Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 192052
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
252 PM MDT SUN OCT 19 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 245 PM MDT SUN OCT 19 2014

THE AFTERNOON WATER VAPOR IMAGERY DEPICTED A UPPER RIDGE FROM THE
SOUTHERN ROCKIES/HIGH PLAINS INTO SOUTHWEST CANADA AND A POTENT
EASTERN PACIFIC UPPER TROUGH. SUBTROPICAL MOISTURE SPREAD NORTHEAST
AHEAD OF A CLOSED LOW SITUATED OVER FAR NORTHWEST MEXICO. A SUBSIDENT
NORTHWEST FLOW ALOFT AND SURFACE RIDGE PROVIDED SUNNY SKIES...LIGHT
WINDS AND UNSEASONABLY MILD TEMPERATURES THROUGHOUT THE CWA.

LATEST NUMERICAL MODEL GUIDANCE MAINTAINS THE DRY AND UNSEASONABLY
MILD PATTERN FOR THE NEXT 24 TO 48 HOURS AS THE LARGE SCALE RIDGE
TRANSLATES EAST ACROSS THE ROCKIES AND INTO THE GREAT PLAINS. LIGHT
WINDS EARLY THIS EVENING WILL BECOME SOUTHERLY TONIGHT THEN MORE
SOUTH TO SOUTHWEST MONDAY. THE GRADIENT INCREASES SLIGHTLY MONDAY
AND MORE TUESDAY WITH THE APPROACH OF THE PACIFIC TROUGH AND FRONT.
THIS WILL RESULT IN BREEZY CONDITIONS WEST OF THE LARAMIE RANGE
MONDAY AFTERNOON...AND MUCH OF THE CWA TUESDAY AFTERNOON. THE
LEADING EDGE OF PACIFIC MOISTURE WILL BEGIN TO SPREAD NORTHEAST
INTO SOUTH CENTRAL WYOMING LATE TUESDAY MORNING WITH ISOLATED SHOWERS
DEVELOPING OVER SOUTHERN CARBON COUNTY. SHOWERS WILL BECOME MORE
NUMEROUS AND SPREAD TO THE LARAMIE RANGE TUESDAY AFTERNOON. THERE
MAY BE ENOUGH INSTABILITY AVAILABLE FOR A FEW TSTORMS OVER SOUTHERN
CARBON AND ALBANY COUNTIES. THE SHOWERS CONTINUE TO EXPAND EAST
ACROSS THE SOUTHEAST WYOMING PLAINS AND INTO WESTERN NEBRASKA
TUESDAY NIGHT. AREAS WEST OF THE LARAMIE RANGE COULD MEASURE UP
TO A QUARTER INCH OF PRECIPITATION...WHILE AREAS FURTHER EAST
MAY ONLY RECEIVE LESS THAN A TENTH OF AN INCH. HIGH TEMPERATURES
MONDAY AND TUESDAY WILL WARM INTO THE 70S FOR THE PLAINS...WITH
50S AND 60S TO THE WEST. LOW TEMPERATURES IN THE 30S TO AROUND
40 TONIGHT WILL BE ABOUT 5 TO 8 DEGREES MILDER MONDAY NIGHT.
IT WILL TURN A TAD COOLER TUESDAY NIGHT WEST OF THE LARAMIE
RANGE...WHILE TO THE EAST...LOWS WILL BE IN THE 40S.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 250 PM MDT SUN OCT 19 2014

