Special Weather Statement, NWS Cheyenne, WY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1157 AM MDT WED AUG 6 2014

.SHORT TERM...(TODAY AND THROUGH FRIDAY)
ISSUED AT 418 AM MDT WED AUG 6 2014

SUBTROPICAL MOISTURE CONTINUES TO SPREAD ACROSS THE CWA THIS AM
AHEAD OF A WEAK UPPER LOW OVER CENTRAL CA. VERY MOIST LLVL AIR
MASS IS IN PLACE OVER EASTERN ZONES AS OF 09Z WITH SFC DEWPOINTS
AROUND 65F AT CDR. LOW CLOUDS AND PATCHY FOG WILL MOST LIKELY
PERSIST HERE THROUGH MUCH OF THE MORNING AS FCST SOUNDINGS SHOW
LITTLE IMPROVEMENT IN LLVL MOISTURE PROGS ACROSS EAST CENTRAL WY
AND THE NORTHERN PANHANDLE. LATEST KCYS RADAR LOOP IS FREE OF ANY
SHOWER ACTIVITY. ISOLATED SHOWERS STILL POSSIBLE THOUGH WITH AMPLE
MOISTURE AND WEAK DISTURBANCES PRESENT ALOFT. GFS AND NAM AGREE
THAT FLOW ALOFT WILL STRENGTHEN BY EARLY TO MID AFTN WITH H5 FLOW
APPROACHING 25 TO 30 KTS ACROSS MUCH OF THE AREA. UPPER DIFFLUENCE
INCREASES CONSIDERABLY OVER THE CWA IN THE LEFT EXIT OF A MODEST
70 KT H25 JET. THIS WILL ENHANCE A WEAK FRONT DRAPED FROM NW TO SE
ACROSS THE AREA. IT WILL BE ALONG AND NORTH OF THIS BOUNDARY WHERE
CONVECTIVE COVERAGE WILL BE HIGHEST TODAY IN THE DEEPER MOISTURE /
HIGHER 700-300 MILLIBAR RH PROGS. MIDLVL DRYING ON WATER VAPOR
COULD LIMIT COVERAGE A BIT OVER SOUTHERN ZONES IF IT SPREADS NORTH
FROM CO. NOT RULING OUT A FEW STRONG TO LOCALLY SEVERE STORMS OVER
THE PLAINS TODAY. WE DID HAVE SOME IMPRESSIVE UPDRAFTS ON TUE AND
INSTABILITY WILL BE SIMILAR WITH SBCAPE AROUND 1500 J/KG EAST. GFS
AND NAM DIFFER CONSIDERABLY WITH JUST HOW QUICKLY THE BETTER JET
ENERGY MOVES IN...BUT SOME STORM ORGANIZATION POSSIBLE AS FLOW
ALOFT IMPROVES. ADDED HEAVY RAIN AND SMALL HAIL TO THE GRIDS WITH
FCST PWATS WELL OVER AN INCH ALONG AND NORTH OF A DGW TO IBM LINE.

TRICKY FCST FOR THU AND FRI IN THIS TYPE OF PATTERN. BROAD UPPER
RIDGING GENERALLY GIVES WAY TO ACTIVE QUASI-ZONAL FLOW ALOFT OVER
THE CWA. PCPN CHANCES WILL BE GOVERNED BY INDIVIDUAL SHORTWAVE
DISTURBANCES / SOME MORE PRONOUNCED THAN OTHERS / TRAVERSING THE
FLOW. MAIN WAVE CURRENTLY OVER SOUTHERN CA IS PROGGED TO LIFT EAST
AND NORTHEAST INTO SOUTHERN WY ON FRI. MODELS ARE IN EXCELLENT
AGREEMENT WITH MULTIPLE SHOTS OF MONSOONAL MOISTURE DURING THIS
TIME FRAME...SO FELT COMFORTABLE MAINTAINING ISOLATED TO WIDELY
SCATTERED POPS THROUGH THE END OF THE WEEK FOR MOST AREAS. ANOTHER
ROUND OF LOW CLOUDS POSSIBLE FOR THE PANHANDLE ON THU AM WITH
DECENT LLVL MOISTURE ON GFS AND NAM BUFKIT SOUNDINGS. TEMPERATURES
WILL MOST LIKELY BE NEAR TO MAYBE A BIT BELOW SEASONAL NORMS. TEND
TO BELIEVE OBSERVED VALUES WILL BE SKEWED TOWARD THE LOWER END OF
THE MOS SPECTRUM WITH LOTS OF CLOUDS AND PCPN EACH DAY DURING PEAK
HEATING. H7 TEMPS AROUND 10C WILL LIMIT HIGHS TO THE MID 80S FOR
AREAS THAT ARE LUCKY ENOUGH TO SEE SOME SUNSHINE.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 418 AM MDT WED AUG 6 2014

