Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 241726
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1020 AM MST SAT JAN 24 2015

.UPDATE...
ISSUED AT 1020 AM MST SAT JAN 24 2015

WINDS SEEM TO BE HOLDING STEADY WITH GUSTS IN THE MID 50S NEAR
ARLINGTON AND IN THE SOUTHERN LARAMIE RANGE FOOTHILLS...SO WILL
MAINTAIN SPS HEADLINES FOR THESE LOCATIONS FOR NOW. WILL KEEP A
CLOSE EYE OUT FOR ANY SUBSTANTIAL BREAKS IN THE THICK CIRRUS DECK
AS THAT SITUATION COULD PROMOTE JUST ENOUGH MIXING TO BRING
STRONGER GUSTS TO THE SURFACE...AND THUS A NEED FOR A SHORT FUSED
HIGH WIND WARNING. THE HIGH WIND WARNING FOR BORDEAUX AREA
REMAINS IN GOOD SHAPE FOR NOW. OTHERWISE...TRENDS CONTINUE TO
SUGGEST THE GRADIENT WILL RELAX THRU THE AFTERNOON AS THE WEAK
COLD FRONT MOVES ACROSS THE PLAINS...WITH WINDS EASING AS A
RESULT. BUMPED UP POPS INTO THE CHANCE CATEGORY FOR THE EASTERN
PLAINS...IN PARTICULAR THE PINE RIDGE AND LOCALES DOWNSTREAM OF
THE NORTH LARAMIE RANGE...BASED ON RADAR TRENDS AND CURRENT OBS
DEPICTING LIGHT SHOWERS IN NORTHERN WY MOVING SOUTHEAST. PRECIP
TYPE SHOULD REMAIN LIGHT RAIN AS TEMPS WILL LIKELY HOLD IN THE MID
40S.

&&

.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 139 AM MST SAT JAN 24 2015

WEST WINDS HAVE REALLY STARTED TO RAMP UP IN THE BORDEAUX AREA THIS
MORNING. RECENT HIGHWAY OBSERVATIONS HAVE ALREADY SHOWN A FEW GUSTS
APPROACHING 55 MPH WITH SUSTAINED WINDS HOVERING AROUND 40 MPH. THIS
IS A BIT EARLIER THAN EXPECTED AS GRADIENTS ARE NOT EXPECTED TO PEAK
UNTIL LATER THIS AM. THE NAM H85 CAG-CPR GRADIENT CONTINUES TO CLIMB
THROUGH THE MORNING WITH A MAX OF 64 METERS AROUND 12Z. WEST-TO-EAST
ORIENTED LLVL GRADIENTS MORE FAVORABLE FOR BORDEAUX REACH THEIR PEAK
AROUND 18Z. EXPECT SUBSIDENCE TO GRADUALLY INCREASE THROUGH THE AFTN
IN THE RFQ OF A 130 KT H25 JET SHIFTING INTO WESTERN NE. STILL SOME
QUESTIONS AS MODELED DOWNWARD H85-H5 OMEGA NEVER SPREADS FAR ENOUGH
EAST TO ENCOMPASS BORDEAUX...BUT BELIEVE CURRENT WINDS WOULD BE LESS
IF THIS WAS A MAJOR INHIBITING FACTOR. WENT AHEAD AND ISSUED A HIGH
WIND WARNING FOR BORDEAUX AS 50-55 KT FLOW ALOFT IS PROGGED TO STAY
INTACT ALONG WITH GRADIENTS ONLY GETTING STRONGER. OTHER WIND PRONE
AREAS WILL BE WINDY AS WELL...BUT GENERALLY EXPECT GUSTS TO BE A BIT
LESS WITH AN UNFAVORABLE ORIENTATION OF HEIGHT/MSLP GRADIENTS. WILL
NEED TO WATCH THE SOUTH LARAMIE RANGE THIS AFTERNOON AS MIXING COULD
TAP INTO STRONGER FLOW ALOFT BEFORE CLOUDS INCREASE. MAV GUIDANCE AS
WELL AS GFS BUFKIT SOUNDINGS ARE A BIT CONCERNING FOR THE INTERSTATE
80 CORRIDOR OVER THE PLAINS AS WELL WITH 40 TO 50 KT FLOW AT THE TOP
OF THE MIXED LAYER AROUND MID AFTN. INCREASED WINDS...BUT DID NOT GO
AS STRONG AS THE GFS WOULD SUGGEST AS CLOUDS COULD AFFECT LLVL LAPSE
RATES.

