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000
FXUS65 KCYS 011832
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1132 AM MST SAT MAR 1 2014

.UPDATE...
ISSUED AT 1020 AM MST SAT MAR 1 2014

MAIN FORECAST ADJUSTMENTS THIS MORNING WERE SPENT TWEAKING
SNOWFALL AMOUNTS ACROSS THE AREA AS WELL AS SHORTENING THE TIMING
SOMEWHAT. HIGHEST SNOWFALL TOTALS THUS FAR HAVE FALLEN ACROSS
SOUTHERN PLATTE AND GOSHEN COUNTIES WERE 6 TO 8 INCHES HAVE BEEN
OBSERVED. AREAS SURROUNDING THESE...HAVE GENERALLY PICKED UP 2 TO 4
INCHES THIS MORNING. LATEST KCYS 88D RETURNS SHOW BEST AREAS OF
SNOW SHIFTING EAST TOWARDS THE SOUTHERN NEBRASKA PANHANDLE...AN
AREA THAT HASNT RECEIVED MUCH JUST YET. SATELLITE PIX SHOW SOME
BREAKS IN THE CLOUDS OVER SOUTHERN CARBON AND ALBANY COUNTIES.
INITIAL LOOKS AT 12Z MODEL OUTPUT CONTINUES TO POINT TO EAST
CENTRAL WYOMING AS THE AREA TO SEE CONTINUED SNOWFALL THRU THE
REST OF THE DAY. MODELS HAVE ALSO DRIES THINGS OUT ACROSS THE
INTERSTATE 80 CORRIDOR A BIT QUICKER THAN EARLIER INDICATING.
SO...HAVE ADJUSTED THE FORECAST TO END THE WINTER WEATHER ADVISORY
AT 6 PM TONIGHT HERE. HAVE ALSO DOWNGRADED CENTRAL CARBON AND
ARLINGTON AS SNOWFALL AMOUNTS HAVE NOT BEEN IMPRESSIVE THUS FAR.
ALSO PULLED BACK THE ENDING TIME OF THE WINTER STORM WARNING TO 3
AM TONIGHT. AFTER THE SNOW ENDS...MANY AREAS EAST OF THE LARAMIE
RANGE WILL LIKELY NEED TO BE TRANSITIONED TO WIND CHILL
HIGHLIGHTS. WILL EXAMINE THAT FURTHER FOR THE AFTERNOON FORECAST
PACKAGE.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)

ISSUED AT 400 AM MST SAT MAR 1 2014

OVERALL...CURRENT FORECAST FOR THE WEEKEND LOOKS ON TRACK WITH
ONLY MINOR ADJUSTMENTS MADE TO EXPECTED WEATHER...SNOW
ACCUMULATION...AND HEADLINES. VERY LITTLE CHANGES MADE TO ANY
OTHER ELEMENT THROUGH SUNDAY. THE ARCTIC FRONTAL BOUNDARY HAS NOW
MADE IT AS FAR WEST AS CARBON COUNTY...WITH THE LEADING EDGE OF
THE FRONT EXTENDING FROM JUST NORTH OF RAWLINS...EASTWARD TO THE
SNOWY RANGE...AND THEN EXTENDING SOUTHEAST FROM THE SNOWY RANGE
ALONG THE FRONT RANGE OF COLORADO. IT HAS BEEN SNOWING ACROSS MOST
OF THE AREA...ALTHOUGH IT HAS BEEN VERY LIGHT THUS FAR AS OF 230 AM.
RADAR IS SHOWING SIGNS OF MODERATE TO HEAVY SNOWFALL DEVELOPING
JUST NORTH OF I80...NORTHEAST OF THE ACTUALLY FRONTAL
POSITION...FROM NEAR RAWLINS EASTWARD TO WHEATLAND TO JUST SOUTH OF
TORRINGTON. THIS BAND IS LIFTING TO THE EAST NORTHEAST SLOWLY AND
IS IN THE AREA COVERED BY A WINTER STORM WARNING. SO ALL LOOKS
GOOD ON THAT END WITH SOME AREAS NEAR THE NORTHERN LARAMIE RANGE
AND PINE RIDGE APPROACHING ONE FOOT OF SNOW BY TONIGHT.
HOWEVER...BELIEVE MOST AREAS WILL SEE BETWEEN 5 TO 9 INCHES OF
SNOW IN THE WARNING AREA. REMOVED MOST OF THE BLOWING SNOW FROM
THE FORECAST WITH BREEZY CONDITIONS AT BEST AND GENERALLY UNDER 15
KNOTS. COULD BE SOME PATCHY DRIFTING SNOW OVER THE ROADWAYS...BUT
DO NOT EXPECT BLOWING SNOW TO BECOME A MAJOR CONCERN.

