Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 251809 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
1209 PM MDT THU JUN 25 2015

.UPDATE...
ISSUED AT 1201 PM MDT THU JUN 25 2015

MADE A QUICK UPDATE TO BRING POPS UP A BIT OVER NORTHERN CARBON
COUNTY WHERE WE MAU GET SOME ISOALTED STORMS MOVE IN FROM THE
NORTH LATE TODAY. OTHERWISE...MOST OF THE STORMS SHOULD CONTINUE
TO FIRE ALONG AND EAST OF THE LARAMIE RANGE TODAY...AND SOME OF
THOSE STORMS COULD BE SEVERE WITH DAMAGING WIND AND LARGE HAIL
BEING THE PRIMARY THREATS. CURRENT COMPLEX OF STORMS OVER THE
NORTHERN NEBRASKA PANHANDLE HAVE WEAKENED A BIT...HOWEVER AS WE
CONTINUE TO SEE HEATING OVER THE CENTRAL AND SOUTHERN AREAS EAST
OF THE LARAMIE RANGE TODAY...WE EXPECT NUMEROUS STORMS TO FIRE IN
THE MID TO LATE AFTERNOON AND GREATEST THREAT FOR SEVERE STORMS
WOULD BE LATE AFTERNOON INTO THE EARLY EVENING HOURS.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 330 AM MDT THU JUN 25 2015

QUITE A LIGHTNING SHOW ACCORDING TO OUR INFRARED SATELLITE LOOPS
OVERLAID WITH THE LIGHTNING STRIKES OVER NORTHERN CONVERSE AND
NORTHERN NIOBRARA COUNTIES. ISOLATED STRONG TO SEVERE STORMS STILL
ONGOING AT 330 AM MDT OVER AFOREMENTIONED COUNTIES...THOUGH
FORTUNATELY...THEY ARE OVER SPARSELY POPULATED TERRITORY.

BASED ON NARROWING TEMPERATURE AND DEWPOINT SPREADS...WILL SEE
PATCHY FOG THROUGH DAWN OR SHORTLY THEREAFTER ALONG AND EAST OF
INTERSTATE 25.

MAIN CHALLENGE AGAIN TODAY WILL BE AREAL COVERAGE OF THUNDERSTORMS
AND THEIR STRENGTH. THANK YOU TO THE STORM PREDICTION CENTER FOR
THEIR CHAT COORDINATIONS SUGGESTING AN UPGRADE TO ENHANCED RISK FROM
THE CURRENT SLIGHT RISK THIS AFTERNOON AND EVENING EAST OF A DOUGLAS
TO LARAMIE LINE.

WITH SHORTWAVE TROUGH ALOFT MOVING SOUTHEAST ACROSS OUR COUNTIES
NEAR OR SLIGHTLY AFTER MIDDAY...WE EXPECT SCATTERED THUNDERSTORMS TO
ERUPT THIS AFTERNOON IN THE BUOYANT AIRMASS ALONG AND EAST OF
INTERSTATE 25 ALONG THE INSTABILITY AXIS AND LOW AND MID LEVEL THETA-
E RIDGE AXIS...AND AS MENTIONED BY THE STORM PREDICTION CENTER...A
SEVERE MESOSCALE CONVECTIVE SYSTEM...MCS...MAY DEVELOP AND PROPAGATE
SOUTHEASTWARD ACROSS PORTIONS OF OUR PLAINS COUNTIES IN THE LATE
AFTERNOON AND EVENING. WITH PROGGED CAPES OF 2000-3000 J/KG AND 0-6
KM BULK SHEAR VALUES OF 35 TO 50 KNOTS...ISOLATED TO WIDELY
SCATTERED SEVERE STORMS LOOK LIKELY...ESPECIALLY WITH BRISK MID
LEVEL WINDS AND DECENT WIND SHEAR. PRIMARY THREATS WILL BE LARGE
HAIL AND DAMAGING WINDS.

