Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 130210
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
710 PM MST FRI FEB 12 2016

.UPDATE...
ISSUED AT 708 PM MST FRI FEB 12 2016

GETTINGS REPORTS FROM THE SIDNEY AND KIMBALL ASOS/AWOS OF REDUCED
VISIBILITIES IN FOG ALREADY THIS EVENING. CERTAINLY NEED TO WATCH
CONDITIONS TO SEE IF THIS FOG BECOMES MORE WIDESPREAD. WENT AHEAD
AND EXPANDED FOG WEST UP THE PLATTE RIVER VALLEY INTO TORRINGTON
AND ACROSS THE NORTHERN PANHANDLE AS WELL. WILL CONTINUE
MONITORING. UPDATES HAVE BEEN SENT.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 300 PM MST FRI FEB 12 2016

EARLY AFTERNOON WATER VAPOR IMAGERY SHOWED A UPPER RIDGE AXIS
SITUATED OVER THE INTERMTN WEST WITH A DEEP UPPER TROUGH FROM
HUDSON BAY CANADA TO FL. NORTHWEST FLOW ALOFT PREVAILED ACROSS
THE FRONT RANGE AND HIGH PLAINS. THE LEADING EDGE OF A SHALLOW
COLD AIR MASS HAD DRIFTED WEST INTO THE EASTERN 1/3 OF THE COWBOY
STATE. EAST-NORTHEAST WINDS AND WESTERN EDGE OF STRATUS CLOUD
DECK EXTENDED FROM NEAR LUSK WY TO JUST WEST OF SIDNEY NE.
TEMPERATURES EAST OF THE FRONT WERE IN THE 20S AND 30S...WHILE
WESTERLY WINDS AND 40S PREVAILED TO THE WEST.

DURING THE NEXT 12-18 HOURS...PRIMARY CONCERNS WILL DEAL WITH
POTENTIAL FOR PATCHY FREEZING DRIZZLE AND FOG OVER WESTERN
NE PANHANDLE ASSOCIATED WITH THE SHALLOW COLD AIR MASS. THERE
IS GOOD MODEL AGREEMENT PROGGING THE ARCTIC FRONT TO REMAIN
NEARLY STATIONARY TONIGHT ACROSS THE EASTERN WY PLAINS THEN
SLOWLY SHIFTING EAST INTO WESTERN NE SATURDAY MORNING. LATEST
GFS/NAM BUFR SOUNDINGS INDICATE A NEARLY SATURATED LAYER FROM
700-950MB ALONG WITH A LIGHT LOW LEVEL SOUTHEASTERLY FLOW
TONIGHT AND EARLY SATURDAY MORNING OVER WESTERN NE. PATCHY
FREEZING DRIZZLE AND FOG DEVELOPING LATER THIS EVENING AND
LINGERING THROUGH MID-LATE MORNING. THE FOG/DRIZZLE MAY EXTEND
AS FAR WEST AS A LUSK WY-KIMBALL NE LINE...BUT CONFIDENCE NOT
HIGH ATTM AND NEXT SHIFT CAN REEVALUATE WITH 00Z MODEL GUIDANCE.

A SHORTWAVE TROUGH ENTERING THE PACIFIC NORTHWEST TONIGHT WILL
QUICK MOVE ACROSS THE ID/MT SATURDAY MORNING...NORTHERN WY
SATURDAY AFTERNOON...AND SD/NORTHERN NE SATURDAY NIGHT. THIS
SHORTWAVE WILL INCREASE THE LEESIDE SURFACE PRESSURE GRADIENT
WITH THE POTENTIAL FOR A GAP WIND EPISODE FOR ARLINGTON AND
BORDEAUX SATURDAY AFTERNOON AND EVENING. THE CRAIG-CASPER HEIGHT
700-850MB GRADIENT EXCEEDS 60M BY 21Z SATURDAY...AND DECREASED
BELOW 50M BY 06Z SUNDAY. WINDS AT 700MB PEAK NEAR 60 KT AT 00Z
SUNDAY. ISSUED A HIGH WIND WATCH FOR WY ZONES 106 AND 110 FROM
NOON TO 9 PM SATURDAY FOR THE POTENTIAL FOR WEST WIND GUSTS TO
60 MPH. SATURDAY WILL BE MILDER...ESPECIALLY EAST OF I-25 AS
WESTERLY DOWNSLOPING WINDS SCOUR OUT THE SHALLOW COLD AIR MASS.