SOUTH OF THIS LINE IS WHERE SOME UNCERTAINTY REMAINS MAINLY
BECAUSE AREAS ALONG AND SOUTH OF I80 ARE STUCK ALONG THE
TRANSITIONAL ZONES BETWEEN WARM/COLD AIR OR MARGINAL DYNAMIC
LIFT. WEST OF THE LARAMIE RANGE...WARMER AIR SOUTHWEST OF THE
ARCTIC BOUNDARY WILL RESULT IN MAINLY RAIN TODAY WITH SARATOGA AND
DWX REPORTING RAINFALL MOST OF THE NIGHT AND TEMPS IN THE MID 30S.
REMOVED THE UPPER NORTH PLATTE RIVER VALLEY FROM THE WINTER
WEATHER ADVISORY DUE TO THE WARMER AIR. THE FRONT IS NOT EXPECTED
TO MOVE MUCH FURTHER TO THE WEST TODAY...BUT SOME SNOW WILL MIX IN
AT TIMES. WITH FAVORABLE DYNAMICS...CAN NOT RULE OUT A FEW RUMBLES
OF THUNDER SOUTHWEST OF THIS FRONT WITH MODEL SOUNDINGS SHOWING
FAVORABLE CONDITIONS FOR THUNDER AND SNOW NEAR AND SOUTH OF
RAWLINS WITH LI/S AROUND -3C AND CAPE VALUES AROUND 500 J/KG.
BRIEF...BUT VERY HEAVY SNOWFALL IS POSSIBLE IN THESE AREAS SO KEPT
THE WINTER STORM WARNING OUT FOR MOST OF CARBON COUNTY AS WELL AS
THE MOUNTAINS. WAS GOING TO DELAY THE START OF THE WARNING ACROSS
WESTERN CARBON COUNTY...BUT RAWLINS IS OBSERVED OFF AND ON
MODERATE SNOW THIS MORNING...SO WILL KEEP IT GOING FOR NOW.
FURTHER EAST...WILL KEEP THE LARAMIE VALLEY IN THE WINTER WEATHER
ADVISORY WITH PERIODS OF MODERATE SNOW OBSERVED...BUT DO NOT THINK
LARAMIE ITSELF WILL SEE CONTINUOUS SNOWFALL TODAY. HOWEVER...AREAS
NORTH OF I80 WILL LIKELY SEE CLOSE TO 5 INCHES OF NEW SNOW SINCE
THE HEAVY SNOW BAND HAS TRAINED OVER THIS AREA THE LAST FEW HOURS.
FROM CHEYENNE TO THE SOUTHERN PANHANDLE...CHEYENNE HAS RECEIVED
FREEZING DRIZZLE MOST OF THE NIGHT. THEREFORE...REWORDED THE
ADVISORY FOR FREEZING DRIZZLE. DO NOT THINK LARAMIE COUNTY
WILL GET MUCH SNOW...WITH MAYBE 1 TO 3 INCHES WITH THE MAIN
PRECIPITATION BAND LATER THIS MORNING. HOWEVER...THE FREEZING
DRIZZLE IS OF GREATER CONCERN WITH REPORTS OF BLACK ICE ALONG I80.
THE SOUTHERN PANHANDLE WILL RECEIVE THE SAME AMOUNTS OF
SNOWFALL...BUT WITHOUT THE FREEZING DRIZZLE...SO WILL KEEP KIMBALL
AND CHEYENNE COUNTY OUT OF ANY HEADLINES FOR NOW EVEN THOUGH A
WIND CHILL STATEMENT MAY BE NEEDED SHORTLY.

SNOWFALL IS STILL EXPECTED TO DEVELOP FROM LARAMIE EASTWARD TO
CHEYENNE AND SIDNEY SOMETIME THIS MORNING. WAITING FOR THE JET
AXIS TO SHIFT EASTWARD FOR SOME DYNAMIC LIFT SINCE THE SOUTH TO
SOUTHEAST LLVL WINDS ARE NOT PRODUCING ENOUGH OF BROAD UPSLOPE IN
THESE AREAS IN ADDITION TO THE 700MB DIVERGENCE MODELS HAVE BEEN
SHOWING. TEMPERATURES WILL BE BITTERLY COLD EAST OF THE LARAMIE
RANGE. TODAYS HIGHS HAVE LIKELY ALREADY BEEN OBSERVED WITH
TEMPERATURES LOWERING TO NEAR ZERO OR A FEW DEGREES BELOW ZERO.
HIGHS WILL BE IN THE 30S TO NEAR 40 WEST OF THE LARAMIE
RANGE...ESPECIALLY EAST OF THE MAJOR MOUNTAIN RANGES.

