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000
FXUS65 KCYS 160537
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1137 PM MDT SAT MAR 15 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 429 PM MDT SAT MAR 15 2014

SEASONABLY COOL AND BREEZY CONDITIONS HAVE BEEN THE RULE ACROSS
MUCH OF THE AREA TODAY BEHIND A STRONG COLD FRONT NOW MOVING INTO
THE CENTRAL PLAINS STATES. SURFACE OBSERVATIONS OVER THE PAST FEW
HOURS HAVE SHOWN WINDS FINALLY INCREASING INTO THE 30 TO 35 MPH
RANGE WITH A FEW GUSTS NEAR 45 MPH OVER THE WESTERN NE PANHANDLE.
THIS IS PROBABLY DUE TO IMPROVED LLVL MIXING BENEATH THINNING
CLOUD COVER. WILL KEEP THE WIND ADZY GOING THROUGH ITS SCHEDULED
EXPIRATION TIME OF 6PM MDT...AT WHICH POINT WINDS SHOULD BEGIN TO
DIMINISH WITH THE LOSS OF DAYTIME HEATING AND WEAKENING LLVL
GRADIENTS. AFTN WATER VAPOR SHOWS THE BACK EDGE OF THE WAVE WHICH
WAS PARTIALLY RESPONSIBLE FOR TODAYS SNOWFALL NOW MOVING ACROSS
THE WESTERN PANHANDLE. RADAR TRENDS HAVE SHOWN A DECREASE IN
SHOWER ACTIVITY THIS AFTN...AND THAT SHOULD CONTINUE WITH
INCREASING SUBSIDENCE BEHIND THE WAVE. THIS SHOULD GIVE WAY TO A
DRY NIGHT FOR MOST AREAS. ONLY CONCERN IS THE POSSIBLY OF FOG IN
THE NORTHERN PANHANDLE AS FCST SOUNDINGS FOR KCDR AND KAIA SHOW
GOOD NEAR-SFC MOISTURE AND LLVL UPSLOPE ALONG THE PINE RIDGE.

A WARMING TREND WILL QUICKLY ENSUE FOR SUN. MODELS SHOW BROAD
UPPER-LEVEL RIDGING STARTING TO ENVELOPE MUCH OF THE WESTERN
CONUS. WEST TO NORTHWEST DOWNSLOPE FLOW WILL SCOUR OUT THE COLD
AIR OVER THE HIGH PLAINS AS H7 TEMPS CLIMB TO BETWEEN 0C AND -2C
BY 00Z MON. A DECREASE IN 700-300 MILLIBAR MOISTURE ALSO HINTS AT
AMPLE SUNSHINE. MOST OF THE HIGH LEVEL CLOUD COVER SHOULD BE WELL
TO OUR NORTH AND WEST ALONG THE EDGE OF THE RIDGE. GIVEN THAT MOST
OF THE TODAYS SNOW MELTED VERY QUICKLY ON THE WARM GROUND...STAYED
CLOSE TO GUIDANCE FOR FCST HIGHS ON SUN. SHOULD SEE WIDESPREAD
UPPER 50S AND LOW 60S OVER THE HIGH PLAINS.

ATTENTION QUICKLY SHIFTS TO THE WIND POTENTIAL FROM LATE SUN NIGHT
THROUGH MON AFTN. BOTH THE GFS AND NAM HAVE SHOWN BEEN RATHER
CONSISTENT WITH 50 TO 60 KT WINDS DEVELOPING BETWEEN H7 AND H8
AFTER 06Z MON. THIS IS DUE TO STRENGTHENING LLVL GRADIENTS
RESULTING FROM LEE CYCLOGENESIS OVER THE NORTHERN HIGH PLAINS AND
A STRONG HIGH WEST OF THE CONTINENTAL DIVIDE OVER CO. BOTH THE 700
AND 850 MILLIBAR CAG-CPR GRADIENT ALSO INCREASE ABOVE 50 METERS BY
12Z AS WELL. WITH STRONG SUBSIDENCE IN THE RFQ OF A 100 KT JET
STREAK...AM CONFIDENT THAT HIGH WIND WARNING CRITERIA COULD BE
ATTAINED IN THE PRIMARY WIND CORRIDORS AS EARLY AS 09Z. THE GFS
SHOWS STRONG PRESSURE FALLS IN EXCESS OF 10 MB/6 HR SPREADING INTO
SOUTHEAST WY AT THAT TIME. STRONGEST WINDS WILL PROBABLY OCCUR
DURING THE LATE MORNING AND AFTERNOON WHEN LLVL MIXING TAPS INTO
STRENGTHENING FLOW ALOFT. WENT AHEAD AND ISSUED A HIGH WIND WATCH
FOR ARL AND BRX...AS WELL AS THE I80 SUMMIT AND ADJACENT FOOTHILLS
STARTING AT 09Z MON. THIS EVENT WILL QUICKLY TRANSITION FROM A
GAP/CHINOOK TO A BORA AS A STRONG COLD FRONT MOVES ACROSS THE
AREA. NOT ENTIRELY OUT OF THE QUESTION FOR WINDS TO REMAIN STRONG
WELL INTO THE EVENING...OR PERHAPS EVEN SPREAD ONTO THE PLAINS
LATER IN THE DAY AS THIS OCCURS.

