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000
FXUS65 KCYS 030545
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1045 PM MST MON MAR 2 2015

.UPDATE...
ISSUED AT 715 PM MST MON MAR 2 2015

CURRENT FORECAST PACKAGE ON TRACK THIS EVENING...SO WILL NOT MAKE
ANY CHANGES TO THE HEADLINES AS THE TIMING IS NEARLY PERFECT.

BAND OF HEAVY SNOW IS NOW PUSHING EASTWARD AND IS ABOUT TO CROSS
INTO THE LARAMIE VALLEY. CURRENT OBSERVATIONS ACROSS CARBON AND
ALBANY COUNTIES SHOW SOME HEAVY SNOW AMOUNTS IN THE
MOUNTAINS...WITH A FEW PLACES ALREADY FLIRTING WITH ONE FOOT OF
SNOW. EXPECT THIS HEAVY BAND OF SNOW TO IMPACT
CONVERSE...PLATTE...AND GOSHEN COUNTY ALONG WITH MOST OF NORTHWEST
NEBRASKA OVER THE NEXT FEW HOURS. VISIBILITIES WILL DROP TO ONE
QUARTER MILE THROUGH 10 PM. THIS BAND IS MAINLY DUE TO THE
INTERACTION OF THE VIGOROUS SHORTWAVE TROUGH ALOFT PUSHING
NORTHEAST...ALONG WITH SOME SURFACE CYCLOGENESIS NEAR THE COLORADO
BORDER. DO NOT EXPECT MUCH FROM THIS BAND ALONG I80 FROM LARAMIE
EASTWARD TOWARDS CHEYENNE AND SIDNEY...DUE TO LOCALIZED DOWNSLOPE
WINDS. HOWEVER...MOST OF THE SNOWFALL IN THESE LOCATIONS WILL BE
FROM THE ARCTIC COLD FRONT CURRENT ACROSS MONTANA. THIS FRONT WILL
RAPIDLY MOVE SOUTHEAST ACROSS THE AREA AND WILL LIKELY BE THROUGH
THE I80 CORRIDOR BY SUNRISE TUESDAY WITH AREAS OF LIGHT TO
MODERATE SNOW.

WILL CONTINUE TO MONITOR NIOBRARA COUNTY ALONG WITH THE NORTHERN
NEBRASKA PANHANDLE FOR HEAVY SNOW AMOUNTS. AS OF RIGHT
NOW...TEMPERATURES ARE STILL ON THE WARM SIDE AND THEY MAY ONLY
GET CLIPPED BY THE HEAVIEST SNOWFALL...SO A WINTER WEATHER
ADVISORY APPEARS OK AT THIS TIME.


&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 400 PM MST MON MAR 2 2015

MAIN CONCERN IN THE SHORT TERM IS HOW MUCH SNOW WILL FALL ACROSS
THE AREA TONIGHT. THE GENERAL MODEL TREND HAS PUSHED THE HIGHER
SNOW AMOUNTS TO THE WEST AND NORTH...WHICH SEEMS TO BE PLAYING OUT
AT THIS TIME. THE HEAVIEST SNOW AT THIS TIME IS OVER NORTHWEST
CARBON COUNTY. IMPACTS AT THIS TIME ARE NOT ALL THAT BAD ACROSS
CARBON COUNTY AS TEMPERATURES ARE NEAR OR SLIGHTLY ABOVE
FREEZING...SUCH THAT SNOW IS GENERALLY NOT STICKING TO ROAD
SURFACES. THE WORST TRAVEL CONDITIONS WILL OCCUR TONIGHT AS WET
ROADS COOL AND BECOME ICY. THIS WILL CERTAINLY HAPPEN ONCE THE
COLD FRONT MOVES ACROSS THE AREA LATER TONIGHT.

WINTER STORM WARNINGS AND ADVISORIES REMAIN IN PLACE AN NOT
EXPECTING ANY CHANGES AT THIS TIME BUT WILL HAVE TO SEE WHAT THE
00Z FORECAST MODELS SHOW THIS EVENING. TREND HAS BEEN LOWER WITH
QFP AMOUNTS IN FAR SOUTHEAST WYOMING AND SOUTHERN NEBRASKA
PANHANDLE...WHICH MAKES SENSE AS THE MAIN UPPER FORCING WILL SHIFT
EAST OF THE AREA AS THE COLD FRONT IS ARRIVING. GFS IS STILL
HITTING THE NORTHERN LARAMIE RANGE INTO CONVERSE AND NIOBRARA
COUNTIES PARTICULARLY HARD. THIS IS WHERE THE BEST LOW LEVEL
CONVERGENCE WILL OCCUR AND THE BEST INTERACTION BETWEEN THE UPPER
AND LOWER LEVELS OF THE ATMOSPHERE. NOT CONVINCED THERE WILL BE AS
MUCH PRECIPITATION AS THE GFS BUT CAN NOT RULE IT OUT EITHER...SO
DID NOT CHANCE SNOWFALL AMOUNTS MUCH FROM THE PREVIOUS FORECAST.