TONIGHT...WITH PASSING SHORTWAVE TROUGH ALOFT AND DECREASING LOW AND
MID LEVEL MOISTURE WITH DRYING IN THE WAKE OF THE SHORTWAVE...WILL
SEE CLOUDS AND SHOWERS AND THUNDERSTORMS ENDING FROM NORTHWEST TO
SOUTHEAST.

FRIDAY...LOW LEVEL NEGATIVE THETA-E ADVECTION WILL ADVECT IN A DRIER
AND MORE STABLE AIRMASS IN THE AFTERNOON...THUS ONLY SOME ISOLATED
THUNDERSTORMS POSSIBLE ACROSS OUR SOUTHERN LARAMIE RANGE NEAR THE
COLORADO STATE LINE...DRY ELSEWHERE.

FRIDAY NIGHT/SATURDAY/SATURDAY NIGHT...MOSTLY DRY AND PLEASANT START
TO THE WEEKEND WITH OUR COUNTIES ON THE EASTERN EDGE OF THE GREAT
BASIN RIDGE ALOFT. LOOKS LIKE LOW AND MID LEVEL MOISTURE WILL BE TOO
SCANT FOR ANYTHING OTHER THAN ISOLATED LATE DAY THUNDERSTORMS OVER
OUR SNOWY AND SIERRA MADRE RANGES.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 330 AM MDT THU JUN 25 2015

LARGE UPPER HIGH WILL RESIDE OVER THE WESTERN CONUS SUNDAY AND
MONDAY WITH A NNW UPPER FLOW OVER THE CWA PROVIDING WARM AND
MAINLY DRY CONDITIONS WITH JUST A BIT OF CONVECTION POSSIBLE
MAINLY OVER THE FAR SRN MTNS. A SHORTWAVE WILL MOVE ONSHORE OVER
THE PACIFIC NW LATE MONDAY AND TRAVERSE THE TOP OF THE UPPER HIGH
MONDAY NIGHT INTO TUESDAY BEFORE TURNING SE OVER THE HIGH PLAINS.
THIS SHOULD BRING SOME INCREASE IN CONVECTIVE ACTIVITY TO THE CWA
LATE TUESDAY. SIMILAR PATTERN EXPECTED FOR WEDS WITH ANOTHER
RIPPLE IN THE FLOW DROPPING SOUTHEAST ACROSS THE REGION ALONG WITH
A MODEST COOL FRONT. TEMPS QUITE WARM MONDAY AND TUESDAY BEFORE
LOWERING TO NEAR SEASONAL AVERAGES FOR WEDS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1201 PM MDT THU JUN 25 2015

MOST OF THE THUNDERSTORM ACTIVITY TODAY SHOULD AFFECT AREAS FROM
CHEYENNE EAST INTO THE NEBRASKA PANHANDLE. LESS COVERAGE FROM
CHEYENNE WEST AND CARRIED A VCTS MID TO LATE AFTENROON IN
CHEYENNE...WITH PREVAILING PERIODS OF THUNDER FOR CHADRON THROUGH
MID AFTERNOON...THEN SOUTH ACROSS THE REMAINDER OF THE NEBRASKA
PANHANDLE TAF SITE MID TO LATE AFTERNOON. MOST FO THE STORMS
SHOULD DIMINISH MID TO LATE EVENING...THEN WITH LIGHT WINDS WE MAY
SEE A PERIOD OF LOW CLOUDS AND FOG TOWARD EARLY MORNING FOR THE
WESTERN NEBRASKA PANHANDLE SITES.

&&

.FIRE WEATHER...
ISSUED AT 330 AM MDT THU JUN 25 2015

MINIMAL CONCERNS THE NEXT FEW DAYS BASED ON PROJECTED HUMIDITIES AND
WINDS REMAINING INSIDE CRITICAL THRESHOLDS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...FLASH FLOOD WATCH UNTIL MIDNIGHT MDT TONIGHT FOR WYZ102.

NE...FLASH FLOOD WATCH UNTIL MIDNIGHT MDT TONIGHT FOR NEZ002-095.

&&

$$

UPDATE...JG
SHORT TERM...RUBIN
LONG TERM...RE
AVIATION...JG
FIRE WEATHER...RUBIN


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