Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 201901
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1 PM MDT SAT SEP 20 2014

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

A QUIET BEGINNING TO THE FORECAST PERIOD WITH A RIDGE OF HIGH
PRESSURE LEAVING DRY CONDITIONS ACROSS THE FORECAST AREA. COOLER H7
TEMPERATURES CONTINUE TO INVADE THE AREA OVERALL...WITH RESULTING
COOLER DAYTIME TEMPERATURES EXPECTED THROUGH THE WEEKEND. SOME
AFTERNOON WIND MAY DEVELOP OVER NATRONA COUNTY EACH DAY...BUT MOST
OTHER LOCATIONS WILL SEE LIGHTER WIND THROUGH THE FORECAST PERIOD.

A STRONG AREA OF LOW PRESSURE OFF THE CALIFORNIA COAST WILL MOVE
INLAND BY THIS EVENING...EDGING ITS WAY INTO THE INFLUENCING AREA OF
HIGH PRESSURE. THIS AREA OF LOW PRESSURE WILL LIFT INTO THE
INTERMOUNTAIN WEST SUNDAY AFTERNOON AND INTO MONDAY. SHOWERS AND
THUNDERSTORMS WILL MOVE INTO SOUTHWESTERN WYOMING SUNDAY
AFTERNOON...AND WILL SPREAD EAST OF THE DIVIDE BY SUNDAY EVENING.

COVERAGE IS EXPECTED TO INCREASE THROUGH MONDAY AFTERNOON AS THE
AREA OF LOW PRESSURE MOVES THROUGH THE STATE. WITH THE PASSAGE OF
THE SYSTEM MONDAY AFTERNOON...SHOWER AND THUNDERSTORM COVERAGE WILL
WEAKEN THROUGH MONDAY EVENING...THOUGH SCATTERED ACTIVITY WILL
PERSIST ACROSS THE NORTHERN HALF OF THE STATE.

.LONG TERM...TUESDAY THROUGH SATURDAY

A FEW LINGERING SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
THROUGH THE DAY TUESDAY...MAINLY ACROSS THE WESTERN MOUNTAINS AND
EASTERN PORTIONS OF THE CWA...AS MONDAYS TROUGH EXITS THE REGION.
HIGH PRESSURE RIDGE WILL THEN PUSH INTO THE REGION TUESDAY
EVENING...AND BRING DRY AND WARMING CONDITIONS THROUGH THURSDAY.
TEMPERATURES COULD WARM BACK INTO THE LOW TO MID 80S FOR
WEDNESDAY...WITH MID TO POSSIBLY UPPER 80S BY THURSDAY FOR
PORTIONS EAST OF THE DIVIDE.

A LARGE CLOSE LOW TROUGH STILL APPEARS TO BE THE MAJOR WEATHER
MAKER FOR LATE IN THE PERIOD. MODELS ARE NO LONGER SHOWING THE
AGREEMENT AS PREVIOUS RUNS. GFS IS STILL THE MORE PROGRESSIVE
MODEL...WITH THE ECMWF NOW TAKING A MORE NORTHERLY...AND LESS
ACTIVE...TRACK. A GFS SOLUTION WOULD BRING ISOLATED THUNDERSTORMS
ACROSS THE WEST THURSDAY AFTERNOON...THEN INCREASING POPS FROM
WEST TO EAST...FRIDAY THROUGH SATURDAY. TIMING AND TRACK OF THIS
SYSTEM WILL STILL NEED TO BE MONITORED...BUT FOR NOW MAINTAINED
SMALL POPS FOR LATER IN THE PERIOD.

&&

.AVIATION.../12Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND CENTRAL WYOMING
THROUGH 12Z SUNDAY.  NORTHEAST SURFACE WINDS OF 10 TO 15 KTS WITH
GUSTS TO 25 KTS WILL BE ENCOUNTERED VICINITY KBYG THIS AFTERNOON.

&&

.FIRE WEATHER...

HIGH PRESSURE WILL LINGER OVER THE AREA...THOUGH THE PASSAGE OF A
WEAK WAVE WILL CONTINUE TO COOL DAYTIME TEMPERATURES TO BE CLOSER TO
SEASONAL VALUES. DRY CONDITIONS EXPECTED THROUGH SUNDAY MORNING.
SUNDAY AFTERNOON WILL SEE THE ARRIVAL OF MOISTURE INFLUENCED BY AN
APPROACHING AREA OF LOW PRESSURE FROM CALIFORNIA. SHOWERS AND
THUNDERSTORMS WILL MOVE INTO SOUTHWESTERN WYOMING SUNDAY EVENING AND
SPREAD TO COVER THE VAST MAJORITY OF THE FORECAST AREA BY MONDAY
MORNING. SHOWER ACTIVITY WILL WEAKEN MONDAY EVENING ACROSS
SOUTHWESTERN WYOMING...THOUGH SHOWERS WILL CONTINUE ACROSS THE
NORTHERN HALF OF THE AREA THROUGH MONDAY NIGHT.

&&

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

$$

SHORT TERM...BRANHAM
LONG TERM...ANGLIN
AVIATION...C.BAKER/LIPSON
FIRE WEATHER...BRANHAM







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