Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 272040
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
240 PM MDT SAT JUN 27 2015

.SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY)
ISSUED AT 240 PM MDT SAT JUN 27 2015

OUTSIDE OF A FEW MOUNTAIN THUNDER SHOWERS...QUIET AND BENIGN
WEATHER WILL CONTINUE THROUGH TONIGHT. CURRENT WATER VAPOR LOOP
SHOWS THE STRONG UPPER LEVEL HIGH CENTERED OVER SOUTHERN UTAH THIS
AFTERNOON. THIS HIGH WILL DRIFT NORTHWARD OVER THE NEXT 24 HOURS
AND SLIGHTLY WESTWARD. HIGHS WILL REMAIN IN THE 80S WITH MAYBE A
FEW AREAS OVER WESTERN NEBRASKA REACHING 90 SUNDAY AFTERNOON. THE
ONLY MINOR FORECAST CONCERN WILL BE THE POTENTIAL FOR
THUNDERSTORMS CHANCES OVER THE MOUNTAINS AND ADJACENT VALLEYS.
THUNDERSTORM POTENTIAL WILL GREATLY DEPEND ON THE EXACT LOCATION
OF THE UPPER LEVEL HIGH...AS THE MIDLEVEL SUBSIDENCE ASSOCIATED
WITH THE CENTER OF THE HIGH WILL BE TOO GREAT FOR DEEP CONVECTION
TO OVERCOME. WITH THE CENTER OF THE HIGH DRIFTING NORTHWEST ON
SUNDAY...CAN NOT RULE OUT ISOLATED TO WIDELY SCATTERED COVERAGE OF
THUNDERSTORMS IN AND AROUND THE MOUNTAINS...POSSIBLY EXTENDING
TOWARDS THE I25 CORRIDOR. EAST OF I25...MODEL SOUNDINGS SHOW TOO
MUCH CIN OVER THE HIGH PLAINS. KEPT POP BETWEEN 15 TO 30 PERCENT
ALONG AND WEST OF I25.

FOR MONDAY...ALL MODELS SHOW THE CENTER OF THE UPPER LEVEL HIGH
NUDGING EASTWARD...WHICH WILL LOWER TSTORM CHANCES ONCE AGAIN OVER
THE FORECAST AREA. THIS WILL BE SHORT LIVED HOWEVER. FOR
TUESDAY...MODELS INDICATE THE UPPER LEVEL HIGH BEGINNING TO
FLATTEN AND DRIFT SOUTH AS SHORTWAVE ENERGY BEGINS TO PUSH INTO
THE PACIFIC NORTHWEST. CHANCES FOR SHOWERS AND TSTORMS WILL
INCREASE IN THE AFTERNOON FOR MOST OF SOUTHEAST WYOMING AND
NORTHWEST NEBRASKA. 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.

.LONG TERM...(TUESDAY NIGHT THROUGH FRIDAY)
ISSUED AT 220 PM MDT SAT JUN 27 2015

TODAYS MODEL RUNS CONTINUE TO DEPICT THE LARGE WESTERN HIGH
PRESSURE RIDGE TO FLATTEN A BIT ON THE NORTHEAST SIDE AS A SERIES
OF SHORTWAVES MOVES SOUTHEAST ACROSS WYOMING AND WESTERN
NEBRASKA...WHILE SLOWLY RETROGRADING THE CENTER OF THE RIDGE BACK
TOWARDS THE WEST COAST. THIS MEANS WE WILL PROBABLY SEE A MORE
ACTIVE NORTHWESTERLY FLOW PATTERN CONDUCIVE FOR AN INCREASE IN
DAILY SHOWER AND THUNDERSTORM ACTIVITY WEDNESDAY THROUGH EARLY
NEXT WEEKEND. AS FOR WHICH DAYS LOOK TO BE THE MOST ACTIVE...THE
GFS AND THE ECMWF CONTINUE TO ADVERTISE A STRONGER PIECE OF UPPER
LEVEL ENERGY DRIVING SOUTHEAST ACROSS NORTHERN WYOMING AND SOUTH
DAKOTA ON WEDNESDAY (WHERE WE COULD SEE STORMS FORMING TO OUR
NORTH THEN PUSH SOUTHEAST ACROSS OUR REGION)...THEN A BROADER
SERIES OF SHORTWAVES MOVE SOUTHEAST ACROSS WYOMING AND NEBRASKA
FRIDAY INTO EARLY SATURDAY AND INTERACT WITH A STALLED SURFACE
BOUNDARY ALONG THE FRONT RANGE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1119 AM MDT SAT JUN 27 2015

NO CHANGES FOR THIS FORECAST CYCLE. STILL EXPECTING VFR ALL SITES
THROUGH SUNDAY MORNING WITH SCATTERED CUMULUS ACROSS THE AREA
TODAY WITH SHALLOW MOISTURE.

&&

.FIRE WEATHER...
ISSUED AT 300 PM MDT SAT JUN 27 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 THIS WEEKEND. THUNDERSTORM AND WETTING
RAINFALL CHANCES GRADUALLY INCREASE TUESDAY THROUGH FRIDAY ACROSS
THE REGION.

&&

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

$$

SHORT TERM...TJT
LONG TERM...JG
AVIATION...JG
FIRE WEATHER...TJT



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