Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 292036
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
236 PM MDT FRI MAY 29 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

SCATTERED SHOWERS OVER JOHNSON AND NATRONA COUNTIES HAS DWINDLED TO
ISOLATED SHOWERS OVER PORTIONS OF FREMONT AND SWEETWATER COUNTIES
THIS AFTERNOON. BREAKS IN THE CLOUD SHIELD ARE EVIDENT EAST OF THE
DIVIDE...AS NORTHEAST FLOW BEHIND THURSDAYS TROUGH CONTINUES ACROSS
EASTERN WYOMING. WEST OF THE DIVIDE IS DOMINATED BY CU DEVELOPMENT
THIS AFTERNOON. AN ISOLATED SHOWER CANNOT BE RULED OUT OVER THIS
AREA THIS AFTERNOON. HOWEVER...CLOUDS ARE EXPECTED TO CLEAR OUT THIS
EVENING...SETTING UP FOG TO FORM AGAIN TONIGHT IN JACKSON HOLE AND
THE STAR VALLEY. OTHER LOCATIONS THAT COULD HAVE FOG SATURDAY
MORNING ARE THE GREEN RIVER BASIN NEAR ROCK SPRINGS...THE WIND RIVER
BASIN NEAR RIVERTON AND BOYSEN RESERVOIR AND THE NORTH PLATTE RIVER
NEAR CASPER. OTHERWISE...DRY CONDITIONS TONIGHT AS SHOWER ACTIVITY
ENDS LATER THIS EVENING. THE ATMOSPHERE BEGINS TO RESET
SATURDAY...AS THE STATIONARY FRONT LEFT OVER FROM WEDNESDAYS COLD
FRONT LINGERS ALONG THE DIVIDE. WINDS WILL SWITCH TO THE SOUTHWEST
AHEAD OF THE NEXT COLD FRONT. THIS BOUNDARY WILL BEGIN TO ENTER
NORTHWEST PORTIONS BY EARLY AFTERNOON...GENERATING SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS. THE STRONGER STORMS WILL BE CAPABLE OF
PRODUCING SMALL HAIL.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY NIGHT

ANY LINGERING EVENING THUNDERSTORMS FROM SATURDAY AFTERNOON SHOULD
DIE OFF WITH THE LOSS OF DAYTIME HEATING...WITH THE BALANCE OF
THE NIGHTTIME HOURS REMAINING LARGELY DRY. ANOTHER SHORTWAVE WILL
THEN CROSS THE FLATTENING RIDGE WITH ANOTHER CHANCE OF SHOWERS AND
THUNDERSTORMS. AND...WHAT IS NEW...THE MODELS CONTINUE TO DIFFER
ON THE PLACEMENT OF THE MOST STORMS. THE GFS KEEPS THE CONVECTION
CONFINED MAINLY TO THE HIGHER ELEVATIONS WITH THE HIGH ELEVATION
HEAT SOURCE. THE NAM BRINGS A MORE CONCENTRATED AREA OF SHOWERS
ACROSS THE SOUTH BUT ITS PLACEMENT IS DIFFERENT FROM YESTERDAY AT
THIS TIME. SO AS A RESULT...WE LIFT THE GRIDS FOR SUNDAY AFTERNOON
AND NIGHT AS IS AT THIS TIME UNTIL THERE IS MORE MODEL CONSENSUS.
WITH SOUTHWESTERLY FLOW INCREASING...THIS COULD BE THE DAY MANY
AREAS COULD SEE THE FIRST 80 DEGREE READING OF THE YEAR ACROSS THE
LOWER ELEVATIONS.

