Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 290135
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
735 PM MDT SUN JUN 28 2015

.UPDATE...
ISSUED AT 735 PM MDT SUN JUN 28 2015

VIGOROUS THUNDERSTORMS POPPED UP QUICKLY EARLIER THIS AFTERNOON
NEAR THE CO/WY/NE BORDER WITHIN AN SBCAPE BULLSEYE AROUND 2000
J/KG ACCORDING TO MESOANALYSIS. THIS ACTIVITY HAS SINCE PUSHED
WELL SOUTH OF OUR FORECAST AREA AND DROPPED A STRONG COLD POOL
ACROSS THE TRI-STATE AREA SO AM THINKING THAT THIS AREA WILL
REMAIN CLEAR FOR THE EVENING OUTSIDE OF A STRAY SHOWER DEVELOPING
OFF THE BOUNDARY ITSELF. A BROAD AREA OF SHOWERS WITH A FEW
EMBEDDED T-STORMS CONTINUES TO MOVE SOUTHEAST FROM CENTRAL WYOMING
AND SHOULD BRING SOME LIGHT RAIN AND A FEW CLAPS OF THUNDER TO
AREAS ALONG AND WEST OF I-25 THROUGH THE EVENING. ADJUSTED POPS
OVER THIS AREA TO REFLECT A MORE SCATTERED COVERAGE FOR SHOWERS
OVER THE NEXT FEW HOURS...BUT STILL THINK THIS ACTIVITY WILL
DISSIPATE AS THE SUN CONTINUES TO SET. OTHERWISE...THE ONGOING
FORECAST IS IN GOOD SHAPE.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 300 PM MDT SUN JUN 28 2015

CURRENT KCYS RADAR LOOP SHOWS ISOLATED THUNDERSTORMS OVER
SOUTHEAST WYOMING. ALTHOUGH THE UPPER LEVEL HIGH HAS SHIFTED A BIT
WESTWARD TODAY...THERE IS STILL ENOUGH SUBSIDENCE ALOFT TO LIMIT
CONVECTIVE UPDRAFTS. EXPECT MAYBE SOME BRIEF MODERATE TO HEAVY
RAINFALL AND GUSTY WINDS WITH THESE CELLS AS THEY SLOWLY MOVE
SOUTH. FURTHER TO THE EAST...THERE SHOULD BE TOO MUCH CIN JUST
ABOVE THE BOUNDARY LAYER...BUT A STRAY THUNDERSHOWER IS POSSIBLE
NEAR THE NEBRASKA BORDER THIS EVENING. ANY THUNDERSTORMS WILL
GRADUALLY DISSIPATE AROUND SUNSET...BUT RAIN SHOWERS MAY LINGER
TOWARDS MIDNIGHT NEAR THE MOUNTAINS.

FOR MONDAY AND TUESDAY...ALL MODELS SHOW THE CENTER OF THE UPPER
LEVEL HIGH NUDGING EASTWARD...WHICH WILL LOWER TSTORM CHANCES ONCE
AGAIN OVER THE FORECAST AREA DUE TO MIDLEVEL SUBSIDENCE...BUT THIS
WILL BE SHORT LIVED. FOR TUESDAY...ALL MODELS INDICATE THE
NORTHERN PORTION OF THE UPPER LEVEL HIGH BEGINNING TO FLATTEN AND
DRIFT SOUTH AS SHORTWAVE ENERGY PUSHES INTO THE PACIFIC
NORTHWEST. CHANCES FOR SHOWERS AND TSTORMS WILL INCREASE IN THE
AFTERNOON FOR MOST OF SOUTHEAST WYOMING AND NORTHWEST
NEBRASKA...AND MAY LINGER INTO TUESDAY NIGHT AS WELL. TUESDAY
WILL LIKELY BE THE WARMEST DAY OF THE WEEK WITH HIGHS IN THE MID
80S TO MID 90S AFTER A RELATIVELY MILD START TO THE DAY. INCREASED
HIGH TEMPERATURES A FEW DEGREES FOR TUESDAY AFTERNOON...WITH EVEN
THE I25 CORRIDOR AROUND 90 DEGREES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 206 PM MDT SUN JUN 28 2015

