Special Weather Statement, NWS Cheyenne, WY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1105 AM MDT SUN JUN 8 2014

.UPDATE...
ISSUED AT 749 AM MDT SUN JUN 8 2014

WENT AHEAD AND CANCELLED THE DENSE FOG ADVISORY A LITTLE EARLY
THIS MORNING AS LATEST WYDOT WEBCAMS ARE SHOWING PRETTY GOOD
VISIBILITIES ACROSS THE I-80 SUMMIT AND AROUND CHEYENNE. UPDATES
HAVE BEEN SENT.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY NIGHT)
ISSUED AT 400 AM MDT SUN JUN 8 2014

MOIST SOUTH TO SOUTHEASTERLY UPSLOPE HAS CAUSED LOW CLOUDS TO
DEVELOP OVER MUCH OF THE PLAINS ONCE AGAIN. WEBCAMS SHOW DENSE FOG
ALONG INTERSTATE 8O FROM CHEYENNE TO THE SUMMIT AND WITH THE
UPSLOPE SOUTHERLY WINDS CONTINUING ALONG THE CHEYENNE RIDGE THROUGH
AT LEAST MID-MORNING...WOULD EXPECT THIS TO CONTINUE. ISSUED A
DENSE FOG ADVISORY THROUGH 15Z FOR THE SOUTHERN LARAMIE RANGE AND
ADJACENT FOOTHILL ZONE. WILL HAVE TO MONITOR CENTRAL LARAMIE
COUNTY SINCE VIS AT CYS HAS DROPPED TO A QUARTER MILE. SHORTWAVE
SHOWS UP ON WATER VAPOR IMAGERY ACROSS EASTERN IDAHO AND WESTERN
WY. GOOD ISENTROPIC ASCENT AHEAD OF THIS FEATURE IS CAUSING SOME
SHOWERS AND ISOLATED TSTMS TO DEVELOP OVER PORTIONS OF
CONVERSE/NIOBRARA COUNTIES AND THE NORTHERN NEBRASKA PANHANDLE.
THE COLDEST CLOUD TOPS ARE MAINLY NORTH OF THE CWA HOWEVER INTO
CAMPBELL AND WESTON COUNTIES. THE HRRR MODEL SHOWS WIDESPREAD
IFR/LIFR CONDITIONS ACROSS THE PLAINS THROUGH AT LEAST 16Z. COLD
FRONT ASSOCIATED WITH THE SHORTWAVE WILL HAVE MOVED ACROSS THE
NORTHWESTERN COUNTIES BY 18Z AND THEN THROUGH THE REST OF THE CWA
BY 00Z. WILL HAVE TO SEE HOW MUCH SFC HEATING AND INSTABILITY
THERE IS BY EARLY AFTN OVER THE SOUTHERN PANHANDLE AS THIS SEEMS
LIKE THE MOST FAVORABLE AREA FOR SCATTERED TSTMS TO DEVELOP. TSTM
POTENTIAL REALLY DROPS OFF AFTER AROUND 21Z BEHIND THE FROPA.  THE
COMBINATION OF SFC CONVERGENCE ALONG THE FRONT AND INCREASING
LARGE SCALE ASCENT WILL CAUSE WIDESPREAD RAIN OVER THE PLAINS AND
ESPECIALLY THE PANHANDLE BY THIS AFTN THAT WILL PERSIST INTO THE
EVENING.

SUBSIDENCE BEHIND THE UPPER LEVEL WAVE WILL CAUSE PRECIP TO
RAPIDLY SHUT OFF BY LATE EVENING. IT WILL BE A QUITE COOL NIGHT
UPCOMING AS THE SFC HIGH IS LOCATED OVER SOUTHEAST WY. GUIDANCE
HAS LOWS IN LARAMIE AROUND FREEZING SO DAY SHIFT MAY WANT TO
CONSIDER A FROST ADVISORY IN THE LARAMIE VALLEY AS RADIATIONAL
COOLING WILL BE EXCELLENT BY LATE TONIGHT. A MUCH DRIER AIRMASS IS
STILL PROGGED OVER THE REGION BY MON AND INTO TUES WITH PW VALUES
DROPPING TO BELOW 0.5 INCHES. PRECIP CHANCES WILL BE SLIM AND DONT
REALLY HAVE ANY SLIGHT CHANCE POPS THRU TUES. MAY EVEN HAVE
TROUBLE GETTING MUCH CUMULUS ON MON (LI VALUES ARE ABOVE 3C).
WHILE TEMPS WILL WARM SLIGHTLY ON MON...THE BIGGER WARMUP IS NOT
UNTIL TUES WHEN 700MB TEMPS RISE TO AROUND 14C. THIS TRANSLATES
INTO A 20-25 DEGREE WARMUP COMPARED TO THIS WEEKENDS COOL TEMPS.

