Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 171736
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1036 AM MST MON NOV 17 2014

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT

WV IMAGERY SHOWS LONGWAVE TROF ACROSS ENTIRE CONUS WITH CENTER OF
CLOSED LOW ROTATING AROUND IN SCNTRL CANADA WITH A COUPLE OF SMALL
SWIFT SW/JET STREAKS MOVING S INTO THE PLAINS. ONE JET STREAK MOVED
THRU EARLIER TODAY AND IS NOW OVR NE/KS...WHILE THE OTHER IS JUST
NOW MOVING DOWN THE BORDER BETWEEN MT AND ND. OTHER EMBEDDED
DISTURBANCES ARE LOCATED FURTHER N AND E INTO CNTRL CA. AT THE
SFC...BACK DOOR STATIONARY FRONT EXTENDS FROM THE MAIN COLD FRONT...
NOW WELL SOUTH ACROSS THE HIGH PLAINS OF CO AND E INTO KS...UP THRU
W CNTRL MT. SFC COLD POOL OVR THE FA LIES JUST TO THE WEST OF THIS
FRONT UNDER CLEAR SKIES AND INCREASING HIGH PRESSURE...WITH A
BULLSEYE OVR THE BIGHORN BASIN.

MOST IMPORTANTLY IN THE FCST WILL BE THE WARM ADVECTION ACROSS MUCH
OF THE CWA THRU THE FCST PERIOD WHICH HOPEFULLY WILL HELP TO
MODERATE THE ARCTIC TEMPS THAT HAVE BEEN IN PLACE OVR NEARLY THE
PAST WEEK...TOPPING OUT ACROSS THE LOWER ELEVATIONS AT NEARLY THE
FREEZING MARK BY WED. OTHERWISE...MOST OF THE FCST WILL BE OF THE
DRY SORT WITH ONLY LOCALIZED SLIGHT CHANCES IN THE BIGHORN MOUNTAINS
ACCOMPANYING ANOTHER BRUSH BY A CLIPPER FRONT ON TUE. BRISK NW WINDS
WILL ONCE AGAIN BE PREVALENT ACROSS NRN JOHNSON COUNTY TUE WITH
INCREASED WEST WIND AHEAD OF THE FRONT BETWEEN SWEETWATER AND
NATRONA COUNTIES. ATTM THE SETUP DOES NOT LOOK CONDUCIVE TO
PRODUCING WIND AS STRONG AS THOSE TODAY. ADDITIONALLY...THE SNOWPACK
SHOULD BE MORE MORE STABLE/ICY AND NOT AS DRY AT LEAST ACROSS THE
LOWER ELEVATIONS...HOPEFULLY FOREGOING THE NEED FOR ANOTHER BLOWING
SNOW SITUATION. HOWEVER...THE HIGH MOUNTAINS MAY EXPERIENCE BLOWING
SNOW CONDITIONS BY TUE AFTERNOON...PARTICULARLY OVR THE WIND RIVER
AND ABSAROKA MOUNTAINS. WILL WAIT FOR ANOTHER DAY TO SEE IF IT LOOKS
LIKE ANY HIGHLIGHTS WILL BE NEEDED. WED...A MODEST INFLUX OF MID LVL
MOISTURE WILL TOP AN UPR LVL RIDGE LOCATED TO THE WEST...OFFERING UP
A LOW END CHC FOR SOME ISOLATED MAINLY TERRAIN FORCED LIGHT SNOW
ACROSS THE WRN/NWRN MOUNTAINS BY THE END OF THE FCST.

.LONG TERM...THURSDAY THROUGH MONDAY

GLOBAL MODELS SHOW A SPLIT WESTERLY FLOW IMPACTING THE ROCKIES THURSDAY
AND FRIDAY. THE MAIN SHORTWAVE TROUGH IN THIS FLOW/TIME FRAME IS
EXPECTED TO SLIDE INTO CALIFORNIA THURSDAY NIGHT...ACROSS THE
DESERT SOUTHWEST FRIDAY...AND THEN ACROSS SOUTHERN ROCKIES FRIDAY
NIGHT. ALTHOUGH THE MAIN ENERGY WILL BE WELL SOUTH OF THE
AREA...THE FAR WEST SHOULD SEE PERIODS OF LIGHT SNOW/FLURRIES.

A STRONG...ZONAL PACIFIC JET...SOUTH OF THE GULF OF ALASKA LOW...
FOR MUCH OF THE WEEK IS PROJECTED BY MODELS TO PUSH INTO THE
WESTERN U.S FRIDAY NIGHT AND SATURDAY. THIS STRONG...MAINLY ZONAL 150+
KT JET SHOULD IMPACT THE AREA SATURDAY AND SUNDAY...BEFORE MODELS
SHOW AMPLIFICATION WITH A LONGWAVE TROUGH OVER MUCH OF THE U.S. AND
SOME RIDGING OVER THE EASTERN PACIFIC/WEST COAST BY LATE SUNDAY/MONDAY.

THE MAIN STORM ASSOCIATED WITH THIS STRONG JET IS PROGGED BY THE
MODELS TO PUSH ACROSS THE NORTHERN/CENTRAL ROCKIES LATE SATURDAY
INTO SATURDAY NIGHT. THE PROGGED MOIST WESTERLY OROGRAPHIC
FLOW...COMBINING WITH A STRONG DISTURBANCE IN THE FLOW AND
POSSIBLY BEING IN THE FAVORABLE LEFT FRONT JET LOCATION...ALL
POINT TO THE POTENTIAL FOR A SIGNIFICANT WINTER STORM ACROSS
WESTERN WYOMING AROUND SATURDAY. DUE TO THE STRONG WESTERLY
FLOW...THE MAIN IMPACT WITH THIS SYSTEM WOULD BE OVER THE
WEST...HOWEVER AS THE ASSOCIATED COLD FRONT PUSHES EAST ACROSS THE
AREA LATE SATURDAY INTO SATURDAY NIGHT...SOME PRECIPITATION COULD
IMPACT AREAS EAST OF THE DIVIDE. AN UNSETTLED...MAINLY NORTHWEST
FLOW PATTERN WILL DEVELOP IN WAKE OF THE STORM SYSTEM SATURDAY
WHICH SHOULD RESULT IN CHANCES OF SNOW SHOWERS ACROSS THE ENTIRE
AREA SUNDAY AND MONDAY...WITH AN EMPHASIS REMAINING OVER THE
WEST.

&&

.AVIATION.../18Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL THROUGH TUESDAY IN MOST AREAS. THE EXCEPTION
WILL BE IN THE FAR WEST VALLEYS AND BASINS WHERE CONSIDERABLE LOW CLOUDS
AND PATCHY FOG ARE EXPECTED TO DEVELOP AGAIN TONIGHT AND LAST THROUGH
MUCH OF TUESDAY MORNING. LOW LYING AREAS IN CENTRAL WYOMING WILL ALSO
SEE AREAS OF LOW CLOUDS AND PATCHY FOG ALONG THE BIGHORN BASIN AND
AROUND BOYSEN RESERVOIR NORTH OF RIVERTON. BREEZY TO WINDY
CONDITIONS WILL OCCUR THROUGH TUESDAY IN THE FAVORED WIND LOCATIONS. NOT
ALL TERMINAL SITES WILL HAVE THE WIND DUE TO BASIN INVERSIONS. SEE
INDIVIDUAL TAF SITES FOR MORE DETAILS.

&&

.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 ON TUESDAY AS A
CLIPPER TYPE WEATHER SYSTEM MOVES THROUGH THE REGION MAINLY EAST
OF THE DIVIDE.

&&

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

&&

$$

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










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