Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 170252
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
750 PM MST SUN NOV 16 2014

.UPDATE...DROPPED THE WINTER WEATHER ADVISORIES FOR BLOWING SNOW.

.SHORT TERM...TONIGHT THROUGH MONDAY
THE ALBERTA CLIPPER NOSING INTO THE NORTHERN PLAINS IS WHIPPING
THE FRESH SNOWFALL INTO A SWIRLING FRENZIE WITH THE RESULTANT
NORTHWEST WINDS ON THE ABSAROKA AND BIG HORN MOUNTAINS...NOT TO
MENTION THE HIGHER TETONS WHICH ARE NOT IN THE WSW ADDRESSING THE
BLOWING SNOW HAZARD...AS WELL AS THE LOWER ELEVATIONS OF JOHNSON
COUNTY WHERE WINDS HAVE GUSTED AS HIGH AS 60 MPH AT THE BUFFALO
AIRPORT. WILL LET THESE HILITES CONTINUE THROUGH 06Z TONIGHT. THE
LOCAL WRF IS INDICATING A FEW MORE INSIGNIFICANT LIGHT SNOW
SHOWERS OR FLURRIES TO PARADE THROUGH THE BIG HORNS THIS EVENING.
THE ASSOCIATED SURFACE FRONT IS BEHAVING LIKE A NORMAL COLD FRONT
AT THE HIGHER ELEVATIONS...BUT AS A WARM OCCLUSION IN THE TRAPPED
BASINS...IF ONE WERE TO THINK OF THE LEADING EDGE OF THE TRAPPED
COLDEST AIR IN THE BASINS AS A CIRCULAR SFC STATIONARY
FRONT...ESPECIALLY WITH THE INITIAL MIXING OF MILDER AIR AT THE
VERY LEADING EDGE OF THE APPROACHING CLIPPER ASCT FRONT. NORTHWEST
WINDS WILL CONTINUE IN MANY AREAS MONDAY...ESP JOHNSON COUNTY...AS
ADDITIONAL PIECES OF VORT ENERGY STREAM SSE IN THE NNW FLOW ON THE
BACKSIDE OF THE SLOWLY EXITING MAIN TROUGH. SOUTHWEST WINDS WILL
BLOW ALONG THE SOUTHERN WIND CORRIDOR MONDAY WHERE THE TERRAIN
CHANNELS THE WIND. HIGH TEMPS MONDAY WILL BE SLIGHTLY MILDER THAN
THEY WERE TODAY SINCE THE AIR BEHIND THIS CLIPPER WILL BE -20C
OVER JOHNSON CO AS APPOSED TO -23C OVER THE SAME AREA FROM
YESTERDAYS FROPA.

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
OVERALL EXTENDED SHOULD SHOW GENERAL MODERATION AS COLD AIR
GENERALLY ERODES AND THEN A GENERAL WLY SPLIT FLOW PATTERN STARTS TO
DEVELOP FOR THE SECOND HALF OF THE UPCOMING WEEK. BASINS AND VALLEYS
WILL STILL REMAIN TRAPPED BUT WITH A GENERAL MODERATION THROUGH THE
WEEK WITH NO ADDITIONAL COLD AIR COMING IN AND GRADUAL EROSION OF
SNOW IN SOME SPOTS. STILL WELL BELOW NORMAL AND COLDER THAN MOST IF
NOT ALL THE GUIDANCE. MOUNTAINS AND WINDY AREAS HOWEVER WILL HAVE A
CHANCE TO WARM UP EVEN MORE...ESPECIALLY AS MILDER PACIFIC AIR MOVES
IN. ON TUESDAY...WE STILL HAVE A SHORTWAVE MOVING QUICKLY SWD ACROSS
MAINLY OUR NRN ZONES LATE TUESDAY INTO TUESDAY NIGHT WITH A PERIOD
OF FLURRIES OR LIGHT SNOW MAINLY IN THE NRN MTNS. OTHERWISE...DRY
THROUGH MIDWEEK. GFS IS A LITTLE CLOSER WITH A NRN PLAINS SHORTWAVE
THURSDAY WITH A SHALLOW FRONT MOVING INTO THE ERN ZONES. THE ECMWF
IS FURTHER EAST WITH THIS SHORTWAVE WITH LITTLE IMPACT IN OUR AREA.
GFS MAY STILL HAVE ENOUGH IMPACT FOR LOW CLOUDS IN THE FAR ERN ZONES
BUT NOT SO MUCH ON THE EURO. FIRST WEAK WAVE COMES THROUGH ON
THURSDAY WITH A CHANCE OF LIGHT SNOW IN THE WEST. NEXT SYSTEM IS
STILL EXPECTED TO SPLIT WITH MOST OF THE ENERGY GOING WELL SOUTH
LEAVING A MOIST BUT WEAK GENERAL WLY FLOW ACROSS THE AREA FRIDAY AND
FRIDAY NIGHT. AS MENTIONED YESTERDAY...PROBABLY A HIGH POP...LOW QPF
EVENT FOR MAINLY THE WEST. NEXT SYSTEM ON SATURDAY COMES IN AT
HIGHER LATITUDE AND BY THE TIME IT SPLITS...THERE IS ALREADY
SUFFICIENT MOISTURE AND A LITTLE MORE FORCING/WIND TO PRODUCE AT
LEAST WIDESPREAD LIGHT SNOW IN THE WEST. COLDER AIR FILTERS IN
SUNDAY WITH A MORE UNSTABLE NW FLOW RESULTING IN A CHANCE OF SNOW
SHOWERS EVEN EAST OF THE DIVIDE.

&&

.AVIATION.../00Z ISSUANCE/
VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. STRONG WIND GUSTS
ARE EXPECTED ALONG NORTHERN MOUNTAINS AS WELL AS AT KBYG THROUGH
06Z TONIGHT. OTHERWISE BRISK WEST TO NORTHWEST WINDS WILL CONTINUE
THROUGH MONDAY.

&&

.FIRE WEATHER...
FIRE DANGER LOW AND REMAINING LOW THROUGH THE REST OF THE WORK WEEK
AS SNOW COVER OR MINIMUM RH VALUES STAY WELL ABOVE CRITICAL LEVELS
EVEN WITH BOUTS OF BRISK WEST TO NORTHWEST WINDS THROUGH TUESDAY
MAINLY EAST OF THE DIVIDE.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BRAUN
LONG TERM...SKRBAC
AVIATION...LIPSON
FIRE WEATHER...LIPSON








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