Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 210536
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1036 PM MST TUE JAN 20 2015

.UPDATE...
ISSUED AT 1030 PM MST TUE JAN 20 2015

NEXT POSITIVELY TILTED SHORTWAVE TROUGH ALOFT MOVES SOUTHEAST
ACROSS WYOMING OVERNIGHT...WITH A FEW SNOW SHOWERS OVER THE
SNOWY AND SIERRA MADRE RANGES...DRY ELSEWHERE. BULK OF SNOW WITH
THIS WAVE WILL LIE FURTHER SOUTH OVER SOUTH CENTRAL AND SOUTHEAST
COLORADO. BOUNDARY LAYER BECOMES MORE SATURATED OVERNIGHT PER
THE NAM...OVER CARBON AND ALBANY COUNTIES OF WYOMING...SO HAVE
ADDED AREAS OF FOG THERE...ESPECIALLY WITH RAWLINS AND LARAMIE
TEMPERATURE AND DEWPOINT SPREADS 4 DEGREES. ADJUSTED TEMPERATURES
...DEWPOINTS...WINDS AND CLOUD COVER THE REST OF THE NIGHT BASED
ON TRENDS.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 300 PM MST TUE JAN 20 2015

COLD AIR MASS TO REMAIN IN PLACE WITH 700MB TEMPERATURES OF -14 TO
-16C TODAY THROUGH WEDNESDAY NIGHT. SURFACE TEMPERATURES COLD WITH
OVERNIGHT LOWS IN THE SINGLE DIGITS TO LOW TEENS AND DAYTIME HIGHS
STRUGGLING TO GET ABOVE FREEZING. THIS IS DUE TO A SLOW MOVING UPPER
LOW THAT TRACKS ACROSS COLORADO THROUGH THURSDAY THAT KEEPS A NORTH
WIND OVER THE AREA.

WILL STAY DRY FOR THE MOST PART...MAYBE SOME SCATTERED SNOW SHOWERS
OVER THE SNOWY AND SIERRA MADRE RANGES...BUT THATS ABOUT IT. START
TO SEE A CHANGE THURSDAY NIGHT AS THE LOW FINALLY TRACKS OFF TO THE
SOUTHEAST WITH UPPER LEVEL RIDGING BUILDING BACK OVER WYOMING. 700MB
TEMPERATURES WARM UP ABOUT 8 DEGREES C INTO THURSDAY MORNING TO -6
TO -10C. NO ISSUES WITH WINDS OR PRECIP THROUGH THE SHORT TERM.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 300 PM MST TUE JAN 20 2015

THE LATEST MEDIUM RANGE MODELS AND THEIR ENSEMBLES ARE IN GENERAL
AGREEMENT. THE LARGE SCALE PATTERN WILL BE DOMINATED BY A WESTERN
CONUS UPPER RIDGE AND EASTERN CONUS UPPER TROUGH. CONSEQUENTLY...
NORTHWEST FLOW ALOFT WILL PREVAIL. NO SENSIBLE WEATHER IS FORECAST
FRIDAY WITH BREEZY NORTHWEST WINDS. DOWNSLOPE FLOW LEE OF THE LARAMIE
RANGE WILL PUSH THE MERCURY INTO THE 40S DURING THE AFTERNOON. A
CLIPPER LOW PRESSURE SYSTEM AND COLD FRONT WILL MOVE SOUTHEAST
ACROSS THE NORTHERN PLAINS AND MIDWEST LATE SATURDAY THROUGH
SUNDAY. THE ECMWF/GEM ARE PRODUCING SOME LIGHT PRECIPITATION OVER
EAST CENTRAL WY AND THE SOUTHEAST WY MOUNTAINS SATURDAY AFTERNOON
AND NIGHT. AS THIS CLIPPER PASSES TO THE NORTHEAST OF THE CWFA
SATURDAY...THE PRESSURE GRADIENT TIGHTENS ACROSS SOUTHEAST WY WITH
WEST WINDS GUSTING TO 40 KT THROUGH WIND PRONE AREAS. DOWNSLOPE
FLOW ONCE AGAIN WILL PROVIDE ABOVE NORMAL HIGH TEMPERATURES. UPPER
RIDGE AMPLIFIES SUNDAY WITH ANOTHER SHORTWAVE MOVING SOUTHEAST
THROUGH THE NORTHERN HIGH PLAINS. GFS DEPICTS LITTLE OR NO
PRECIPITATION WHILE THE ECMWF/GEM PRODUCE A BAND OF LIGHT QPF FROM
NORTHERN WY INTO NORTHWEST NE. REGARDLESS...THE MAJORITY OF THE
CWFA WILL BE DRY SUNDAY...EXCEPT FOR ISOLATED OROGRAPHIC SNOW
SHOWERS OVER THE SNOWY/SIERRA MADRE RANGES. AS THE UPPER RIDGE
MOVES OVERHEAD EARLY NEXT WEEK...EXPECT DRY AND UNSEASONABLY MILD
CONDITIONS WITH HIGHS INTO THE 50S FOR THE PLAINS. WEST TO NORTHWEST
WINDS WILL BE BREEZY...MAINLY DURING THE DAYTIME HOURS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1030 PM MST TUE JAN 20 2015

POSITIVELY TILTED SHORTWAVE TROUGH ALOFT MOVES TO NORTHERN WYOMING
BY DAWN WEDNESDAY...THEN TO SOUTHERN WYOMING BY LATE WEDNESDAY
AFTERNOON.

WYOMING TAFS...CEILINGS GRADUALLY LOWERING TONIGHT WITH MVFR
DEVELOPING AT RAWLINS AND LOWER END VFR CEILINGS AT LARAMIE AND
CHEYENNE WITH MOUNTAINS OBSCURED OCCASIONALLY. AREAS OF FOG
AT RAWLINS. AFTER DAYBREAK ON WEDNESDAY...BECOMING VFR WITH
SCATTERED CLOUDS FROM 5000 TO 10000 FEET AGL AND GUSTS OF 20 TO 25
KNOTS AT LARAMIE AND CHEYENNE.

NEBRASKA TAFS...CEILINGS GRADUALLY LOWERING TONIGHT WITH LOW END
VFR CEILINGS DEVELOPING THEN CLOUDS BECOMING SCATTERED TO BROKEN
5000 TO 8000 FEET AGL AFTER DAYBREAK WEDNESDAY WITH NORTHWEST
WIND GUSTING TO NEAR 25 KNOTS.

&&

.FIRE WEATHER...
ISSUED AT 300 PM MST TUE JAN 20 2015

MINIMAL FIRE WEATHER CONCERNS AS A COLD FRONT WILL REMAIN OVER THE
AREA THROUGH THE NEXT COUPLE DAYS. WILL SEE SOME MOUNTAIN SNOW...BUT
ACCUMULATIONS WILL BE LIGHT. AFTERNOON HUMIDITIES WELL ABOVE CRITICAL
THRESHOLDS WITH EXCELLENT OVERNIGHT RECOVERIES.

&&

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

$$

UPDATE...RUBIN
SHORT TERM...GCC
LONG TERM...MJ
AVIATION...RUBIN
FIRE WEATHER...GCC



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