Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 121053
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
353 AM MST FRI FEB 12 2016

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 400 AM MST FRI FEB 12 2016

MODIFIED ARCTIC BOUNDARY HAS NUDGED SOUTHWEST INTO THE NEBRASKA
PANHANDLE EARLY THIS MORNING BUT NOT MAKING MUCH PROGRESS FARTHER
SOUTHWEST SO FAR. AREA OF LOW CLOUDS RESIDING JUST NORTHEAST OF
CHADRON HAS CHANGED LITTLE IN POSITION AS WELL. EXPECT THIS FRONT
TO PUSH SOUTHWESTWARD THIS MORNING AS THE MAIN SURFACE HIGH
SETTLES OUT OF CANADA WITH LOW CLOUDS SPREADING ACROSS MUCH OF THE
PANHANDLE AS WELL. FRONT SHOULD BACK UP AGAINST THE MTNS THIS
AFTERNOON THEN WASH BACK EAST TONIGHT AS AN APPROACHING SHORTWAVE
OVER THE PACIFIC NW INDUCES LEE TROUGHING OVER THE HIGH PLAINS.
COLD AIRMASS QUITE SHALLOW BUT THERE STILL COULD BE SOME PATCHY
LIGHT FREEZING DRIZZLE OVER THE PANHANDLE FOR A TIME THIS EVENING
BEFORE ERODING OUT LATER TONIGHT.

WARMER AIR RETURNS ACROSS THE PLAINS SATURDAY WITH MAX TEMPS A BIT
TRICKY OVER THE PANHANDLE...DEPENDING ON HOW FAST THE COLD AIR
RETREATS/MIXES OUT. OTHERWISE CONCERNS WILL SWITCH TO INCREASING
WINDS AROUND THE SE WYOMING MTNS/WIND PRONE AREAS LATER SATURDAY
AS 700MB WINDS INCREASE TO OVER 50KTS AS THE UPPER SHORTWAVE MOVES
ACROSS THE REGION. SFC COLD FRONT SWEEP ACROSS THE CWA SATURDAY
EVENING WITH A RELATIVELY SHORT PERIOD OF STRONGER WINDS BEHIND
IT. LATEST GFS HAS DRIED OUT PCPN OVER THE CWA WHILE LATEST NAM
HAS RETURNED A BIT OF PCPN OVER THE NRN CWA SATURDAY EVENING. NOT
MUCH IF ANY DOES OCCUR. SUNDAY WILL BE COOLER AND A BIT BREEZY
WITH AN INCREASINGLY MOIST NWLY FLOW ENHANCING SNOW SHOWER
ACTIVITY OVER AND NEAR THE HIGHER MTNS.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 328 AM MST FRI FEB 12 2016

MEDIUM TO LONG RANGE MODELS ARE IN GOOD AGREEMENT...SHOWING
NORTHWEST FLOW ALOFT GRADUALLY BACKING INTO THE WEST AND
SOUTHWEST BY MID TO LATE NEXT WEEK. THE ONLY MINOR CHANGE COMPARED
TO 24 HOURS AGO IS THAT THE MEAN POSITION OF THE JET STREAM IS
FURTHER SOUTH AND WEST SUNDAY NIGHT THROUGH TUESDAY...WHICH MAY
RESULT IN A SOMEWHAT BETTER CHANCE FOR PRECIPITATION AND STRONG
WINDS. BY THE MIDDLE OF NEXT WEEK...ALL MODELS SHOW THE JET STREAM
LIFTING NORTHWARD WITH MILD TEMPERATURES EXPECTED ON WEDNESDAY AND
THURSDAY.

