Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 020458
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1058 PM MDT FRI MAY 1 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

ISOLATED SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS SOUTHERN
SWEETWATER COUNTY WITH WIND GUSTS TO 45KTS POSSIBLE THIS EVENING.
THE REST OF THE AREA WILL BE MOSTLY CLEAR OVERNIGHT WITH WARMER
TEMPERATURES. SUBTROPICAL MOISTURE WILL MOVE NORTHEAST FROM THE
GREAT BASIN INTO THE SOUTHWEST BY EARLY MORNING. A PACIFIC LOW
PRESSURE TROUGH IN THE PACIFIC NORTHWEST WILL ENTER THE NORTHWEST
CORNER OF WYOMING AROUND NOON SATURDAY. THE NORTHERN TROUGH WILL
COMBINE WITH THE SUBTROPICAL MOISTURE TO PRODUCE SCATTERED RAIN
SHOWERS...POSSIBLE SNOW ABOVE 9500 FEET... AND ISOLATED
THUNDERSTORMS OVER THE SOUTHWEST AND WESTERN MOUNTAINS FROM NOON
TO 6 PM MDT. SMALL HAIL AND STRONG WIND GUSTS ARE EXPECTED WITH
THE THUNDERSTORMS. EAST OF THE CONTINENTAL DIVIDE ACROSS THE NORTH
AND EAST WILL HAVE INCREASING CLOUDS BUT THE SHOWERS AND
THUNDERSTORMS ARE NOT EXPECTED IN THESE AREAS UNTIL THE EVENING
HOURS. TEMPERATURES WILL WARM ACROSS THE AREA WITH LOCAL COOLING
WITH HEAVIER PRECIPITATION.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A SLIGHT TURN TO A SOUTHWEST FLOW PATTERN WILL LEAVE A LIGHT AMOUNT
OF MOISTURE ACROSS THE AREA SATURDAY EVENING...WITH A FEW SHOWERS
AND THUNDERSTORMS POSSIBLE. THIS FLOW PATTERN WILL CONTINUE INTO
SUNDAY...WITH SHOWERS MORE FAVORABLE ACROSS SOUTHERN WYOMING DUE TO
THE CONTINUED ZONAL FLOW PATTERN ACROSS THE NORTHER HALF OF THE
STATE. A FEW SHOWERS IS CERTAINLY NOT OUT OF THE QUESTION ACROSS THE
ENTIRETY OF THE FORECAST AREA...AS IS INDICATED IN THE CURRENT
FORECAST. THIS PATTERN CONTINUES ON MONDAY...WITH AN APPROACHING
WAVE OF LOW PRESSURE MOVING OFF THE PACIFIC COAST.

THIS WAVE WILL MOVE INTO THE INTERMOUNTAIN WEST TUESDAY...WITH A
CLOSED AREA OF LOW PRESSURE MOVING OVER THE PACIFIC NORTHWEST. THIS
AREA OF LOW PRESSURE IS EXPECTED TO MOVE SOUTH ACROSS WASHINGTON AND
INTO THE INTERMOUNTAIN WEST BY WEDNESDAY AFTERNOON...WITH SOME
MODELS INDICATING THE SYSTEM DIVING STRAIGHT SOUTH INTO THE DESERT
SOUTHWEST BY THURSDAY AFTERNOON. THIS WILL BRING IN SOME COOLER
TEMPERATURES ACROSS THE FORECAST AREA.

DEPENDING ON MODEL PREFERENCE...THE END OF THE FORECAST PERIOD CAN
VARY SIGNIFICANTLY. THE GFS PUSHES THE AREA OF LOW PRESSURE THROUGH
THE AREA WITH SHOWER COVERAGE INCREASING OVER THE AREA THROUGH THE
EARLY PART OF THE WEEKEND. HOWEVER...THE ECMWF KEEPS THE AREA OF LOW
PRESSURE OVER WESTERN HALF OF THE FORECAST AREA....THOUGH
PRECIPITATION MAY STILL SPREAD ACROSS MUCH OF THE FORECAST AREA
THROUGH FRIDAY NIGHT. TEMPERATURES WILL GENERALLY CONTINUE TO COOL
IN RESPONSE TO THIS SYSTEM THOUGH WILL REMAIN SEASONALLY MILD.

&&

.AVIATION.../06Z ISSUANCE/

VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD AT THE AIRPORTS. A
PACIFIC TROUGH WILL ENTER NORTHWEST WYOMING AFTER 18Z SATURDAY AND
HELP PRODUCE SCATTERED RAIN SHOWERS...POSSIBLE SNOW ABOVE 9500
FEET... AND ISOLATED THUNDERSTORMS OVER THE SOUTHWEST AND WESTERN
MOUNTAINS FROM 18Z TO 05Z SUNDAY. THE HIGHER MOUNTAINS WILL BE
OBSCURED LOCALLY WITH THE HEAVIER SHOWERS AND THUNDERSTORMS. THE
COVERAGE IS NOT EXPECTED TO BE WIDESPREAD ENOUGH TO SINGLE OUT ANY
AIRPORT FOR LOWER CEILINGS AND VISIBILITY SATURDAY AFTERNOON.

&&

.FIRE WEATHER...

ISOLATED SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS SOUTHERN
SWEETWATER COUNTY WITH WIND GUSTS TO 45KTS POSSIBLE THIS EVENING.
THE REST OF THE AREA WILL BE MOSTLY CLEAR OVERNIGHT.  SUBTROPICAL
MOISTURE WILL MOVE NORTHEAST FROM THE GREAT BASIN INTO THE
SOUTHWEST BY EARLY MORNING. A PACIFIC LOW PRESSURE TROUGH IN THE
PACIFIC NORTHWEST WILL ENTER THE NORTHWEST CORNER OF WYOMING
AROUND NOON SATURDAY. THE TROUGH WILL COMBINE WITH THE
SUBTROPICAL MOISTURE TO PRODUCE SCATTERED RAIN SHOWERS...POSSIBLE
SNOW ABOVE 9500 FEET... AND ISOLATED THUNDERSTORMS OVER THE
SOUTHWEST AND WESTERN MOUNTAINS FROM NOON TO 6 PM MDT. SMALL HAIL AND
STRONG WIND GUSTS ARE EXPECTED WITH THE THUNDERSTORMS. EAST OF THE
CONTINENTAL DIVIDE ACROSS THE NORTH AND EAST WILL HAVE INCREASING
CLOUDS BUT THE SHOWERS AND THUNDERSTORMS ARE NOT EXPECTED IN THESE
AREAS UNTIL THE EVENING HOURS. TEMPERATURES WILL WARM ACROSS THE
AREA WITH LOCAL COOLING WITH HEAVIER PRECIPITATION. TRANSPORT
WINDS AND MIXING HEIGHTS WILL COMBINE FOR GOOD TO BETTER SMOKE
DISPERSAL SATURDAY AFTERNOON.

&&

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

$$

SHORT TERM...C.BAKER
LONG TERM...BRANHAM
AVIATION...HATTINGS
FIRE WEATHER...C.BAKER










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