AFTER A BRIEF LULL IN THE HIGH WINDS SATURDAY NIGHT...THEY PICK
UP AGAIN SUNDAY MORNING WITH THE POTENTIAL FOR HIGH WINDS SPREADING
EAST TO I-25 SUNDAY AFTERNOON. IF THE MODELS REMAIN
CONSISTENT...HIGH WIND HEADLINES MAY BE ISSUED SATURDAY. SUNDAY
WILL BE 5-10 DEGREES FOLLOWING THE PASSAGE OF A PACIFIC COLD FRONT.

SOME LIGHT PRECIPITATION DEVELOPS INITIALLY ACROSS NORTHEAST
WY/WESTERN SD SATURDAY EVENING AND SHIFTS EAST SATURDAY NIGHT.
PACIFIC MOISTURE INCREASES WEST OF THE LARAMIE RANGE SUNDAY
MORNING WITH LIGHT SNOW BECOMING MORE WIDESPREAD SUNDAY
AFTERNOON. THERE IS A SLIGHT CHANCE OF LIGHT SNOW SPREADING EAST
ONTO THE SOUTHEAST WY PLAINS SUNDAY NIGHT. MOST OF THE
ACCUMULATING SNOW WILL OCCUR OVER THE SNOWY/SIERRA MADRE RANGES
WITH UP TO 3 INCHES POSSIBLE.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 200 PM MST FRI FEB 12 2016

MONDAY...RELATIVELY MOIST NORTHWEST FLOW ALOFT WILL PRODUCE
OROGRAPHIC SNOWFALL ACROSS THE SNOWY AND SIERRA MADRE RANGES WITH
A SLIGHT CHANCE OF PRECIPITATION NORTH OF A DOUGLAS TO SCOTTSBLUFF
LINE.

TUESDAY...DRIER AND WARMER AS HEIGHTS AND THICKNESSES RISE AND THE
ATMOSPHERE DRIES OUT SOMEWHAT.

WEDNESDAY...PERHAPS THE WARMEST DAY NEXT WEEK AS THE RIDGE ALOFT
MOVES OVERHEAD AND SURFACE LEE TROUGHING BECOMES WELL ESTABLISHED
WITH VERY DRY ATMOSPHERE PROMOTING WARMING TEMPERATURES.

THURSDAY...CONTINUED MILD IN THE WARM SECTOR AHEAD OF APPROACHING
COLD FRONT. SOME OROGRAPHIC SNOW SHOWERS POSSIBLE NEAR THE SNOWY
AND SIERRA MADRE RANGES LATE IN THE DAY WITH A SHORTWAVE TROUGH
APPROACHING.

FRIDAY...COOLER IN THE WAKE OF THE SHORTWAVE TROUGH ALOFT AND ITS
ASSOCIATED COLD FRONT PASSAGE...THOUGH STILL RELATIVELY MILD FOR
MID FEBRUARY BASED ON PROJECTED HEIGHTS AND THICKNESSES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 408 PM MST FRI FEB 12 2016

BACKDOOR FRONT TO REMAIN ALONG THE EAST SLOPES OF THE LARAMIE
RANGE THROUGH THE OVERNIGHT HOURS. EASTERLY UPSLOPING WINDS OVER
THE PANHANDLE WILL CONTINUE WIDESPREAD IFR/LIFR CONDITIONS FOR OUR
NEBRASKA PANHANDLE AIRPORTS AT LEAST THROUGH 18Z. FOLLOWED LATEST
HRRR GUIDANCE AND CONFIDENCE IS HIGH THAT LOW CONDITIONS WILL
CONTINUE. WEST WINDS RETURN AFTER 18Z THAT WILL SCOUR OUT THE
LOWER STRATUS.


&&

.FIRE WEATHER...
ISSUED AT 200 PM MST FRI FEB 12 2016

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND WITH COOL TO MILD
TEMPERATURES AND RESIDUAL SNOW COVER. A NORTH-SOUTH ORIENTED COLD
FRONT OVER THE HIGH PLAINS WILL SHIFT EASTWARD SATURDAY AS A QUICK
MOVING UPPER LEVEL DISTURBANCE MOVES INTO NORTHERN WYOMING. THIS
DISTURBANCE WILL TIGHTEN THE LEESIDE SURFACE PRESSURE GRADIENT
WITH WEST WINDS BECOMING STRONG AND GUSTY ACROSS MUCH OF SOUTHEAST
WYOMING. THE WINDY CONDITIONS WILL CONTINUE SUNDAY AS WELL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING
     FOR WYZ106-110.

NE...NONE.
&&

$$

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


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