National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS65 KCYS 301140
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
440 AM MST SAT NOV 30 2013

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 325 AM MST SAT NOV 30 2013

A CHANGE IN THE WEATHER PATTERN BEGINNING TO TAKE SHAPE FOR THE
UPCOMING WEEK. FORECAST CHALLENGES IN THE SHORT TERM DEAL
PRIMARILY WITH STRONG WIND TIMING AND LOCATIONS.

CURRENTLY...FAIRLY TRANQUIL CONDITIONS EARLY THIS MORNING WITH
MOSTLY CLEAR SKIES AS HIGH PRESSURE TO OUR SOUTH REMAINS IN
CONTROL. SOME OF OUR WIND PRONE AREAS ARE SEEING GUSTY
WINDS...NAMELY BORDEAUX AND ARLINGTON. ELSEWHERE...WINDS ARE 10MPH
OR LESS THIS MORNING. LOW PRESSURE CURRENTLY OUT IN THE SOUTHERN
GULF OF ALASKA WILL BE OUR NEXT WEATHER PRODUCER HERE OVER THE
NEXT SEVERAL DAYS.

TODAY LOOKS TO BE FAIRLY NICE WITH FAIR SKIES. IT LOOKS TO BECOME
BREEZY THIS AFTERNOON FOR QUITE A FEW OF US HERE IN SOUTHEAST
WYOMING AS 700MB WINDS INCREASE AGAIN TO 40KTS. SHOULD SEE GUSTS
IN THE 20S FOR MOST LOCATIONS OUTSIDE THE MOUNTAINS WITH 40MPH
GUSTS OVER HIGHER TERRAIN AND WIND PRONE AREAS.

GRADIENT REALLY BEGINS TO TIGHTEN UP TONIGHT INTO SUNDAY MORNING.
THE CRAIG TO CASPER 700MB HEIGHT GRADIENT UP TO 50MTRS BY 12Z
SUNDAY...THEN 70MTRS BY 18Z. HAVE GONE AHEAD WITH A HIGH WIND
WATCH FOR OUR WIND PRONE AREAS FOR SUNDAY 18Z THROUGH MONDAY
AFTERNOON AS 700MB WINDS INCREASE TO 50KTS AT 18Z AND CONTINUE TO
INCREASE TO 65KTS SUNDAY EVENING ACROSS SOUTHEAST WYOMING. WITH
THAT IN MIND...DO THINK THIS WILL BECOME A MORE WIDESPREAD WIND
EVENT. BY 06Z SUNDAY NIGHT/MONDAY MORNING...LOCAL WRKHGT PRODUCT
HAS 850/700MB CRAIG-CASPER HGT GRADIENTS INCREASING TO 74/65 MTRS
RESPECTIVELY AFTER 06Z. WENT AHEAD WITH A HIGH WIND WATCH FOR
NORTHERN CARBON COUNTY...MOST OF ALBANY AND WESTERN LARAMIE/PLATTE
COUNTIES. CHEYENNE MAY BE JUST ON THE CUSP OF SEEING THESE HIGH
WINDS. DECIDED TO INCLUDE THE CITY ANYWAY IN THE WATCH AND LET THE
DAY SHIFT TAKE ANOTHER LOOK THIS AFTERNOON.

WITH THE STRONG UPSLOPING WINDS...THE SNOWY AND SIERRA MADRE
RANGES COULD BE SEEING SOME HEAVY SNOWS...AS WELL AS THE STRONG
WINDS SUNDAY AFTERNOON INTO MONDAY. GFS 700MB WINDS OVER THESE
RANGES AT 65KTS AND ECMWF/NAM PAINTING CLOSE TO A HALF INCH OF
QPF. IN THESE STRONG UPSLOPE EVENTS THOUGH...MODEL QPF IS
TYPICALLY UNDERDONE. AGAIN...DAY SHIFT CAN TAKE ANOTHER LOOK
BEFORE DECIDING ON WHAT TO DO WITH THE WINTER STORM WATCH.

MODELS DRY OUT THE MOUNTAINS MONDAY AFTERNOON AND SLOWLY DECREASE
WINDS...SO HAVE TIMING ON ALL WATCHES ENDING MONDAY AFTERNOON.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MST SAT NOV 30 2013

SOUTHWEST WINDS WILL CONTINUE TO BE STRONG IN THE WIND PRONE AREAS
THROUGH MONDAY NIGHT...AND WILL GRADUALLY EASE THROUGH THE MORNING
AS THE STRONG ARCTIC FRONT BEGINS TO PLOW SOUTH TOWARD THE FORECAST
AREA. MODELS ARE IN SLIGHT DISAGREEMENT WITH WHEN THE FRONT WILL
BLAST THROUGH...WITH THE GFS AND SREF BASICALLY THROUGH BY 18Z...AND
NAM AND ECMWF ABOUT 6HRS SLOWER. THAT WILL MAKE A DIFFERENCE ON MAX
TEMPS FOR TUESDAY...AND MAINTAINED THE TREND FOR MILD TEMPS IN THE
SOUTHERN ZONES THROUGH THE MORNING...WITH FALLING TEMPS THROUGH THE
REMAINDER OF THE DAY.

