Severe Thunderstorm Warning 76, NWS Cheyenne, WY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
524 PM MDT WED JUN 9 2010

.UPDATE TO AVIATION...

SHORT TERM...TONIGHT THROUGH FRIDAY
TONIGHT...ABUNDANT LOW LEVEL MOISTURE HAS ADVECTED NORTHWARD
ACROSS OUR COUNTIES WITH MIDDAY DEW POINTS WELL INTO THE 50S EAST
OF INTERSTATE 25. STILL EXPECTING SCATTERED THUNDERSTORMS TO
DEVELOP AS THE AFTERNOON PROGRESSES...FOCUSED ALONG THE LOW LEVEL
INSTABILITY AND THETA-E RIDGE AXES NORTH-SOUTH ALONG INTERSTATE
25. MID LEVEL CLOUDS WILL LIMIT INSTABILITY THOUGH. WITH ADEQUATE
WIND SHEAR AND INSTABILITY...A FEW OF THE THUNDERSTORMS PRIMARILY
EAST OF INTERSTATE 25...WILL LIKELY BECOME SEVERE THIS AFTERNOON
AND EVENING. WITH LOSS OF DAYTIME HEATING AND LIMITED LIFT
ALOFT...SHOWERS AND THUNDERSTORMS WILL DECREASE IN COVERAGE AND
INTENSITY BY LATE THIS EVENING...WITH SCATTERED SHOWERS ON TAP
ACROSS OUR NORTHERN AND EASTERN COUNTIES AFTER MIDNIGHT. WILL
ADD PATCHY FOG TO EASTERN ZONES LATE TONIGHT AND EARLY THURSDAY
MORNING WITH FAVORABLE BOUNDARY LAYER MOISTURE IN PLACE.

THURSDAY...LEE SURFACE LOW INTENSIFIES ACROSS NORTHEAST COLORADO
WITH A FRONTAL BOUNDARY ACROSS OUR SOUTHEAST COUNTIES IN THE
AFTERNOON. WILL AGAIN SEE SCATTERED AFTERNOON THUNDERSTORMS
DEVELOP NEAR AND BEHIND THE FRONTAL BOUNDARY WITH A FEW STRONG TO
SEVERE THUNDERSTORMS POSSIBLE ALONG THE LOW/MID LEVEL THETA-E
RIDGE AND INSTABILITY AXES...AS DEPICTED BY THE STORM PREDICTION
CENTER'S DAY 2 OUTLOOK. IT WILL BE QUITE WARM EAST OF THE LARAMIE
RANGE WITH HIGHS FROM 85 TO 90...WITH 60S AND 70S IN OVER THE
HIGHER TERRAIN WEST OF THE RANGE.

THURSDAY NIGHT...EXPECT SCATTERED SHOWERS AND SOME THUNDERSTORMS IN
THE WAKE OF THE COLD FRONT WITH MOIST EAST TO NORTHEAST UPSLOPE
FLOW AND SHORTWAVE TROUGH MOVING ACROSS THE REGION. WILL ALSO SEE
AREAS OF FOG DEVELOP IN THE WAKE OF THE COLD FRONT...PRIMARILY
EAST OF INTERSTATE 25.

FRIDAY...IT WILL BE A COOLER AND DAMP DAY WITH SCATTERED SHOWERS
AND THUNDERSTORMS. SOUTHWEST FLOW ALOFT WILL RIDE OVER THE MOIST
NORTHEAST UPSLOPE FLOW AT LOW LEVELS. HIGH TEMPERATURES FROM THE
MID 50S TO NEAR 70 DEGREES DUE TO CLOUD COVER AND PRECIPITATION.

LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
THE 12Z GFS...GEM AND ECMWF MODELS CONTINUE TO HAVE A GOOD
HANDLE ON THE NEXT LATE SEASON STORM AFFECTING OUR CWA FRIDAY
THROUGH MONDAY. THE FLOW ALOFT SPLITS INTO A NORTHERN AND
SOUTHERN STREAM. IN THE SOUTHERN STREAM...THE CLOSED MID/UPPER
LOW OVER THE GREAT BASIN FRIDAY NIGHT REMAINS IN THAT GENERAL
VICINITY BEFORE FINALLY EJECTING NORTHEASTWARD ACROSS CO...WY AND
UT SUNDAY AND SUNDAY NIGHT. MEANWHILE...NORTHERN STREAM HEIGHTS
BUILD OVER ALBERTA AND SASKATCHEWAN CANADA WITH A LARGE AMPLITUDE
RIDGE TAKING SHAPE. A SHORTWAVE TROUGH MOVES OVER THE NORTHERN
PLAINS SUNDAY AND SUNDAY NIGHT. BOTH FACTORS RESULT IN THE SLOW
MOVEMENT OF THE MID/UPPER LOW. THE 12Z ECMWF SEEMS TO HAVE BETTER
RUN TO RUN CONSISTENCY...AND IS FURTHER NORTH AND FASTER WITH THE
EASTWARD PROGRESSION OF THE TROUGH ACROSS THE CWA MONDAY NIGHT AND
TUESDAY. SIGNIFICANT BOUNDARY LAYER UPSLOPE FLOW DEVELOPS OVER THE
CWA FRIDAY THROUGH SATURDAY WITH SURFACE LOW PRESSURE SITUATED
SOUTH OF THE CWA. SURFACE HIGH PRESSURE SLOWLY MOVES SOUTHEAST
FROM THE NORTHERN ROCKIES TO THE CENTRAL PLAINS SUNDAY AND MONDAY.
SYNOPTIC LIFT WILL ALSO BE ENHANCED BY 300 MB DIVERGENCE OVER THE
AND MID LEVEL FRONTOGENESIS. THE MODELS CONTINUE TO SHOW WIDESPREAD
PRECIPITATION THROUGH SUNDAY EVENING AS WELL AS COOLER TEMPERATURES.
RAINFALL AMOUNTS FROM FRIDAY THROUGH SUNDAY WILL AVERAGE BETWEEN
0.25 AND 0.75 INCHES...WITH AMOUNTS IN EXCESS OF AN INCH A GOOD
POSSIBILITY. THIS PREDICTED RAINFALL WILL EXACERBATE THE CURRENT
BANKFULL OR FLOODING RIVERS...RESULTING FROM RECENT SNOW MELT FROM
THE SNOWY AND SIERRA MADRE RANGES. HIGHS SATURDAY WILL BE IN THE
40S AND 50S AND EVEN COOLER OVER THE MOUNTAINS. SNOW WITH AMOUNTS
LESS THAN AN INCH MAY ACCUMULATE OVER THE MOUNTAINS ABOVE 9000
FT... ESPECIALLY SATURDAY NIGHT AND SUNDAY MORNING. A SOMEWHAT
DRIER AND WARMER AIR MASS BEGINS ON TUESDAY WITH THE DEVELOPMENT
OF A SURFACE LEE TROUGH ALONG THE EASTERN WYOMING BORDER. ISOLATED
CONVECTION WILL BE POSSIBLE TUESDAY AND WEDNESDAY AFTERNOON AND
EVENING OVER NORTHERN AND EASTERN PORTIONS OF THE CWA.

&&

AVIATION...00Z TAF ISSUANCE
CONVECTION EXPECTED TO DIE OFF AFTER SUNSET. THERE IS SOME CONCERN
FOR FOG/STRATUS DEVELOPMENT OUT OVER THE PANHANDLE AREA AFTER
MIDNIGHT AS THEY HAVE SEEN SOME PRETTY GOOD RAINFALL WITH UPSLOPE
WINDS. WILL CONTINUE MVFR CONDITIONS FOR EARLY THURSDAY MORNING TO
ACCOUNT FOR THIS AND SEE WHAT THE NEW GUIDANCE SHOWS FOR THE 06Z
TAFS. CONVECTION EXPECTED TO RETURN WITH DAYTIME HEATING THURSDAY.

&&

FIRE WEATHER...NO CONCERNS DUE TO ADEQUATE SURFACE MOISTURE FROM
SNOW MELT AND RECENT/FORECAST PRECIPITATION. THE FIRE DANGER WILL
REMAIN LOW THROUGH THE WEEKEND.

&&

HYDROLOGY...FLOODING CONTINUES FOR RIVERS FLOWING FROM THE SNOWY
AND SIERRA MADRE RANGES DUE TO RAPID SNOW MELT. FLOOD WARNINGS
REMAIN IN EFFECT FOR SOUTHERN AND EASTERN CARBON COUNTY...INCLUDING
THE MEDICINE BOW AND ENCAMPMENT RIVERS AND THEIR TRIBUTARIES. A
FLOOD WATCH HAS BEEN EXTENDED THROUGH THURSDAY AFTERNOON FOR
INCREASED FLOWS IN RIVERS AND STREAMS IN THE LARAMIE VALLEY. FLOWS
ALONG THE NORTH PLATTE RIVER REMAIN ELEVATED AT HENRY AND MITCHELL
IN THE NEB PANHANDLE. MANY OF THE RIVERS WILL REMAIN ABOVE FLOOD
STAGE THROUGH THE WEEKEND. ADDITIONAL RAINFALL FRIDAY THROUGH
SUNDAY MAY KEEP RIVER LEVELS HIGHER THAN PREDICTED.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...FLOOD WATCH UNTIL 6 PM THURSDAY FOR WYZ115.
NE...NONE.