.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 400 AM MDT SUN JUN 8 2014

AN UPPER LEVEL SHORTWAVE WILL MOVE INTO THE NORTHERN PLAINS ON
WEDNESDAY WITH AN ASSOCIATED COLD FRONT BEGINNING TO DROP SOUTH
ACROSS THE EASTERN PLAINS OF WYOMING AND THE NEBRASKA PANHANDLE IN
THE LATE MORNING. WESTERLY SFC FLOW AHEAD OF THE FRONT WILL KEEP
THE LLVLS SOMEWHAT DRY SO CONVECTIVE INHIBITION MAY BE TOO STRONG
FOR DEEP CONVECTION TO FIRE ALONG THE FRONT. AS THE BETTER UPPER
FORCING MOVES OVERHEAD IN THE AFTERNOON...LOOKING AT A HIGHER
CHANCE FOR ISOLATED ELEVATED STORMS IN THE POST FRONTAL
ENVIRONMENT. HEIGHTS WILL RISE OVERHEAD ON THURSDAY AS AN UPPER
LOW DIGS INTO THE PAC NW. THE THERMAL RIDGE WILL BE SITUATED OVER
THE GREAT BASIN JUST TO THE WEST OF THE RIDGE AXIS...SO TEMPS WILL
BE WARMER OUT WEST AND SLIGHTLY COOLER IN THE EAST WITHIN THE POST
FRONTAL AIRMASS. SOUTH-SOUTHEASTERLY UPSLOPE FLOW WILL ADVECT
HIGHER DEW POINTS TO THE LEE OF THE LARAMIE RANGE...SO EXPECT A
BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AND
EVENING WITHIN THE ZONE OF STRONGEST UPSLOPE FORCING AND HIGHER
LLVL MOISTURE.

THE UPPER LOW WILL MOVE OVER THE NORTHERN ROCKIES ON FRIDAY WITH
LEESIDE CYCLOGENESIS OCCURRING OVER EASTERN WY/MT. THE THERMAL
RIDGE WILL MOVE OVERHEAD THROUGH THIS TIME SO LOOKING AT SFC
TEMPS INCREASING INTO THE UPPER 70S TO UPPER 80S WITH 700 MB TEMPS
CLIMBING TO 12-14C. EVEN WITH STRONG CONVERGENCE WITHIN THE
LEESIDE TROUGH AS THE SFC LOW DEVELOPS...AND CONTINUED LLVL
MOISTURE ADVECTION EAST OF THE TROUGH AXIS...THE WARMING TEMPS
ALOFT COULD CAP THE ENVIRONMENT ENOUGH TO KEEP THINGS DRY. LEFT IN
A SLIGHT CHANCE FOR T-STORMS IN THE AFTERNOON ACROSS THE EASTERN
PLAINS BUT NOT CONFIDENT WILL SEE MUCH ACTIVITY DEVELOP. THE
PACIFIC FRONT WILL MOVE THROUGH THE FORECAST AREA FRIDAY EVENING
WITH DRY AND COOLER CONDITIONS EXPECTED IN ITS WAKE THROUGH EARLY
SATURDAY. SFC FLOW WILL TURN UPSLOPE IN THE AFTERNOON AS A RESULT
OF HEATING OVER THE MOUNTAINS AND SFC HIGH PRESSURE BUILDING INTO
THE CENTRAL PLAINS. COULD SEE A FEW T-STORMS DEVELOP IN THE LATE
AFTERNOON AND EVENING AS A WEAK UPPER DISTURBANCE APPROACHES FROM
THE WEST...BUT CHANCES WILL BE SLIGHT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY MORNING)
ISSUED AT 1103 AM MDT SUN JUN 8 2014

CHALLENGING AVIATION FORECAST AS A COLD FRONT MOVES THROUGH THE
AREA THIS AFTERNOON. RELIED A LOT ON THE CURRENT HRRR
FORECAST...LIFTING IFR CONDITIONS AS THE FRONT MOVES INTO THE
PANHANDLE EARLY THIS AFTERNOON...THEN COMING BACK DOWN NEAR...OR
SHORTLY AFTER 00Z IN NORTHEAST WIND FLOW BEHIND THE FRONT. WILL
CONTINUE TO MONITOR AS THE AFTERNOON PROGRESSES.

