Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 140537
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1137 PM MDT SUN APR 13 2014

.UPDATE...
ISSUED AT 1133 PM MDT SUN APR 13 2014

WENT AHEAD AND LET THE WINTER HIGHLIGHTS EXPIRE AT 11 PM THIS
EVENING. LATEST RADAR SHOWING ONLY LIGHT RETURNS WITH THE AERIAL
COVERAGE SHRINKING FAIRLY QUICKLY. UPDATES HAVE BEEN SENT.

UPDATE ISSUED AT 538 PM MDT SUN APR 13 2014

WENT AHEAD AND EXTENDED WINTER HEADLINES FOR THE I-80 CORRIDOR
THROUGH 11 PM THIS EVENING. HAVE ANOTHER BAND OF SNOW MOVING
NORTHEAST OUT OF COLORADO ON IR IMAGERY. MAY NOT LAST THROUGH 11
PM...BUT IT DOES LOOK LIKE ACCUMULATING SNOW WILL CONTINUE AT
LEAST THROUGH MID EVENING BEFORE EASING SOME. SOME MODEL GUIDANCE
SUGGESTING THAT SNOW COULD LAST LONGER. WILL RE-EVALUATE IN A
COUPLE HOURS. DID GO AHEAD AND EXPIRE OUR NORTHERN WINTER
HEADLINES AS RADAR MOSAIC SHOWING SNOW COVERAGE DECREASING.
UPDATES HAVE BEEN SENT.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 240 PM MDT SUN APR 13 2014

SATELLITE PIX SHOW WELL-DEFINED CIRCULATION SPINNING THRU UTAH
WITH A JET STREAK BEGINNING TO ROUND ITS BASE. THE RELATIVE LULL
THIS MORNING ACROSS MUCH OF THE AREA WAS A RESULT OF A BREAK
BETWEEN A DEPARTING SHORTWAVE MOVING INTO THE CENTRAL PLAINS AND
THE NEXT ONE OVR UTAH. AT 20Z...THE NEXT LINE OF ENHANCED CLOUD-
TOPS WERE JUST BEGINNING TO ENTER SRN ALBANY AND LARAMIE
COUNTIES...WITH SIMILAR TRENDS NOTICED ON KCYS 88D RETURNS. SO
WILL SEE SNOW RATES PICK UP AGAIN ESPECIALLY ACROSS EXTREME SE
WYOMING THRU AT LEAST SUNSET. AS WAS FEARED...THE HIGH APRIL SUN-
ANGLE HAS RESULTED IN SUBSTANTIAL MELTING ON AREA ROADWAYS...
WHICH HAS LESSENED IMPACT SOME. HOWEVER A FEW ROAD CLOSURES HAVE
OCCURRED ALONG PORTIONS OF INTERSTATE 80. AN ADDITIONAL 1 TO 3
INCHES OF ACCUMULATION CAN BE EXPECTED THRU EARLY THIS EVENING.
SO WILL KEEP THE HIGHLIGHT PACKAGE UNCHANGED FOR NOW AND CONTINUE
TO RE-EVALUATE TRENDS THRU THE REST OF THE AFTERNOON. LATEST
MODELS CONTINUE TO LINGER SNOW INTO THIS EVENING... HOWEVER RATES
SHOULD BE MUCH LESS AS BEST LIFT SHIFTS SOUTH OUT OF THE CWFA.
ANY LINGERING LIGHT SNOW WILL GRADUALLY END THIS EVENING...WITH
DRYING CONDITIONS THEN OVERNIGHT. OTHERWISE...OVERNIGHT LOWS WILL
FALL INTO THE TEENS ACROSS SOUTHEAST WYOMING...WITH LOW 20S OVR
THE PANHANDLE.

HEIGHTS BUILD RAPIDLY BEHIND THE DEPARTING SHORTWAVE ON
MONDAY...YIELDING DRY AND MOSTLY SUNNY CONDITIONS. NORTHWEST
WINDS WILL BE BREEZY ESPECIALLY OVER THE EASTERN PLAINS WHERE
GUSTS OF 25 TO 30 MPH ARE EXPECTED. TEMPERATURES WILL REBOUND
SOME ON MONDAY TOO...ALTHOUGH WILL BE TEMPERED BY TODAYS SNOW.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 240 PM MDT SUN APR 13 2014

TUESDAY...QUICK WARMUP ON TAP AS OUR FLOW ALOFT BECOMES
ZONAL...WEST TO EAST...AHEAD OF THE PROGRESSIVE LOW AMPLITUDE
SHORTWAVE TROUGH ALOFT OVER MONTANA...AIDING THE DEVELOPMENT OF
SURFACE LOW PRESSURE OVER WESTERN SOUTH DAKOTA...AND PRODUCING
DOWNSLOPE KATABATIC WARMING ACROSS OUR COUNTIES WITH MAXIMUM
TEMPERATURES OVER OUR COUNTIES IN THE 50S WEST OF INTERSTATE
25...AND UPPER 50S TO MID 60S ELSEWHERE.

