Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 261726
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1025 AM MST THU FEB 26 2015

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 330 AM MST THU FEB 26 2015

VERY COLD DAY IN STORE FOR THE REGION WITH 700MB TEMPS AROUND -20C
AND WIDESPREAD CLOUD COVER.  HIGHS WILL STRUGGLE TO GET ABOVE 20
WHICH IS AROUND 30 DEGREES BELOW NORMAL FOR LATE FEB.  NOT EXPECTING
MUCH SNOW THROUGH MIDDAY.  ALL MODELS INDICATE LIGHT SNOW DEVELOPING
ALONG INTERSTATE 80 FROM ARLINGTON TO CHEYENNE DURING THE AFTN.
THIS OCCURS AS SFC WINDS BECOMING MORE EASTERLY AND LOW LEVEL UPSLOPE
IMPROVES...ESPECIALLY EAST OF THE LARAMIE RANGE. MAIN CHANGE TO
THE FCST WAS TO INCREASE POPS TO 60-70 PERCENT AND INCREASE QPF
SLIGHTLY DURING THE EVENING ALONG THE CHEYENNE RIDGE. LOW LEVEL WINDS
GO SOUTHEASTERLY AND SOUNDINGS INDICATE DECENT UPWARD MOTION FROM
THE SFC TO AROUND 5000 FT AGL. IT IS INTERESTING TO NOTE THAT THIS
IS ACTUALLY IN THE DENDRITIC GROWTH ZONE SINCE LOW LEVEL TEMPS
ARE SO COLD. WHILE THE SNOWFALL RATES AND WINDS ARE LIKELY NOT
ENOUGH TO WARRANT A WINTER WEATHER ADVISORY...CURRENTLY HAVE
ACCUMULATIONS OF 1-3 INCHES FROM THIS AFTN THROUGH FRI MORNING
FROM THE INTERSTATE 80 SUMMIT TO CHEYENNE. PRECIP CHANCES REALLY
DROP OFF TO THE NORTH AND EAST OF CHEYENNE WITH LESS THAN AN INCH
EXPECTED. ALTHOUGH IFR/LIFR CIGS WILL OCCUR ALONG THE CHEYENNE
RIDGE TONIGHT...SOUNDINGS SUGGEST THE FOG THREAT WILL BE MINIMAL
SO DROPPED THE PATCHY FOG.

REMAINDER OF SHORT TERM WILL FEATURE COLD TEMPS WITH GENERALLY WEAK
WINDS.  SOUTHERLY SFC WINDS OVER THE PLAINS THROUGH THE EARLY AFTN
ON FRI WILL KEEP LOW CLOUDS PERSISTENT...ESPECIALLY ALONG THE
CHEYENNE RIDGE.  TEMPS WILL RISE AROUND 5 DEGREES MOSTLY IN AREAS
THAT CLEAR DURING THE MORNING.  PRECIP CHANCES WILL BE SLIM FROM FRI
MORNING THROUGH MIDDAY SAT.  IT IS AFTER 18Z SAT THAT SCATTERED SNOW
SHOWERS COULD RETURN TO AREAS ALONG THE COLORADO BORDER.  ISENTROPIC
LIFT DEVELOPS BY SAT AFTN BUT MORESO BY SAT EVENING.  THE GFS HAS
BEEN CONSISTENT AT SHOWING THE HIGHEST QPF AMOUNTS (0.05-0.1 INCHES)
FROM MIDDAY SAT INTO THE EVENING.  SO AT THIS POINT IT IS JUST LIGHT
SNOW AMOUNTS...WHICH IS REALLY THE THEME THROUGH THE WEEKEND.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 AM MST THU FEB 26 2015

A CONSENSUS OF THE 00Z MEDIUM RANGE MODEL GUIDANCE MAINTAINS A
POSITIVELY TILTED UPPER TROUGH BISECTING THE NATION FROM NORTHEAST
TO SOUTHWEST...REINFORCED BY PERIODIC SHORTWAVES INTO EARLY NEXT WEEK.
THE TROUGH BEGINS TO SHIFT EASTWARD IN RESPONSE TO FLATTENING OF THE
EASTERN PACIFIC UPSTREAM RIDGE BY MIDWEEK. LOOKING AT A COMPLICATED
SURFACE PATTERN THIS WEEKEND WITH A SERIES OF LOW PRESSURE SYSTEMS
IMPACTING THE FOUR CORNERS ACROSS THE CENTRAL/SOUTHERN ROCKIES AND
HIGH PLAINS. COLD HIGH PRESSURE RIDGE WILL TAKE RESIDENCE ACROSS
THE NORTHERN ROCKIES...PLAINS AND MIDWEST. ABUNDANT PACIFIC MOISTURE
AND FAVORABLE UPSLOPE FLOW WILL RESULT IN WIDESPREAD PRECIPITATION...
WITH FOCUS FOR HEAVIER QPF TO THE SOUTH OF THE CWA THROUGH MONDAY.
INCREASED POPS TO 60-70 PERCENT FOR THE SOUTHERN MOUNTAINS SATURDAY
NIGHT...DECREASING TO 30-50 PERCENT SUNDAY THROUGH MONDAY. BEST
CHANCE FOR MOISTURE FOR THE PLAINS WILL BE SATURDAY NIGHT. SUNDAY`S
TEMPERATURES WILL REMAIN IN THE 20S. A SLIGHT MODERATION IN TEMPERATURES
COMMENCES MONDAY WITH SOUTHERLY FLOW PUSHING THE MERCURY TO LOWER-MID
30S. ANOTHER ARCTIC COLD SURGE ARRIVES TUESDAY WITH CHANCES FOR
LIGHT SNOW INTO WEDNESDAY ALONG WITH MUCH BELOW NORMAL TEMPERATURES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY MORNING)
ISSUED AT 1025 AM MST THU FEB 26 2015

MVFR/IFR CIGS AND VSBYS WILL AFFECT PARTS OF THE AREA...PRIMARILY
FAR SE WY AND SOUTHERN NEBRASKA TERMINALS...THROUGH THIS EVENING
BEFORE IMPROVING SLOWLY OVERNIGHT INTO FRIDAY MORNING.  AREAS OF
LIGHT SNOW WILL PERSIST OVER SE WY THROUGH THIS EVENING MAINLY
AFFECTING KCYS AND KLAR.

&&

.FIRE WEATHER...
ISSUED AT 249 AM MST THU FEB 26 2015

NO FIRE WEATHER CONCERNS THROUGH EARLY NEXT WEEK. TEMPERATURES WILL
REMAIN WELL BELOW NORMAL WITH HIGH RELATIVE HUMIDITY VALUES.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...FINCH
LONG TERM...JAMSKI
AVIATION...JAMSKI
FIRE WEATHER...FINCH



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