THE WEAK UPPER LEVEL TROUGH IS STILL EXPECTED TO MOVE ACROSS EARLY
WEDNESDAY PUSHING A WEAK COLD FRONT ACROSS SOUTHEAST WYOMING AND
WESTERN NEBRASKA. THERE IS JUST ENOUGH INSTABILITY ALONG THE
COLORADO BORDER MID-DAY WEDNESDAY TO WARRANT LEAVING A SLIGHT
CHANCE OF THUNDERSTORMS GOING INTO THE EARLY AFTERNOON AS THE
SYSTEM PUSHES THROUGH...HOWEVER EXPECT MOSTLY PATCHY LIGHT RAIN OR
SCATTERED RAIN SHOWERS ACROSS THE AREA WEDNESDAY MORNING THEN
TAPERING OFF IN THE AFTERNOON. HIGHER ELEVATIONS MAY SEE SOME
PATCHY MIXED PRECIPITATION EARLY WEDNESDAY MORNING...HOWEVER
MID LEVEL TEMPS STILL LOOK TO BE TOO WARM FOR MUCH IN THE WAY OF
SNOW. GFS AND LATEST 12Z ECMWF ARE IN FAIR AGREEMENT PUSHING THE
WEDNESDAY SYSTEM ACROSS SOUTHEAST WYOMING AND WESTERN NEBRASKA A
LITTLE FASTER...THUS THE AFTERNOON FORECAST PACKAGE WILL CLEAR ANY
SCATTERED PRECIPITATION OUT TO THE EAST DURING THE AFTERNOON HOURS
WITH ANOTHER EXTENDED DRY PERIOD PROJECTED THROUGH SATURDAY. WE
CAN EXPECT A BIT OF A COOL DOWN WEDNESDAY...BUT ONLY TO NEAR
NORMAL VALUES FOR LATE OCTOBER...THEN WE SHOULD SEE ANOTHER WARM
UP THROUGH LATE IN THE WEEK AS WE COME UNDER THE INFLUENCE OF
ANOTHER LARGE AMPLITUDE UPPER HIGH PRESSURE SYSTEM CENTERED TO OUR
SOUTHWEST. LATEST GFS WANTS TO BRING ANOTHER UPPER LEVEL TROUGH
ACROSS OUR AREA NEXT SUNDAY...HOWEVER THE ECMWF IS QUITE A BIT
SLOWER WITH THIS FEATURE AND FOR NOW WE CONTINUED WITH GENERAL
CONSENSUS TO KEEP POPS LOW LATE NEXT WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY MORNING)
ISSUED AT 1144 AM MDT SUN OCT 19 2014

ONLY SIGNIFICANT CHANGE WEATHER-WISE THAT WE WILL SEE ACROSS OUR
AREA OVER THE NEXT 24 HOURS WILL BE A GRADUAL CHANGE IN THE WIND
DIRECTION AS THE CENTER OF SURFACE HIGH PRESSURE MOVES SLOWLY EAST
OF OUR REGION. WIND SPEEDS WILL REMAIN RELATIVELY LIGHT, AND THE
WIND DIRECTION WILL GRADUALLY GO FROM NORTHEASTERLY TO SOUTHERLY
LATE TODAY THROUGH TOMORROW MORNING. THE MODELS (PARTICULARLY THE
HRRR, GFS AND NAM20) KEEP THE MOISTURE RETURN ON THE BACKSIDE OF
THE HIGH PRESSURE RIDGE TO THE SOUTHWEST OF OUR AREA THROUGH AT
LEAST LATE MORNING ON MONDAY.

&&

.FIRE WEATHER...
ISSUED AT 210 PM MDT SUN OCT 19 2014

CRITICAL FIRE WEATHER CONDITIONS NOT EXPECTED THIS WEEK. GUSTY
SOUTH TO SOUTHWEST WINDS WEST OF THE LARAMIE RANGE AND OVER THE
PLAINS WILL DEVELOP MONDAY AND TUESDAY AFTERNOONS...HOWEVER
MINIMUM HUMIDITIES WILL RANGE FROM 20 TO 25 PERCENT. ABOVE NORMAL
TEMPERATURES WILL CONTINUE EARLY THIS WEEK. A PACIFIC UPPER LEVEL
TROUGH AND SURFACE COLD FRONT WILL APPROACH FROM THE WEST TUESDAY
AND MOVE THROUGH WEDNESDAY. SCATTERED RAIN SHOWERS AND ISOLATED
AFTERNOON THUNDERSTORMS WILL DEVELOP TUESDAY WEST OF THE LARAMIE
RANGE...THEN SPREAD ONTO THE PLAINS TUESDAY NIGHT AND WEDNESDAY.
BEST CHANCES FOR WETTING RAIN WILL BE WEST OF THE LARAMIE RANGE.
WEDNESDAY WILL BE MUCH COOLER BEHIND THE FRONT...FOLLOWED BY A
DRIER AND WARMER PATTERN FOR THE END OF THE WEEK.

&&

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

$$

SHORT TERM...JAMSKI
LONG TERM...GARMON
AVIATION...GARMON
FIRE WEATHER...JAMSKI






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