Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 270008
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
608 PM MDT SUN OCT 26 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 215 PM MDT SUN OCT 26 2014

A STRONG SURFACE COLD FRONT WAS ANALYZED FROM NORTHERN CO INTO THE
WESTERN NE PANHANDLE THIS AFTN. MUCH OF THE CWA IS NOW IN THE POST
FRONTAL AIR MASS...HELPING EASE THE THREAT FOR HIGH WINDS. GUSTS IN
EXCESS OF 40 MPH HAVE BEEN COMMON OVER THE PAST FEW HOURS ACROSS A
LARGE PART OF SOUTHEAST WY WITH GOOD LOW LEVEL MIXING AND ENHANCED
FLOW ALOFT. ENDED UP CANCELLING THE HIGH WIND WARNING FOR ARL EARLY
AS THE H85 CAG-CPR GRADIENT CONTINUES TO WEAKEN BELOW 45 METERS AND
CRITERIA HAS NOT BEEN MET SINCE EARLY THIS MORNING. CONCERN FOR THE
NEXT FEW HOURS INTO THE OVERNIGHT IS PCPN CHANCES. CAA WILL INCREASE
BEHIND THE FRONT TONIGHT WITH BOTH THE GFS/NAM SHOWING A BAND OF MID
LEVEL FRONTOGENESIS FROM THE SNOWIES AND SIERRA MADRES NORTHEASTWARD
INTO THE PANHANDLE. SHOWERS SHOULD BE MOST NUMEROUS ALONG THIS AXIS
AS WE HEAD INTO THE NIGHTTIME HOURS...SO THAT IS WHERE THE HIGHEST
POPS REMAIN WITH THIS FORECAST PACKAGE. CANNOT ENTIRELY RULE OUT A
RUMBLE OF THUNDER WITH GFS LIFTED INDEX VALUES SLIGHTLY NEGATIVE
ALONG AND SOUTH OF I80. NAM SOUNDINGS ONLY SHOW AROUND 150-200 J/KG
OF MUCAPE THOUGH...SO OPTED TO LEAVE MENTION OF THUNDER OUT. COLD
AIR WILL BE SUFFICIENT FOR MOUNTAIN SNOW WITH H7 TEMPS FALLING TO
-5C BY 12Z MON. ONLY AN INCH OR TWO EXPECTED WITH THE PROGRESSIVE
SYSTEM. SNOW COULD MIX IN WITH RAIN OVER THE PLAINS AS WELL...BUT
THERMAL PROFILES LOOK TOO WARM TO SUPPORT ACCUMULATING SNOW.

MUCH COLDER FOR MON...BUT CERTAINLY FEELING MORE LIKE FALL. AREAS OF
PCPN MAY LINGER THROUGH EARLY AFTN WITH PLENTIFUL CLOUD COVER AS THE
SHORTWAVE TROUGH AXIS ROTATES OVERHEAD. THE MODELS AGREE WITH TEMPS
BETWEEN -5C AND -8C AT H7 AT 21Z TUE. MANY AREAS WILL HAVE A HARD
TIME GETTING ABOVE 50 FOR HIGHS TOMORROW...ESPECIALLY ON THE WYOMING
SIDE. CONTEMPLATED ADDING SLIGHT CHANCE POPS BEYOND 18Z MON AS THE
MID LEVEL VORT LOBE MAY STILL BE AFFECTING THE AREA. HOWEVER...IT
LOOKS LIKE MOST OF THE CWA WILL BE IN NVA ALONG WITH MODEST DRYING
ALOFT. WEAK RIDGING RETURNS TO THE AREA BY TUE...SO TRANQUIL WEATHER
CONDITIONS SHOULD PREVAIL THROUGH THE MIDDLE OF THE WEEK.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 315 PM MDT SUN OCT 26 2014

LATEST NUMERICAL MODEL GUIDANCE IS IN REASONABLE AGREEMENT WITH
THE OVERALL LARGE SCALE PATTERN. A UPPER RIDGE CENTERED OVER THE
GREAT BASIN WEDNESDAY AMPLIFIES AS IT TRANSLATES EAST TO THE
CONTINENTAL DIVIDE THURSDAY...FRONT RANGE FRIDAY...AND GREAT PLAINS
NEXT WEEKEND. THE NEXT EASTERN PACIFIC UPPER TROUGH DIGS SOUTHEAST
ALONG THE WEST COAST EARLY SATURDAY...THEN SLIDES EAST ACROSS THE
GREAT BASIN AND EVENTUALLY THE ROCKIES ON SUNDAY.