MODELS SHOW SOME DIFFERENCES IN HANDLING THE STRONG UPPER TROUGH
THAT WILL BRING SNOW AND BITTERLY COLD TEMPS TO THE FORECAST AREA
THROUGH THE REMAINDER OF THE PERIOD. THE ECMWF IS TRENDING QUICKER
WITH THE MAIN PIECE OF UPPER LEVEL ENERGY AND ITS ASSOCIATED SFC
LOW. BOTH FEATURES ARE WELL EAST OF THE CWA BY 00Z THURSDAY
ACCORDING TO THE ECMWF...WHILE THE GFS DEVELOPS A STRONGER CO LEESIDE
SFC LOW WITH LESS PROGRESSIVE UPPER LEVEL ENERGY DURING THIS TIME.
AS CAN BE EXPECTED...THIS WILL HAVE A SIGNIFICANT IMPACT ON HOW
MUCH SNOW WILL FALL OVER THE FORECAST AREA TUESDAY THROUGH
WEDNESDAY NIGHT. WINDS WILL SWITCH TO A NORTHERLY FETCH BEHIND THE
ARCTIC FRONT ALTHO GFS DEVELOPS NORTHEAST WINDS WHILE EC BRINGS IN
NORTHWESTERLIES DUE TO THE PROGRESSIVE NATURE OF THE UPPER LEVEL
ENERGY. THIS WILL HAVE MAJOR IMPACT ON LONGEVITY OF UPSLOPE
CONTRIBUTION TO OVERALL LIFT...AND MAY INSTEAD INTRODUCE
DOWNSLOPE DRYING DEPENDING ON WHETHER THE EC VERIFIES. LOOKING
BACK AT THE PAST COUPLE OF MODEL RUNS...LOOKS LIKE THE CURRENT
SUITE OF MODELS IS SLIGHTLY MORE PROGRESSIVE SO WILL HIT POPS
FAIRLY HARD ON TUESDAY AND WEDNESDAY WHEN THE STRONGEST COMBO OF
SYNOPTIC AND MESOSCALE LIFT WILL BE IN PLACE. WILL QUICKLY END THE
SNOW FROM NW TO SE WEDNESDAY NIGHT INTO THURSDAY. STILL LOOKS TO
BE A FAIRLY WIDESPREAD SNOW EVENT...WITH THE HIGHEST QPF PROJECTED
TO BE OVER SOUTHEAST WYOMING MOUNTAINS AND NEARBY PLAINS.

TEMPERATURES WILL FALL RADICALLY BEHIND THE FRONT WITH MAX TEMPS
LIKELY STRUGGLING TO MAKE IT OUT OF THE SINGLE DIGITS ON
THURSDAY. AS SKIES BEGIN TO CLEAR AND WINDS EASE THURSDAY NIGHT
WITH THE SFC HIGH MOVING INTO THE FORECAST AREA...WILL SEE TEMPS
PLUMMET TO SOME OF THE COLDEST READINGS OF THE SEASON SO FAR. 700
MB TEMPS ARE PROGGED TO DROP BETWEEN MINUS 22 AND MINUS 24 CELSIUS
THURSDAY NIGHT AS THE UPPER TROUGH MOVES OVERHEAD...WHICH SHOULD
TRANSLATE INTO MIN TEMPS WELL BELOW ZERO FOR MOST IF NOT ALL OF
THE FORECAST AREA. SOME OF THE HIGH VALLEYS OUT WEST AND MORE
SHELTERED LOWER ELEVATIONS OUT EAST COULD DROP INTO THE MINUS MID
TEENS. FINALLY...ANOTHER WEAK SHORTWAVE WITH MIDLEVEL MOISTURE
PLUME WILL BRING ANOTHER CHANCE FOR LIGHT SNOW TO MAINLY WESTERN
AREAS ON FRIDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 440 AM MST SAT NOV 30 2013

VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH THE PERIOD.
SNOW SHOWERS WILL DEVELOP LATE TONIGHT OVER THE SNOWY AND SIERRA
MADRE MOUNTAINS...AND WILL OBSCURE THE PEAKS. THESE SHOWERS LOOK TO
PERSIST THROUGH EARLY NEXT WEEK. WEST WINDS WILL BECOME GUSTY
AT THE WYOMING TAF SITS AFTER 17Z TODAY...AND WILL EASE JUST BEFORE
SUNSET. BREEZY CONDITIONS ARE THEN EXPECTED TO RETURN TONIGHT FOR
KRWL...KLAR AND KCYS WITH STRONG WINDS BECOMING MORE WIDESPREAD
ACROSS SOUTHEAST WYOMING LATE SUNDAY MORNING.

&&

.FIRE WEATHER...
ISSUED AT 325 AM MST SAT NOV 30 2013

WINDS TO REMAIN BREEZY TODAY AND TONIGHT WITH INCREASING WINDS
THROUGH THE DAY SUNDAY INTO MONDAY. THEY COULD BECOME QUITE STRONG
SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR AREAS ALONG AND WEST
OF THE LARAMIE RANGE AND IMMEDIATELY TO THE EAST HERE NEAR
CHEYENNE AND UP BY WHEATLAND. FORTUNATELY...WE ARE LOOKING AT
AFTERNOON HUMIDITIES TO REMAIN IN THE 20S AND LOW 30S THROUGH
MONDAY WITH FAIR TO EXCELLENT OVERNIGHT RECOVERIES. SNOW WILL
BECOME WIDESPREAD NEXT WEEK FROM TUESDAY THROUGH THURSDAY. MOST
LOCATIONS WILL SEE ACCUMULATING SNOWS AS A LOW PRESSURE SYSTEM
TRACKS THROUGH THE AREA.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH MONDAY AFTERNOON
     FOR WYZ112-114.

     HIGH WIND WATCH FROM SUNDAY MORNING THROUGH MONDAY AFTERNOON FOR
     WYZ106-110-116-117.

     HIGH WIND WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR
     WYZ104-105-107-109-115-118.

NE...NONE.
&&

$$

SHORT TERM...CLAYCOMB
LONG TERM...RJM
AVIATION...RJM
FIRE WEATHER...CLAYCOMB