Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 260944
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
244 AM MST MON JAN 26 2015

.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 300 AM MST MON JAN 26 2015

WINDS ARE THE FORECAST CHALLENGE IN THE SHORT TERM...FOLLOWED BY
TEMPERATURES.

CURRENTLY...SURFACE HIGH PRESSURE OVER NORTHWESTERN COLORADO INTO
WESTERN WYOMING THIS MORNING. SURFACE PRESSURE TROUGH LOCATED OVER
EASTERN NORTH DAKOTA...TO NORTHWESTERN KANSAS. WINDS REMAIN
SOMEWHAT GUSTY IN OUR WIND PRONE AREAS...BORDEAUX AND ARLINGTON GUSTING
TO 30 MPH. FAIRLY DENSE LAYER OF MID AND HIGH CLOUDS MOVING OVER
EASTERN WYOMING THIS MORNING HAS HELPED TO KEEP TEMPERATURES UP IN
THE UPPER 30S SO FAR THIS MORNING. IT IS SHOWING SIGNS OF
DISSIPATING OUT SOME THOUGH AS AREAL COVERAGE OF CLOUDS HAS BEEN
DECREASING ON SATELLITE.

GOING TO BE A WARM DAY TODAY AS 700MB TEMPERATURES CLIMB TO +7C
ACROSS OUR WESTERN ZONES. DOWNSLOPING WINDS OFF THE LARAMIE RANGE
SHOULD GIVE A A COUPLE EXTRA DEGREES OF WARMING TODAY...SO WENT
ABOVE GUIDANCE ON FORECAST HIGHS TODAY. MUCH OF THE AREA EAST OF
THE LARAMIE RANGE SHOULD SEE RECORD HIGHS TODAY.

EVEN WARMER TEMPERATURES TUESDAY AS GFS FORECASTING 700MB
TEMPERATURES UP NEAR +9C. DID GO MORE WITH THE GFS GUIDANCE ON
TEMPERATURES. INCREASING WINDS TUESDAY AS WELL SHOULD GIVE US MORE
DOWNSLOPING.

SOME DISAGREEMENT IN SHORT TERM GUIDANCE TUESDAY NIGHT INTO
WEDNESDAY. GFS 700MB WINDS UP NEAR 50KTS ACROSS SOUTHERN WYOMING
TUESDAY NIGHT INTO WEDNESDAY MORNING. NAM 700MB WINDS ALSO AT
50KTS DURING THIS TIME...BUT SHOWING LESS SURFACE WIND. GFS212
FORECAST SOUNDINGS SHOWING 50KTS RIGHT OFF THE SURFACE. WENT
AHEAD WITH A HIGH WIND WATCH FOR THE WIND PRONE AREAS AS THE GFS
HAS BEEN VERY CONSISTENT WITH THIS BORA TYPE WIND EVENT SETTING
UP. DAY SHIFT CAN TAKE ANOTHER LOOK TODAY BEFORE DECIDING TO
UPGRADE OR NOT.

.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 300 AM MST MON JAN 26 2015

THURSDAY...SYNOPTIC PATTERN REVEALS RIDGING ALOFT PREVAILING OVER
THE ROCKY MOUNTAINS...THUS DRY OVER OUR COUNTIES. SEASONABLY
TEMPERATE MAXIMUM TEMPERATURES NEAR CLIMATOLOGICAL NORMALS BASED ON
EXPECTED MIDDLE AND HIGH CLOUDS ENCROACHING FROM AN APPROACHING
SHORTWAVE TROUGH ALOFT OVER THE GREAT BASIN STATES...AND PROGGED
THICKNESSES AND 700 MB TEMPERATURES.

FRIDAY...FOR THE PENULTIMATE DAY OF JANUARY...CONTINUED NEAR
CLIMATOLOGICAL NORMALS FOR TEMPERATURES BASED ON PROGGED THICKNESSES
AND 700 MB TEMPERATURES ALONG WITH EXPECTED CLOUD COVER. BOTH THE
GFS AND ECMWF KEEP THE BULK OF PRECIPITATION TO OUR SOUTH OVER
COLORADO ASSOCIATED WITH THE SHORTWAVE TROUGH ALOFT NEAR THE FOUR
CORNERS...THOUGH WE MAY SEE ENOUGH MOISTURE AND OROGRAPHICS FOR
SCATTERED SNOW SHOWERS OVER OUR SIERRA AND SNOWY MADRE RANGES.