MESSY FORECAST THROUGH THE EXTENDED PERIOD. WILL START OUT WEDNESDAY
NIGHT WITH A WEAK RIDGE OVER THE FORECAST AREA AND A SHORTWAVE OVER
OVER IDAHO. TROPICAL MOISTURE AND SUBTLE WEAK DISTURBANCES WILL BE
MOVING THROUGH THE MAIN UPPER FLOW WHICH MAKES TIMING PRECIPITATION
AND COVERAGE A BIT TRICKY. RIDGE WILL BREAK DOWN EARLY INTO THE
WEEKEND AS THE SHORTWAVE OVER IDAHO VERY SLOWLY SHIFTS EAST ACROSS
SOUTHEAST WYOMING SATURDAY INTO SUNDAY. SHOWERS AND THUNDERSTORMS
SHOULD DEVELOP EVERY AFTERNOON WITH THE HEATING OF THE DAY.
INTENSITY AND COVERAGE WILL DECREASE EVERY NIGHT BUT GIVEN AN
ABUNDANCE OF MID TO UPPER LEVEL MOISTURE AND A SHORTWAVE IN THE
AREA...AT LEAST A FEW SHOWERS WILL LINGER INTO THE OVERNIGHT. SEVERE
WEATHER THREAT WILL BE ON THE LOW END BUT NOT OUT OF THE QUESTION.
SATURDAY AFTERNOON LOOKS TO HAVE THE GREATEST POTENTIAL FOR SEVERE
STORMS INTO THE NEBRASKA PANHANDLE GIVEN LOW LEVEL MOISTURE AND CAPE
VALUES POTENTIALLY REACHING 2500 J/KG BUT SHEAR MAY NOT BE ENOUGH TO
SUSTAIN UPDRAFTS FOR ANY PERIOD OF TIME. OVERALL CONFIDENCE IS NOT
HIGH UNDER THE CURRENT FLOW PATTERN.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING)
ISSUED AT 1148 AM MDT WED AUG 6 2014

SCATTERED SHOWERS AND TSTMS WILL DEVELOP ACROSS SOUTHEAST WY OVER
THE NEXT FEW HOURS AND THEN PROGRESS EASTWARD INTO THE NEBRASKA
PANHANDLE THROUGH THE EARLY EVENING. MAIN THREAT FROM THE STORMS
WILL BE BRIEF GUSTY AND ERRATIC WINDS.  KEPT MVFR CIGS AT CDR
THROUGH THE EARLY AFTERNOON. IFR CONDITIONS COULD DEVELOP ACROSS
THE NORTHERN NEBRASKA PANHANDLE AFTER 09Z THURS.

&&

.FIRE WEATHER...
ISSUED AT 418 AM MDT WED AUG 6 2014

MONSOON MOISTURE AND ACTIVE FLOW ALOFT WILL CONTINUE TO SUPPORT
ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THE
REST OF THE WEEK. THE WET WEATHER PATTERN WILL KEEP HUMIDITY VALUES
ABOVE CRITICAL THRESHOLDS EACH AFTERNOON. THIS COMBINED WITH LIGHT
WINDS WILL KEEP FIRE WEATHER CONCERNS LOW.

&&

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

SHORT TERM...HAMMER
LONG TERM...SML
AVIATION...FINCH
FIRE WEATHER...HAMMER

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
1032 AM MDT WED AUG 6 2014

WYZ103>106-109>118-071130-
NORTH LARAMIE RANGE-FERRIS/SEMINOE/SHIRLEY MOUNTAINS-
SHIRLEY BASIN-CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE 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-
1032 AM MDT WED AUG 6 2014

THIS HAZARDOUS WEATHER OUTLOOK IS PORTIONS OF SOUTHEAST WYOMING.

.DAY ONE...TODAY AND TONIGHT

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER
SOUTHEAST AND SOUTH CENTRAL WYOMING BY THIS AFTERNOON. SEVERE
THUNDERSTORMS ARE NOT EXPECTED BUT A FEW STRONGER THUNDERSTORMS
ARE POSSIBLE.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ISOLATED TO SCATTERED AFTERNOON THUNDERSTORMS WILL AGAIN DEVELOP
ACROSS SOUTHEAST WYOMING THURSDAY...FRIDAY...AND SATURDAY. SEVERE
THUNDERSTORMS ARE NOT EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION SHOULD 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-WYZ101-102-107-108-119-071130-
DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE-
NORTH SIOUX-SOUTH SIOUX-CONVERSE COUNTY LOWER ELEVATIONS-
NIOBRARA COUNTY-EAST PLATTE COUNTY-GOSHEN COUNTY-
EAST LARAMIE COUNTY-
1032 AM MDT WED AUG 6 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE
AND PORTIONS OF SOUTHEAST WYOMING.

.DAY ONE...TODAY AND TONIGHT

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER
FAR SOUTHEAST WYOMING...AND THE WESTERN NEBRASKA PANHANDLE THIS
AFTERNOON. EAST OF INTERSTATE 25...SOME STRONGER THUNDERSTORMS
WILL PRODUCE SMALL HAIL...GUSTY WINDS...AND BRIEF HEAVY RAIN. A
FEW STORMS COULD BECOME SEVERE BUT THE OVERALL SEVERE THREAT IS
LOW.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ISOLATED TO SCATTERED AFTERNOON THUNDERSTORMS WILL AGAIN DEVELOP
ACROSS SOUTHEAST WYOMING THURSDAY...FRIDAY...AND SATURDAY. STRONG
THUNDERSTORMS WITH GUSTY WINDS...SMALL HAIL...HEAVY RAIN WILL BE
POSSIBLE EACH DAY WITH A SMALL THREAT FOR SEVERE THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

&&

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
218 PM MDT WED AUG 6 2014

NEZ003-062100-
BOX BUTTE NE-
218 PM MDT WED AUG 6 2014

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN BOX BUTTE COUNTY UNTIL
300 PM MDT...

AT 215 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 8 MILES NORTH OF KILPATRICK LAKE...OR 22 MILES
WEST OF ALLIANCE...MOVING EAST AT 25 MPH.

HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT
DANGEROUS LIGHTNING.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
  BEREA...

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 4227 10285 4200 10289 4216 10343 4231 10337
TIME...MOT...LOC 2017Z 285DEG 20KT 4220 10328

/02