Special Weather Statement, NWS Cheyenne, WY

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
1229 PM MDT WED JUL 15 2015

.UPDATE...FOR THE NOON AVIATION FORECAST PACKAGE RELEASE.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 428 AM MDT WED JUL 15 2015

A FEW SHOWERS AND T-STORMS CONTINUE TO REDEVELOP EARLY THIS
MORNING OVER OUR FAR NORTHERN COUNTIES IN THE AREA OF HIGHEST
ELEVATED INSTABILITY AS A VORT MAX MOVES NORTHEAST ACROSS THE
FORECAST AREA. SOME OF THIS ACTIVITY IS LIKELY ALSO BEING
SUPPORTED BY A NUMBER OF OUTFLOW BOUNDARIES MOVING SOUTH FROM THE
CONVECTION IN NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA. IN
ADDITION...LIGHT RAIN SHOWERS CONTINUE TO MOVE WESTWARD BACK INTO
THE EASTERN PANHANDLE COUNTIES WITHIN WRAPAROUND MOISTURE
ASSOCIATED WITH THE VORT MAX. EXPECT THIS ACTIVITY TO CONTINUE
OVER THE NEXT FEW HOURS...DIMINISHING THRU THE LATER MORNING AS
THE WAVE STEADILY SHIFTS NORTHEAST.

MONSOONAL FLOW WILL REMAIN OVERHEAD TODAY SO ANTICIPATE ANOTHER
ROUND OF SHOWERS AND STORMS TO FIRE OVER THE HIGH COUNTRY IN THE
LATE MORNING AND AFTERNOON. LOWERED POPS A BIT ACROSS THE EASTERN
ZONES FOR TODAY AS THIS AREA WILL BE WITHIN AN AREA OF SUBSIDENCE
IN THE WAKE OF THE DEPARTING UPPER WAVE. DO THINK ISOLATED
SHOWERS/STORMS ARE NOT OUT OF THE QUESTION THOUGH ESPECIALLY LATE
IN THE AFTERNOON/EVENING AS CONVECTION THAT FIRES OVER THE
MOUNTAINS COULD CERTAINLY PERSIST INTO THE PLAINS WHERE SBCAPES
ARE PROGGED TO BE 500-1000 J/KG. PW VALUES WILL AGAIN BE AROUND
ONE INCH TODAY SO LOOKING AT MAINLY HEAVY RAIN OUT OF THE STRONGER
STORMS...ALTHO REALLY CAN'T RULE OUT SOME SMALL HAIL WITH THE
HIGHER INSTABILITY IN PLACE.

CONDITIONS SHOULD BEGIN TO DRY OUT ON THURSDAY AS FLOW ALOFT TURNS
A BIT MORE WESTERLY AND THE MONSOONAL PLUME IS PUSHED SOUTH.
CONVECTION WILL LIKELY REMAIN FOCUSED IN THE MOUNTAINS AND NEARBY
LOCATIONS IN THE LATE AFTERNOON AND EVENING...AND TEMPS WILL
INCREASE BACK UP INTO THE 80S-90S/EAST AND 70S-80S/WEST UNDER LESS
CLOUD COVER. THE WEAK SFC FRONT STILL LOOKS TO SAG SOUTH AND STALL
ACROSS OUR NORTHERN COUNTIES FRIDAY MORNING...WHICH COULD SUPPORT
A BETTER COVERAGE FOR SHOWERS/STORMS ESPECIALLY UP NORTH IN THE
AFTERNOON AND EVENING. TRENDED POPS HIGHER TO CONSIDER THIS
STRONGER SFC FORCING BUT NOT TOO HIGH AS THE DRIER AIRMASS WILL
STILL BE OVERHEAD.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 428 AM MDT WED JUL 15 2015

THE MODELS HAVE COME INTO BETTER AGREEMENT AT SHOWING A RATHER DEEP
UPPER LEVEL TROUGH (FOR MID JULY) DIGGING INTO THE INTERMOUNTAIN
WEST BY SAT.  DRY SOUTHWESTERLY FLOW ALOFT WILL BE IN PLACE THROUGH
MUCH OF THE DAY AHEAD OF THE COLD FRONT.  THE FRONT WILL PUSH
THROUGH THE REGION BY SAT NIGHT/SUN MORNING WITH COOLER TEMPS BEHIND
IT.  ISOLATED/SCATTERED SHOWERS WILL LIKELY OCCUR SAT NIGHT RIGHT
BEHIND THE FRONT.  TEMPS WILL BE 10-15 DEGREES COOLER ON SUN IN THE
POST FRONTAL AIRMASS.  CHANCES FOR AFTN STORMS ON SUN WILL BE
CONFINED TO THE SOUTHERN LARAMIE RANGE AND SOUTHWARD INTO COLORADO
ALONG THE STALLING FRONT.  MODEL DIFFERENCES BETWEEN THE GFS AND
ECMWF ARISE BY MON WITH THE ECMWF INDICATING MUCH DRIER WEST TO
NORTHWEST 700-500MB FLOW.  THE GFS INDICATES A WEAK SHORTWAVE MOVING
INTO WESTERN COLORADO THAT WOULD RESULT IN AT LEAST A CHANCE OF
STORMS OVER SOUTHERN AREAS AND MUCH MORE CLOUD COVER.  TEMPS WOULD
BEGIN TO WARM UP BY EARLY NEXT WEEK WITH THE DRIER ECMWF SOLN.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1229 PM MDT WED JUL 15 2015

