WHICH MAY CAUSE FLOODING. A FLASH FLOOD
WATCH HAS BEEN POSTED FOR SOUTH CENTRAL NEBRASKA WHERE THE
HEAVIEST RAINS CAN BE EXPECTED.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THUNDERSTORM CHANCES CONTINUE FRIDAY THROUGH SATURDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED AFTER 4 PM.

&&

MORE INFORMATION MAY BE OBTAINED AT THE FOLLOWING WEB PAGE:
   HTTP://WWW.WEATHER.GOV/HASTINGS  (ALL LOWERCASE)