THE MODELS HAVE BACKED OFF ON THE AMOUNT OF PRECIPITATION TOMORROW
ACROSS THE ENTIRE AREA. AS THE FIRST DISTURBANCE MOVES EAST OF THE
AREA AND COLD STABLE AIR MOVES IN FROM THE NORTH...NOT EXPECTING
MUCH IN THE WAY OF ADDITIONAL SNOW ACCUMULATIONS BUT WITH SOME
BLOWING SNOW AND LIGHT SNOW AROUND...CONDITIONS MAY REMAIN
UNPLEASANT INTO THE AFTERNOON. VERY COLD WIND CHILLS STILL LIKELY
TUESDAY NIGHT INTO WEDNESDAY MORNING.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 400 PM MST MON MAR 2 2015

AFTER A CHILLY MORNING THURSDAY..GENERALLY DRY AND MILD WEATHER
LOOKS TO RETURN AND SET UP OVER THE CWA DURING THIS PERIOD AS THE
UPPER WIND FLOW BECOMES ESTABLISHED MORE OUT OF A WNW TO NWLY
DIRECTION WITH COLD ARCTIC AIR RETREATING WELL NORTH OVER CANADA.
SNOW COVER MAY LIMIT WARMING INITIALLY BUT MAX TEMPS IN THE 40S
AND 50S SHOULD RETURN BY THE WEEKEND. A WEAK UPPER TROF MAY BRING
A FEW SNOW SHOWERS TO MAINLY THE MTNS SATURDAY OTHERWISE QUIET
WEATHER APPEARS LIKELY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH TUESDAY EVENING)

PERIODS OF SNOW AND IFR CONDITIONS WILL CONTINUE NORTH OF INTERSTATE
80 TONIGHT BEFORE A SURFACE COLD FRONT MOVES SOUTH ACROSS THE AREA
TONIGHT. IFR CONDITIONS WILL BECOME MORE WIDESPREAD AFTER MIDNIGHT
AND INTO TUESDAY MORNING AS THE ARCTIC FRONT MOVES ACROSS THE
AREA...AFFECTING TERMINALS ALONG I80 FROM KLAR TO KSNY TOWARDS
SUNRISE. AFTER A BRIEF LULL IN THE ACTIVITY LATE TUESDAY MORNING
INTO EARLY TUESDAY AFTERNOON...THE SECOND DISTURBANCE ALOFT WILL
PUSH ACROSS THE AREA...INCREASING CHANCES OF SNOW ACROSS SOUTHEAST
WYOMING AND SOUTHERN NEBRASKA.

&&

.FIRE WEATHER...
ISSUED AT 430 AM MST MON MAR 2 2015
NO FIRE WEATHER CONCERNS. SNOW WILL BECOME MORE WIDESPREAD
TONIGHT. SIGNIFICANT ACCUMULATIONS ARE POSSIBLE...ESPECIALLY IN
THE MOUNTAINS AND LOWER ELEVATION AREAS WEST OF THE LARAMIE RANGE.
THE SNOW WILL GRADUALLY DIMINISH BY TUESDAY NIGHT. AN ARCTIC COLD
FRONT WILL BRING BITTERLY COLD TEMPERATURES AND DANGEROUS WIND
CHILLS FROM TUESDAY NIGHT THROUGH WEDNESDAY. MODERATING
TEMPERATURES ARE EXPECTED LATE IN THE WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 PM MST TUESDAY FOR WYZ102-
     106>108-115>117.

     WINTER STORM WARNING UNTIL 6 PM MST TUESDAY FOR WYZ101-103>105-
     109>114.

NE...WINTER WEATHER ADVISORY UNTIL 6 PM MST TUESDAY FOR NEZ002-003-
     095-096.

&&

$$

UPDATE...TJT
SHORT TERM...SML
LONG TERM...RE
AVIATION...RE
FIRE WEATHER...SML/CLH