VERY WARM TEMPERATURES ARE LIKELY FOR MON AFTN AS WELL. BUT ACTUAL
HIGHS WILL BE TRICKY TO HANDLE WITH THE TIMING OF THE COLD FRONT
AND THE ONSET OF LLVL COLD ADVECTION. STILL EXPECTING 65 TO NEAR
70F OVER MUCH OF THE WESTERN PANHANDLE WHICH WILL PROBABLY BE
AHEAD OF THE FRONT FOR MOST OF THE DAY. RAIN AND SNOW SHOWERS WILL
ACCOMPANY THE COLD AIR GIVEN STRONG ASCENT ASSOCIATED WITH THE
VIGOROUS UPPER-LEVEL SYSTEM ON MON NIGHT. MODELS ARE HANDLING THIS
IN A VERY SIMILAR MANNER TO THE LAST TWO THOUGH...SO WOULD EXPECT
THE PROGRESSIVE NATURE OF THE SYSTEM TO MINIMIZE IMPACTS. MULTIPLE
WARM DAYS BEFOREHAND WILL PROBABLY LIMIT ACCUMULATIONS FOR THE
PLAINS AS WELL. THE SNOWY AND SIERRA MADRE MOUNTAIN RANGES WILL
PROBABLY SEE SEVERAL INCHES OF SNOW FROM THIS EVENT GIVEN THE
FAVORABLE OROGRAPHICS.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 429 PM MDT SAT MAR 15 2014

SOME DIFFERENCES IN MODELS ON THE LOW PRESSURE SYSTEM FOR TUESDAY.
THE 12Z GFS CONTINUES TO SHOW A MORE NORTHERLY TRACK ON THE
LOW...TRACKING IT THROUGH CENTRAL WYOMING. SHOULD THIS SCENARIO
HOLD TRUE...WE WOULD BE MAINLY DRY WITH MAYBE SOME LIGHT SNOW IN
THE MOUNTAINS. THE 12Z ECMWF SHOWS A MORE SOUTHERLY
TRACK...TRACKING THE UPPER LOW THROUGH NORTHERN AND NORTHEASTERN
COLORADO. SHOULD THIS SCENARIO HOLD TRUE...THEN WE COULD BE IN FOR
QUITE A BIT OF SNOW. HAVE A BLEND OF THE TWO MODELS WITH HIGH
CHANCE TO LIKELY POPS GOING FOR MUCH OF THE CWFA.

REGARDLESS OF WHICH TRACK ULTIMATELY PREVAILS...WRAP AROUND
MOISTURE BEHIND BOTH LOW TRACKS COULD BRING SIGNIFICANT SNOW TO
PORTIONS OF THE CWFA. WILL NEED TO WATCH THIS EVENT AS IT DRAWS
CLOSER. WILL CERTAINLY HAVE TO CONSIDER WINTER HEADLINES.

AFTER TUESDAY...THE REMAINDER OF THE WEEK LOOKS BREEZY TO WINDY.
GFS WINDS INCREASING TO 50KTS AT TIMES WITH A STRONG 700MB CRAIG
TO CASPER HEIGHT GRADIENT REMAINING OVER THE CWFA THROUGH FRIDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY EVENING)
ISSUED AT 1128 PM MDT SAT MAR 15 2014

VFR CONDITIONS ARE EXPECTED ACROSS THE WY SITES OVERNIGHT.
MVFR/IFR CIGS WILL BE POSSIBLE OVER THE PANHANDLE THROUGH SUNRISE.
WINDS WILL GENERALLY BE BELOW 15 KTS THROUGH SUNDAY MORNING. WEST
WINDS WILL INCREASE ACROSS SOUTHEAST WY BY LATE MORNING WITH
OCCASIONAL GUSTS TO 25-30 KTS THROUGH THE AFTN.

&&

.FIRE WEATHER...
ISSUED AT 429 PM MDT SAT MAR 15 2014

ELEVATED FIRE WEATHER CONCERNS ARE EXPECTED FOR FAR SOUTHEAST WY
AND THE WESTERN NE PANHANDLE ON MON. WINDS MAY GUST BETWEEN 25 AND
30 MPH DURING THE MID TO LATE AFTERNOON ALONGSIDE RELATIVE
HUMIDITY VALUES BETWEEN 15 AND 20 PERCENT. THIS WILL BE SHORT
LIVED AS A STRONG COLD FRONT WILL BRING COOLER TEMPERATURES AND
INCREASING CHANCES FOR MOISTURE AS EARLY AS MONDAY NIGHT AND
TUESDAY.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY AFTERNOON
     FOR WYZ106-110-116-117.

NE...NONE.
&&

$$

SHORT TERM...HAMMER
LONG TERM...CLAYCOMB
AVIATION...FINCH
FIRE WEATHER...HAMMER