Area Forecast Discussion
Issued by NWS Riverton, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KRIW 152036
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
236 PM MDT MON SEP 15 2014

.SHORT TERM...TONIGHT THROUGH TUESDAY

MOST OF THE STATE IS EXPERIENCING A NICE SEPTEMBER DAY WITH PLEASANT
TEMPERATURES AND LIGHT TO MODERATE WINDS. THERE IS A BIT OF HAZE
AROUND IN ASSOCIATION WITH SOME SMOKE MOVING IN FROM THE FIRES IN
CALIFORNIA. IN ADDITION...THERE IS A BIT OF CONVECTION NOTED ACROSS
PORTIONS OF UTAH AND COLORADO WHERE SOME DEEPER MOISTURE IS FOUND.
AT THIS POINT...WE HAVE KEPT THE FORECAST DRY FOR THIS AFTERNOON.
HOWEVER...WE MAY HAVE TO ADD SOME ISOLATED SHOWERS OR THUNDERSHOWERS
THIS AFTERNOON IN SOUTHERN SWEETWATER COUNTY IF ANYTHING SNEAKS
NORTHWARD. THIS WILL BE A GAMETIME DECISION THOUGH. ANY CONVECTION
SHOULD END THIS EVENING WITH TONIGHT AND TUESDAY MORNING LOOKING DRY
WITH MAINLY LIGHT WINDS.

WE DID MAKE A BIT OF CHANGE TO THE FORECAST FOR TUESDAY AFTERNOON
THOUGH. A WEAK SHORTWAVE WILL BE RIDING OVER THE TOP OF THE RIDGE. A
COUPLE OF MODELS...ESPECIALLY THE NAM BUT ALSO THE EUROPEAN TRY TO
FIRE SOME SHOWERS AND THUNDERSTORMS IN NORTHWESTERN PORTIONS OF THE
COUNTY WARNING AREA. MEANWHILE...THE GFS LOOKS DRY. FOR NOW...WE
COMPROMISED FOR HAVING ISOLATED CONVECTION AND HAVING IT REMAIN
MAINLY OVER THE HIGHER TERRAIN WEST OF THE DIVIDE. AS FOR EAST OF
THE DIVIDE...EXPECT ANOTHER MAINLY DRY AND WARM DAY WITH A BIT MORE
OF A BREEZE IN THE FAVORED AREAS BUT NOTHING UNUSUAL FOR WYOMING.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY

CURRENT AMPLIFIED/DIRTYING RIDGE WRN CONUS WITH DECENT TROF WEST OF
THE RIDGE OVR EPAC AND WITH SEVERAL RATHER WEAK SW IMPULSES DUE TO
MOVE THRU THE RIDGE OVR TIME. BROAD TROF ACROSS ERN CONUS.

BEGINNING OF THE FCST PERIOD...CURRENT WEAK SW MOVING UP RIDGE AND
JUST NOW CUTTING INTO NRN CALIFORNIA WILL AFFECT OUR WRN FA TO A
MINOR EXTENT...WITH INCREASED MID/UPR MOISTURE BUT ONLY WEAK
DYNAMICAL FORCING. WILL NEED TO ALSO TAKE ADVANTAGE OF THE MOUNTAIN
TERRAIN IN ORDER TO SQUEEZE OUT MORE THAN SPRINKLES AND ACTUALLY
MEASURE...BUT IT`S POSSIBLE. WED...THE NEXT WEAK RIDGE
RIDING/TOPPING SW MOVES ACROSS THE PEAK OF THE RIDGE. GOOD STRONG
LAPSE RATES ACCOMPANY THE SYSTEM ON A RELATIVELY WARM DAY...BUT
AGAIN LITTLE MOISTURE WILL NOT MUCH MORE THAN A SPRINKLE OR LIGHT
SHOWERS WITH LOW QPF THRU THE EVENING PERIOD OVR THE WRN MOUNTAINS.
THEN BY THURSDAY MORNING...WITH APPROACH OF WRN TROF HELPING TO PUSH
RIDGE ACROSS THE FA...THE WRN CWA WILL OPEN UP TO SW FLOW AND
LEADING LIFT AND UPR DIFLUENCE...ALONG WITH SOMEWHAT BETTER/DEEPER
MOISTURE...ALBEIT MOSTLY MID/UPR LVL AT FIRST. MOISTURE FEED FROM
SWRN CONUS AND THEN EX-HURRICANE ODILE WILL HELP EVER SO SLIGHTLY IN
INCREASING BOUNDARY LAYER MOISTURE BY LATE THURSDAY AFTERNOON AND
THROUGH THE OVERNIGHT PERIOD...ESPECIALLY ACROSS THE SWRN/SRN
ZONES...AS ZONES ACROSS THE CNTRL...ERN AND NRN ZONES WILL HAVE TO
DO SOME WORK AT MOISTENING UP TO OVERCOME THE PREVIOUS FEW DAYS
WORTH OF DRY AIR. OTHERWISE...SPLITTING TROF...W SRN PORTION LOSING
WRN UPR LVL ATTACHMENT AND BECOMING CUT OFF...WILL MOSTLY CLEAR THE
REGION OVERNIGHT FRIDAY...WITH DRYING ENSUING SAT.