SURFACE RIDGES OF HIGH PRESSURE WILL BE SITUATED OVER CENTRAL
ROCKIES AND EAST CENTRAL GREAT PLAINS WEDNESDAY. IN BETWEEN THESE
FEATURES WILL BE A LEE TROUGH FROM NORTHEAST WY TO EASTERN CO. THE
PRESSURE GRADIENT WILL INCREASE WITH WINDY CONDITIONS FOR MUCH OF
SOUTHEAST WY. OTHER THAN WINDS...THERE WILL BE NO OTHER SENSIBLE
WEATHER DUE TO THE DRY WEST-NORTHWEST FLOW ALOFT. HIGH TEMPERATURES
ALA DOWNSLOPE WINDS WILL WARM INTO THE 60S ACROSS THE PLAINS.

A DRY CLIPPER FRONT WILL MOVE QUICKLY SOUTHEAST ACROSS THE PLAINS
LATE WEDNESDAY WITH WINDS SHIFTING TO THE NORTHWEST. THURSDAY WILL
BE SLIGHTLY COOLER...BUT STILL ABOUT 5 DEGREES ABOVE SEASONAL
NORMALS. ANOTHER CLIPPER FRONT WILL IMPACT THE NORTHERN AND CENTRAL
GREAT PLAINS THURSDAY NIGHT AND FRIDAY. IT WILL BE MILDER FOR MUCH
OF THE CWA FRIDAY WITH BREEZY SOUTHERLY WINDS.

SATURDAY WILL BE THE WARMEST DAY OF THE LONG TERM AS SOUTHWESTERLY
WINDS INCREASE...LEE TROUGH DEEPENS AND 700MB TEMPERATURES RISE TO
AROUND 8C. HIGH TEMPERATURES FOR THE PLAINS WILL RANGE FROM THE
60S TO LOWER 70S. CLOUDS WILL INCREASE WEST OF THE LARAMIE RANGE AS
PACIFIC MOISTURE SURGES NORTHEAST IN ADVANCE OF THE NEXT TROUGH
AND COLD FRONT. SHOWERS WILL DEVELOP OVER THE SNOWY/SIERRA MADRES
AS EARLY AS SATURDAY NIGHT...THEN SPREAD NORTHEAST ACROSS SOUTH
AND EAST CENTRAL WY SUNDAY. IT WILL BE MUCH COOLER WITH HIGHS IN
THE 30S AND 40S WEST...WHILE THE MAJORITY OF THE PLAINS ENJOY
ANOTHER MILD AND BREEZY AFTERNOON WITH UPPER 50S TO MID 60S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 602 PM MDT SUN OCT 26 2014

FORECAST FOCUS WAS THE TIMING...COVERAGE AND PHASE OF PRECIP THAT
WILL DEVELOP OVR SE WYOMING AND THE WRN NEBRASKA PANHANDLE THIS
EVENING AND CONTINUE TONIGHT...BEFORE DISSIPATING BY SUNRISE
MONDAY. LATEST RADAR RETURNS SHOW SHOWERS BEGINNING TO DEVELOP
OVR THE SNOWY RANGE...WITH SOME VERY WK RETURNS SW OF KBFF. EXPECT
THIS COVERAGE TO EXPAND THROUGH MIDNIGHT AS A FAST-MOVING STORMS
SYSTEM SWEEPS THROUGH. TEMPERATURES WILL BE WARM ENOUGH FOR RAIN
AT AREA TERMINALS...THOUGH KLAR AND KRWL WOULD BE CLOSE SHOULD
PRECIP BE CONSISTENT AND STRONG ENOUGH. THAT SAID...KEPT MOST
LOCATIONS VFR THROUGH THE PERIOD AS RAINFALL INTENSITY ISNT
EXPECTED TO BE STRONG ENOUGH FOR VISIBILITY REDUCTION. THE CLOUD
DECK SHOULD STAY VFR AS WELL...BUT JUST BARELY IN SPOTS. WOULD NOT
BE SURPRISED TO SEE A BRIEF DIP INTO MVFR...BUT WASNT CONFIDENT IN
LOCATION TO INCLUDE. CONDITIONS WILL IMPROVE AFTER 09Z OR 10Z
GIVING WAY TO BREEZY NORTHWEST WINDS FOR MONDAY.

&&

.FIRE WEATHER...
ISSUED AT 215 PM MDT SUN OCT 26 2014

NO MAJOR CONCERNS OVER THE NEXT FEW DAYS. LOOK FOR AN INCREASED RISK
FOR RAIN AND MOUNTAIN SNOW TONIGHT THROUGH EARLY MON. A SUBSTANTIAL
COOLDOWN IS EXPECTED FOR TOMORROW WITH HIGHS 45 TO 55 OVER THE LOWER
ELEVATIONS. THIS WILL KEEP FIRE WEATHER CONCERNS AT BAY THROUGH THE
MIDDLE OF NEXT WEEK.

&&

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

$$

SHORT TERM...HAMMER
LONG TERM...JAMSKI
AVIATION...CAH
FIRE WEATHER...HAMMER



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