WEDNESDAY...ANOTHER RELATIVELY STRONG CANADIAN ORIGIN COLD
FRONTAL PASSAGE OCCURS EARLY IN THE DAY...WITH TEMPERATURES LIKELY
STEADY OR SLOWLY FALLING DURING THE DAY. THIS SHORTWAVE TROUGH
WILL NOT HAVE AS MUCH MOISTURE AS OUR CURRENT SUNDAY STORM...AND
LESS MESOSCALE AND DYNAMIC LIFT...THUS 30 TO 60 PERCENT POPS AT
LOWER ELEVATIONS WITH 80 TO 100 PERCENT POPS DUE TO FAVORABLE
OROGRAPHICS OVER THE NORTHERN LARAMIE...SNOWY AND SIERRA MADRE
RANGES.

THURSDAY...DRYING OUT PERIOD IN THE WAKE OF THE SHORTWAVE TROUGH
ALOFT WITH A FEW LEFTOVER SHOWERS OVER THE MOUNTAINS. CONTINUED
RELATIVELY COOL WITH SURFACE HIGH PRESSURE KEEPING THE COLD AIR
REINFORCED OVER THE CENTRAL PLAINS STATES.

FRIDAY...SPRINGTIME IN THE ROCKIES CONTINUES WITH A MILD SPRING
DAY TO END OUR TRADITIONAL WORKWEEK...AS TRANSITORY RIDGING ALOFT
MOVES OVER THE ROCKIES...INDUCING STRENGTHENING SURFACE LEE
TROUGHING AND DOWNSLOPE WARMING AIDING HIGH TEMPERATURES SOARING
INTO THE 50S... AND PERHAPS EVEN WARMER IF THE WARMER ECMWF CAN BE
BELIEVED...AS IT SHOWS 1000-500 MB THICKNESSES NEAR 5640 METERS
WITH 700 MB TEMPERATURES NEAR 7 CELSIUS.

SATURDAY...ANOTHER MILD DAY UNDER NORTHWEST FLOW ALOFT AND
RELATIVELY HIGH THICKNESSES AND 700 MB TEMPERATURES.

SUNDAY...EASTER SUNDAY LOOKS MILD AND DRY WITH NORTHWEST FLOW
ALOFT AND A RIDGE ALOFT OVERHEAD...AND EASTER SUNRISE SERVICES
SHOULD BE PLEASANT FOR OUTDOOR ACTIVITIES WITH MINIMAL CLOUD COVER
AND RELATIVELY MILD TEMPERATURES ABOVE FREEZING TO START THE DAY.

.AVIATION...MOUNTAINS OBSCURED. WIDESPREAD IFR AND MVFR THROUGH
THIS AFTERNOON IN SNOW AND LOW CLOUDS...THEN AREAS OF FOG AND LOW
CLOUDS OVERNIGHT PRODUCING IFR AND MVFR...WITH VFR DEVELOPING LATE
TONIGHT AND MONDAY MORNING FROM NORTH TO SOUTH.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 1133 PM MDT SUN APR 13 2014

ONLY TROUBLE AIRFIELD AT THIS TIME LOOKS TO BE LARAMIE WITH IFR
VISIBILITIES IN SNOW. THE LATEST HRRR FORECAST HAS IFR CONDITIONS
HANGING IN AROUND KLAR FOR A FEW MORE HOURS BEFORE DISSIPATING
AFTER 10Z OR SO. VFR CONDITIONS ALL AIRPORTS AFTER SUNRISE MONDAY.

&&

.FIRE WEATHER...
ISSUED AT 240 PM MDT SUN APR 13 2014

NO FIRE WEATHER CONCERNS THROUGH EARLY NEXT WEEK AS FRESH
MOISTURE AND SNOW COVER FROM TODAYS SNOWSTORM LINGERS. SNOW-COVER
WILL ALSO KEEP TEMPERATURES COOLER THROUGH EARLY IN THE
WEEK...WHICH WILL KEEP HUMIDITIES UP. THE NEXT CHANCE OF
PRECIPITATION RETURNS TO THE DISTRICTS ON WEDNESDAY.

&&

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

$$

UPDATE...CLAYCOMB
SHORT TERM...HAHN
LONG TERM...RUBIN
AVIATION...CLAYCOMB
FIRE WEATHER...HAHN






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