THE HEAVIEST SNOW WILL COME TO AN END LATE THIS AFTERNOON WITH
GENERALLY VERY LIGHT SNOW OR FLURRIES TONIGHT AS WARM AIR
ADVECTION ALOFT WILL BECOME THE PRIMARY LIFTING MECHANISM AFTER
THE DYNAMICS ASSOCIATED WITH THE STORM SYSTEM GRADUALLY WEAKEN.
MAY SEE SOME LINGERING FLURRIES INTO SUNDAY SINCE THE ARCTIC FRONT
WILL REMAIN NEAR THE LARAMIE RANGE THROUGH THE WEEKEND. WITH A
SOUTH TO SOUTHEAST WIND NEAR THE CHEYENNE RIDGE...DO NOT FEEL
COMFORTABLE REMOVING PATCHY FOG AND LOW CLOUDS...SO KEPT PATCHY
FOG FROM THE I80 SUMMIT EASTWARD INTO SOUTHERN NEBRASKA THROUGH
SUNDAY. LOW CLOUDS WILL LIKELY LINGERING INTO SUNDAY NIGHT BEFORE
LLVL WINDS GRADUALLY SHIFT INTO THE SOUTHWEST BRINGING DRIER AIR
TO CHEYENNE AND POINTS EAST OF CHEYENNE. MODELS THEN SHOW THE
ARCTIC FRONT RETREATING EASTWARD AS A WARM FRONT BY LATE SUNDAY
NIGHT AS AN UPPER LEVEL RIDGE BEGINS TO BUILD INTO THE
INTER MOUNTAIN WEST. HIGH TEMPERATURES FOR SUNDAY WILL BE SIMILAR
TO TODAY...BUT A FEW DEGREES WARMER.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 300 AM MST SAT MAR 1 2014

WEST WINDS RETURN MONDAY AS THE ARCTIC BOUNDARY SHIFTS EAST INTO
WESTERN NEBRASKA AND SOUTH DAKOTA. LOOKS FAIRLY WARM WITH 700MB
TEMPERATURES CLIMBING TO -4C. THIS UP FROM -6 TO -8C SUNDAY. GOING
LOWER THAN GUIDANCE AS WE SHOULD HAVE A PRETTY GOOD SNOW PACK
STILL.

HAVE ANOTHER DISTURBANCE MOVING THROUGH THE AREA TUESDAY WHICH
WILL BRING AREAS OF SNOW TO JUST ABOUT EVERYONE TUESDAY NIGHT INTO
WEDNESDAY MORNING. LOOKS LIKE THE ARCTIC BOUNDARY GETS PULLED BACK
WEST WITH THIS SHORTWAVE INTO THE PANHANDLE. HAVE FAIRLY COLD
TEMPERATURES FOR OVERNIGHT LOWS WEDNESDAY MORNING AS THIS HAPPENS.

WEDNESDAY NIGHT INTO THURSDAY LOOKS TO BE WINDY AS GFS FORECASTING
700MB WINDS OF 45 TO 50KTS. COULD BE SEEING SOME WIND HIGHLIGHTS
FOR OUR WIND PRONE AREAS THURSDAY. GOOD NEWS THOUGH IS THAT
TEMPERATURES SHOULD BE FAIRLY WARM WITH DOWNSLOPING WINDS OFF THE
LARAMIE RANGE. COULD SEE HIGH TEMPERATURES APPROACHING 60 IN THE
PANHANDLE THURSDAY AFTERNOON.

GFS AND ECMWF BRING THE NEXT COLD FRONT INTO THE AREA FRIDAY.
ECMWF MORE BULLISH ON QPF OVER THE GFS AND IS SLIGHTLY SLOWER
MOVING THE FRONT THROUGH THE AREA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING)
ISSUED AT 1121 AM MST SAT MAR 1 2014

SNOW HAS BEGUN TO TAPER OFF AT MOST OF THE SITES OVER THE PAST FEW
HOURS. WHILE SHORT PERIODS OF IFR VIS WILL BE POSSIBLE THROUGH THE
AFTERNOON IN LIGHT SNOW SHOWERS...THE MAJORITY OF THE TIME WILL BE
MVFR/VFR CONDITIONS. EXPECTING FOG TO DEVELOP ALONG THE CHEYENNE
RIDGE AND AT CYS BY THIS EVENING AS THE SFC WINDS TURN SOUTHERLY.
WIDESPREAD LOW CLOUDS WILL PERSIST THROUGH TONIGHT...ESPECIALLY
ACROSS THE PLAINS WITH THE EAST TO SOUTHEAST UPSLOPE WINDS.

&&

.FIRE WEATHER...
ISSUED AT 245 AM MST SAT MAR 1 2014

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK DUE TO WIDESPREAD SNOWFALL AND AN ARCTIC AIRMASS. HIGH
TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH MONDAY WITH
TEMPERATURES RETURNING TO NORMAL BY THE MIDDLE OF NEXT WEEK.
RELATIVE HUMIDITY VALUES WILL THEN LOWER TO 25 PERCENT BY
WEDNESDAY AND THURSDAY.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 3 AM MST SUNDAY FOR WYZ101>108-112-
     114.

     WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS EVENING FOR WYZ109-
     110-115>119.

NE...WINTER STORM WARNING UNTIL 3 AM MST SUNDAY FOR NEZ002-095-096.

     WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS EVENING FOR NEZ003-
     019>021.

&&

$$

UPDATE...HAHN
SHORT TERM...TJT
LONG TERM...CLAYCOMB
AVIATION...FINCH
FIRE WEATHER...TJT