Area Forecast Discussion
Issued by NWS Cheyenne, WY

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503
FXUS65 KCYS 280520
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1120 PM MDT WED APR 27 2016

.UPDATE...
ISSUED AT 936 PM MDT WED APR 27 2016

FORECAST LOOKS ON TRACK FOR TONIGHT. LIGHT SNOW HAS JUST ABOUT
FINISHED IN THE NORTHERN COUNTIES BASED ON RECENT RADAR AND
SURFACE OBS...BUT THERE COULD BE A FEW LINGERING SHOWERS THROUGH
MIDNIGHT ALONG THE PINE RIDGE. AS WINDS CONTINUE TO SHIFT TO A
MORE NORTH-NORTHEAST UPSLOPE COMPONENT...WILL LIKELY SEE PATCHY
FOG BECOME MORE PREVALENT ACROSS THE REGION WITHIN HIGH BOUNDARY
LAYER MOISTURE. THE AREAS MOST LIKELY TO SEE FOG WILL BE ALONG THE
I-80 CORRIDOR FROM CHEYENNE TO RAWLINS AND LOW LYING RIVER
VALLEYS.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 120 PM MDT WED APR 27 2016

TONIGHT...RIDGE ALOFT BUILDS ACROSS OUR FORECAST AREA. ENOUGH LOW
AND MID LEVEL MOISTURE PLUS SOME WEAK UPWARD VERTICAL MOTION TO
PRODUCE A SLIGHT CHANCE OF PRECIPITATION OVER OUR NORTHERN COUNTIES.
BOUNDARY LAYER NEAR SATURATION...SO AT LEAST PATCHY FOG ANTICIPATED
AFTER MIDNIGHT.

THURSDAY...NEXT IN A SERIES OF UPPER LOWS MOVES ACROSS ARIZONA IN
THE AFTERNOON. LOW AND MID LEVEL WINDS BECOME EASTERLY UPSLOPE WITH
DIFFLUENCE ALOFT. WITH LOW AND MID LEVELS SATURATING AND DECENT
UPWARD VERTICAL MOTION PROGGED...WILL PAINT 60 TO 100 PERCENT POPS
IN THE AFTERNOON ALONG OUR SOUTHERN THIRD OF OUR FORECAST AREA
ALONG THE COLORADO STATE LINE.

THURSDAY NIGHT...UPPER LOW MOVES SLOWLY INTO NORTHERN NEW MEXICO BY
DAWN WITH IMPRESSIVE LOW AND MID LEVEL UPSLOPE EASTERLY FLOW PROGGED
ACROSS OUR COUNTIES. ALTHOUGH THE BEST QG FORCING IN THE 500-300 MB
AND 700-500 MB LAYERS IS PROGGED TO REMAIN JUST TO OUR SOUTH OVER
NORTHERN COLORADO...IF THE LOW TRACKS SLIGHTLY FARTHER NORTH...WE
WILL SEE MODERATE TO HEAVY SNOW FALL ALONG OUR SOUTHERN TIER OF
COUNTIES FROM THE SIERRA MADRE MOUNTAINS EASTWARD ACROSS THE SNOWY
RANGE...LARAMIE VALLEY...SOUTHERN LARAMIE RANGE AND LARAMIE COUNTY
INCLUDING CHEYENNE. THANK YOU TO WPC SNOWFALL FORECAST AND OUR LOCAL
EXPECTATIONS...WE WILL ISSUE A WINTER STORM WATCH FROM THE SIERRA
MADRE RANGE EASTWARD ACROSS THE LARAMIE VALLEY AND LARAMIE COUNTY
INCLUDING CHEYENNE.

FRIDAY...UPPER LOW MOVES SLOWLY TO SOUTHEAST COLORADO WITH THE BEST
UPWARD VERTICAL MOTION PROGGED TO MOVE EAST OF OUR COUNTIES IN THE
AFTERNOON...THOUGH LOOKS LIKE ENOUGH OVERALL QPF FOR THE NECESSITY
OF A WINTER STORM WATCH FOR OUR SOUTHERN COUNTIES. GUIDANCE MAXIMUM
TEMPERATURES TOO WARM ACROSS OUR SOUTHERN TIER WITH EXPECTED SNOW
AND CLOUD COVER.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 120 PM MDT WED APR 27 2016

UPPER LOW TRACKING ACROSS NORTHEAST COLORADO FRIDAY NIGHT WITH
WRAP AROUND MOISTURE CONTINUING FOR THE SOUTHEASTERN HALF OF THE
CWFA. 700MB TEMPERATURES STILL COLD ENOUGH FOR SNOW FRIDAY NIGHT
INTO SATURDAY. ECMWF 850MB TEMPERATURES OVER THE PANHANDLE AROUND
FREEZING...SO PRECIP OUT THERE SHOULD BE SNOW AS WELL.

UPPER LOW TAKES ITS SWEET TIME MOVING THROUGH OUT AREA. IN
FACT...SATURDAY NIGHT...THE UPPER LOW CENTER FORECAST TO BE RIGHT
ALONG THE BORDER OF THE NEBRASKA PANHANDLE AND SOUTHEAST WYOMING.
SO UNSETTLED WEATHER TO CONTINUE MUCH OF THE DAY SATURDAY.

WE FINALLY START TO SEE A CHANGE IN THE WEATHER MONDAY AS THE LOW
BEGINS TO MOVE EAST INTO MINNESOTA. STARTED TO DRY OUT THE
FORECAST AFTER MONDAY. 700MB TEMPERATURES BEGIN TO WARM...CLIMBING
ABOVE FREEZING.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY EVENING)
ISSUED AT 1120 PM MDT WED APR 27 2016

SCTD MVFR CIGS EXPECTED TO LOWER TO IFR/LIFR OVER MOST TERMINALS BY
THURSDAY MORNING IN MOIST UPSLOPE FLOW.  RAIN AND SNOW SHOULD
SPREADINTO SE WY DURING THE DAY THURSDAY AS AN UPPER LOW MOVES TO
THE FOUR CORNERS AREA.

&&

.FIRE WEATHER...
ISSUED AT 120 PM MDT WED APR 27 2016

NO FIRE WEATHER ISSUES BASED ON PROJECTED HUMIDITIES AND WINDS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WATCH FROM THURSDAY EVENING THROUGH FRIDAY
     AFTERNOON FOR WYZ110-112-114>119.

NE...NONE.
&&

$$

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



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