Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 282124
AFDCYS

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

.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 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1040 AM MST WED JAN 28 2015

VFR TO OCCASIONAL MVFR CEILINGS ARE EXPECTED TODAY WITH WINDS
BECOMING NORTHWEST BEHIND A COLD FRONT. BREEZY TO LOCALLY WINDY
CONDITIONS ARE LIKELY FOR ALL LOCATIONS WITH GUSTS TO 40 KTS
POSSIBLE. A FEW RAIN AND/OR SNOW SHOWERS WILL BE POSSIBLE TODAY
AND TONIGHT AT MOST TERMINALS ACROSS SOUTHEAST WY AND THE WESTERN
NE PANHANDLE. LOCALIZED IFR CIGS/VSBYS ARE UNLIKELY...BUT CANNOT
BE COMPLETELY RULED OUT IN THE NEXT 12 HOURS. IMPROVING CONDITIONS
ARE EXPECTED OVERNIGHT.

&&

.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...WIND ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR NEZ002-003-
     019>021-054-055-095-096.

&&

$$

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



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