050
FXUS65 KCYS 141624 CCA
AFDCYS
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE CHEYENNE WY
1024 AM MDT FRI AUG 14 2020
UPDATE
ISSUED AT 948 AM MDT FRI AUG 14 2020
COLD FRONT EXTENDED FROM CENTRAL NEBRASKA THROUGH NORTHEAST COLORADO
AND INTO SOUTHEAST WYOMING. GUSTY NORTHERLY WINDS UP TO 30 MPH AND
DEW POINTS IN THE 30S AND 40S PREVAILED BEHIND THE FRONT, WITH GUSTY
WESTERLY WINDS AND DEW POINTS IN THE TEENS AND 20S AHEAD OF IT.
CANCELLED RED FLAG WARNING FOR FIRE WEATHER ZONES 302 AND 310 AS
HUMIDITIES WILL REMAIN ABOVE 15 PERCENT TODAY. UPDATES SENT.
SHORT TERM
(TODAY THROUGH SUNDAY)
ISSUED AT 330 AM MDT FRI AUG 14 2020
CURRENT SURFACE OBS AND IR SATELLITE SHOW A SURFACE COLD FRONT
PUSHING SOUTH ACROSS THE AREA, GENERALLY LOCATED JUST SOUTH OF
CASPER AND EXTENDING EASTWARD TO THE PLATTE/NIOBRARA/GOSHEN COUNTY
BORDERS, BUT NOT QUITE INTO THE NORTHERN NEBRASKA PANHANDLE QUITE
YET. THIS FRONT WILL CONTINUE MOVING SOUTH TOWARDS COLORADO
AROUND SUNRISE WITH WINDS SHIFTING INTO THE NORTH AND INCREASING
MOISTURE WITH SLIGHTLY LOWER TEMPERATURES. EXPECT DAYTIME HIGH
TEMPERATURES TO BE 10 TO 15 DEGREES COOLER TODAY COMPARED TO
THURSDAY AFTERNOON WITH HIGHS GENERALLY IN THE 80S. MAYBE A FEW
AREAS IN THE UPPER 70S WITH MODELS SHOWING 700MB TEMPERATURES
LOWERING TO 6C THIS AFTERNOON ACROSS THE FAR NORTHEAST ZONES NEAR
THE NEBRASKA AND SOUTH DAKOTA BORDERS. ANY PRECIP ASSOCIATED WITH
THIS FRONT WILL BE FURTHER TO THE EAST ACROSS CENTRAL/EASTERN
NEBRASKA WITH DRY CONDITIONS ACROSS EASTERN WYOMING AND WESTERN
NEBRASKA. THERE ARE SOME LOW CLOUDS ASSOCIATED WITH THE COLD
FRONT, AS SHOWN ON THE 10.3-3.9 FOG PRODUCT. DO NOT EXPECT ANY FOG
AT THIS TIME SINCE CEILINGS ARE AROUND 2500 TO 3500 FEET AGL SO
FAR WITH PRETTY DRY CONDITIONS NEAR THE SURFACE.
FOR THE WEEKEND, SURFACE COLD FRONT WILL LINGER ACROSS THE LARAMIE
RANGE AND EVENTUALLY PUSH EAST AS A WARM FRONT AS IT WEAKENS.
SHOULD BE ENOUGH INSTABILITY AND LLVL MOISTURE PRESENT FOR A FEW
THUNDERSTORMS ACROSS THE EASTERN PLAINS, SO KEPT POP AROUND 15
PERCENT ACROSS THE SOUTHERN PANHANDLE AND FAR EASTERN WYOMING.
TEMPERATURES WILL INCREASE FOR SUNDAY AS THE UPPER LEVEL HIGH
BEGINS TO INTENSIFY AND DRIFT NORTH. EXPECT MOST AREAS TO BE DRY
WITH LOW POP DUE TO SUBSIDENCE ASSOCIATED WITH THE UPPER LEVEL HIGH.
HOWEVER, A NATURAL CONVERGENCE BOUNDARY WILL DEVELOP ALONG THE
LARAMIE RANGE DUE TO UPSLOPE RETURN FLOW AT THE SURFACE OVER THE HIGH
PLAINS. CAN NOT COMPLETELY RULE OUT A FEW THUNDERSTORMS IN AND
NEAR THE MOUNTAINS SUNDAY AFTERNOON AND EVENING. ALTHOUGH
HUMIDITIES ACROSS INTERIOR WYOMING WILL BE LOW, WINDS ARE EXPECTED
TO DECREASE DUE TO THE PROXIMITY OF THE UPPER LEVEL HIGH WITH
LIGHT AND VARIABLE WINDS ALOFT.
