767
FXUS65 KRIW 042119
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
319 PM MDT SAT JUL 4 2009
SHORT TERM
TONIGHT THROUGH TUESDAY
CONVECTION UNDERWAY ACROSS MOST OF THE AREA THIS AFTERNOON. THE
NORTHWEST AND SOUTH ARE SEEING THE MOST ACTIVITY THROUGH 21Z.
EXPECT OTHER AREAS TO FILL IN AS THE DAY GOES INTO THE EVENING.
KEEPING A CLOSE EYE ON NATRONA COUNTY DUE TO RECENT FLOODING ISSUES.
UPPER LEVEL SYSTEM NEARING NW WY AT 21Z AND THIS WILL MOVE ACROSS
THE NORTH TONIGHT. THIS WILL AID IN KEEPING CONVECTION GOING WELL
INTO THE EVENING HOURS IN THE CENTRAL AND EAST. HAVE ADJUSTED
PRECIP CHANCES A LITTLE TONIGHT TO REFLECT THINKING. KEEPING SMALL
HAIL...GUSTY WIND AND HEAVY RAIN IN THE FORECAST THROUGH MIDNIGHT.
SUNDAY WILL SEE CONVECTION FIRE UP AGAIN IN THE AFTERNOON THROUGH
THE EVENING HOURS IN MOST AREAS. THE MODELS CONTINUE TO HINT AT A
WEAK SHORTWAVE IN THE FLOW SUNDAY PM. PRECIPITABLE WATER VALUES ARE
FORECAST FROM ONE HALF TO THREE QUARTERS OF AN INCH OVER THE REGION.
DEWPOINTS IN THE CENTRAL AND EAST SHOULD STILL BE FAIRLY HIGH TO
SUPPORT A FEW STRONG STORMS WITH HAIL AND HEAVY RAIN SUNDAY AFTERNOON
AND EVENING. MONDAY AND TUESDAY WILL SEE LESS CONVECTION AS DRIER
AIR BEGINS TO PUSH INTO THE REGION FROM THE SOUTHWEST. THE UPPER
RIDGE MOVES OVER THE AREA MONDAY AND THEN TO OUR EAST ON TUESDAY
SETTING UP A SW FLOW ALOFT. WILL SEE BREEZY AREAS ON TUE AS WELL.
BEST CHANCE OF STORMS MONDAY LOOKS TO BE OVER THE NORTH AND
NORTHEAST ZONES WITH ISOLATED ACTIVITY ELSEWHERE. ON TUESDAY THE
FAR NORTH AND NORTHEAST ZONES WILL SEE ISOLATED ACTIVITY. TEMPS
WILL BE WARMING UP THROUGH THE SHORT TERM WITH 80S TO AROUND 90 ON
MONDAY THEN 80S AND 90S ON TUESDAY FOR THE LOWER ELEVATIONS.
LONG TERM
TUESDAY NIGHT THROUGH SATURDAY
ECMWF/GFS AND GEFS MEAN CONTINUE IN GOOD AGREEMENT WITH CLOSED LOW
OFF OF NW COAST EJECTING SEVERAL SHORTWAVES NE INTO CENTRAL CANADA
OVER STRONG RIDGE OVER THE PLAINS. WYOMING WILL MOSTLY REMAIN
UNDER INFLUENCE OF DRY AND WARM SOUTHWEST FLOW WITH SHORTWAVES
PUSHING MOSTLY DRY FRONTS INTO THE NORTH TUESDAY NIGHT AND
WEDNESDAY NIGHT. FORECAST KEEPS LOW POPS NEAR THE FRONT ACROSS
THE FAR NORTH. H7 TEMPERATURES ACROSS THE SOUTH AND CENTRAL FROM
16C-18C...SO BREEZY TO WINDY AND VERY DRY CONDITIONS WILL RESULT
IN TEMPERATURES IN THE MID 80S TO MID 90S ALONG WITH LOW RH/S
MOSTLY IN THE 10-15 PERCENT RANGE. THIS PATTERN WILL DRY OUT FINE
FUELS AND INCREASE THE FIRE DANGER THROUGH THE WEEK. UPPER LOW
OVER THE NORTHWEST TO WEAKEN/FILL FRIDAY AND SATURDAY WITH UPPER
HIGH CENTERED OVER NEW MEXICO STRENGTHENING AND EXPANDING ACROSS
THE ROCKY MOUNTAIN REGION. THIS PATTERN SHOULD BRING BACK THE
RETURN OF MONSOONAL MOISTURE NEXT WEEKEND WITH FORECAST BRINGING
SLIGHT CHANCES OF LATE DAY THUNDERSTORMS OVER THE SOUTHWEST
SATURDAY.
AVIATION
MOISTURE TRAPPED BENEATH AN UPPER LEVEL HIGH PRESSURE SYSTEM WILL
REMAIN OVER WYOMING TONIGHT AND SUNDAY. THUNDERSTORMS WITH THE
CAPABILITY OF PRODUCING HEAVY RAIN AND LARGE HAIL WILL CONTINUE
THROUGH AROUND 03Z ACROSS MOST OF THE REGION...BUT COULD CONTINUE
THROUGH 05Z IN NATRONA AND JOHNSON COUNTIES. THESE STORMS WILL
GENERALLY PRODUCE MVFR VISIBILITIES...BUT BRIEF IFR CONDITIONS ARE
POSSIBLE. VFR CONDITIONS AND LIGHT WINDS ARE EXPECTED ACROSS THE
REGION AFTER 08Z...BUT PATCHY DENSE FOG WILL BE POSSIBLE IN THE
VICINITY OF KRIW...KLND AND KCPR FROM 08Z THROUGH 15Z SUNDAY.
SLIGHTLY DRIER...WEST FLOW WILL MOVE ACROSS WYOMING SUNDAY...BUT
ISOLATED SHOWERS AND THUNDERSTORMS WILL SUNDAY AFTERNOON AND EVENING
WITH BRIEF MVFR CONDITIONS POSSIBLE AT TAF SITES.
FIRE WEATHER
SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR TONIGHT AND AGAIN
SUNDAY AFTERNOON AND EVENING AS THE MOISTURE REMAINS OVER THE REGION.
DRIER AIR WILL BE PUSHING INTO THE SOUTHWEST ZONES MONDAY AND
OVER MUCH OF THE REGION ON TUESDAY. THIS WILL BRING A DECREASE IN
SHOWER AND THUNDERSTORM COVERAGE MONDAY AND TUESDAY. TEMPERATURES
WILL BE MUCH WARMER MONDAY AND TUESDAY WITH LOWER AFTERNOON
RELATIVE HUMIDITY.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...AR
LONG TERM...AEM
AVIATION...SMITH
FIRE WEATHER...AR
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