Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 250504
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1104 PM MDT THU JUL 24 2014

.SHORT TERM...TONIGHT AND FRIDAY

SUBTROPICAL PLUME WHICH BROUGHT WEAK MORNING CONVECTION WITH GUSTY
WIND TO 40 MPH IS NOW BRINGING ISOLATED THUNDERSTORMS TO THE MIX FOR
OUR SERN THIRD. AIRMASS HAS ACTUALLY JUICED UP IN THE FAR SOUTH SO
RED FLAG WARNING IS ACTUALLY STRUGGLING TO VERIFY DUE TO THE HIGHER
DEW POINTS AND COOLER TEMPERATURES. OTHERWISE...HOT AND DUSTY WITH
PLENTY OF SUNSHINE FURTHER NORTH. ONE OTHER ITEM OF NOTE TODAY IS
SOME MOUNTAIN WAVE ACTION GOING ON IN CENTRAL WYO WITH STRONG SW
WINDS MIXING DOWN AT TIMES BETWEEN 40 AND 50 MPH. BEEFED UP WINDS
SOME MORE TO COVER THIS. ONE AREA TO WATCH OVER THE NEXT SEVERAL
HOURS WILL BE OUR NERN ZONES WHERE SURFACE LOW IS SITTING WITH VERY
MOIST AIRMASS JUST TO THE NORTH AND EAST. FRONTAL BOUNDARY AIDED BY
APPROACHING UPPER LOW WILL LIKELY PUSH SOUTH INTO THE AREA SO
POTENTIAL FOR A FEW STRONGER STORMS EXIST FOR A COUPLE HOURS INTO
THE EVENING UP THERE IN JOHNSON COUNTY. FLOW TURNS MORE WLY ON
FRIDAY SO MONSOONAL PLUME SHOULD BE PUSHED SOUTH TO THE NRN CO
BORDER WITH ONLY FAR SERN SWEETWATER SEEING THE POTENTIAL FOR ISOLD
TSTMS. FRONTAL BOUNDARY WHICH SAGS SOUTH INTO CENTRAL WYO TONIGHT
WILL WASH OUR ON FRIDAY ACROSS ALL BUT POTENTIALLY THE NERN ZONES
LEADING TO ANOTHER HOT DAY WITH LOW RH`S AND GUSTY WEST WIND.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AN AREA OF LOW PRESSURE OVER THE CANADIAN AND MONTANA BORDER WILL
CAUSE THE RIDGE OF HIGH PRESSURE TO FLATTEN FRIDAY EVENING. THE
RESULTANT ZONAL FLOW WILL REMAIN DRY...THOUGH THE INFLUENCE OF THE
LOW WILL BRING COOLER TEMPERATURES ACROSS THE FORECAST AREA ON
SATURDAY. THE RIDGE OF HIGH PRESSURE WILL WORK TO AMPLIFY AGAIN
SATURDAY AFTERNOON AND EVENING. AS THE SYSTEM AMPLIFIES...IT MAY
PERMIT SOME MOISTURE TO MOVE INT SOUTHERN WYOMING SATURDAY WITH SOME
ADDITIONAL CLOUD COVER POSSIBLE.

THE RIDGE WILL CONTINUE TO AMPLIFY AND MOVE EAST THROUGH SUNDAY. THE
AXIS OF THE RIDGE WILL BE OVER WESTERN WYOMING BY SUNDAY EVENING.
THE AXIS WILL STRUGGLE TO MOVE FULLY INTO THE STATE AS A SERIES OF
DISTURBANCES IN THE FLOW IMPACT THE FORECAST AREA. DISTURBANCES WILL
BRING REPEATING PERIODS OF SHOWERS AND THUNDERSTORMS DURING THE
AFTERNOON AND EVENING HOURS. AN UPSLOPE COMPONENT IS POSSIBLE DURING
THESE SHOWERS...WHICH INCREASES THE CHANCES FOR ACTIVITY ACROSS
FAVORED LOCATIONS. TEMPERATURES ACROSS THE AREA ARE NOT EXPECTED TO
FLUCTUATE SIGNIFICANTLY EACH DAY. THE COMBINATION OF CLOUD
COVER...SHOWERS...AND HIGH PRESSURE WILL PERMIT TEMPERATURES TO
REMAIN FAIRLY PERSISTENT EACH AFTERNOON.

&&

.AVIATION.../06Z ISSUANCE/

GENERALLY CLEAR SKY WITH VFR CONDITIONS THROUGH FRIDAY NIGHT. THE
SURFACE WIND WILL ONCE AGAIN INCREASE BY MID AFTERNOON ON FRIDAY.
WEST WIND COULD BE GUSTY...ESPECIALLY ALONG THE CENTRAL AND NORTHERN
MOUNTAIN RANGES OF WYOMING.

&&

.FIRE WEATHER...

THE COMBINATION OF HOT TEMPERATURES...LOW RH`S...HAINES INDEX OF
5 TO 6 AND GUSTY WEST WIND WILL CONTINUE THE THREAT OF CRITICAL
FIRE CONDITIONS THROUGH FRIDAY EVENING. MOISTURE LEVELS HAVE COME
UP SOME IN 279 TODAY BUT IT WILL DRY OUT MORE AGAIN ON FRIDAY.
OTHERWISE... EXPECT MORE CRITICAL FIRE CONDITIONS TO CONTINUE
THROUGH FRIDAY. THERE IS A COOL FRONT THAT WILL DROP SOUTH INTO
THE CENTRAL ZONES TONIGHT BUT IT IS EXPECTED TO WEAKEN AND BE
PUSHED EAST OF THE AREA FRIDAY AFTERNOON BUT A DRY...HOT WESTERLY
WIND. MANY AREAS WILL SEE WEST WINDS OF 15 TO 25 MPH DURING THE
AFTERNOON AND EVENING WITH GUSTS VARYING FROM 30 TO 35 MPH.
ISOLATED GUSTY SHOWERS AND THUNDERSTORMS WILL CONTINUE FOR
279...280...289 AND 300 THROUGH THIS EVENING. THE REST OF THE AREA
WILL CONTINUE WARM TO HOT WITH GUSTY WIND AT TIMES WITH MIN RH`S
BETWEEN 10 AND 20 PERCENT. CRITICAL FIRE CONDITIONS MAY CONTINUE
IN 279 THROUGH SATURDAY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 9 PM MDT FRIDAY
WYZ276-279-280-283-285-287-300.

&&

$$

SHORT TERM...SKRBAC
LONG TERM...BRANHAM
AVIATION...KPL
FIRE WEATHER...SKRBAC




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