Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 260932
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
332 AM MDT FRI SEP 26 2014

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 300 AM MDT FRI SEP 26 2014

UNSEASONABLY WARM TEMPERATURES WILL CONTINUE TODAY AND SATURDAY AS
AN UPPER RIDGE WILL BE VERY SLOW TO MOVE OUT. CLEAR ACROSS THE CWA
TODAY AND TONIGHT. CHANGES BEGIN TO IMPINGE OVER WESTERN PARTS OF
THE CWA SAT AFTERNOON AS AN UPPER LOW WHICH WILL CLOSE OFF OVER
CALIFORNIA TONIGHT EDGES SLOWLY EASTWARD OVER NEVADA SATURDAY.
THIS WILL ALLOW FOR SOME MOISTURE TRANSPORT NORTHWARD ACROSS
WESTERN AND CENTRAL WYOMING WHICH SHOULD INTERACT WITH ANY WEAK
IMPULSES TO SET OFF SOME SHOWERS AND A FEW TSTMS...MAINLY OVER
THE MTNS. ACTIVITY WILL DECREASE SAT NIGHT BUT SPREAD BACK IN
SUNDAY AS A STRONGER IMPULSE RIDES NORTHWARD ACROSS WESTERN
COLORADO INTO WESTERN WYOMING BY SUNDAY EVENING. ACTIVITY SHOULD
ALSO MAKE A LITTLE MORE PROGRESS EASTWARD AND MAYBE INTO THE
EASTERN PLAINS BY EVENING. AT THE SAME TIME A COOL FRONT WILL ALSO
BEGIN PUSHING SOUTHWARD ACROSS THE CWA SUNDAY AFTERNOON SIGNALING
EVEN MORE CHANGES UPCOMING.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 325 AM MDT FRI SEP 26 2014

MODELS CONTINUE TO SHOW A RATHER UNSETTLED AND COOL WEATHER
PATTERN ACROSS THE FORECAST AREA THROUGH MOST OF NEXT WEEK. THE
MAIN FORECAST CONCERN LATE IN THE WEEKEND AND EARLY NEXT WEEK WILL
BE THE TRACK AND EVOLUTION OF A VIGOROUS UPPER LEVEL LOW ACROSS
THE GREAT BASIN. SEVERAL DISTURBANCES ALOFT WILL PUSH ACROSS
WYOMING WELL AHEAD OF THE LOW AS IT DRIFTS ACROSS NEVADA AND UTAH
THROUGH EARLY MONDAY. THE UPPER LOW WILL EVENTUALLY BECOME AND
OPEN WAVE NEGATIVELY TILTED TROUGH AS IT EJECTS NORTHEAST OVER
THE FORECAST AREA LATE ON MONDAY...LIKELY RESULTING IN WIDESPREAD
MODERATE TO HEAVY RAINFALL ACROSS THE HIGH PLAINS AS A DIVERGENT
90 KNOT JET MAX PUSHES ACROSS WYOMING AND COLORADO. INCREASED POP
BETWEEN 40 TO 70 PERCENT ACROSS THE AREA...ESPECIALLY OVER THE
HIGH PLAINS AND MOUNTAINS. RAIN WILL MIX WITH AND CHANGE TO SNOW
ACROSS THE MOUNTAINS ABOVE 9500 FEET...WITH SEVERAL INCHES
POSSIBLE. LLVLS ARE PRETTY UNSTABLE FOR THIS TIME OF THE YEAR...SO
ISOLATED TSTORMS ARE EXPECTED AS WELL ON MONDAY. HIGH TEMPERATURES
WILL BE TRICKY AND WILL GREATLY DEPEND ON CLOUD COVER ALONG WITH
COVERAGE OF PRECIP. KEPT TEMPERATURES NEAR NORMAL...GENERALLY IN
THE 60S ACROSS SOUTHEAST WYOMING WITH LOW TO MID 70S OVER WESTERN
NEBRASKA.

DRIER AIR WILL PUSH INTO SOUTHEAST WYOMING LATE MONDAY NIGHT AS
WINDS SHIFT INTO THE WEST. MODEL SOUNDINGS SHOW SOME VERY STRONG
WINDS ALOFT...50 TO 60 KNOTS BELOW 700 MB ALONG AND WEST OF THE
LARAMIE RANGE. WILL NEED TO MONITOR THIS DURING THE
WEEKEND...ALTHOUGH IT IS A BIT EARLY TO SEE HIGH WIND WARNING
CRITERIA. ALL MODELS SHOW MAINLY DRY CONDITIONS OVER THE AREA ON
TUESDAY...BUT ANOTHER PACIFIC TROUGH AND ASSOCIATED COLD FRONT WILL
RAPIDLY PUSH INTO THE AREA FOR WEDNESDAY...RESULTING IN ANOTHER
CHANCE OF SHOWERS...ISOLATED THUNDER...AND COOLER TEMPERATURES.
NORTHWEST FLOW WILL DEVELOP OVER THE AREA PROVIDING COOLER THAN
NORMAL TEMPERATURES INTO LATE NEXT WEEK...WITH HIGHS IN THE MID
50S TO MID 60S. THE ECMWF IS A LITTLE BIT WARMER...SHOWING THE
UPPER LEVEL HIGH FURTHER NORTHEAST ACROSS SOUTHERN CALIF. KEPT
TEMPERATURES A FEW DEGREES BELOW MOS FOR NOW...BUT DID NOT GO
QUITE AS COOL AND WINDY AS THE GFS IS SUGGESTING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH FRIDAY NIGHT)

ANOTHER QUIET DAY WITH CLEAR SKIES AND RELATIVELY LIGHT WINDS UNDER
THE INFLUENCE OF HIGH PRESSURE ALOFT. SOUTH TO SOUTHWEST WINDS
WILL ONLY GUST UP TO 20 MPH OVER THE HIGH PLAINS THIS AFTERNOON.
VFR CONDITIONS EXPECTED THROUGH THE PERIOD.

&&

.FIRE WEATHER...
ISSUED AT 300 AM MDT FRI SEP 26 2014

UNSEASONABLY WARM TEMPERATURES WILL CONTINUE TODAY AND SATURDAY
ALLOWING LOWEST RELATIVE HUMIDITY PERCENTAGES TO FALL INTO THE
TEENS IN SOME AREAS OF THE PLAINS. WINDS WILL REMAIN BELOW
CRITICAL THRESHOLDS HOWEVER SO FIRE WEATHER CONDITIONS SHOULD
STAY ELEVATED MAINLY OVER EAST-CENTRAL WYOMING TODAY. A TREND TO
COOLER WEATHER WILL ENSUE SUNDAY AND CONTINUE INTO NEXT WEEK.

&&

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

$$

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






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