Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 240222
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
822 PM MDT SAT AUG 23 2014

.UPDATE...
ISSUED AT 819 PM MDT SAT AUG 23 2014

LATEST RADAR TRENDS SHOWING THAT SHOWERS AND THUNDERSTORMS HAVE
BEEN DECREASING IN COVERAGE. MOST OF THE CWFA IS PPINE CURRENTLY.
UPPER LOW OVER NORTHWESTERN WYOMING CONTINUES TO MOVE
EAST...GIVING OUR AREA A WESTERLY/DOWNSLOPING WIND COMPONENT. WENT
AHEAD AND LOWERED POPS FOR THE OVERNIGHT HOURS. ONLY AREA THAT MAY
SEE SHOWERS TONIGHT WOULD BE CONVERSE/NIOBRARA ZONES AFTER
MIDNIGHT. UPDATES HAVE BEEN SENT.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 320 PM MDT SAT AUG 23 2014

CURRENT KCYS RADAR LOOP SHOWS SCATTERED SHOWERS DEVELOPING NEAR
AND EAST OF THE LARAMIE RANGE EARLY THIS AFTERNOON WITH ISOLATED
THUNDERSTORMS EXTENDING EASTWARD INTO WESTERN NEBRASKA. THERE IS A
SMALL CHANCE THAT ONE OR TWO OF THESE TSTORMS MAY BECOME
STRONG WITH HAIL AND GUSTY WINDS...OTHERWISE...MOST OF THE
TSTORM ACTIVITY WILL BE RATHER WEAK WITH MAINLY HEAVY RAINS IN
SOME GUSTY WINDS. A STRONG SURFACE COLD FRONT FOR THIS TIME OF
THE YEAR IS CURRENTLY STALLED ACROSS SOUTHEAST WYOMING...WITH
MAYBE A SLIGHT NUDGE EASTWARD FROM LATE THIS MORNING. 2 PM
TEMPERATURES HAVE LOWERED INTO THE 40S ACROSS CARBON COUNTY...IN
LATE AUGUST...WITH 70S AND AROUND 80 FURTHER TO THE EAST ACROSS
THE HIGH PLAINS OF SOUTHEAST WYOMING. THIS FRONT WILL SLOWLY MOVE
EASTWARD ACROSS THE AREA INTO TONIGHT. OVERNIGHT LOWS WILL BE
CHILLY...WITH READINGS GENERALLY IN THE 40S TO LOW 50S ACROSS THE
EAST PLAINS. SOME OF THE MORE SHELTERED VALLEYS WEST OF THE
LARAMIE RANGE MAY DROP INTO THE MID 30S BY SUNDAY MORNING. DO NOT
EXPECT ANY FOG TONIGHT DUE TO COLD AIR ADVECTION.

SUNDAY WILL LIKELY BE OUR ONLY QUIET DRY DAY IN THE NEAR FUTURE AS
THE UPPER LEVEL LOW LIFTS NORTHEAST OVER EASTERN MONTANA. DRY
WESTERLY FLOW WILL DEVELOP AT ALL LEVELS AS THE NEXT DEEP UPPER
LEVEL TROUGH DIGS SOUTH OUT OF WESTERN CANADA. IT WILL BE ON THE
COOL SIDE AND BREEZY...WITH WEST TO SOUTHWEST WINDS BETWEEN 15 TO
25 MPH AND GUSTS UP TO 40 MPH IN THE AFTERNOON ACROSS SOUTHEAST
WYOMING. HIGH TEMPERATURES WILL STRUGGLE TO REACH THE MID 70S
ACROSS SOUTHEAST WYOMING WITH MOST LOCATIONS NEAR AND WEST OF THE
LARAMIE RANGE IN THE UPPER 60S TO LOW 70S. BY SUNDAY
EVENING...MODELS INDICATE FRONTOGENESIS STARTING TO DEVELOP AS THE
UPPER LEVEL FLOW BECOMES MORE SOUTHERLY. PW/S BELOW ONE HALF INCH
WILL QUICKLY BE REPLACED BY DEWPOINTS CLIMBING INTO THE MID TO
UPPER 40S AND PW/S AROUND 1.00 INCH AS A STATIONARY FRONT DEVELOPS
ACROSS SOUTH CENTRAL WYOMING. THIS WILL RESULT IN SHOWERS AND EVEN
SOME NOCTURNAL THUNDERSTORMS THROUGH MIDNIGHT SUNDAY
NIGHT...MAINLY ACROSS THE SOUTHERN ZONES SOUTH OF THE PLATTE RIVER
VALLEY.