&&

SHORT TERM/AVIATION...RUBIN/CLAYCOMB
LONG TERM...JAMSKI

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
941 PM MDT WED JUN 9 2010

NEZ054-055-WYZ104-109>119-110345-
KIMBALL-CHEYENNE-FERRIS/SEMINOE/SHIRLEY MOUNTAINS-
CENTRAL CARBON COUNTY-NORTH SNOWY RANGE FOOTHILLS-
SOUTHWEST CARBON COUNTY-SIERRA MADRE RANGE-
UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE-LARAMIE VALLEY-
SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS-
CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY-
941 PM MDT WED JUN 9 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA
PANHANDLE...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING.

.DAY ONE...TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP
ACROSS THE REGION THIS EVENING. SOME OF THE STORMS MAY BE STRONG
WITH GUSTY WINDS AND SMALL HAIL. THE SHOWERS AND STORMS WILL
DECREASE IN COVERAGE AND INTENSITY AFTER MIDNIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL AGAIN FORM OVER
SOUTH CENTRAL WYOMING THURSDAY AFTERNOON.

A PACIFIC STORM SYSTEM WILL BRING COOLER TEMPERATURES AND A GOOD
CHANCE OF SHOWERS AND THUNDERSTORMS TO SOUTH CENTRAL WYOMING
FRIDAY THROUGH MONDAY. FLOODING OF MANY RIVERS AND STREAMS FLOWING
FROM THE SNOWY AND SIERRA MADRE RANGES WILL CONTINUE THROUGH THE
WEEKEND. THE ADDITIONAL RAINFALL MAY CAUSE THE RIVERS AND STREAMS
TO RISE EVEN FURTHER.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT.

&&

THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND
CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT...
HTTP://WEATHER.GOV/CHEYENNE

NEZ002-003-019>021-095-096-WYZ101>103-105>108-110345-
DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-NORTH SIOUX-
SOUTH SIOUX-CONVERSE COUNTY LOWER ELEVATIONS-NIOBRARA COUNTY-
NORTH LARAMIE RANGE-SHIRLEY BASIN-
CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY-
EAST PLATTE COUNTY-GOSHEN COUNTY-
941 PM MDT WED JUN 9 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA
PANHANDLE...SOUTH CENTRAL WYOMING.

.DAY ONE...TONIGHT

SEVERE THUNDERSTORM WATCH 289 IS IN EFFECT UNTIL 3 AM THURSDAY.
SCATTERED THUNDERSTORMS WILL CONTINUE TO DEVELOP THIS
EVENING...WITH SOME STORMS BECOMING SEVERE. THE MAIN THREATS WILL
BE LARGE HAIL...DAMAGING WINDS AND VERY HEAVY RAIN. THE SHOWERS
AND STORMS WILL DECREASE IN COVERAGE AND INTENSITY AFTER MIDNIGHT.
PATCHY FOG WILL BE POSSIBLE OVERNIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SCATTERED THUNDERSTORMS WILL AGAIN FORM OVER AND EAST OF THE
LARAMIE RANGE THURSDAY AFTERNOON AND EVENING. SOME OF THE STORMS
WILL BE STRONG TO SEVERE WITH LARGE HAIL AND DAMAGING WINDS
POSSIBLE.

A PACIFIC STORM SYSTEM WILL BRING COOLER TEMPERATURES AND A GOOD
CHANCE OF SHOWERS AND THUNDERSTORMS OVER AND EAST OF THE LARAMIE
RANGE FRIDAY THROUGH MONDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED THIS AFTERNOON AND TONIGHT.
PLEASE RELAY REPORTS OF SEVERE WEATHER TO YOUR NEAREST LAW
ENFORCEMENT OR COUNTY EMERGENCY MANAGEMENT AGENCY.

&&

THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND
CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT...
HTTP://WEATHER.GOV/CHEYENNE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
1204 AM MDT THU JUN 10 2010

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

1204 AM     HAIL             7 NW MORRILL            42.04N 104.02W
06/10/2010  E1.25 INCH       SIOUX              NE   PUBLIC

&&

GCLAYCOM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
1207 AM MDT THU JUN 10 2010

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

1200 AM     HAIL             MORRILL                 41.96N 103.92W
06/10/2010  E1.75 INCH       SCOTTS BLUFF       NE   LAW ENFORCEMENT

&&

HAHN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
1216 AM MDT THU JUN 10 2010

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

1202 AM     TSTM WND GST     CHADRON                 42.83N 103.00W
06/10/2010  E60.00 MPH       DAWES              NE   ASOS

&&

GCLAYCOM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
1231 AM MDT THU JUN 10 2010

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

1228 AM     HAIL             6 NNW MORRILL           42.04N 103.97W
06/10/2010  E1.00 INCH       SIOUX              NE   TRAINED SPOTTER

&&

HAHN

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