Severe Thunderstorm Warning 220, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
352 PM CDT TUE AUG 7 2007

.DISCUSSION...

THE EARLY PARTS OF THE FORECAST ARE DEPENDENT ON MESOSCALE DETAILS
OF FRONTAL AND OUTFLOW BOUNDARIES...AND POSITIONS OF WEAK SHORT
WAVES RIDING ACROSS OUR AREA AT THE EDGE OF THE UPPER RIDGE.  THIS
IS NOT A HIGH CONFIDENCE SITUATION.

IT APPEARS THAT SCT TSTMS WILL CONTINUE THIS EVE AND EARLY TONIGHT
MAINLY TO THE SOUTH OF WEAKENING MCV TRACKING OUT OF NORTHEAST NEB.
AGREE WITH SPC THAT FRONTAL BOUNDARY JUST S OF FNB HAS POTENTIAL TO
ERUPT INTO SVR MULTICELLS...BUT HAS NOT SHOWN MUCH INDICATION OF
SERIOUSLY BREAKING CAP TO THIS POINT.

LATE TONIGHT EXPECT THE AREA TO COME UNDER THE INFLUENCE OF NEXT
SHORT WAVE CURRENTLY MOVING NORTHEAST FROM NM INTO CO.  AREA WILL
REMAIN IN SUBTROP MOIST AXIS NORTH OF THE FRONTAL BOUNDARY THROUGH
TOMORROW...BUT IT APPEARS THAT DIURNAL TIMING OF THE NEXT WAVE WILL
NOT ESPECIALLY FAVOR HEAVY RAIN.  LLJ MAY HELP CONVECTION AS IT
ENTERS AREA LATE TNGT...BUT UNCERTAIN THAT IT WILL BE AS STRONG AS
DEPICTED BY NAM...WHICH HAS BEEN HAVING TROUBLE PLACING SYSTEMS.
DECIDED NOT TO ISSUE FLASH FLOOD WATCH AS ONLY A FEW COUNTIES HAVE
RECENTLY RECEIVED ENOUGH RAIN TO BE VERY SUSCEPTABLE.
INSTEAD...THINK BEST CHC PRECIP WILL BE DURING THE DAY WED...KEEPING
CLOUDS OVER MOST OF THE AREA AND TEMPS DOWN FOR ONE MORE DAY.

ACTIVITY COULD LAST INTO WED NIGHT...ESPCEIALLY IF ANOTHER WAVE
MATERIALIZES IN SW FLOW ALOFT.  AFTER THAT...RIDGE WILL BE BUILDING
ALOFT AND WARMER MID LEVEL TEMPS WILL MAKE IT DIFFICULT FOR
ORGANIZED PRECIP TO DEVELOP.  AREA WILL STILL BE IN WEAK OUTFLOW FROM
SFC HIGH TO OUR NORTHEAST ON THU.  HOWEVER...EXPECT CAPPING AND LOTS
OF SUN TO ALLOW TEMPS TO REBOUND INTO THE 90S...ALONG WITH
UNCOMFORTABLY HIGH SFC DEWPOINTS DUE TO EVAPORATION INTO SHALLOW
INVERSION.

FROM THURSDAY ONWARD EXPECT THAT THE MAIN WEATHER STORY WILL BE THE
HEAT.  AREA WILL BE UNDER HOT RIDGE ALOFT AT LEAST INTO EARLY NEXT
WEEK.  AGREE WITH HPC IN KEEPING FRONTAL BOUNDARY NORTH OF THE AREA
THRU TUESDAY WITH LITTLE CHC OF RAIN EXCEPT PERHAPS IN THE FAR N.
WHILE SOME EROSION OF THE UPPER RIDGE IS POSSIBLE BY TUE...ENSEMBLES
SUGGEST THAT THE BALANCE OF PROBABILITY IS FOR HIGHS WELL INTO THE
90S AND DEW POINTS HIGH ENOUGH THAT A HEAT ADVSRY MAY BE NEEDED.
MENTION OF HEAT WAS ADDED TO THE HAZARDS OUTLOOK.
&&

.AVIATION...

CONVECTION EXPECTED TO CONTINUE ACROSS KOFK/KOMA/KLNK TAF SITES THRU
18Z TAF PD. SEVERAL SFC BOUNDARIES TO FOCUS ACTIVITY ON SO TOUGH TO
PIN DOWN EXACT DEVELOPMENT. HAVE INCLUDED TEMP GROUPS TO COVER
HEAVIER TSTMS. OTHERWISE...CEILINGS WL BE MVFR WITH IFR CONDITIONS
DURING TSTMS.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.

&&

POLLACK/GRIFFIS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
430 PM CDT TUE AUG 7 2007

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-081000-
ANTELOPE-BOONE-BURT-BUTLER-CASS-CEDAR-COLFAX-CUMING-DODGE-DOUGLAS-
FREMONT IA-GAGE-HARRISON IA-JEFFERSON-JOHNSON-KNOX-LANCASTER-MADISON-
MILLS IA-MONONA IA-MONTGOMERY IA-NEMAHA-OTOE-PAGE IA-PAWNEE-PIERCE-
PLATTE-POTTAWATTAMIE IA-RICHARDSON-SALINE-SARPY-SAUNDERS-SEWARD-
SHELBY IA-STANTON-THURSTON-WASHINGTON-WAYNE-
430 PM CDT TUE AUG 7 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF EASTERN NEBRASKA AND
SOUTHWEST IOWA.

.DAY ONE...TONIGHT AND WEDNESDAY

THERE WILL BE A CHANCE OF THUNDERSTORMS AGAIN TONIGHT...MAINLY
FROM SOUTHEAST NEBRASKA INTO SOUTHWEST IOWA...SOUTH OF A LINE FROM
HARLAN IOWA TO OMAHA TO DAVID CITY. A FEW STORMS MAY BE SEVERE THIS
EVENING WITH DAMAGING WINDS AND LARGE HAIL THE PRIMARY HAZARDS.
IN ADDITION...HEAVY RAIN IS ALSO LIKELY WITH THE STORMS WHICH MAY
PRODUCE LOCALIZED FLOODING.

THE CHANCE OF THUNDERSTORMS WILL CONTINUE ACROSS THE AREA ON
WEDNESDAY WITH DAMAGING WINDS AGAIN THE PRIMARY HAZARD.

.DAYS TWO THROUGH SEVEN...WEDNESDAY NIGHT THROUGH TUESDAY

HOT AND HUMID WEATHER WILL PREDOMINATE BEGINNING THURSDAY AS THE
REGION STARTS INTO A PROLONGED SUMMER HEAT WAVE. AFTERNOON HEAT
INDICES MAY EXCEED 105.

THE CHANCE OF THUNDERSTORMS WILL CONTINUE INTO WEDNESDAY NIGHT AS
THE FRONT REMAINS IN THE AREA.

.SPOTTER INFORMATION STATEMENT...

STORM SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING.

FOBERT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
443 PM CDT TUE AUG 07 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0430 PM     HAIL             9 S JOHNSON             40.28N 96.00W
08/07/2007  E1.00 INCH       NEMAHA             NE   PUBLIC

&&

DEWALD