LATEST WATER VAPOR SATELLITE LOOP WAS INDICATIVE OF A STRONG MIDLVL
SHORTWAVE OVER ALBERTA/BRITISH COLUMBIA AT 09Z. GFS/NAM/ECMWF ARE IN
GOOD AGREEMENT WITH THIS FEATURE DEEPENING CONSIDERABLY AS IT DIVES
INTO NORTHERN NE BY 00Z SUN. THIS WILL ALSO DRIVE A WEAK COLD FRONT
ACROSS SOUTHEAST WY AND THE WESTERN NE PANHANDLE THIS AFTN. STILL A
FEW QUESTIONS WITH JUST HOW STRONG THIS FRONT WILL BE...AND WHETHER
IT WILL BE CAPABLE OF GENERATING WIDESPREAD SHOWERS. 00Z NAM SHOWS
VERY LITTLE IN THE WAY OF QPF...WHILE THE THE GFS AND ECMWF PAINT A
BAND OF VERY LIGHT QPF WITH GOOD FRONTOGENESIS. WILL SIDE TOWARD THE
GFS AS PLENTY OF MID AND HIGH LEVEL MOISTURE IS EVIDENT UPSTREAM ON
SATELLITE IMAGERY. ENOUGH CONFIDENCE TO BUMP UP POPS FOR ALL AREAS
EAST OF THE LARAMIE RANGE THIS AFTERNOON. IN EITHER CASE...THIS WILL
BE LOW IMPACT AS PRECIPITATION SHOULD BE RAIN WITH THE WARM THERMAL
ENVIRONMENT IN PLACE OVER THE CWA. THE MODELS SUGGEST HIGH-AMPLITUDE
RIDGING ENCOMPASSING MUCH OF THE WESTERN CONUS ON SUN AND MON. LARGE
SCALE SUBSIDENCE AND VERY WARM TEMPERATURES ALOFT SUGGESTS A RECORD
HIGHS COULD BE THREATENED ON MON. H7 TEMPS COULD APPROACH 5-6 DEG C
AND MOST MOS GUIDANCE STILL SUGGESTS WIDESPREAD HIGHS IN THE MID 60S
OVER THE PLAINS...SO EXPECT A VERY WARM AND PLEASANT DAY. A POSSIBLE
LIMITING FACTOR FOR TEMPS WILL BE ANY HIGH CLOUDS THAT MAY ACCOMPANY
THE RIDGE AXIS...BUT GFS H25 RH PROGS DO NOT SUGGEST THICKER CIRRUS
UNTIL WELL BEYOND PEAK HEATING. CONTINUED TO TREND WARMER FOR HIGHS
ON MON.

.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 300 AM MST SAT JAN 24 2015

PRETTY NICE DAY TUESDAY WITH A RIDGE OF HIGH PRESSURE OVERHEAD.
700MB TEMPERATURES REMAIN WARM...GFS SHOWING +6 TO +7C...ECMWF A
LITTLE COOLER WITH +5C. REGARDLESS...TUESDAY SHOULD BE WARM AND
DRY WITH WIDESPREAD 60S EAST OF THE LARAMIE RANGE AND LOW TO MID
50S WEST. DID GO A LITTLE HIGHER THAN GUIDANCE ON TEMPERATURES.
GOING TO BE WINDY WEST WITH 700MB WINDS 40 TO 45KTS...SO
DOWNSLOPING OFF THE LARAMIE RANGE SHOULD HELP WITH WARMER
TEMPERATURES.

HAVE A SHORTWAVE TROUGH MOVING INTO THE AREA TUESDAY NIGHT THAT
SHOULD BEGIN TO COOL THINGS OFF. GFS 700MB TEMPERATURES FALL TO -2
TO -4C WEDNESDAY AFTERNOON. GFS DRY WITH THE ASSOCIATED COLD FRONT
MOVING THROUGH WHILE THE ECMWF HAS FAIRLY WIDESPREAD QPF OFF TO
THE WEST IN CARBON AND ALBANY COUNTIES. DID INCREASE POPS OUT WEST
AND IN THE MOUNTAINS.

SOMETHING TO WATCH FOR...THE GFS HITTING US PRETTY HARD FOR
THURSDAY NIGHT/FRIDAY WITH A POTENT SHORTWAVE MOVING IN FROM THE
NORTHWEST. QUICK MOVING THOUGH WITH PRECIP ENDING BY SATURDAY
MORNING. ECMWF HAS THIS SHORTWAVE PASSING OFF TO THE NORTH AND
EAST OF OUR CWFA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING)
ISSUED AT 1020 AM MST SAT JAN 24 2015

VFR CONDITIONS EXPECTED TO PREVAIL OVER THE TERMINALS THROUGH SUNDAY
THOUGH A PERIOD OF MVFR CIGS NOT OUT OF THE QUESTION IN WDLY SCTD
SHOWERS THROUGH THIS EVENING.

&&

.FIRE WEATHER...
ISSUED AT 139 AM MST SAT JAN 24 2015

NO MAJOR FIRE WEATHER CONCERNS. GUSTY WINDS ARE EXPECTED ACROSS MUCH
OF THE AREA THIS WEEKEND...BUT ALL OTHER PARAMETERS ARE EXPECTED TO
BE NON-CRITICAL.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WARNING UNTIL 5 PM MST THIS AFTERNOON FOR WYZ106.

NE...NONE.
&&

$$

UPDATE...RJM
SHORT TERM...CLH
LONG TERM...GCC
AVIATION...RE
FIRE WEATHER...CLH



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