Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 121010
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
410 AM MDT SAT APR 12 2014

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 300 AM MDT SAT APR 12 2014

MAIN FORECAST FOCUS CONTINUES TO BE ON THE STORM SYSTEM WHICH
WILL IMPACT THE AREA LATE TODAY THROUGH SUNDAY. WINTER STORM WATCH
REMAINS IN EFFECT FOR MUCH OF SOUTHEAST WYOMING. FORECAST CHANGES
WERE VERY MINOR AS THE SYSTEM STILL LOOKS LIKE IT WILL BRING A
GOOD DEAL OF MOISTURE TO SOUTHEAST WYOMING AND LESS AMOUNTS TO
THE NEBRASKA PANHANDLE.

NORTHERN STREAM WAVE CURRENTLY OVER WASHINGTON AND OREGON WILL
MAKE ITS WAY SOUTH AND EAST INTO UTAH THIS EVENING. AT THE SAME
TIME A PIECE OF SOUTHERN STREAM ENERGY OVER SOUTHERN CALIFORNIA
WILL MAKE ITS WAY INTO COLORADO AND NEW MEXICO. SOUTHEAST WYOMING
WILL BE SANDWICHED IN BETWEEN THE TWO SYSTEMS WITH PLENTY OF
UPWARD VERTICAL MOTION DEVELOPING BY THIS EVENING. SHOULD SEE A
FEW SHOWERS AND THUNDERSTORMS DEVELOP THIS AFTERNOON WITH SHOWER
ACTIVITY BECOMING RATHER WIDESPREAD BY THIS EVENING. OUTSIDE OF
THE MOUNTAINS PRECIPITATION WILL MOSTLY BE RAIN THROUGH THIS
AFTERNOON...THEN COOLER AIR ALOFT WILL SLOWLY WORK ITS WAY INTO
THE AREA THIS EVENING AND INTO THE OVERNIGHT WITH SNOW LEVELS
STEADILY FALLING.

BIGGEST FORECAST CHALLENGE AND CONCERN IS SNOW RATES AND AMOUNTS.
WITH THE LAST FEW DAYS BEING WARM AND HIGH MID APRIL SUN
ANGLE...WILL NEED THE HIGHER SNOW RATES TO REALLY GET SNOW TO
STICK TO THE GROUND...AT LEAST IN LOWER ELEVATIONS...AND IT MAY BE
PARTICULARLY TOUGH FOR SNOW TO ACCUMULATE ON ROADS SURFACES.
DYNAMICS APPEAR STRONG ENOUGH FOR SOME HIGHER SNOW RATES. LAPSE
RATES NOT THE MOST IMPRESSIVE BUT THERE IS THE POTENTIAL FOR
DENDRITIC GROWTH SO CANT RULE OUT THE 1 INCH AN HOUR SNOW RATES AT
TIMES. ANOTHER MINOR CONCERN IS THE TRACK OF THE NORTHERN STREAM
WAVE. PROVIDED IT DOES NOT TRACK FURTHER WEST...CURRENT FORECAST
SNOW AMOUNTS LOOK REASONABLE.

INTERESTING NOTE...THE AVERAGE SNOW AMOUNTS FROM THE TOP 15 STORM
ANALOGS IS PRETTY CLOSE TO THE CURRENT FORECAST...MAYBE AN INCH OR
SO LESS. THE EXCEPTION BEING THE NORTHERN CWA AND NORTHERN LARAMIE
RANGE WHERE THE AVERAGE SNOW AMOUNTS IN THIS TYPE WEATHER PATTERN
WERE FEW INCHES OR LESS.


.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 300 AM MDT SAT APR 12 2014

WARMING CONDITIONS EXPECTED MONDAY NIGHT AND TUESDAY AS AN UPPER
RIDGE PASSES ACROSS AND DOWNSLOPE FLOW OCCURS OVER THE CWA. NEXT
UPPER SYSTEM WILL THEN PASS ACROSS WEDNESDAY WITH THE NEXT PUSH OF
COLDER CANADIAN AIR SPREADING ACROSS THE CWA AT THAT TIME. THIS
TIME IT IS THE GFS THAT IS STRONGER AND SLOWER WITH THE SYSTEM AS
OPPOSED TO THE EC WHICH IS OPEN AND MORE PROGRESSIVE. EC HAS
TENDED TO BE BETTER WITH THESE SYSTEMS AND WILL FAVOR SOMEWHAT BUT
WILL HAVE TO KEEP AN EYE ON HOW THINGS DEVELOP. DRY AND COOL
THURSDAY THEN WARMING AGAIN FRIDAY WITH SOME LATE DAY RAIN AND
SNOW SHOWERS POSSIBLE IN ASSOCIATION WITH THE NEXT SHORTWAVE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 300 AM MDT FRI APR 11 2014

VFR EXPECTED OVER ALL AERODROMES TODAY. A FEW WEAK AND HIGH BASED
SHOWERS WITH POSSIBLY A TSTRM THIS AFTERNOON MAINLY OVER THE
PLAINS. SFC COLD FRONT WILL SAG SOUTH ACROSS THE AREA THIS
AFTERNOON INTO EARLY THIS EVENING WITH MVFR/IFR CIGS AND
VISIBILITIES DEVELOPING ESPECIALLY OVER THE PLAINS TONIGHT IN
UPSLOPE FLOW AND INCREASING AREAS OF RAIN AND SNOW.

&&

.FIRE WEATHER...
ISSUED AT 300 AM MDT SAT APR 12 2014

NO BIG FIRE WEATHER CONCERNS TODAY OR OVER THE NEXT WEEK FOR THAT
MATTER. A FEW LIGHTING STRIKES POSSIBLE THIS AFTERNOON AND EVENING
BUT THAT WILL GENERALLY BE ASSOCIATED WITH WETTING RAIN. OTHERWISE
WIDESPREAD RAIN AND SNOW DEVELOPING TONIGHT AND CONTINUING THROUGH
MUCH OF SUNDAY. DRY MONDAY AND TUESDAY BUT ANOTHER CHANCE FOR
PRECIPITATION...MAINLY SNOW WEDNESDAY.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY AFTERNOON
     FOR WYZ101-103>107-110-112-114>118.

NE...NONE.
&&

$$

SHORT TERM...SML
LONG TERM...RE
AVIATION...RE
FIRE WEATHER...SML






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