AS FOR THE NEXT WORK WEEK...NOT TOO MANY CHANGES TO CONTINUITY.
WE HAVE THE SAME DILEMMA AS THE NIGHT CREW DID. THE MODELS DO
AGREE ON THE LARGE SCALE PATTERN WITH YET ANOTHER TROUGH BUILDING
INTO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES WITH ANOTHER BOUT
OF UNSETTLED WEATHER FOR MUCH OF THE WEEK. THE PROBLEM IS...LIKE
PREVIOUSLY STATED...THIS MAKES THINGS DEPENDENT ON FRONTAL
POSITION AND TIMING OF SHORTWAVES ROTATING AROUND THE PARENT LOW.
AND OF COURSE...THE MODELS ARE ALWAYS IN PERFECT AGREEMENT ON THE
TIMING AND PLACEMENT OF THESE FEATURES 3 TO 7 DAYS OUT...NOTE
SARCASM. ANYWAY...ON MONDAY THERE IS FAIR AGREEMENT THAT THE MOST
ACTIVE AREA WOULD BE ACROSS NORTHWESTERN WYOMING ALTHOUGH THE
EUROPEAN MODEL SPREADS A BETTER CHANCE OF THUNDERSTORMS EAST OF
THE DIVIDE. FOR NOW...WE MADE FEW CHANGES. THIS ALSO LOOKS TO BE
THE WARMEST DAY OF THE WEEK WITH A SOUTHWESTERLY BREEZE BRINGING
SOME DOWNSLOPING HEATING. THIS COULD ALSO BE THE FIRST 90 DEGREE
HIGH SOMEWHERE IN THE COUNTY WARNING AREA. THERE IS STILL THE
CHANCE OF STRONG TO SEVERE THUNDERSTORMS ACROSS THE NORTH ON
TUESDAY WITH SOME JET SUPPORT AND A FRONTAL BOUNDARY HANGING IN
THE AREA. TEMPERATURES SHOULD COOL SOME...BUT STILL QUITE
WARM...ESPECIALLY SOUTH OF THE FRONT. AS FOR THE REST OF THE
PERIOD...MUCH DEPENDS ON THE POSITION OF THE FRONT AND TIMING OF
SHORTWAVES AND WITH THE MODELS ALL OVER THE PLACE OF THE
DETAILS...AGAIN WE DID NOT CHANGE VERY MUCH. TEMPERATURES WILL BE
DEPENDENT ON CLOUD COVER AND FRONT POSITION..BUT WE CONTINUED THE
COOLING TREND INTO LATER IN THE WEEK.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

ISOLATED SHOWERS WILL GRADUALLY END THIS EVENING AROUND 03Z NEAR
KLND AND KRIW. OTHERWISE...MVFR CONDITIONS WILL PERSIST NEAR KCPR THROUGH
01Z. MTN OBSCURATIONS DUE TO CLOUD COVER WILL CONTINUE THROUGH
06Z. VCFG WILL ALSO BE POSSIBLE SATURDAY MORNING FOR KCPR AND KRIW
BY 06Z AND 09Z RESPECTIVELY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

ISOLATED SHOWERS WILL BE POSSIBLE THROUGH 03Z. OTHERWISE...SKIES
WILL CLEAR OVERNIGHT WITH VFR CONDITIONS. HOWEVER...VCFG WILL
LIKELY RETURN TO KRKS AND KJAC BY 05Z AND 06Z RESPECTIVELY.

&&

.FIRE WEATHER...

ISOLATED SHOWERS WILL CONTINUE THIS AFTERNOON...MAINLY ALONG THE
CENTRAL AND WESTERN MOUNTAINS. SKIES WILL BE MOSTLY CLOUDY THIS
AFTERNOON AND EVENING EAST OF THE DIVIDE...TO PARTLY CLOUDY SKIES
WEST OF THE DIVIDE. SHOWERS WILL END AND SKIES WILL BECOME PARTLY
CLOUDY TONIGHT. THERE WILL BE A CHANCE FOR DRIER AND WARMER
WEATHER FOR MUCH OF THE AREA SATURDAY...HOWEVER...ISOLATED TO
SCATTERED SHOWERS WILL RETURN SUNDAY AFTERNOON ACROSS NORTHERN AND
CENTRAL PORTIONS. THIS WILL MARK A RETURN TO ANOTHER ACTIVE
WEATHER PATTERN THROUGH THE MIDDLE OF NEXT WEEK. SMOKE DISPERSAL
EACH DAY WILL BE GOOD TO EXCELLENT...EXCEPT FOR SHORT PERIODS IN
THE VERY EARLY MORNING HOURS.

&&

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

$$

SHORT TERM...LAVOIE
LONG TERM...HATTINGS
AVIATION...LAVOIE
FIRE WEATHER...LAVOIE





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