BEYOND SAT...MOSTLY DRY/DRYING WEEKEND IN STORE ACROSS THE REGION W/
ONLY THE SLIGHTEST OF PRECIP POSSIBILITIES SHOWING UP ACROSS THE
EXTREME SRN FA UNDER THE STEERING GUIDANCE OF BUILDING UPR LVL SRN
CONUS/MEX HIGH. LR MDLS DIVERGE ON HOW TO HANDLE THE COL WITH THE
GFS KICKING IT OUT UNDER THE INFLUENCE A THE FIRST UPSTREAM SW TROF
APPROACHING THE PAC NW SUNDAY...MODELED WELL SPATIALLY AND
TEMPORALLY BY BOTH THE GFS AND EURO BY THE WAY...WHILE THE EURO IS NOT
AFFECTED BY THIS FIRST WAVE IN THE SAME WAY AND WAITS FOR THE SECOND
WAVE TO KICK IT OUT BY TUE MORNING. HOWEVER...BOTH RESULT IN SIMILAR
SOLUTIONS THRU THIS FCST PERIOD REGARDLESS...REALLY ONLY AFFECTING
EXTENDED WX POSSIBILITIES BEYOND THIS EXTEND FCST.
&&

.AVIATION.../00Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL THROUGH 18Z TUESDAY. ISOLATED SHOWERS OR
STORMS WILL OCCUR NEAR THE FAR SOUTHERN WYOMING BORDER UNTIL 02Z
TUE. THE ACTIVITY WILL SHOULD SOUTH OF THE KRKS AIRPORT. A WEAK
UPPER LEVEL DISTURBANCE MAY BRING ISOLATED SHOWERS AND THUNDERSTORMS
WEST OF THE DIVIDE AFTER 21Z TUESDAY BUT THESE MOST OF THESE SHOULD
REMAIN OVER THE MOUNTAINS AND AWAY FROM THE TAF SITES.
&&

.FIRE WEATHER...

A BUILDING AREA OF HIGH PRESSURE WILL REMAIN OVER THE AREA FOR THE
NEXT FEW DAYS. THE HIGH PRESSURE SYSTEM WILL KEEP WARMING
TEMPERATURES AND DRY CONDITIONS PRESENT INTO TUESDAY MORNING. A BIT
OF BREEZE MAY DEVELOP ON TUESDAY AFTERNOON ACROSS THE SOUTHWESTERN
WIND CORRIDOR BUT SHOULD MAIN BELOW CRITICAL LEVELS.  THE CHANCES OF
AFTERNOON SHOWERS OR THUNDERSTORMS WILL INCREASE FOR THE LATTER HALF
OF THE WEEK BEGINNING WEDNESDAY AFTERNOON AS THE NEXT UPSTREAM
TROUGH APPROACHES. WINDS WILL INCREASE BY TUESDAY NIGHT OR WEDNESDAY
AS WELL.
&&

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

$$

SHORT TERM...HATTINGS
LONG TERM...BRAUN
AVIATION...HATTINGS
FIRE WEATHER...HATTINGS




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.