Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 192025
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
225 PM MDT SAT JUL 19 2014

.SHORT TERM...TONIGHT THROUGH SUNDAY

STRONG DRY WEST SOUTHWEST WINDS WILL BLOW ACROSS FREMONT...NATRONA...
LINCOLN...SUBLETTE...AND SWEETWATER COUNTIES THROUGH 9 PM MDT THIS
EVENING...AND AGAIN FROM NOON TO 8 PM MDT SUNDAY WITH WIND GUSTS OF 25
TO 35 MPH.  WEST NORTHWEST FLOW ALOFT WILL GRADUALLY SHIFT TO THE
WEST SOUTHWEST. AS THIS OCCURS...THE DRY SMOKEY AIR FROM THE
PACIFIC NORTHWEST WILL MOVE NORTH...AND THE NORTHERN EDGE OF
MONSOON MOISTURE WILL MOVE NORTH FROM THE GREAT BASIN INTO
SOUTHERN...WESTERN AND SOUTH CENTRAL WYOMING. THIS WILL BRING A
THREAT OF ISOLATED THUNDERSTORMS INTO THE WYOMING AND SALT RIVER
RANGES...AND THE WIND RIVER...GROS VENTRE AND TETON MOUNTAINS. AND
THE SOUTHWEST INTO SOUTHERN FREMONT AND NATRONA COUNTIES. STRONG
GUSTY WINDS ARE EXPECTED WITH THESE THUNDERSTORMS. THE THUNDERSTORMS
MAY MAKE IT INTO EXTREME SOUTHERN PARTS OF YELLOWSTONE NATIONAL
PARK AND THE ABSAROKA MOUNTAINS. TEMPERATURES WILL ALSO WARM ON SUNDAY.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

THE NEXT MAIN UPSTREAM TROUGH NOW OUT AT 150W WILL KICK A LEAD VORT
LOBE TOWARD THE EAST NORTHEAST AND WILL GRAZE MAINLY OUR WESTERN AND
NORTHERN ZONES SUNDAY NIGHT AND ESPECIALLY MONDAY WITH SOME MONSOON
MOISTURE STREAMING IN FROM THE SOUTHWEST ALONG WITH IT. EXPECT ISOLD
CONVECTION SUNDAY NIGHT IN THE WEST. HAVE INCREASED POPS IN THE WEST
AND THEN THE NORTH MONDAY AS THIS WEATHER FEATURE TRACKS NORTHEAST.
HAVE RAISED SOME MTN POPS ABOVE 50 FOR MONDAY. THEN ON
TUESDAY...ONLY ISOLD TO WDLY SCT CONVECTION IS EXPECTED MAINLY IN
THE NORTHERN MTNS. ON WEDNESDAY EXPECT MORE WIDESPREAD ISOLD TO WDLY
SCT CONVECTION TO FORM OVER THE FAR NORTH AND ACROSS JOHNSON COUNTY
AS A DRY LINE FORMS BETWEEN RELATIVELY MORE MOIST SSE WINDS TO THE
NORTH AND EAST OF THIS SURFACE BOUNDARY ALONG WITH DRY SW WINDS TO
THE SOUTH AND WEST. THE AFOREMENTIONED MAIN TROUGH WELL OFF THE
PACIFIC COAST WILL TRACK EAST NORTHEAST AS A CLOSED LOW AT H7 AND H5
FROM WASHINGTON STATE 06Z THU TO SOUTHERN SASK BY 12Z FRIDAY. THIS
FEATURE WILL SWING A MAIN TROUGH ACROSS THE CWA THU NT. BEHIND THIS
MAIN TROUGH...THE STEERING FLOW WILL VEER FROM THE SOUTHWEST TO THE
WEST WHICH WILL SHUNT ANY MONSOON MOISTURE WELL TO OUR SOUTH WITH
VIRTUALLY NO CHANCE OF PRECIP BY NEXT FRIDAY INTO SATURDAY WITH VERY
STABLE CONDITIONS EXPECTED. THE MOST DRAMATIC COOLING BEHIND THIS
ASCT DRY COLD FRONT/TROUGH WILL TAKE PLACE IN JOHNSON COUNTY AND IN
NORTH CENTRAL WY. HIGHS WILL BE IN THE 90S AT THE LOWER ELEVATIONS
EAST OF THE DIVIDE AND 80S WEST THIS UPCOMING WEEK...COOLING ABOUT 5 TO
10 DEGREES MOST AREAS EXCEPT 10 TO 15 DEGREES JOHNSON COUNTY AND IN
NORTH CENTRAL WY BY LATE NEXT WEEK.

