Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 292109
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
309 PM MDT TUE JUL 29 2014

.SHORT TERM...TONIGHT THROUGH WEDNESDAY

A DEEP PLUME OF MONSOONAL MOISTURE HAS MOVED OVER THE COUNTY WARNING
AREA. WITH SOME UPLIFT PROVIDED BY A MID LEVEL LOW MOVING ACROSS
UTAH MANY AREAS HAVE BEEN SEEING SHOWERY RAINS THROUGH THE MORNING
AND INTO THE AFTERNOON HOURS. THE GOOD PART ABOUT THIS IS THAT OVER
A MAJORITY OF THE AREA THERE HAS BEEN A MAINLY OVERCAST SKY THAT HAS
LIMITED INSTABILITY. AS A RESULT...MOST OF THE RAIN HAS BEEN OF THE
LIGHT TO MODERATE VARIETY WITH ONLY A FEW LIGHTNING STRIKES. THE
EXCEPTION SO FAR HAS BEEN SOUTHERN NATRONA COUNTY WHERE A STRONG
THUNDERSTORM DEVELOPED OVER CASPER MOUNTAIN. SOME CLEARING HAS BEEN
TRYING TO DEVELOP ACROSS SOUTHWESTERN WYOMING BUT ANY BREAKS SO FAR
HAVE CLOSED AS QUICKLY AS THEY HAVE FORMED. AS A RESULT...WE EXPECT
LITTLE SEVERE WEATHER. THE MAIN THREAT CONTINUES TO BE FLOODING WITH
PRECIPITABLE WATER VALUES RUNNING WELL OVER AN INCH. WITH THE
STRATIFORM NATURE OF THE RAIN...WE HAVE DECIDED AGAINST ISSUING A
FLOOD WATCH AT THIS POINT.

MODELS HAVE DIFFERING OPINIONS ON HOW FAST THE DEEPER MOISTURE GETS
MOVED OUT OF THE AREA. THE NAM HAS TRENDED SLOWER WITH KEEPING DEEP
MOISTURE OVER AREAS SOUTH OF THE OWL CREEK RANGE THROUGH TONIGHT.
MEANWHILE...THE GFS IS MUCH FASTER WITH PUSHING THE DEEP MOISTURE
OUT OF THE AREA BY AROUND 9Z. AT THIS POINT... CONTINUITY LOOKED
LIKE A DECENT SOLUTION. AS A RESULT WE KEPT THE HEAVY RAIN WORDING
THROUGH MIDNIGHT AND TAPERED THINGS OFF AFTER MIDNIGHT.

IT IS THE SAME PROBLEM FOR WEDNESDAY. THE NAM KEEPS MORE MOISTURE
OVER THE AREA...ALTHOUGH A DECENT AMOUNT LESS THAN TODAY. IT HAS
CONVECTION ACROSS MAINLY THE SOUTHWESTERN HALF OF THE COUNTY WARNING
AREA. THE GFS IS ONCE AGAIN THE DRIER MODEL IN BRINGING IN DRIER AIR
FURTHER SOUTH AND CONFINES ANY SHOWERS AND THUNDERSTORMS TO
NORTHWESTERN PORTIONS OF THE COUNTY WARNING AREA. ONCE AGAIN...WITH
THE UNCERTAINTY CONTINUITY LOOKED LIKE A REASONABLE COMPROMISE SO WE
MADE FEW CHANGES. WITH MORE SUNSHINE TOMORROW...TEMPERATURES SHOULD
BE WARMER THAN TODAY BY AROUND 5 TO 10 DEGREES BUT STILL BELOW
NORMAL FOR THE END OF JULY.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

WEAK OR DIRTY RIDGE OVER FORECAST AREA MUCH OF THE EXTENDED PERIOD.
THIS GENERALLY MEANS THERE WILL BE WIDELY SCATTERED AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS EACH DAY WITH JUST ENOUGH MOISTURE
AND LIFT FROM TERRAIN ACROSS WEST CENTRAL WYOMING. FACTORING IN
AMOUNT OF SUNSHINE AND TEMPERATURES ALOFT...DAYTIME HIGHS AND
OVERNIGHT LOWS SHOULD BE SIMILAR...OR NEAR NORMAL...FROM DAY TO DAY.

POSSIBLE INCREASE IN MONSOONAL MOISTURE SUNDAY AFTERNOON INTO EARLY
MONDAY...ESPECIALLY WEST OF THE DIVIDE PER MEDIUM RANGE MODELS.
COULD RESULT IN HIGHER POPS ACROSS THE WEST. SUNDAY NIGHT SHOULD BE
MILD. PATTERN THEN LOOKS UNSETTLED WITH THIS RIDGE FLATTENING AND
SERIES OF SHORTWAVES MOVING OVER WEST CENTRAL WYOMING.
THEREFORE...MONDAY NIGHT AND TUESDAY WILL BE COOLER WITH SCATTERED
SHOWERS AND THUNDERSTORMS FOR ALL AREAS.
&&

.AVIATION.../00Z ISSUANCE/

SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO THE EVENING
HOURS MAINLY SOUTH OF A KJAC TO KWRL TO KCPR LINE.  ALTHOUGH WINDS
WILL BE VARIABLE DUE TO THE CONVECTION...PREVAILING WINDS WILL
GENERALLY BE EASTERLY. MUCH OF THE CONVECTION IS EXPECTED TO
GRADUALLY END FROM THE NORTH TO SOUTH BETWEEN 03Z AND
09Z...ESPECIALLY NORTH OF THE WIND RIVER RANGE AS DRIER PRESSES IN
FROM MONTANA BUT THE CHANCE OF SPOTTY SHOWERS WILL CONTINUE INTO THE
EVENING. MOUNTAINS WILL BE OBSCURED MUCH OF THE TIME THROUGH AT
LEAST EARLY THIS EVENING. SOMEWHAT MORE SETTLED WEATHER IS EXPECTED
FOR WEDNESDAY. HOWEVER...SHOWERS AND THUNDERSTORMS WILL STILL BE
POSSIBLE SOUTH OF A LINE FROM KCPR TO KRIW TO YELLOWSTONE
PARK...MAINLY OF THE ISOLATED VARIETY.
&&

.FIRE WEATHER...

A MORE SIGNIFICANT PUSH OF MOISTURE EXPECTED WILL CONTINUE INTO THIS
EVENING WITH WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY. SHOWERS
ARE ANTICIPATED TO CONTAIN HEAVY RAIN...HELPING TO ALLEVIATE SOME
FIRE WEATHER CONCERNS. WEDNESDAY WILL SEE A CONTINUATION OF SHOWER
ACTIVITY ALTHOUGH NOT AS HEAVY OR AS WIDESPREAD AS TODAY.
TEMPERATURES WILL BE WARMER BUT REMAIN BELOW NORMAL AND RELATIVE
HUMIDITY SHOULD REMAIN BELOW CRITICAL LEVELS FOR MOST AREAS.
&&

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

$$

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





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