Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 290022
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
522 PM MST WED JAN 28 2015

.UPDATE...
ISSUED AT 505 PM MST WED JAN 28 2015

A FEW LIGHT RAIN SHOWERS...AND SNOW SHOWERS OVER HIGHER
ELEVATIONS WILL CONTINUE THIS EVENING MAINLY NEAR AND WEST OF THE
LARAMIE RANGE. COULD SEE LOCALIZED LIGHT SNOW ACCUMULATIONS ON
THE ORDER OF A FEW TENTHS OF AN INCH IN THE MOUNTAINS...OTHERWISE
MAINLY LOOKING AT NUISANCE SHOWERS.

WIND ADVISORY FOR THE NEBRASKA PANHANDLE HAS BEEN ALLOWED TO
EXPIRE AS WINDS HAVE DROPPED BELOW CRITICAL THRESHOLDS. WINDS
WILL CONTINUE TO DROP OFF OVER THE NEXT FEW HOURS.

&&

.SHORT TERM...(LATE THIS AFTERNOON THROUGH FRIDAY NIGHT)
ISSUED AT 215 PM MST WED JAN 28 2015

EARLY AFTERNOON WATER VAPOR IMAGERY SHOWED THE UPPER LEVEL TROUGH
CROSSING THE HIGH PLAINS...WITH ITS ASSOCIATED SURFACE COLD FRONT
THROUGH THE NE PANHANDLE. GUSTY NORTHWEST WINDS UP TO 50 MPH
PREVAILED BEHIND THE FRONT DUE TO A TIGHT LOW LEVEL PRESSURE
GRADIENT. THE GUSTY WINDS WILL CONTINUE THROUGH LATE AFTERNOON.
REGIONAL RADARS INDICATED AREAS OF LIGHT RAIN WITH LIGHT SNOW
ABOVE 8000 FEET. DOUGLAS RECEIVED A TENTH OF AN INCH DURING THE
PAST FEW HOURS. TEMPERATURES REMAINED STEADY OR SLOWLY FELL BEHIND
THE FRONT...RANGING FROM THE 30S WEST OF THE LARAMIE RANGE...TO
THE 40S AND 50S EAST.

12Z NUMERICAL MODELS ARE IN GOOD AGREEMENT...DEPICTING A PROGRESSIVE
LARGE SCALE FLOW ACROSS THE LOWER 48. UPPER TROUGH TRACKS EAST ACROSS
THE GREAT PLAINS AND MIDWEST THROUGH THURSDAY. LINGERING POST-
FRONTAL PRECIPITATION WILL END TONIGHT. COULD SEE AN ADDITIONAL
FEW INCHES OF SNOW FOR HIGHER ELEVATIONS OUT WEST. DRIER
NORTHWESTERLY FLOW DOWNSTREAM OF INTERMOUNTAIN WEST UPPER RIDGE
WILL BECOME THE DOMINANT FEATURE. WINDS DECREASE TONIGHT WITH THE
RELAXING LOW LEVEL PRESSURE GRADIENT...WITH LIGHTER WINDS THURSDAY
THROUGH FRIDAY AS THE RIDGE AXIS MOV3ES OVERHEAD. LATE IN THE
PERIOD...A UPPER LOW PRESSURE SYSTEM WILL TRACK ACROSS NORTHERN
BAJA/SOUTHERN CA TOWARD AZ AND PRODUCE A LARGE PRECIPITATION
SHIELD OVER THE FOUR CORNERS REGION. THE NORTHERN EDGE OF THE
MOISTURE WILL SPREAD NORTH INTO FAR SOUTH CENTRAL AND SOUTHEAST WY
FRIDAY AFTERNOON AND NIGHT. ONLY LIGHT QPF IS FORECAST FROM THE
SNOWY/SIERRA MADRES EAST INTO FAR SOUTHEAST WY PLAINS.
TEMPERATURES WILL REMAIN ABOVE SEASONAL NORMALS WITH HIGHS IN THE
40S EAST AND 30S WEST...AND LOWS MAINLY IN THE 20S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 125 PM MST WED JAN 28 2015