&&

.FIRE WEATHER...
ISSUED AT 400 AM MDT SUN JUN 8 2014

MINIMAL FIRE WEATHER CONCERNS THROUGH EARLY NEXT WEEK.  SCATTERED
SHOWERS WILL DEVELOP ACROSS MUCH OF THE REGION BY LATE THIS MORNING
AND PERSIST THROUGH THE AFTERNOON.  THE BEST CHANCE OF WETTING RAINS
WILL BE TO THE EAST OF THE LARAMIE RANGE.  A DRIER AND SLIGHTLY
WARMER AIRMASS ON MONDAY WILL CAUSE MINIMUM AFTERNOON HUMIDITY
VALUES TO FALL TO AROUND 20-30 PERCENT.  MORE WARMING IS EXPECTED
FOR TUESDAY WHEN HUMIDITY VALUES WILL DROP TO 15-20 PERCENT FOR
AREAS TO THE WEST OF THE LARAMIE RANGE.

&&

.HYDROLOGY...
ISSUED AT 400 AM MDT SUN JUN 8 2014

RIVER FLOODING CONTINUES TO WANE SLOWLY AS MELTING FROM SOURCE SNOW
COVER DIMINISHES.  STAGES ARE EXPECTED TO CONTINUE TO RECEDE ALONG
THE UPPER NORTH PLATTE AND LARAMIE RIVERS THROUGH EARLY NEXT WEEK.
LOCATIONS THAT ARE CURRENTLY SEEING MINOR FLOODING WILL DROP BELOW
FLOOD STAGE BY LATE TUESDAY. THERE IS THE POTENTIAL FOR ISOLATED TO
SCATTERED SHOWERS TO THE WEST OF THE LARAMIE RANGE BY THIS
AFTERNOON...HOWEVER RAINFALL AMOUNTS WILL NOT BE SUBSTANTIAL.

&&

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

UPDATE...CLAYCOMB
SHORT TERM...FINCH
LONG TERM...RJM
AVIATION...CLAYCOMB
FIRE WEATHER...FINCH
HYDROLOGY...FINCH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
1034 AM MDT SUN JUN 8 2014

WYZ101>119-091400-
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-
1034 AM MDT SUN JUN 8 2014

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

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS ACROSS SOUTHEAST
WYOMING THIS AFTERNOON AND EVENING. GUSTY WINDS...SMALL HAIL...AND
BRIEF MODERATE TO HEAVY RAIN MAY ACCOMPANY ANY STRONGER STORMS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS ACROSS SOUTHEAST
WYOMING WEDNESDAY AND THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

&&

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

NEZ002-003-019>021-054-055-095-096-091400-
DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE-
NORTH SIOUX-SOUTH SIOUX-
1034 AM MDT SUN JUN 8 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA
PANHANDLE.

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS ACROSS THE NEBRASKA
PANHANDLE THIS AFTERNOON AND EVENING. GUSTY WINDS...SMALL HAIL...
AND BRIEF MODERATE TO HEAVY RAIN MAY ACCOMPANY ANY STRONGER
STORMS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS ACROSS THE NEBRASKA
PANHANDLE WEDNESDAY AND THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

&&

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
1121 AM MDT SUN JUN 8 2014

WYZ119-081800-
EAST LARAMIE COUNTY WY-
1121 AM MDT SUN JUN 8 2014

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN LARAMIE COUNTY UNTIL
NOON MDT...

AT 1120 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A STRONG THUNDERSTORM NEAR CARPENTER...OR 29 MILES EAST OF
CHEYENNE...MOVING NORTHEAST AT 15 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT
DANGEROUS LIGHTNING.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
  PINE BLUFFS...AND OTHERWISE RURAL AREAS OF SOUTHEASTERN LARAMIE
  COUNTY.

THIS INCLUDES INTERSTATE 80 IN WYOMING BETWEEN MILE MARKERS 395 AND
402.

IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.

TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED
ROADWAY.

&&

LAT...LON 4122 10406 4100 10406 4100 10438 4106 10438
TIME...MOT...LOC 1721Z 235DEG 14KT 4104 10425

HAMMER