WEDNESDAY-WEDNESDAY NIGHT:
LATEST WATER VAPOR LOOP WAS SHOWING A FAIRLY POTENT UPPER LEVEL
TROF DEVELOPING BEHIND THE SHORTWAVE LIFTING NORTH ALONG THE
PACIFIC NORTHWEST. THE MODELS ARE IN PRETTY GOOD AGREEMENT IN
BRINGING THIS SECONDARY TROF THROUGH THE CANADIAN PROVIDENCES OF
BRITISH COLUMBIA AND SASKATCHEWAN ON MONDAY AND TUESDAY AND THEN
DIVES SOUTHEAST THROUGH THE NORTHERN PLAINS WEDNESDAY INTO
THURSDAY. AHEAD OF THIS WAVE...NOT REAL CONFIDENT ON HOW DEEP THE
MOISTURE WILL BE PRIOR TO THE FRONTAL BOUNDARY MOVING THROUGH.
HOWEVER...THE MODELS ARE SHOWING SURFACE DEWPOINTS IN THE LOW TO
MID 50S WHICH MAY BE ENOUGH TO TRIGGER STRONG TO SEVERE STORMS
ESPECIALLY WITH 0-6KM SHEAR VALUES AROUND 35 TO 45KTS. HEAVY
RAINFALL POTENTIAL DOES NOT LOOK TOO FAVORABLE AT THIS POINT DUE
TO LACK OF WARM CLOUD DEPTH AND FAIRLY PROGRESSIVE STORM MOTIONS
AT SPEEDS OF 15 TO 20KTS FROM THE WEST-NORTHWEST. THE FRONTAL
BOUNDARY IS EXPECTED TO SHIFT THROUGH THE AREA WEDNESDAY NIGHT
WHICH SHOULD BRING IN COOLER TEMPERATURES AND SOMEWHAT DRIER
CONDITIONS.

THURSDAY-SUNDAY:
THE UPPER LEVEL RIDGE OVER THE INTERMOUNTAIN WEST IS PROGGED TO
GRADUALLY BUILD BACK OVER THE REGION LATE NEXT WEEK WHICH SHOULD
ALLOW FOR THE DRY AND MILD CONDITIONS TO PERSIST THROUGH THE 4TH
OF JULY. STILL CANNOT RULE OUT AN ISOLATED STORM OR TWO OVER THE
MOUNTAINS. OTHERWISE...THE NEXT WAVE OF CONCERN COULD MOVE INTO

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 542 PM MDT SUN JUN 28 2015

VFR CONDITIONS THROUGH THE TAF PERIOD. ISOLATED THUNDERSTORMS WILL
BE POSSIBLE NEAR CYS THROUGH THE EARLY EVENING. WINDS WILL BE WEAK
AND GENERALLY LESS THAN 10 KTS...EXCEPT NEAR ANY STORMS NEAR THE
COLORADO BORDER.


&&

.FIRE WEATHER...
ISSUED AT 206 PM MDT SUN JUN 28 2015

NO FIRE WEATHER CONCERNS ARE EXPECTED THROUGH MUCH OF NEXT WEEK
FOR AREAS EAST OF THE LARAMIE RANGE AS DAYTIME HUMIDITIES WILL
RANGE BETWEEN 25 AND 40 PERCENT. WEST OF THE LARAMIE RANGE...FIRE
WEATHER CONCERNS WILL BE LOW WITH MAINLY DRY CONDITIONS EXPECTED
OUTSIDE OF THE MOUNTAINS...WHERE AN ISOLATED THUNDERSTORM IS
POSSIBLE EACH AFTERNOON INTO MONDAY. THUNDERSTORM AND WETTING
RAINFALL CHANCES GRADUALLY INCREASE TUESDAY THROUGH THURSDAY
ACROSS THE REGION.

&&

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

$$

UPDATE...RJM
SHORT TERM...TJT
LONG TERM...REC
AVIATION...ZF
FIRE WEATHER...TJT



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