Severe Thunderstorm Warning 91, NWS Cheyenne, WY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
120 PM MDT SAT JUL 26 2003

18Z SFC ANALYSIS SHOWS COLD FRONT IN COLORADO ALREADY WITH LIGHT
NORTH TO NORTHEAST SURFACE WINDS.  CHEYENNE 88D VAD WIND PROFILER
SHOWS LIGHT EAST WINDS IN LOWEST 4000 FT...WITH CROSS OVER TO LIGHT
WEST WINDS ABOVE THAT. A FEW STORMS HAVE ALREADY FORMED DURING THE
EARLY AFTERNOON...THOUGH THEY HAVE BEEN SHORT LIVED AND VISUALLY
APPEAR TO BE SMALL SO FAR.  MAIN SHORT WAVE TROF ALREADY IN CENTRAL
PART OF THE NEBRASKA PANHANDLE AND MOVING AWAY.  THAT APPEARS TO BE
ONE REASON FOR STORMS TO BE FAIRLY WELL BEHAVED.  THINK THAT
INSTABILITY HAS BEEN HELD IN CHECK BY WARM TEMPERATURES ALOFT AND
SOMEWHAT COOLER TEMPERATURES AT LOW LEVELS...THOUGH INCREASED
SURFACE DEWPOINTS MAY JUST BE ENOUGH TO OFFSET COOLER TEMPS.

WILL CONTINUE SCATTERED SHOWERS AND EVENING THUNDERSTORMS MOST AREAS
IN TONIGHTS FORECAST.  HAVE INCREASED LOW TEMPS JUST A TAD BASED ON
UPSTREAM VALUES THIS MORNING AND EXPECTED CLOUD COVER. SHORTWAVE
TROF VISIBILE ON WATER VAPOR SATELLITE IMAGERY OVER NV/ID THIS
AFTERNOON SHOULD BE APPROACHING FORECAST AREA ON SUNDAY...SO ANOTHER
CHANCE OF SHOWERS AND LATE DAY THUNDERSTORMS.  TEMPERATURES COOLER
ON SUNDAY THAN TODAY...AND SHOULD BE HELD IN THE 70S/80S AT LOWER
ELEVATIONS.

IN LATER PDS...SOME LINGERING SHWRS AROUND SUN EVNG...WITH CLDS
HANGING AROUND INTO MON MRNG...THEN DECRSG CLDS FROM N TO S ACRS THE
AREA AS DRIER NW FLOW ALOFT SPREADS IN.  HAVE KEPT A TOKEN 10% POP
FOR MON AND TUE LATE DAY ISOLD SHWRS/TSTMS BASED ON SOME INSTBLTY
AND PERHAPS POCKETS OF LINGERING MID LVL MSTR.  ETA SHOWS THE NEXT
UPR TROF DIGGING SEWD INTO THE UPR MIDWEST ON TUE A BIT STGR THAN
AVN...WITH ITS ASSOCD CDFNT MOVG A LTL FURTHER S INTO THE NRN PARTS
OF THE AREA.  ETA ALSO HAS SOME PCPN WITH THIS FTR WHILE AVN DRY...
ANOTHER REASON TO AT LEAST HANG ON TO 10% POPS.  BY WED INTO
THU...SHOULD BE MAINLY DRY AS THE PERSISTENT UPR HIGH STARTS
MIGRATING EWD AGAIN.  WILL PROBABLY BE SOME MSTR WORKING BACK INTO
THE REGION THU AFTN/EVNG...WITH GFS SHOWING A BETTER AMT MOVING IN
ON FRI INTO SAT...SO WILL HAVE 20-30% LATE DAY POPS THOSE DAYS.
TEMPS GRADUALLY WARM UP MON-WED...THEN BACK TO SEMI-HOT AGAIN FOR
THU THRU SAT.

.CYS...
WY...NONE.
NE...NONE.

NEZ001>003-019>021-054-055-WYZ059>070-271130-

HAZARDOUS WEATHER OUTLOOK...UPDATED/CORRECTED
NATIONAL WEATHER SERVICE CHEYENNE WY
257 PM MDT SAT JUL 26 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEASTERN WYOMING AND THE
WESTERN NEBRASKA PANHANDLE.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS...A FEW CAPABLE OF PRODUCING VERY HEAVY
RAIN...LARGE AMOUNTS OF SMALL HAIL AND WIND GUSTS UP TO 50
MPH...WILL SPREAD FROM THE LARAMIE VALLEY ACROSS THE LARAMIE RANGE.
THE STORMS SHOULD WEAKEN A LITTLE AS THEY MOVE ACROSS THE SOUTHEAST
WYOMING PLAINS AND WESTERN NEBRASKA PANHANDLE DURING THE EVENING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

COOLER AIR WILL SPREAD ACROSS THE REGION SUNDAY WITH UPSLOPE FLOW
CONTINUING THE CHANCE FOR SHOWERS AND THUNDERSTORMS.  ON MONDAY
DRIER AIR WILL RETURN TO THE REGION AS NORTHWESTERLY UPPER LEVEL
WINDS DEVELOP WITH DRY AND SEASONABLE CONDITIONS EXPECTED THROUGH
NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED FROM THE LARAMIE VALLEY EASTWARD
INTO THE SOUTHWEST CORNER OF THE NEBRASKA PANHANDLE THIS AFTERNOON
AND EVENING. SPOTTER ACTIVITATION IS NOT EXPECTED ELSEWHERE.

BANN