&&

.AVIATION.../00Z ISSUANCE/

VFR CONDITIONS ARE EXPECTED AT THE AIRPORTS THROUGH 00Z MONDAY.
LAYERS OF SMOKE FROM WILDFIRES IN THE PACIFIC NORTHWEST WILL
RESTRICT VISIBILITY LOCALLY FROM 3SM TO 5SM FROM THE SURFACE TO
20000 FEET.  AS THE FLOW ALOFT SHIFTS FROM WEST NORTHWEST TO WEST
SOUTHWEST...THE LAYERS OF SMOKE WILL DRIFT NORTH OUT OF THE AREA
FROM 18Z SUNDAY THROUGH 00Z MONDAY.  EXPECT SURFACE WIND OF
15-25KTS AT KBPI...KPNA... KRKS AND KCPR WITH GUSTS NEAR 30KTS.
WINDS WILL BE DIURNALLY DRIVEN AND WILL DECREASE BETWEEN 02Z-03Z
SUNDAY. UPPER FLOW WILL BACK MORE TO THE SOUTHWEST ON SUNDAY
LEADING TO THE NEXT POSSIBILITY FOR CONVECTION LATE IN THE DAY
ACROSS THE WEST BUT SHOULD HOLD OFF UNTIL AFTER 18Z SUNDAY. ISOLATED
THUNDERSTORMS WITH STRONG GUSTY WINDS WILL BE A THREAT FROM 18Z SUNDAY
THROUGH 00Z MONDAY ACROSS THE SOUTHWEST INTO SOUTH CENTRAL AREAS.

&&

.FIRE WEATHER...

STRONG DRY WEST SOUTHWEST WINDS WILL CREATE RED FLAG CONDITIONS
ACROSS NATRONA AND SWEETWATER COUNTIES...FIRE WEATHER ZONES
279 AND 280 THROUGH 9 PM MDT THIS EVENING...AND AGAIN FROM NOON
TO 8 PM MDT SUNDAY. WIND GUST OF 25 TO 35 MPH WILL COMBINE WITH
RELATIVE HUMIDITY FORM 10 TO 15 PERCENT. THE CONDITIONS WILL BE
PREVALENT ACROSS SOUTHWEST AND CENTRAL AREAS...BUT THE RED FLAG
WARNING HAS BEEN ISSUED ONLY FOR THE TWO ZONES IN THE AREA WITH
CRITICAL FUELS.

WEST NORTHWEST FLOW ALOFT WILL GRADUALLY SHIFT TO THE WEST SOUTHWEST.
AS THIS OCCURS...THE DRY SMOKEY AIR FROM THE PACIFIC NORTHWEST WILL
MOVE NORTH...AND THE NORTHERN EDGE OF MONSOON MOISTURE WILL MOVE
NORTH FROM THE GREAT BASIN INTO SOUTHERN...WESTERN AND SOUTH CENTRAL
WYOMING.  THIS WILL BRING A THREAT OF ISOLATED THUNDERSTORMS INTO
THE WYOMING AND SALT RIVER RANGES...AND THE WIND RIVER...GROS
VENTRE AND TETON MOUNTAINS. AND THE SOUTHWEST INTO SOUTHERN
FREMONT AND NATRONA COUNTIES.  STRONG GUSTY WINDS ARE EXPECTED
WITH THESE THUNDERSTORMS. THE THUNDERSTORMS MAY MAKE IT INTO
EXTREME SOUTHERN PARTS OF YELLOWSTONE NATIONAL PARK AND THE ABSAROKA
MOUNTAINS.  TEMPERATURES WILL ALSO WARM.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING WYZ279-280.

RED FLAG WARNING FROM NOON TO 8 PM MDT SUNDAY WYZ279-280.

&&

$$

SHORT TERM...C.BAKER
LONG TERM...LIPSON
AVIATION...C.BAKER
FIRE WEATHER...C.BAKER








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