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000
FXUS65 KRIW 132139
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
339 PM MDT MON MAY 13 2013

.SHORT TERM...TONIGHT THROUGH TUESDAY

ISOLATED SHOWERS AND EVENING THUNDERSTORMS WILL BE POSSIBLE OVER
THE WESTERN AND NORTHERN MOUNTAINS EARLY THIS EVENING. HIGH
PRESSURE ALOFT WILL BUILD INTO THE WEST WITH INCREASING SOUTHWEST
FLOW ALOFT AND INCREASED SURFACE WINDS ACROSS CENTRAL AND SOUTHERN
AREAS TUESDAY AFTERNOON. A COLD FRONT WILL MOVE INTO THE NORTH
LATE TONIGHT AND MOVE SOUTH TO THE OWL CREEK AND BRIDGER MOUNTAINS
AND NORTHERN NATRONA COUNTY BY MID DAY THEN STALL OUT UNTIL
TUESDAY NIGHT WHEN THE FRONT WILL CONTINUE SOUTH ACROSS THE AREA. THE
NORTH WILL SEE COOLER TEMPERATURES WHILE THE SOUTH REMAINS WARM
ON TUESDAY.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY NIGHT

ANY ISOLATED SHOWERS THAT MAY HAVE FIRED TUESDAY AFTERNOON SHOULD
END DURING THE EVENING HOURS WITH THE BALANCE OF THE NIGHT LOOKING
LARGELY DRY. WEDNESDAY LOOKS SIMILAR TO TUESDAY WITH FLAT RIDGING
OVER THE AREA AND A WEAK SHORTWAVE MOVING THROUGH. THE NAM DOES SHOW
SOME PRECIPITATION OVER EASTERN PORTIONS OF THE COUNTY WARNING AREA
WITH THE GFS LARGELY DRY. FOR NOW...WE KEPT MOST CONVECTION CONFINED
TO THE HIGHER ELEVATIONS WITH THE BASINS LARGELY DRY. HOWEVER...EVEN
WHERE THERE COULD BE A SHOWER OR THUNDERSTORM A VAST MAJORITY OF THE
DAY WILL BE DRY. MOST CONVECTION SHOULD END ONCE AGAIN ON WEDNESDAY
EVENING WITH LATER WEDNESDAY DRY FOR MOST AREAS.

BY THURSDAY A MORE POTENT TROUGH IS EXPECTED TO APPROACH
NORTHWESTERN WYOMING. THIS SYSTEM HAS A LITTLE MORE KICK TO IT SO WE
UPPED POPS A BIT ACROSS NORTHWESTERN WYOMING. MODELS ARE STILL SPLIT
AS TO IF ANYTHING MAKES IT INTO THE BASINS. RECENTLY THE MODELS HAVE
BEEN OVERDOING THE QPF SO LEFT MOST OF THE LOWER ELEVATIONS DRY FOR
NOW. TEMPERATURES FOR THURSDAY LOOK TO BE SIMILAR TO
WEDNESDAY...ABOVE NORMAL BUT NOT AS WARM AS TODAY.

PRECIPITATION CHANCES LOOK TO INCREASE AGAIN ON FRIDAY AS THE TROUGH
GETS DEEPER AND MORE MOISTURE MOVES INTO THE AREA. AS A RESULT WE
HAVE AT LEAST SLIGHT CHANCE POPS ACROSS MOST OF THE AREA WITH CHANCE
TO LIKELY IN THE MOUNTAINS. MOST THE ACTIVITY STILL LOOKS TO BE
DIURNALLY DRIVEN WITH THE BEST CHANCE IN THE AFTERNOON AND EVENING.

UNSETTLED WEATHER STILL LOOKS TO BE THE RULE FOR THE WEEKEND AND
INTO NEXT MONDAY AS A COLD FRONT PASSES THROUGH WYOMING AND UNSTABLE
NORTHWEST FLOW BRINGS ADDITIONAL SHORTWAVES THROUGH THE REGION. THE
MODELS ARE HAVING SPLIT ON THE DETAILS RIGHT NOW SO TIMING THE WAVES
THIS FAR OUT IS NEARLY IMPOSSIBLE...SO FOR NOW WE BROAD BRUSHED
SLIGHT CHANCE TO CHANCE POPS ACROSS MUCH OF THE AREA WITH THE
HIGHEST CHANCES IN THE THE MOUNTAINS. TEMPERATURES WILL COOL SOME
BUT THERE IS NO REALLY COLD AIR BEHIND THE FRONT SO TEMPERATURES
SHOULD ONLY DROP TO NEAR NORMAL LEVELS.

&&

.AVIATION.../00Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL ACROSS THE REGION MONDAY THROUGH 00Z
WEDNESDAY. AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE
MONTANA/CANADIAN BORDER TONIGHT AND FORCE A COLD FRONT SOUTH INTO
NORTHERN WYOMING AROUND 10Z TUESDAY . SFC SW WINDS WILL INCREASE ACROSS
MOST AREAS AHEAD OF THE COLD FRONT. WINDS WILL CONTINUE TO INCREASE
ACROSS MOST AREAS MONDAY EVENING THROUGH 00Z WEDNESDAY WITH THE
PASSAGE OF A PACIFIC COLD FRONT...ALONG WITH AREAS OF LLWS AND
TURBULENT CONDITIONS VCNTY OF THE CONTINENTAL DIVIDE AND BIGHORN
MOUNTAINS. ISOLATED SHOWERS ARE EXPECTED WITH THE FRONT ACROSS THE
NORTHERN MOUNTAINS.

AFTER MOVING SOUTH ACROSS THE NORTHERN MOUNTAINS...BIG HORN BASIN
AND JOHNSON COUNTY...THE COLD FRONT WILL STALL OUT ALONG THE OWL CREEK
AND BRIDGER MOUNTAINS INTO NORTHERN NATRONA COUNTY AND STAY
STALLED THROUGH 00Z WEDNESDAY.

&&

.FIRE WEATHER...

ISOLATED SHOWERS AND EVENING THUNDERSTORMS WILL BE POSSIBLE OVER
THE WESTERN AND NORTHERN MOUNTAINS EARLY THIS EVENING. HIGH
PRESSURE ALOFT WILL BUILD INTO THE WEST WITH INCREASING SOUTHWEST
FLOW ALOFT AND INCREASED SURFACE WINDS ACROSS CENTRAL AND SOUTHERN
AREAS TUESDAY AFTERNOON WITH LOW RELATIVE HUMIDITY. A COLD FRONT WILL
MOVE INTO THE NORTH LATE TONIGHT AND MOVE SOUTH TO THE OWL CREEK
AND BRIDGER MOUNTAINS AND NORTHERN NATRONA COUNTY BY MID DAY THEN
STALL OUT UNTIL TUESDAY NIGHT WHEN THE FRONT WILL CONTINUE SOUTH
ACROSS THE AREA.THE NORTH WILL SEE COOLER TEMPERATURES WHILE THE
SOUTH REMAINS WARM.

&&

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

$$

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