Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 271800
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1200 PM MDT MON APR 27 2015

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 350 AM MDT MON APR 27 2015

CURRENT KCYS AND KFTG RADAR MOSAIC SHOWS A DEFORMATION PRECIP
BAND STRETCHING FROM SOUTHEAST COLORADO NORTHWEST ACROSS THE I25
CORRIDOR OF SOUTHEAST WYOMING. THIS BAND HAS PRODUCED LOCAL
SNOWFALL RATES OF 2 INCHES PER HOUR AROUND CHEYENNE AROUND
MIDNIGHT LAST NIGHT WITH 1 TO 3 INCHES OF SNOW ACCUMULATION
REPORTED AROUND LARAMIE COUNTY AND PORTIONS OF THE CHEYENNE RIDGE
ABOVE 5500 FEET. THANKFULLY...THIS BAND IS SHOWING SIGNS OF
WEAKENING AT THIS HOUR WITH PRECIP RATES A BIT LESS INTENSE AT 4
AM. MODELS DO SHOW AN INTENSE VORT MAX OVER THE AREA WHICH PUSHED
SOUTHEAST TO NORTHWEST OVERNIGHT. BELIEVE THIS FEATURE PLAYED A
PART IN SOME OF THE REALLY INTENSE RAIN AND SNOWFALL RATES ACROSS
EXTREME SOUTHEAST WYOMING AND PORTIONS OF SOUTHERN NEBRASKA. FOR
NOW...CANCELLED THE WINTER WEATHER ADVISORIES FOR THE MOUNTAINS
SINCE THE DEFORMATION BAND DID NOT MAKE IT THAT FAR WEST...,AND IS
NOT EXPECTED TO DO SO OVER THE NEXT 3 HOURS. HOWEVER...ICY ROADS
HAVE BEEN REPORTED ON THE I80 SUMMIT TONIGHT WITH TEMPERATURES
SLIGHTLY BELOW FREEZING.

MODELS SHOW THE UPPER LEVEL LOW OVER THE TEXAS PANHANDLE REMAINING
NEARLY STATIONARY THROUGH THE DAY TODAY. THEREFORE...EXPECT THE
DEFORMATION PRECIP BAND TO REMAIN OVER SOUTHEAST WYOMING THROUGH
THE DAY. PRECIP TYPE SHOULD MAINLY BE RAIN TODAY...BUT CAN NOT
RULE OUT SOME SNOW MIXING IN AT TIMES DOWN TO 6000 FEET BASED ON
CURRENT SNOWLEVEL TRENDS. PRECIP RATES SHOULD BE LIGHT...SO KEPT
POP AROUND 30 PERCENT FOR SCATTERED RAIN SHOWERS BELOW 6000 FEET
AND RAIN/SNOW SHOWERS ABOVE 6000 FEET. EXPECT ANY FOG TO LIFT BY
MIDDAY...BUT OVERCAST SKIES SHOULD REMAIN OVER MOST OF THE AREA
WITH THE EXCEPTION OF THE LOWER ELEVATIONS OF CARBON AND ALBANY
COUNTIES...WHICH SHOULD START TO SEE SOME SUNSHINE IN THE
AFTERNOON. FOR TONIGHT...NOT COMPLETELY CONVINCED THAT THIS
DEFORMATION BAND WILL NOT PRODUCE SOME WIDELY SCATTERED RAIN
SHOWERS THROUGH THE NIGHT. THE NAM AND SREF CONTINUE TO SHOW AN
INCREASE IN PRECIP RATES BETWEEN 03Z TO 09Z TONIGHT. KEPT LOW POP
BETWEEN 20 TO 40 PERCENT EAST OF A LINE FROM LARAMIE TO LUSK.

FOR TUESDAY AND WEDNESDAY...EXPECT CONDITIONS TO GRADUALLY
IMPROVE EARLY TUESDAY MORNING AS THE UPPER LEVEL LOW MOVES INTO
THE OZARK`S AND WEAKENS. MODELS INDICATE A HIGH AMPLITUDE RIDGE
AXIS MOVING INTO THE ROCKY MOUNTAIN REGION FOR TUESDAY AND
WEDNESDAY...RESULTING IN TEMPERATURES CLIMBING TO NEAR AVERAGE
LEVELS FOR THIS TIME OF THE YEAR ON TUESDAY AND INTO THE 70S ON
THURSDAY ACROSS MOST OF THE AREA. KEPT POP BELOW 10 PERCENT BOTH
DAYS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 320 AM MDT MON APR 27 2015

MILD TEMPERATURES WILL BE OVER THE CWA THIS PERIOD. MAINLY DRY
CONDITIONS EXPECTED ON THURSDAY THEN UNSETTLED CONDITIONS FRIDAY
THROUGH SUNDAY WITH DAILY CHANCES FOR SHOWERS AND A FEW TSTRMS.
UPPER RIDGE AXIS WILL PASS EAST OF THE CWA WEDS NIGHT LEAVING A
GENERALLY ZONAL FLOW OVER THE AREA THURSDAY THROUGH THE WEEKEND.
SEVERAL IMPULSES WILL EJECT EAST ACROSS THE AREA FROM AN UPPER LOW
OVER SRN CALIFORNIA AND THESE DISTURBANCES SHOULD INTERACT WITH
SOME DAYTIME INSTABILITY TO SET OFF AT LEAST SCTD SHOWERS AND A
FEW TSTRMS. ANY SNOWS SHOULD BE CONFINED TO THE HIGHEST MTNS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1152 AM MDT MON APR 27 2015

IFR CIGS WILL CONTINUE AT CYS THROUGH AROUND 21Z...WITH MVFR AND
VFR CIGS ELSEWHERE THROUGH THE AFTERNOON. WITH LIGHT WINDS
OVERNIGHT...FOG IS EXPECTED TO DEVELOP AT CYS AND LAR IN THE HOURS
BEFORE SUNRISE ON TUES. ALSO INCLUDED MVFR VIS AT RWL WHERE
CONFIDENCE IS NOT AS HIGH FOR FOG DEVELOPMENT. WINDS THROUGH THE
TAF PERIOD WILL GENERALLY BE LESS THAN 10-15 KTS.

&&

.FIRE WEATHER...
ISSUED AT 227 AM MDT MON APR 27 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO RECENT WETTING RAINFALL
AND UNSETTLED WEATHER CONTINUING INTO MONDAY. RAIN SHOWERS WILL
BECOME MORE ISOLATED TODAY AND TONIGHT AS THE PACIFIC STORM SYSTEM
DRIFTS EASTWARD INTO TEXAS AND OKLAHOMA. DRIER CONDITIONS AND
WARMER TEMPERATURES WILL RETURN BY MIDWEEK WITH DAYTIME RELATIVE
HUMIDITIES TRENDING LOWER BUT REMAINING ABOVE 15 PERCENT. SHOWERS
AND TSTORMS WILL RETURN TO THE AREA BY LATE THIS WEEK AS ANOTHER
SERIES OF PACIFIC DISTURBANCES MOVE ACROSS THE FORECAST AREA.

&&

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

$$

SHORT TERM...TJT
LONG TERM...RE
AVIATION...ZF
FIRE WEATHER...TJT



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