THE UPPER LEVEL TROUGH WILL DIG SOUTH INTO THE GREAT BASIN ON
MONDAY AND THEN GRADUALLY START MOVING EASTWARD LATER IN THE DAY.
WITH DECENT LOW TO MIDLEVEL INSTABILITY...MOISTURE ADVECTION...AND
CAPE OVER 1000 J/KG...EXPECT AFTERNOON SHOWERS AND TSTORMS TO
DEVELOP ACROSS MOST OF THE AREA. DUE TO THE CLOUD COVER...DAYTIME
TEMPERATURES IN THE 70S TO LOW 80 ARE EXPECTED. A FEW OF THE
THUNDERSTORMS MAY BECOME STRONG WITH STRONG GUSTY WINDS AND HAIL
POSSIBLE DUE TO 35 TO 45 KNOTS OF 0-6KM SHEAR.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED 3 PM MDT SAT AUG 23 2014

GFS AND ECMWF MODELS CONTINUE TO HAVE DIFFERING SOLUTIONS WITH
REGARD TO THE NEXT UPPER SYSTEM DROPPING DOWN THE PACIFIC NORTHWEST
INTO OUR AREA MIDWEEK. THE GFS IS MORE OPEN AND PROGRESSIVE WITH
THE UPPER TROUGH TAKING IT EAST OF OUR AREA BY LATE
WEDNESDAY...WHEREAS THE ECMWF IS STILL MUCH SLOWER AND MORE CLOSED
WITH THE UPPER SYSTEM AS IT MOVES SLOWLY EAST ACROSS SOUTHERN
WYOMING ON THURSDAY. BOTH MODELS SHOW A DECENT AMOUNT OF DEEP
LAYERED MOISTURE ON THE EAST SIDE OF THE UPPER TROUGH TUESDAY INTO
WEDNESDAY WHEN WE EXPECT TO SEE SCATTERED SHOWERS AND
THUNDERSTORMS...AND THEN DIVERGE WITH THE GFS DRYING OUT THE
MIDLEVELS QUICKLY ON THURSDAY. FOR NOW WE PUT SOME LOW POPS IN FOR
THE HIGHER ELEVATIONS ON THURSDAY FOR ISOLATED SHOWERS AND
THUNDERSTORMS...AND THAT MAY HAVE TO BE BUMPED UP ACROSS THE
REGION SHOULD THE GFS START TRENDING TOWARDS THE ECMWF. RELATIVELY
COOLER TEMPERATURES EXPECTED EARLY TO MID WEEK AS THE UPPER SYSTEM
MOVES ACROSS...THEN WE SHOULD SEE A BIT OF A WARM-UP BY LATE WEEK
AS RIDGING WORKS IN FROM THE WEST.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY AFTERNOON)
ISSUED AT 546 PM MDT SAT AUG 23 2014

MAINLY VFR CONDITIONS THROUGH THE TAF PERIOD. SCATTERED SHOWERS
AND A FEW THUNDERSTORMS WILL CONTINUE THROUGH MUCH OF THE EVENING
OVER THE NEBRASKA PANHANDLE. SNY WILL HAVE THE BEST SHOT AT BRIEF
HEAVY RAIN AND BRIEF IFR VIS ALONG WITH GUSTY WINDS. WEST-TO-
SOUTHWEST WINDS WILL OCCASIONALLY GUST TO 25 MPH IN SOUTHEAST WY
THROUGH AROUND 03Z.


&&

.FIRE WEATHER...
ISSUED AT 210 PM MDT SAT AUG 23 2014

NO FIRE WEATHER CONCERNS OVER THE NEXT 7 DAYS DUE TO THE UNSETTLED
WEATHER PATTERN OVER THE AREA WELL INTO NEXT WEEK...WITH THE ONLY
DRY DAY BEING ON SUNDAY. MINIMUM RELATIVE HUMIDITIES WILL LOWER
INTO THE 20 TO 35 PERCENT RANGE ALONG WITH EXCELLENT RECOVERIES
OVERNIGHT THROUGH THE MIDDLE OF NEXT WEEK. HIGH TEMPERATURES WILL
GENERALLY RANGE FROM THE LOW 70S TO LOW 80S THROUGH THE PERIOD.

&&

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

$$

UPDATE...CLAYCOMB
SHORT TERM...TJT
LONG TERM...GARMON
AVIATION...FINCH
FIRE WEATHER...TJT





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