MODELS NOW INDICATE A SERIES OF WEAK DISTURBANCES MOVING ACROSS
WYOMING SUNDAY NIGHT AND MONDAY. THESE DISTURBANCES WILL NOT
PRODUCE MUCH PRECIPITATION...BUT LLVL INSTABILITY MAY RESULT IN
LOCALLY HEAVY RAIN/SNOW SHOWERS SUNDAY EVENING AND AGAIN LATE
MONDAY. KEPT POP HIGH ACROSS THE MOUNTAINS WITH A MENTION OF SNOW
SHOWER ACTIVITY ACROSS THE HIGH VALLEYS AND HIGH PLAINS. DUE TO
MODEL DIFFERENCES...DID NOT INCREASE POP TOO MUCH ACROSS THE LOWER
ELEVATIONS AT THIS TIME. OTHERWISE...THIS PATTERN IS FAVORABLE
FOR VERY WINDY CONDITIONS ACROSS MAINLY SOUTHWEST WYOMING DUE TO
THE POSITION OF THE JET AXIS AS WELL AS WELL A SUBSTANTIAL LLVL
PRESSURE GRADIENT DUE TO PERSISTENT LEE SIDE TROUGHING. FAVORABLE
WIND PRONE LOCATIONS HAVE A HIGH CHANCE OF HIGH WIND CRITERIA LATE
SUNDAY NIGHT THROUGH LATE TUESDAY WITH GUSTS OVER 60 MPH. THERE
IS A CHANCE THAT THESE STRONG WINDS WILL SPREAD INTO THE HIGH
VALLEYS AND HIGH PLAINS BRIEFLY LATE MONDAY NIGHT/EARLY TUESDAY
MORNING. SHOULD GET A BREAK IN THE WIND ACTIVITY ON WEDNESDAY AS
AN UPPER LEVEL RIDGE AXIS QUICKLY MOVES ACROSS THE ROCKY
MOUNTAINS...BUT STRONG WINDS ARE EXPECTED TO RETURN TO THE AREA
AHEAD OF THE NEXT PACIFIC STORM SYSTEM NEXT THURSDAY. TEMPERATURES
NEXT WEEK WILL BE VERY PLEASANT FOR THIS TIME OF THE YEAR...WITH
THE COOLEST DAY ON MONDAY WITH HIGHS IN THE LOW 40S TO LOW 50S.
TEMPERATURES ARE EXPECTED TO CLIMB INTO THE 60S ACROSS THE HIGH
PLAINS BY WEDNESDAY AND THURSDAY AS 700MB TEMPERATURES BETWEEN +4C
TO +8C WILL BE WIDESPREAD ACROSS THE FORECAST AREA.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH SATURDAY MORNING)
ISSUED AT 315 AM MST FRI FEB 12 2016

A SLOW MOVING SHALLOW COLD FRONT IS NEARLY STATIONARY EARLY THIS
MORNING ACROSS WESTERN NEBRASKA AND FAR NORTHEAST WYOMING. THIS
FRONT WILL EVENTUALLY ACCELERATE SOUTH AND WEST AROUND DAWN TO
NEAR THE WYOMING BORDER BY THIS AFTERNOON. IFR CONDITIONS ARE
EXPECTED TO DEVELOP SHORTLY NEAR KCDR AND KAIA...AND THEN LATER
THIS MORNING FURTHER SOUTH NEAR KBFF AND KSNY. LOW STRATUS WITH
PATCHY FOG CAN BE EXPECTED ALONG WITH THE POTENTIAL FOR FREEZING
DRIZZLE. THE MOST LIKELY PERIOD FOR IFR AND FREEZING DRIZZLE WILL
BE THIS EVENING THROUGH SATURDAY MORNING. WINDS WILL SHIFT INTO
THE EAST ACROSS THE HIGH PLAINS BUT REMAIN LIGHT. SOUTH TO
SOUTHWESTERLY WINDS WILL CONTINUE ALONG AND WEST OF THE I25
CORRIDOR WITH WIND SPEEDS INCREASING OVER 20 KNOTS BY EARLY
SATURDAY MORNING.

&&

.FIRE WEATHER...
ISSUED AT 400 AM MST FRI FEB 12 2016

NO SIGNIFICANT CONCERNS ANTICIPATED THROUGH THE WEEKEND INTO EARLY
NEXT WEEK WITH MOST CONDITIONS REMAINING NON-CRITICAL. A COLD
FRONT WILL BANK UP AGAINST THE MOUNTAINS THIS MORNING THEN RETREAT
BACK EAST TONIGHT INTO SATURDAY. IT WILL BE COOLER OVER THE PLAINS
TODAY THEN WARMER AIR WILL RETURN SATURDAY. WINDS WILL INCREASE
AROUND THE MOUNTAINS SATURDAY NIGHT INTO SUNDAY AND CONTINUE WINDY
AT TIMES EARLY 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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