MEDIUM RANGE MODELS CONTINUE TO SHOW A BROAD-SCALE CIRCULATION ALONG
THE US-MEXICO BORDER EARLY IN THE PERIOD. NOT MUCH HAS CHANGED FROM
OUR EARLIER THINKING WITH THIS SYSTEM BEING TOO FAR SOUTH TO HAVE AN
IMPACT ON OUR CWA. GFS/ECMWF/NAM ALL SHOW SPLIT FLOW OVER SOUTHEAST
WY AND THE WESTERN NE PANHANDLE. THE BEST H7-H3 MOISTURE REMAINS TO
THE SOUTH OF THE WY-CO STATE LINE...AND THE NORTHERN STREAM MIDLEVEL
ENERGY STAYS OUT OF REACH OVER THE WESTERN DAKOTAS. THE MODELS PAINT
VERY LITTLE/IF ANY QPF...EVEN OVER THE MOUNTAINS. WENT AHEAD AND CUT
POPS FOR MOST AREAS EXCEPT THE SOUTHERN ZONES. A COOLING TREND WILL
LIKELY PERSIST THROUGH THE WEEKEND WITH THE MAIN COLD FRONT ARRIVING
ON SUNDAY...FORCING H7 TEMPS TO BETWEEN -8 AND -10 DEG C EAST OF THE
LARAMIE RANGE. THE GFS SUGGESTS STRENGTHENING LLVL GRADIENTS BY LATE
SUN NIGHT OR EARLY MON AS A SURFACE LOW OVER NORTHERN WY CONTRIBUTES
TO PRESSURE FALLS OVER THE PLAINS. H7-H8 WINDS ARE PROGGED ABOVE 50
KTS DURING THAT TIME...SO WOULD NOT BE SURPRISED TO SEE A HIGH WIND
EPISODE FOR THE WIND PRONE. MODELS ARE IN DECENT AGREEMENT WITH THE
NORTHERN STREAM TAKING OVER THE FLOW PATTERN ON TUE/WED. A FEW WEAK
DISTURBANCES AND PERIODIC SHOTS OF MID LEVEL MOISTURE SHOULD SUPPORT
LOW END PCPN CHANCES THROUGH MID WEEK...BUT NO MAJOR STORMS APPEAR
LIKELY AT THIS TIME.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 505 PM MST WED JAN 28 2015

LINGERING LIGHT RAIN AND SHOW SHOWERS WILL OCCUR ALONG AND WEST OF
THE LARAMIE RANGE THIS EVENING WITH A FEW SNOW SHOWERS INTO THE
MOUNTAINS THROUGH AROUND 09Z THURSDAY MORNING. ISOLATED IFR WITH
ANY HEAVIER SNOW SHOWERS OTHERWISE MAINLY VFR TO MVFR FOR THE
AFOREMENTIONED AREAS. MOUNTAIN TOPS WILL BE OBSCURED TONIGHT AS
WILL ENTIRE MOUNTAINS AT TIMES. EAST OF THE LARAMIE RANGE VFR
EXPECTED THROUGH THE TAF PERIOD.

&&

.FIRE WEATHER...
ISSUED AT 125 PM MST WED JAN 28 2015

NO FIRE WEATHER CONCERNS THROUGH THE UPCOMING WEEKEND. GUSTY
NORTHWEST WINDS...COOLER TEMPERATURES...HIGHER HUMIDITIES AND
SOME PRECIPITATION WILL SPREAD ACROSS THE DISTRICT THIS AFTERNOON
IN THE WAKE OF THE MORNING COLD FRONTAL PASSAGE. WINDS WILL
FREQUENTLY GUST TO 50 MPH THIS AFTERNOON...THEN DIMINISH TONIGHT
WITH THE RELAXING PRESSURE GRADIENT. SNOW WILL END FROM NORTH TO
SOUTH ALONG AND WEST OF THE LARAMIE RANGE TONIGHT...WITH ANOTHER
ONE TO THREE INCHES POSSIBLE FOR ELEVATIONS ABOVE 8000 FEET. DRIER
CONDITIONS AND LIGHTER WINDS WILL RETURN THURSDAY AND FRIDAY...WITH
MINIMUM HUMIDITIES BETWEEN 35 AND 40 PERCENT. A LOW PRESSURE SYSTEM
WILL MOVE ACROSS THE CENTRAL AND SOUTHERN ROCKIES THIS WEEKEND. WHILE
THE BULK OF THE PRECIPITATION WILL FALL SOUTH OF WYOMING...THERE IS
A CHANCE FOR LIGHT PRECIPITATION OVER PORTIONS OF SOUTHEAST WYOMING
AND WESTERN NEBRASKA.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

WY...NONE.
NE...NONE.

&&

$$

UPDATE...SML
SHORT TERM...MJ
LONG TERM...CLH
AVIATION...SML
FIRE WEATHER...MJ



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