VFR CATEGORY CONDITIONS PREVAIL AT ALL AIRPORTS THROUGH THE NEXT
24 HOURS WITH SHOWERS/ISOLATED THUNDERSTORMS POPPING UP 20Z-02Z IN
THE VICINITY OF ALL SITES. COVERAGE AND CHANCES NOT HIGH ENOUGH TO
WARRANT A PREVAILING PERIOD FOR SHOWERS/THUNDERSTORMS...BUT WE DID
PUT IN A VCNTY MENTION FOR EVERYONE EXCEPT ALLIANCE AND SIDNEY
WHERE AIRMASS A BIT MORE SUBSIDENCE ON THE BACKSIDE OF A DEPARTING
SHORTWAVE WILL KEEP COVERAGES DOWN EVEN MORE.

&&

.FIRE WEATHER...
ISSUED AT 428 AM MDT WED JUL 15 2015

SHOWERS AND T-STORMS WILL CONTINUE THIS MORNING ACROSS NORTHERN AND
EASTERN PORTIONS OF THE DISTRICT...AND WILL DEVELOP OVER THE
MOUNTAINS LATER THIS AFTERNOON. SOME OF THE STORMS THIS
AFTERNOON AND EVENING MAY PRODUCE LOCALLY HEAVY RAINFALL AND
GUSTY WINDS. DRIER AIR WILL MOVE OVERHEAD FOR THURSDAY AND FRIDAY
AND WILL REDUCE THE OVERALL CHANCE FOR SHOWERS AND THUNDERSTORMS.
TEMPERATURES WILL BE ON THE INCREASE WITH HUMIDITIES DROPPING
INTO THE UPPER TEENS TO LOW 20S BOTH DAYS. THERE ARE INDICATIONS
THAT THE MONSOON MOISTURE MAY RETURN THIS WEEKEND WITH A SLIGHT
INCREASE IN SHOWER/STORM CHANCES AT THAT TIME.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

SHORT TERM...RJM
LONG TERM...ZF
AVIATION...JG
FIRE WEATHER...RJM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
1023 AM MDT WED JUL 15 2015

WYZ101>119-161200-
CONVERSE COUNTY LOWER ELEVATIONS-NIOBRARA COUNTY-
NORTH LARAMIE RANGE-FERRIS/SEMINOE/SHIRLEY MOUNTAINS-
SHIRLEY BASIN-CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY-
EAST PLATTE COUNTY-GOSHEN COUNTY-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-
1023 AM MDT WED JUL 15 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL
WYOMING...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING.

.DAY ONE...TODAY AND TONIGHT

SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL DEVELOP EARLY THIS
AFTERNOON ACROSS PARTS OF SOUTHEAST WYOMING AND PERSIST INTO THE
EARLY EVENING. NO SEVERE STORMS ARE EXPECTED.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ISOLATED THUNDERSTORMS WILL BE POSSIBLE THURSDAY THROUGH SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE REQUIRED THROUGH TONIGHT.

NEZ002-003-019>021-054-055-095-096-161200-
DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE-
NORTH SIOUX-SOUTH SIOUX-
1023 AM MDT WED JUL 15 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WESTERN
NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

ISOLATED TO SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL DEVELOP
BY LATE THIS AFTERNOON AND PERSIST THROUGH THE EVENING. NO SEVERE
STORMS ARE EXPECTED.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE REQUIRED THROUGH TONIGHT.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
217 PM MDT WED JUL 15 2015

NEZ002-003-152100-
DAWES NE-BOX BUTTE NE-
217 PM MDT WED JUL 15 2015

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN BOX BUTTE AND
SOUTHEASTERN DAWES COUNTIES UNTIL 300 PM MDT...

AT 216 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 8
MILES EAST OF BOX BUTTE DAM...OR 20 MILES SOUTHWEST OF HAY SPRINGS...
MOVING NORTHWEST AT 15 MPH.

DIME SIZE HAIL AND WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE WITH THIS
STORM.

LOCATIONS IMPACTED INCLUDE...
BOX BUTTE CAMPGROUND AND BOX BUTTE DAM.

LAT...LON 4231 10286 4245 10321 4268 10292 4266 10278
      4260 10277 4245 10277 4244 10275 4243 10275
TIME...MOT...LOC 2016Z 136DEG 14KT 4244 10291

RUBIN

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
221 PM MDT WED JUL 15 2015

WYZ117-118-152100-
SOUTH LARAMIE RANGE FOOTHILLS WY-CENTRAL LARAMIE COUNTY WY-
221 PM MDT WED JUL 15 2015

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL LARAMIE COUNTY
UNTIL 300 PM MDT...

AT 221 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 7
MILES SOUTHEAST OF SOUTH GREELEY...OR 8 MILES SOUTHEAST OF
CHEYENNE...MOVING SOUTHEAST AT 15 MPH.

WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH THIS STORM.

THIS STORM WILL REMAIN OVER MAINLY RURAL AREAS OF SOUTH CENTRAL
LARAMIE COUNTY.

LAT...LON 4109 10472 4109 10447 4107 10448 4100 10452
      4100 10479
TIME...MOT...LOC 2021Z 293DEG 11KT 4104 10469

RUBIN