SATURDAY...STARK AND DRASTIC DIFFERENCES DEVELOP WITH THE GFS AND
ECMWF. THE GFS MAINTAINS BRISK NORTHWEST FLOW ALOFT OVER OUR
COUNTIES...WHEREAS THE ECMWF MAINTAINS A POSITIVELY TILTED
SHORTWAVE TROUGH FROM THE DAKOTAS SOUTHWESTWARD TO SOUTHWEST
COLORADO WITH A COLD ARCTIC TYPE AIRMASS OVER OUR COUNTIES WITH A
BROAD SWATH OF SNOW FROM CENTRAL COLORADO ACROSS OUR SOUTHEAST
COUNTIES INTO KANSAS. BASED ON PROGRESSIVE FLOW ALOFT...THE DRIER
AND WARMER GFS SOLUTION LOOKS MORE PLAUSIBLE THAN THE COLDER AND
WETTER ECMWF SOLUTION...THUS WE WILL BLEND WITH OUR SURROUNDING
NEIGHBORING OFFICES AT DENVER...GRAND JUNCTION...RIVERTON...RAPID
CITY AND NORTH PLATTE...AND KEEP IT DRY WITH HIGH TEMPERATURES AT
OR ABOVE FREEZING.

SUNDAY...ANOTHER DRAMATIC DIFFERENCE BETWEEN THE 26/00Z GFS AND
26/00Z ECMWF. THE GFS MAINTAINS STRONG NORTHWEST FLOW ALOFT WITH A
DAKOTAS SURFACE LOW AND DECENT SURFACE LEE TROUGHING ALONG THE LEE
SLOPES OF THE ROCKIES WHEREAS THE ECMWF HAS STRONG NORTH NORTHWEST
FLOW ALOFT OVER OUR COUNTIES AND THE NORTHERN PLAINS STATES AND
NORTHERN ROCKIES UNDER THE INFLUENCE OF A PSEUDO ARCTIC AIRMASS.

AGAIN...THE MUCH WARMER GFS SOLUTION LOOKS MORE PLAUSIBLE AND THUS
WE WILL BLEND WITH OUR SURROUNDING NEIGHBORING OFFICES IN
FORECASTING A MILD START TO FEBRUARY WITH MAXIMUM TEMPERATURES IN
THE 40S WEST OF INTERSTATE 25...AND MID 40S TO LOWER 50S EAST OF
INTERSTATE 25...ALONG WITH WINDY DOWNSLOPE WEST CHINOOK WINDS AIDING
IN THE WARMING. TO SEE THE STARK CONTRAST...THE GFS MOS FORECAST
HIGH FOR SUNDAY AT CHEYENNE IS 53 DEGREES WHEREAS THE ECMWF MOS HIGH
IS 28...A 25 DEGREE DIFFERENCE. AT SCOTTSBLUFF...GFS FORECAST HIGH
TEMPERATURE FOR SUNDAY IS 54 DEGREES...WITH ECMWF 32 DEGREES...
A 22 DEGREE DIFFERENCE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 1056 PM SUN JAN 25 2015

VFR.

&&

.FIRE WEATHER...
ISSUED AT 1254 AM MST MON JAN 26 2015

ELEVATED FIRE WEATHER CONDITIONS EXPECTED TUESDAY FOR AREAS EAST
OF THE LARAMIE RANGE. HAVE A COLD FRONT MOVING THROUGH THE
AREA...WITH WESTERLY WINDS INCREASING TONIGHT INTO TUESDAY.
AFTERNOON HUMIDITIES APPROACHING CRITICAL LEVELS WITH WINDS
GUSTING TO 45 MPH. WIND PRONE AREAS COULD SEE HIGHER GUSTS. THESE
WINDS ARE EXPECTED TO REMAIN STRONG INTO WEDNESDAY MORNING BEFORE
EASING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING
     FOR WYZ106-110-116-117.

NE...NONE.
&&

$$

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


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