Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 271922
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1222 PM MST SAT DEC 27 2014

.UPDATE...
ISSUED AT 1210 PM MST SAT DEC 27 2014

OUR TEAM HIGH WIND WARNING WORKING OUT WELL FOR THE ARLINGTON
AND ELK MOUNTAIN LOCALES OF EASTERN CARBON COUNTY WYOMING BASED
ON GUSTS NEAR 60 MPH AT ELK MOUNTAIN. OUR MIDNIGHT SHIFT TEAM
EARLY FRIDAY MORNING SET THE TABLE WELL WITH A HIGH WIND WATCH
FOR ARLINGTON...AND OUR DAY SHIFT TEAM FRIDAY UPGRADED TO A HIGH
WIND WARNING.

IN THIS GRIDDED FORECAST UPDATE...WE EXPANDED THE BLOWING SNOW
TO INCLUDE THE INTERSTATE 80 SUMMIT...AS WELL AS ADJUSTING
MAXIMUM TEMPERATURES FOR THIS AFTERNOON BASED ON TRENDS AS
MAXIMUM TEMPERATURES ARE DIFFICULT AT BEST TO FORECAST WITH A
DEEP SNOWFIELD...AND AMOUNT OF LOW LEVEL MIXING...OR WINDS...IN
DOUBT AT SOME LOWER ELEVATION LOCATIONS SUCH AS TORRINGTON...
SCOTTSBLUFF AND ALLIANCE.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)

CURRENT KCYS RADAR LOOP AND OBS ACROSS THE AREA SHOW THE LIGHT
SNOW HAS COME TO AN END OVER SOUTHEAST WYOMING. THE STORM SYSTEM
RESPONSIBLE FOR THE SNOW ON CHRISTMAS DAY IS NOW EJECTING
NORTHEAST INTO THE NORTHERN PLAINS STATES THIS MORNING. VERY COLD
TEMPERATURES OVER THE AREA EARLY THIS MORNING...WITH MOST OF
SOUTHEAST WYOMING IN THE SINGLE DIGITS ABOVE AND BELOW ZERO. WIND
CHILLS ARE GENERALLY BETWEEN -10 TO -20 AS WELL. SLIGHTLY WARMER
ACROSS WESTERN NEBRASKA WHICH SOME LOCATIONS STILL MAINTAINING
SOME CLOUD COVER...KEEPING TEMPS IN THE TEENS ACROSS THE NORTHERN
PANHANDLE OF NEBRASKA. HIGH TEMPERATURES TODAY WILL BE AROUND 10
DEGREES BELOW NORMAL...AND GENERALLY IN THE UPPER TEENS TO MIDDLE
20S. THE MAIN CONCERN OVER THE NEXT 24 HOURS WILL BE STRONG WINDS
ACROSS THE WIND PRONE AREAS OF SOUTHEAST WYOMING. LLVL PRESSURE
GRADIENT WILL STRENGTHEN LATE TODAY...PEAKING AFTER MIDNIGHT
TONIGHT. WEST TO SOUTHWEST WINDS WILL LIKELY GUST IN ACCESS OF 60
MPH ALONG PORTIONS OF I80 BETWEEN RAWLINS AND CHEYENNE...AND THEN
LATER ALONG I25 BETWEEN CHUGWATER AND WHEATLAND. ONE OTHER
CONCERN WITH THESE WINDS WILL BE BLOWING SNOW DUE TO A LARGE
SNOWPACK ACROSS THE REGION. PORTIONS OF I80 AND I25 WILL SEE
VISIBILITIES LOWERING TO NEAR ZERO AT TIMES DUE TO WIND GUSTS OVER
50 MPH AND BLOWING SNOW. DRIFTING SNOW MAY ALSO BE A PROBLEM ALONG
STRETCHES OF HIGHWAY...WITH MAY RESULT IN SLICK SNOW COVERED
ROADWAYS...ESPECIALLY ACROSS A LARGE PORTION OF I80 BETWEEN
CHEYENNE AND RAWLINS.

