Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 011720
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1120 AM MDT SAT AUG 1 2015

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

WV IMAGERY SHOWING RIDGE WRN CONUS...TROF ERN CONUS. UPR LVL CENTER
OF THIS HIGH LOCATED OVR NM WITH A STRONGER EMBEDDED WAVE OVR SFC
LOW...VERY TROPICAL LOOKING...NOW ACROSS AZ. A WEAK EMBEDDED SW IS
NOW MOVING DOWN THE EAST SIDE OF THE RIDGE ACROSS NRN/NERN WY WITH
ONLY A FEW SPURIOUS HIGH BASED SHOWERS ACROSS THE NORTH ATTM...WITH
LITTLE PRECIP...IF ANY...ACTUALLY REACHING THE GROUND. SFC HAS
GENERAL WEAK SFC GRAD ACROSS THE FA...WITH AN ALSO WEAK TROF
STRETCHING N/S FROM NCNTRL WY TO CNTRL WY.

HOT AND DRY TODAY SANS PRECIP AT ANY LOCATION IN THE CWA AS DRY AIR
ADVECTS FROM THE WEST OVR THE FA AND ANY SIGNIFICANT MOISTURE IS
HELD AT BAY WELL TO THE SOUTH. SUNDAY...HOTTEST DAY OF THE
PERIOD...WITH WEAK MOISTURE STARTING TO SLOWLY WORK ITS WAY INTO THE
FA THRU THE DAY...ALLOWING FOR LOW CHANCE PRECIP ACROSS FAVORED HIGH
MOUNTAIN RANGES LATER SUNDAY AFTERNOON/EVENING. HOWEVER...IT DOES
LOOK LIKE MOST OF THE PRECIP WILL STILL BE HELD OFF TO THE SOUTH AS
ON SATURDAY. THIS WILL BE A PRECURSOR TO MUCH BETTER CHCS FOR PRECIP
ON MONDAY...AS THE UPR RIDGE AXIS ROTATES CLOCKWISE AND CENTERS OVR
WY WHILE BETTER MONSOONAL MOISTURE STARTS TO FEED ACROSS WY ALONG
WITH WHAT WAS THE AZ DISTURBANCE...MENTIONED ABOVE...MOVING
OVERHEAD. PWS SHOULD BE HIGHER THAN NORMAL...APPROACHING AN INCH IN
SOME PLACES...AND STORM MOTION WILL BE VERY SLOW WITH JET PUSHED OFF
TO THE N AND E...BOTH CONDITIONS TOGETHER GIVING THE POSSIBILITY
FOR AT LEAST ISOLATED FLASH FLOODING.

.LONG TERM...TUESDAY THROUGH SATURDAY

LONG RANGE MODELS MOVE THIS WEATHER SYSTEM ACROSS THE REGION
TUESDAY AND OUT INTO THE PLAINS STATES TUE NIGHT. EXPECT SOME
SHOWER AND THUNDERSTORM DEVELOPMENT TUE INTO TUE EVENING...THEN
DECREASING. GFS MODEL IS A LITTLE FASTER EXITING THIS FEATURE THAN
THE ECMWF MODEL. IN THE WAKE OF THE DEPARTING SYSTEM A SW FLOW
ALOFT DEVELOPS BY WED MORNING. BOTH MODELS SHOW A WEATHER
DISTURBANCE IMPACTING NW WY WED MORNING THROUGH WED EVENING. THE
BEST CHANCE OF STORMS WILL BE OVER THE NORTH AND NW WITH A LESSER
CHANCE ELSEWHERE. THURSDAY LOOKS DRIER FOR NOW WITH ISOLATED
THUNDERSTORM ACTIVITY OVER THE NORTH. FRIDAY LOOKS MOSTLY DRY AS
WELL WITH ISOLATED STORMS OVER AND NEAR THE MOUNTAINS. NEXT
SATURDAY COULD BE MORE ACTIVE IF THE MODEL TIMING IS CORRECT. FOR
NOW A LOW CHANCE OF SHOWERS AND STORMS. HIGH TEMPS TUESDAY THROUGH
SATURDAY WILL BE ABOUT AVERAGE FOR EARLY AUGUST WITH 80S TO LOW
90S AND 75 TO 85 IN THE FAR WEST VALLEYS.

&&

.AVIATION.../18Z ISSUANCE/

HIGH PRESSURE WILL KEEP VFR CONDITIONS AT AREA TERMINALS THROUGH
18Z SUNDAY. MOSTLY CLEAR SKIES WILL PERSIST...WITH LIGHT WIND. AS
MENTIONED IN PREVIOUS DISCUSSION...SOME DRAINAGE WINDS MAY BUMP UP
WIND SPEEDS AT FOOTHILL TERMINALS AFTER 00Z THIS EVENING...WITH
WIDESPREAD LIGHT WIND RETURNING BY 06Z THIS EVENING.

&&

.FIRE WEATHER...

ENHANCED FIRE DANGER TODAY AND SUNDAY AS HOT AND DRY CONDITIONS WITH
MINIMUM RH VALUES EXPECTED TO REMAIN IN THE LOW TEENS THROUGH THE
WEEKEND ACROSS THE LOWER ELEVATIONS...WITH UPPER TEENS AND 20S OVER
THE MOUNTAINS. EXPECT GENERALLY LIGHT WINDS THROUGH THE WEEKEND.
OTHERWISE...A VERY DRY ATMOSPHERE WITH HIGH PRESSURE AT THE SURFACE
AND ALOFT WILL KEEP LITTLE CHANCE FOR ANY PRECIPITATION TODAY...AND
ONLY ISOLATED AND RELEGATED TO MAINLY A FEW MOUNTAIN OR EASTERN
ZONES SUNDAY. CHANCES WILL INCREASE FOR SCATTERED SHOWERS AND
THUNDERSTORMS FROM MONDAY AFTERNOON THROUGH THE EVENING AS AN UPPER
LEVEL DISTURBANCE COMBINES WITH MONSOONAL MOISTURE.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...BRANHAM
FIRE WEATHER...BRAUN



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