LONG TERM
(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 258 AM MDT FRI AUG 14 2020
MAIN FORECAST CONCERN NEXT WEEK WILL BE FIRE WEATHER AND THE
COVERAGE OF THUNDERSTORM ACTIVITY POSSIBLY RETURNING TO THE REGION
ON THE PERIPHERY OF THE STRONG UPPER LEVEL HIGH FORECAST TO DRIFT
NORTH INTO UTAH/COLORADO/AND SW WYOMING. MODELS IN GOOD AGREEMENT,
SHOWING A 600DM UPPER LEVEL HIGH DRIFTING NORTH AND BECOMING
STATIONARY NEAR THE WYOMING BORDER, AND MAINLY CENTERED NORTHWEST
OF THE FOUR CORNERS REGION. VERY WARM AND DRY CONDITIONS ARE
EXPECTED ACROSS CENTRAL WYOMING, INCLUDING THE RAWLINS AREA.
FURTHER EAST, LOW LEVEL MOISTURE WILL BECOME MORE ABUNDANT DUE TO
UPSLOPE FLOW ACROSS THE PLAINS. ANY DAYTIME CONVECTION WILL
GREATLY DEPEND ON THE POSITION OF THE HIGH ALONG WITH ANY
SHORTWAVE ACTIVITY DIGGING SOUTHEAST ON THE NORTHWEST PERIPHERY
OF THE HIGH. FOR NOW, KEPT POP AROUND 10 TO 20 PERCENT DUE TO LOW
CONFIDENCE. THE GFS IS HINTING AT SUBTROPICAL MONSOON MOISTURE
LIFTING NORTH ON THE WESTERN FRINGE OF THE HIGH AND THEN ADVECTING
INTO THE FORECAST AREA FROM THE NORTHWEST BY LATE IN THE WEEK FOR
A HIGHER COVERAGE OF THUNDERSTORMS AND RAINFALL. HOWEVER, THE
OTHER MODELS ARE MAINLY SHOWING DRY CONDITIONS WITH FEW OR
ISOLATED COVERAGE OF THUNDER AT BEST. THEREFORE, KEPT POP BELOW 20
PERCENT LATER IN THE WEEK. FIRE WEATHER MAY NOT BE TOO MUCH OF A
CONCERN DURING THIS TIME PERIOD DUE TO POSITION OF THE UPPER LEVEL
HIGH, WHICH WILL RESULT IN RELATIVELY LIGHT WINDS NEAR THE
SURFACE AND ALOFT.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 518 AM MDT FRI AUG 14 2020
VFR. MAINLY CLEAR SKIES EXPECTED TODAY W/ THE EXCEPTION OF POCKETS
OF LOWER CEILINGS POSSIBLE DURING THE EARLY MORNING, MAINLY ACROSS
NORTHERN AREAS FROM DGW TO CDR. WIND GUSTS 20 TO 30 KNOTS POSSIBLE
WITH A COLD FRONTAL PASSAGE THIS MORNING/AFTERNOON, THEN GENERALLY
DECREASING BY SUNSET.
FIRE WEATHER
ISSUED AT 954 AM MDT FRI AUG 14 2020
A COLD FRONT MOVED SOUTH ACROSS WESTERN NEBRASKA AND PORTIONS OF
SOUTHEAST WYOMING ALONG AND EAST OF INTERSTATE 25 EARLY THIS MORNING.
HIGHER RELATIVE HUMIDITIES IN THE WAKE OF THE FRONT WILL ALLEVIATE
THE FIRE DANGER TODAY, AND RED FLAG WARNING FOR FIRE WEATHER ZONES
302 AND 310 WERE CANCELLED. HIGH FIRE DANGER WILL CONTINUE TODAY FOR
AREAS WEST OF INTERSTATE 25, ESPECIALLY WEST OF THE LARAMIE RANGE WITH
LOW HUMIDITIES AND GUSTY WINDS.
ELEVATED FIRE WEATHER CONDITIONS FOR SATURDAY MAINLY DUE TO LOWER
WIND SPEEDS ACROSS ZONES 302 THROUGH 309. LIGHTER WINDS WILL CONTINUE
INTO EARLY NEXT WEEK AS THE UPPER LEVEL HIGH BUILDS NORTHWARD INTO
THE AREA.
CYS WATCHES/WARNINGS/ADVISORIES
WY...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR WYZ303>309.
NE...NONE.
UPDATE...MAJ
SHORT TERM...TJT
LONG TERM...TJT
AVIATION...CLH
FIRE WEATHER...TJT/MAJ
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