Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 301728
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1128 AM MDT THU OCT 30 2014

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
AT LEAST TWO MORE PLEASANT FALL DAYS ARE IN STORE THROUGH FRIDAY
WITH PERHAPS ANOTHER BONUS DAY IN THE EASTERN CWA SATURDAY.
TEMPERATURES WILL WARM THROUGH SATURDAY ACROSS THE EAST AND THROUGH
FRIDAY ELSEWHERE BEFORE INCREASING CLOUDS AND PRECIP COOL THINGS OFF
SATURDAY. THE RIDGE AXIS OVER THE PACIFIC STATES WILL SHIFT EAST AND
BE OVERHEAD BY THURSDAY NIGHT. THEN THE FLOW WILL BACK TO A MORE
SOUTHWEST FLOW USHERING IN THE AFOREMENTIONED WARM AIR OVER OUR CWA
FRIDAY. A 1037MB SFC HIGH DIVING SSE ACROSS THE NORTHERN PLAINS WILL
NOT DRIVE A BACKDOOR COOL FRONT FAR ENOUGH WEST TO AFFECT OUR CWA
THURSDAY. THE TROUGH ASSOCIATED WITH THE CIRCULATION OFF THE PACIFIC
COAST OVER 50N/145W WILL SHIFT EAST AND MAKE LANDFALL SATURDAY AND
THEN APPROACH THE ROCKIES BY 12Z SUNDAY. BOTH THE GFS AND THE EURO
CLOSE OFF AND TRACK THE ASCT UPPER LOW NORTHEAST ACROSS NW WY WITH
THE EURO A BIT FASTER THAN THE GFS. EARLIER RUNS OF THE GFS HAD THE
LOW TRACKING NORTHEAST FARTHER SOUTH ACROSS CENTRAL WY BUT NOW MORE
RESEMBLES THE EURO. THE GFS TRACKS THE LOW ACROSS NW WY AROUND 12Z
SUNDAY. SOUTHWEST SFC WINDS WILL INCREASE FRIDAY AHEAD OF THIS
APPROACHING PACIFIC WEATHER SYSTEM.

AS A RESULT OF THIS WX SYSTEM...SATURDAY IS SHAPING UP TO BE AN
INTERESTING DAY. A WELL DEVELOPED SFC LOW WILL TRACK FROM EASTERN
IDAHO TO ALONG THE WY/MT BORDER SATURDAY COMPLETE WITH A WELL
DEVELOPED WARM FRONT AND PACIFIC COLD FRONT AND A LIKELY CLASSIC
COMMA CLOUD SIGNATURE. THE H7 LOW WILL TRACK NORTHEAST FROM IDAHO TO
MT WITH A WEAKER H7 CIRCULATION OVER NW WY SATURDAY. HIGHEST POPS
HAVE BEEN PAINTED ACROSS WESTERN WY BY SATURDAY EVE WITH LIKELY POPS
AND AT LEAST CHC POPS UP NORTH. ISOLD IF ANY IN THE CENTRAL AND
EAST. SOME LEFT FRONT QUAD DYNAMICS MAY COME INTO PLAY SAT NT AS THE
JET SAGS SOUTH. WE SHOULD SEE SOME EMBEDDED THUNDERSTORMS IN WESTERN
WY WHERE LIFTED INDICES WILL BE NEGATIVE. SOUTHWEST WINDS WILL
INCREASE SATURDAY OVER WHAT OCCURS FRIDAY AS THE TROUGH NEARS THE
CWA...ESPECIALLY FROM KRKS TO KCPR. RAIN IN THE WEST WILL TURN TO
SNOW SAT NIGHT AS H7 TEMPS DROP -7C.

.LONG TERM...SUNDAY THROUGH THURSDAY

GFS HAS TRENDED FURTHER WEST WITH THE TRACK OF OUR WEEKEND SYSTEM
AS EXPECTED LAST NIGHT. AT THE START OF THIS PERIOD...THE MAIN
CIRCULATION WILL LIKELY BE AROUND THE SWRN CORNER OF MT WITH
SNOW FALLING ACROSS MUCH OF THE WEST. AS THE LOW CONTINUES TO MOVE
OFF TO THE NE...FAVORABLE NW FLOW BEHIND IT SHOULD KEEP SNOW GOING
ACROSS THE WEST...SPREADING INTO THE BIGHORN MOUNTAINS. BY SUNDAY
NIGHT...UPPER LOW WILL LIKELY BE OVER NERN MT WITH COLD...CYCLONIC
NW FLOW OVER THE AREA. COLDEST H5 AIR IS FORECAST TO ARRIVE LATE
SUNDAY NIGHT. THIS SCENARIO CAN RESULT IN SNOW BANDS OVER CENTRAL
WYO INCLUDING THE WIND RIVER BASIN. GFS IS MOST FAVORABLE WITH
MOST OF THE OTHER MODELS PROVIDING AT LEAST SOME SUPPORT. WILL PUT
IN SOME CHANCE POPS SPREADING SE INTO THE WIND RIVER BASIN AND WRN
NATRONA LATE SUNDAY NIGHT WITH A FEW LINGERING INTO MONDAY MRNG.
COULD SEE 3 TO 6 INCHES OF SNOW ACROSS THE WRN MTNS SUNDAY INTO
SUNDAY NIGHT WITH LOCALLY HIGHER AMOUNTS IN FAVORED NW FLOW. COLDEST
H7 AIR COMES IN BEHIND THIS TROUGH ON MONDAY FOR THE COLDEST DAY OF
THE EXTENDED. BOTH THE HIGHS MONDAY AND THE LOWS MONDAY NIGHT. THEN
SLOW MODERATION THE REST OF THE PERIOD WITH POTENTIAL FOR A MILD DAY
THURSDAY WITH SOME WIND AND BETTER MIXING. RAISED TEMPERATURES SOME
AT THE END OF THE PERIOD BUT NOT AS HIGH AS THEY COULD BE IF WE CAN
FULLY MIX THE ATMOSPHERE BY THURSDAY WHEN POTENTIAL WINDS KICK IN.

&&

.AVIATION.../18Z ISSUANCE/
HIGH PRESSURE AT THE SURFACE AND ALOFT BUILDS INTO THE REGION LATER
TONIGHT AND THURSDAY. THIS WILL RESULT IN A GENERALLY CLEAR SKY AND
VFR CONDITIONS ON BOTH SIDES OF THE CONTINENTAL DIVIDE...AND THEN
CONTINUE INTO FRIDAY. A GUSTY BREEZE WILL DEVELOP AT TIMES ON
FRIDAY...MAINLY IN VICINITY OF KRKS AND KCPR.

&&

.FIRE WEATHER...
AN AREA OF HIGH PRESSURE WILL BUILD INTO THE AREA BRINGING BENIGN
CONDITIONS FOR TODAY. THIS RIDGE OF HIGH PRESSURE IS EXPECTED TO
LAST THROUGH SATURDAY MORNING. THE NEXT POTENTIAL ROUND OF
PRECIPITATION MAY BE FOUND BEGINNING SATURDAY AFTERNOON AS AN AREA
OF LOW PRESSURE APPROACHES WESTERN WYOMING.


&&

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

$$

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











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