Area Forecast Discussion
Issued by NWS Cheyenne, WY

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842
FXUS65 KCYS 140512
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1012 PM MST SAT FEB 13 2016

.UPDATE...
ISSUED AT 848 PM MST SAT FEB 13 2016

WINDS HAVE NOW EASED BEHIND THE FRONT ACROSS THE NEBRASKA
PANHANDLE. SOME PRETTY IMPRESSIVE WIND GUSTS WERE OBSERVED AS THE
FRONT MOVED THROUGH. BUT NOW...WINDS SEEM TO BE ON THE WANE. SO
WENT AHEAD AND CANCELLED THE WIND ADVISORY FOR THE NEBRASKA
PANHANDLE. UPDATES HAVE BEEN SENT.

UPDATE ISSUED AT 550 PM MST SAT FEB 13 2016

PRETTY STRONG COLD FRONT MOVING SOUTH LATE THIS AFTERNOON/EARLY
EVENING. STRONG WINDS BEHIND FRONT PRODUCING GUSTS IN EXCESS OF 50
MPH. GETTING 53 MPH GUSTS AT CHADRON. WENT AHEAD AND ISSUED A WIND
ADVISORY FOR THE PANHANDLE AS THIS IS A FAVORABLE SETUP FOR
STRONG WINDS OUT THERE. HAVE THE ADVISORY RUNNING THROUGH 11
PM...BUT MAY NEED TO EXTEND. WILL CONTINUE TO MONITOR.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 359 PM MST SAT FEB 13 2016

SEVERAL WEATHER CONCERNS THROUGH THE SHORT TERM FORECAST PERIOD.
FIRST CONCERN IS WITH AN AREA OF CONVECTION MOVING SOUTHWARD INTO
NIOBRARA AND CONVERSE COUNTIES AT THIS TIME. STRONG WINDS UPWARDS
OF 55 KTS HAVE BEEN REPORTED WITH THIS AREA OF CONVECTION IN
NORTHEAST WYOMING EARLIER TODAY. LIGHTNING HAS ALSO BEEN SHOWING
UP ON THE LIGHTNING DETECTION NETWORK. A STRONG SHORTWAVE AND
ASSOCIATED COLD FRONT ARE RESPONSIBLE FOR THIS CONVECTIVE
ACTIVITY. AS THE FRONT MOVES SOUTHWARD...STRONG WINDS WILL OCCUR.
A FEW GUSTS PUSHING 60 MPH WILL BE POSSIBLE UNTIL AROUND SUNSET
WHEN THE INSTABILITY WILL QUICKLY DECREASE. ALSO THE STRONGER
FORCING WILL QUICKLY SHIFT OFF TO THE EAST WITH THE FAST MOVING
SHORTWAVE. MAY ALSO HAVE TO WATCH THE NEBRASKA PANHANDLE GIVEN
THE STRENGTH OF THE FAST MOVING SHORTWAVE. WIND ADVISORY TYPE
WIND SPEEDS MAY BE POSSIBLE FOR A FEW HOURS FOLLOWING FROPA.

THE NEXT CONCERN IS THE STRONG WINDS ACROSS WIND PRONE PORTIONS OF
SOUTHEAST WYOMING FOR THE REST OF THIS AFTERNOON AND TONIGHT...AND
EVEN INTO MONDAY AND MONDAY NIGHT. WINDS GUSTING 50 TO 60 MPH WILL
BE COMMON THE NEXT SEVERAL HOURS. THE QUESTION IS WHETHER OR NOT
STRONG WINDS WILL CONTINUE THROUGH TONIGHT. MODELS ARE SHOWING
THE GRADIENT WEAKENING SOMEWHAT TONIGHT SUCH THAT WINDS MAY PUSH
BELOW HIGH WIND CRITERIA BUT THE GRADIENT WILL INCREASE SLIGHTLY
TOMORROW AND REMAIN RELATIVELY ELEVATED THROUGH MONDAY MORNING AT
WHICH TIME THE GRADIENT IS FORECAST TO STRENGTHEN EVEN FURTHER.
BASICALLY LOOKING AT WIND HOVERING AROUND HIGH WIND CRITERIA
TONIGHT THROUGH MONDAY MORNING...THEN WINDS ACCELERATING WELL INTO
THE HIGH WIND CRITERIA RANGE BY LATE MONDAY INTO MONDAY NIGHT. MAY
EVEN SEE SOME OF THE STRONGER WINDS SPREAD INTO THE HIGH PLAINS.

