000
FXUS65 KRIW 101038
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
438 AM MDT TUE SEP 10 2019

.SHORT TERM...(TODAY THROUGH WEDNESDAY)

...MUCH COOLER AND WETTER WEATHER ON THE WAY...

A LOW TRYING TO CLOSE OFF OVER THE PACIFIC NORTHWEST WILL BE 
SENDING A "PRE SHORTWAVE" ACROSS THE CWA TODAY. LIGHT SHOWERS HAVE
ALREADY MOVED INTO WESTERN WYOMING AHEAD OF THIS FEATURE EARLY 
THIS MORNING. THE HRRR BRINGS IN A HEAVIER ROUND OF SHOWERS AND 
THUNDERSTORMS BEGINNING AROUND 17Z TODAY AND MOVES THEM ALONG 
TOWARD THE NORTHEAST TODAY AND TONIGHT IN SEVERAL WAVES. THE 
NORTHERN TWO THIRDS OF OUR CWA IS UNDER A MARGINAL RISK TODAY WITH
WIND SHEAR ALONG WITH DECENT ENOUGH LIFTED INDICES, NOT TO 
MENTION FAIRLY GOOD CAPES IN JOHNSON COUNTY. SMALL HAIL IS A GOOD 
BET TODAY WITH THE COLDER AIR/WET BULB ZERO LOWERING ALOFT. STRONG
GUSTY WINDS AND BRIEF HEAVY RAIN ALSO LIKELY WITH THESE CELLS. 

AS THE ASSOCIATED MAIN TROUGH INCHES CLOSER TO THE AREA, COLDER 
AIR WILL SEEP IN WITH IT TONIGHT. SNOW LEVELS WILL DROP TO 7 TO 
8K LATER TONIGHT AS SHOWERS CONTINUE. 

THEN THE MAIN SHORTWAVE/MAIN TROUGH AXIS WILL TRACK EAST ACROSS
THE AREA WEDNESDAY. OUR EASTERN ZONES, PARTICULARLY JOHNSON
COUNTY, COULD STILL SEE SOME DECENT CONVECTION WEDNESDAY WITH 
CAPES STILL ELEVATED THERE. BY THE TIME THE TROUGHPA OCCURS, 
MOUNTAIN ELEVATIONS ABOVE 7 TO 8000 FEET WILL SEE 1 TO 3 INCHES OF
SNOW ALONG WITH ELEVATIONS ABOVE 10000 FEET RECEIVING 4 TO 10 
INCHES. THE BIG HORN MTNS WILL LIKELY SEE THUNDER SNOW WEDNESDAY 
AFTERNOON. THE MID LEVEL LOW WILL TRACK NORTHEAST ACROSS NORTHWEST
WYOMING, ADDING TO THE SHEAR COMPONENT. 

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY NIGHT)

THE WEATHER SYSTEM WILL BE MOVING THROUGH THE REGION WED NIGHT 
WITH RAIN SHOWERS AND A FEW THUNDERSTORMS. SNOW WILL OCCUR IN THE 
HIGHER MOUNTAIN ELEVATIONS. THE PRECIPITATION WILL BE ENDING FROM 
SOUTHWEST TO NORTHEAST LATE WED NIGHT. SOME LINGERING SHOWERS WILL
OCCUR IN THE NORTHEAST ZONES THURSDAY MORNING, FOLLOWED BY DRYING
FOR THE AFTERNOON. ELSEWHERE THURSDAY, THE WEATHER WILL BE DRY. 
THE LONG RANGE MODELS ARE NOW KEEPING FRIDAY, SATURDAY, AND SUNDAY
DRY WITH A WARMING TREND. NEXT MONDAY LOOKS MOSTLY DRY AND WARM 
WITH ONLY ISOLATED AFTERNOON AND EVENING THUNDERSTORM ACTIVITY AS 
SOME MOISTURE RETURNS TO THE AREA. ELEVATED FIRE WEATHER 
CONDITIONS COULD RETURN SUNDAY AND MONDAY AS IT WILL BE BREEZY AND
WARM WITH LOWER HUMIDITY. THIS WOULD BE AN ISSUE IN THE SOUTH AND
CENTRAL FIRE ZONES. PLENTY OF TIME TO WATCH THIS SCENARIO UNFOLD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY)

VFR CONDITIONS WILL PREVAIL AT THE TERMINAL SITES THROUGH 12Z WED.
ISOLATED SHOWERS AND STORMS OVER THE WEST THIS MORNING. THEN
SCATTERED SHOWERS AND STORMS WILL DEVELOP AFTER 18Z OVER THE
REGION AND THIS ACTIVITY WILL CONTINUE THROUGH 12Z WED. MOUNTAIN
OBSCURATION WILL OCCUR AT TIMES TODAY AND TONIGHT. AREAS OF MVFR
CONDITIONS WILL OCCUR WITH STRONGER STORMS WHERE VISIBILITY WILL 
BE REDUCED IN HEAVY RAIN. THERE WILL BE GUSTY WIND AT SOME 
TERMINAL SITES TODAY. EXPECT A GUSTY WIND TO 35 KNOTS WITH SOME 
STORMS. 

&&

.FIRE WEATHER...

MORE SEASONABLE CONDITIONS HAVE RETURNED TO WESTERN AND CENTRAL 
WY IN TERMS OF TEMPERATURES AND HUMIDITIES AS THE PATTERN CHANGES 
FROM THE HOT & DRY SUMMER. LIGHT SHOWERS WILL CONTINUE TO MOVE 
INTO WESTERN WY EARLY THIS MORNING. A STRONG LOW PRESSURE SYSTEM 
WILL MOVE EASTWARD FROM THE PACIFIC NORTHWEST TOWARD THE ROCKIES 
THIS WEEK, BRINGING SHOWERS AND THUNDERSTORMS TO WESTERN WY THIS 
AFTERNOON, AND TO THE ENTIRE AREA FROM TONIGHT INTO WEDNESDAY. 
CENTRAL WY WILL SEE WINDY SOUTHWEST FLOW THIS AFTERNOON AHEAD OF 
THE SHOWERS, AND SOME OF THE STORMS IN WESTERN WY MAY PRODUCE VERY
STRONG OUTFLOW WINDS. THIS STORM WILL BE COLD ENOUGH TO BRING 
SNOW TO ELEVATIONS ABOVE 7000 TO 8000 FEET. ONE TO THREE INCHES OF
SNOW IS EXPECTED ABOVE 7000 TO 8000 FEET AND 4 TO 10 INCHES ABOVE
SOME OF THE MOUNTAINS ABOVE 10000 FEET. THE STORM WILL EXIT THE 
AREA ON THURSDAY.

&&

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

&&

$$

SHORT TERM...LIPSON
LONG TERM...AR
AVIATION...AR
FIRE WEATHER...LIPSON

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