324
FXUS65 KRIW 130844
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
244 AM MDT TUE AUG 13 2013
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
MOST OF THE EVENING CONVECTION HAS PROPAGATED WELL TO THE NORTHEAST
OF THE CWA OVER MONTANA AND THE NORTHERN PLAINS AS THE ASSOCIATED
VORT LOBE EXITS THE AREA. TODAY WILL FEATURE A SHORTWAVE TROUGH THAT
WILL RIDE UP AND OVER THE RIDGE OVER THE ROCKIES. THIS WILL RESULT
IN RELATIVELY WIDESPREAD CONVECTION ACROSS THE CWA. ONE OF THE
BIGGER THREATS WITH TODAYS STORMS WILL BE LOCALLY HEAVY RAINFALL
GIVEN THE WEAK STEERING FLOW. THE BEST CAPES LOOK TO BE ALONG THE
WESTERN...NORTHERN AND EASTERN PERIMETER OF THE CWA RESULTING IN
MORE SIGNIFICANT CONVECTION IN THOSE AREAS. THIS SHORTWAVE WILL TAKE
ITS TIME MOVING OUT OF NORTHEAST WYOMING SO THIS ACTIVITY WILL
LIKELY LINGER PAST MIDNIGHT TONIGHT IN NATRONA AND JOHNSON COUNTIES.
THEN ON WEDNESDAY ANOTHER SHORTWAVE WILL RIDE UP AND OVER THE RIDGE.
THE DIFFERENCE IS THE RIDGE WILL SHIFT TO THE WEST TOWARD THE GREAT
BASIN. THIS WILL CAUSE THE UPPER FLOW TO VEER TO THE NORTHWEST WHICH
WILL DRAW IN LESS UNSTABLE AIR SO THE CONVECTION WEDNESDAY SHOULD
NOT BE AS SIGNIFICANT OR AS LONG LASTING. THURSDAY WILL BE WARMER
AND DRIER WITH THE UPPER NW FLOW BECOMING MORE CONFLUENT...JUST SOME
SPOTTY ISOLATED ACTIVITY IN THE HIGHER MOUNTAINS.
.LONG TERM...FRIDAY THROUGH TUESDAY
MEDIUM RANGE STARTS OUT HOT AND DRY FRIDAY WITH THE RIDGE AXIS
CENTERED RIGHT ON TOP OF US WITH VERY WARM H7 TEMPERATURES.
WEAKENING SHORTWAVE TROUGH APPROACHES SATURDAY FOR A CHANCE OF
THUNDERSTORMS IN THE WEST AND SOUTH MAINLY...GRADUALLY SHIFTING
EAST OF THE DIVIDE SATURDAY EVENING OR OVERNIGHT. ISOLATED STORMS
LINGERING INTO SUNDAY...MAINLY OVER AND NEAR THE MOUNTAINS. A FEW
STORMS MAY LINGER IN THE SOUTH MONDAY OTHERWISE...IT LOOKS DRY
EARLY NEXT WEEK AND CONTINUED WARM.
&&
.AVIATION.../12Z ISSUANCE/
ISOLATED TO LOCALLY SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO DEVELOP ONCE AGAIN LATE THIS MORNING INTO THE AFTERNOON. THE BEST
SHOT FOR CONVECTION WILL BE OVER THE HIGHER TERRAIN ALONG AND EAST
OF THE DIVIDE. CONVECTION WILL BE SLOW MOVERS AGAIN TODAY...WITH THE
MAIN HAZARDS BEING HEAVY RAINFALL...AND GUSTY AND ERRATIC OUTFLOW
WINDS TO AROUND 40 KTS. THE OUTFLOW WINDS MAY IMPACT AREAS WELL AWAY
FROM THE SHOWERS AND THUNDERSTORMS. OUTSIDE OF THUNDERSTORM INDUCED
STRONG WINDS...WINDS WILL BE ON THE LIGHT SIDE. LOCAL MVFR/IFR
CONDITIONS WILL OCCUR IN THE STRONGER STORMS...WHICH MAY IMPACT A
TERMINAL FORECAST SITE THIS AFTERNOON OR EVENING. VERY ISOLATED
SHOWERS MAY LINGER AFTER 06Z WEDNESDAY.
&&
.FIRE WEATHER...
WIDESPREAD THUNDERSTORMS WILL ENSUE TODAY AND TONIGHT AS A FAIRLY
SIGNIFICANT UPPER LEVEL WEATHER DISTURBANCE TRACKS ACROSS THE AREA
TODAY AND TONIGHT. LOCALLY HEAVY RAINFALL WILL BE A THREAT AS THESE
STORMS CELLS WILL BE SLOW MOVING. WEDNESDAY WILL ALSO FEATURE LATE
DAY THUNDERSTORMS BUT NOT AS WIDESPREAD OR SIGNIFICANT. THURSDAY WILL
BE DRY WITH ONLY SPOTTY THUNDERSTORM ACTIVITY AT BEST OVER THE
HIGHER MOUNTAINS. THE COOLEST DAY WILL BE TODAY WITH A WARMING TREND
WEDNESDAY THROUGH THE WEEKEND.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...LIPSON
LONG TERM...SKRBAC
AVIATION...WM
FIRE WEATHER...LIPSON