ANOTHER WEATHER CONCERN TO KEEP AN EYE ON IS THE SNOWY AND SIERRA
MADRE RANGES FROM LATE SUNDAY MORNING THROUGH MONDAY NIGHT. STRONG
OROGRAPHIC FORCING WILL OCCUR STARTING SUNDAY MORNING AND WILL BE
ACCOMPANIED BY SEVERAL WEAK SHORTWAVES MOVING THROUGH NORTHWEST
FLOW ALOFT. IT IS LOOKING MORE LIKELY THAT A WINTER WEATHER
ADVISORY WILL BE NEEDED FOR THE SIERRA MADRE RANGE AND POSSIBLY
THE SNOWY RANGE FOR SUNDAY AFTERNOON THROUGH MONDAY NIGHT. WILL
ALSO SEE CHANCES FOR RAIN AND SNOW INTO THE PLAINS THE NEXT
FEW AFTERNOONS. LOW LEVEL INSTABILITY AND NORTHWEST FLOW ENERGY
WILL BE THE MAIN TRIGGERS SNOW THE SHOWER ACTIVITY. AT THIS TIME
NOT EXPECTING ANYTHING IN THE WAY OF APPRECIABLE SNOW AMOUNTS BUT
FAST MOVING NORTHWEST FLOW ALWAYS HAS A WAY OF PRODUCING
SURPRISES.

.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 243 PM MST SAT FEB 13 2016

TUESDAY A FAST MOVING SHORTWAVE WILL PUSH OUT OF CANADA INTO THE
DAKOTAS. WINDS WILL BE THE MAIN CONCERN ESPECIALLY FOR THE WIND
PRONE AREAS. THE CAG-CPR GRADIENT WILL REMAIN BETWEEN 50-60 M
THROUGHOUT THE DAY ON TUESDAY. HIGH TEMPERATURES WILL BE INTO THE
MID TO UPPER 50S OVER THE HIGH PLAINS EAST OF THE LARAMIE RANGE.
WEDNESDAY WILL HAVE LESS WIND THAN TUESDAY AS THE UPPER LEVEL
RIDGE MOVES OVERHEAD. THIS WILL ACT TO DECREASE THE LLVL GRADIENT
AND SHIFT WINDS TO THE SOUTHWEST. HIGH TEMPERATURES ON WEDNESDAY
WILL RISE INTO THE UPPER 50S TO LOW 60S FOR THE PLAINS...WITH 40S
TO THE WEST OF THE LARAMIE RANGE.

INTO THURSDAY MODEL DISCREPANCIES BEGIN TO SHOW WITH THE ECMWF
HAVING A MORE AMPLIFIED SHORTWAVE MOVING OVER COLORADO. ON THE
OTHER HAND THE GFS IS MORE PROGRESSIVE AND FURTHER NORTH...MOVING
THE UPPER WAVE OVER WYOMING. IF THE GFS VERIFIES THERE IS
POTENTIAL FOR WIDESPREAD HIGH WIND OVER MOST OF SOUTHEAST WYOMING.
PRECIPITATION CHANCES WILL REMAIN SLIM THROUGH THE
EXTENDED...EXCEPT FOR A CHANCE OF SNOW IN THE MOUNTAINS LATE
THURSDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1010 PM MST SAT FEB 13 2016

VFR CONDITIONS EXPECTED AT ALL SOUTHEAST WYOMING AND NEBRASKA
PANHANDLE AIRPORTS. COLD FRONT MOVED THROUGH EARLIER AND WINDS NOW
OUT OF THE NORTH AND NORTHWEST. DOWNSLOPING OFF THE LARAMIE RANGE
SHOULD KEEP CLOUDS VFR. WINDS INCREASE SUNDAY AND BECOME QUITE
ATRONG AFTER 17Z OOR SO FOR SOUTHEAST WYOMING AIRPORTS.

&&

.FIRE WEATHER...
ISSUED AT 243 PM MST SAT FEB 13 2016

AFTER A BRIEF COOL DOWN...WARMER TEMPERATURES WILL RETURN TO THE
AREA BY THE MIDDLE OF NEXT WEEK WITH HIGH TEMPERATURES 15 TO 20
DEGREES ABOVE NORMAL. DAYTIME RELATIVE HUMIDITIES WILL TREND LOWER
BY WEDNESDAY AND THURSDAY WITH VALUES BETWEEN 20 TO 30 PERCENT.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WARNING UNTIL 9 AM MST SUNDAY FOR WYZ110-116-117.

NE...NONE.
&&

$$

UPDATE...GCC
SHORT TERM...SML
LONG TERM...ZF/KC
AVIATION...GCC
FIRE WEATHER...SML



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