ON SUNDAY AND MONDAY...THE NEXT SYSTEM WILL BEGIN TO IMPACT THE
REGION. THIS TIME AROUND IT WILL NOT BE AN UPPER LEVEL LOW...BUT
INSTEAD AN ARCTIC FRONTAL BOUNDARY IN ADDITION TO A POTENT
SHORTWAVE DIGGING SOUTHEAST FROM THE PAC NORTHWEST. THE POLAR JET
WITH STRENGTHEN SOUTH OF THE AREA AND WILL INTERACT WITH THE
ARCTIC FRONT AND UPSLOPE FLOW...PRODUCING WIDESPREAD LIGHT SNOW
BEGINNING LATE SUNDAY. THIS LIGHT SNOW WILL LIKELY CONTINUE INTO
TUESDAY AND TUESDAY NIGHT. SUNDAY AFTERNOON HIGHS IN THE 20S TO
NEAR 30 WILL LIKELY BE THE WARMEST TEMPERATURES FOR QUITE A
WHILE...WITH TEMPS DROPPING INTO THE SINGLE DIGITS BY SUNDAY
NIGHT. TEMPERATURES ON MONDAY WILL REMAIN IN THE SINGLE DIGITS AS
850-700 TEMPS DROP BETWEEN -15C TO -22C. IN FACT...WOULD NOT BE
SURPRISED IF READING LOWER BELOW ZERO BY MONDAY EVENING. SNOWFALL
APPEARS TO BE LIGHT AT THIS TIME WITH NO MAJOR IMPACTS EXPECTED.
FOR NOW...FORECAST SNOW ACCUMULATIONS SUNDAY NIGHT AND MONDAY ARE
BETWEEN 1 TO 4 INCHES ACROSS THE LOWER ELEVATIONS WITH OVER 6
INCHES FOR THE MOUNTAINS. MAY NEED A WINTER WEATHER ADVISORY FOR
THIS ACTIVITY...BUT IMPACTS SHOULD BE MINOR AT BEST. WIND CHILLS
MAY BECOME THE MORE SIGNIFICANT IMPACT BY LATE MONDAY.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 300 AM MST SAT DEC 27 2014

COLDEST AIR SO FAR THIS WINTER SEASON WILL BE OVER THE ROCKY
MOUNTAINS AND CENTRAL PLAINS MONDAY NIGHT INTO TUESDAY NIGHT.
TEMPERATURES WILL BE VERY COLD WITH WIND CHILL VALUES WELL BELOW
ZERO. FOR MONDAY NIGHT INTO TUESDAY WIND CHILLS WILL MAINLY BE IN
THE MINUS 5 TO MINUS 15 DEGREE RANGE WITH WIND CHILLS LIKELY TO
PLUMMET INTO THE MINUS 20 TO MINUS 35 DEGREE RANGE TUESDAY NIGHT
INTO EARLY WEDNESDAY. WARMER AIR WILL SLOWLY WORK ITS WAY ACROSS THE
REGION THURSDAY THROUGH SATURDAY.

LIGHT SNOW CAN BE EXPECTED FOR MUCH OF THE AREA MONDAY NIGHT INTO
TUESDAY AS BITTER COLD ARCTIC AIR SQUEEZES ALL AVAILABLE MOISTURE
OUT OF THE ATMOSPHERE. SNOW ACCUMULATIONS WILL BE MINIMAL WITH MOST
OF THE AREA LOOKING AT A DUSTING OF SNOW TO UPWARDS OF A FEW INCHES
FOR MONDAY NIGHT THROUGH TUESDAY AFTERNOON. SKIES SHOULD BEGIN TO
CLEAR OUT TUESDAY NIGHT WITH LIGHT SNOW ENDING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1210 PM MST SAT DEC 27 2014

VFR PREVAILS.

WYOMING TAFS...WINDS GUSTING TO 32 KNOTS THROUGH 00Z...THEN
WINDS DECREASING. LOCALIZED IFR IN FOG AND LOW CLOUDS AT LARAMIE
THIS EVENING...WITH MVFR AND MOUNTAIN OBSCUREMENT NEAR RAWLINS
AFTER 15Z SUNDAY. WINDS GUSTING OVER 30 KNOTS AT RAWLINS AND
LARAMIE LATE TONIGHT AND SUNDAY MORNING...AND AT CHEYENNE AFTER
15Z SUNDAY.

NEBRASKA TAFS...INCREASING CLOUDS AROUND 10000 FEET AGL TONIGHT
AND SUNDAY MORNING WITH OCCASIONAL BROKEN CEILINGS.

&&

.FIRE WEATHER...
ISSUED AT 152 AM MST SAT DEC 27 2014

NO FIRE WEATHER CONCERNS THIS WEEKEND AND THROUGH NEXT WEEK WITH
VERY COLD TEMPERATURES AND A WIDESPREAD SNOWPACK EXPECTED. ARCTIC
AIR WILL PUSH INTO SOUTHEAST WYOMING AND WESTERN NEBRASKA STARTING
MONDAY...WITH ANOTHER GOOD CHANCE OF SNOW EXPECTED THROUGH EARLY
WEDNESDAY. LIGHT TO MODERATE SNOW ACCUMULATIONS ARE EXPECTED.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WARNING UNTIL 11 AM MST SUNDAY FOR WYZ110.

     HIGH WIND WARNING FROM 5 PM THIS AFTERNOON TO 11 AM MST SUNDAY
     FOR WYZ106-116-117.

NE...NONE.
&&

$$

UPDATE...RUBIN
SHORT TERM...TJT
LONG TERM...SML
AVIATION...RUBIN
FIRE WEATHER...TJT


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