000
FXUS65 KRIW 200907
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
307 AM MDT THU JUN 20 2013

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT

TEMPERATURES WILL DROP TO NEAR NORMAL LEVELS AS THE COOLER AIR 
ASSOCIATED WITH THE UPPER LOW MOVES INTO THE REGION. DRY SOUTHWEST 
FLOW WILL MAINTAIN A SUNNY SKY AND PREVENT SHOWERS AND THUNDERSTORMS 
FROM FORMING. GUSTY SOUTHWEST WINDS WILL AGAIN RAISE FIRE WEATHER 
CONCERN ACROSS THE SOUTHEASTERN PORTIONS OF THE CWA...AND IT IS 
LOOKING A BIT MORE THAN JUST MARGINAL ACROSS NATRONA COUNTY GIVEN 
THE VERY POOR RH RECOVERY OVERNIGHT...THE VERY LOW RHS EXPECTED 
AGAIN TODAY...AND THE POSSIBLE SET UP OF A SURFACE LOW IN SOUTHERN 
JOHNSON COUNTY LATER TODAY...THAT COULD BRING THE SURFACE WINDS WELL 
INTO THE CRITICAL RANGE. IN ADDITION...THE APPROACHING UPPER LEVEL 
LOW AND ATTENDANT JET STREAK ALOFT WILL ALSO DESTABILIZE THE REGION 
AND ALLOW FOR DEEP MIXING...BRINGING DOWN THE STRONGER WINDS AND 
RAISING THE HAINES INDEX TO A 6.   

BY FRIDAY THE UPPER LEVEL LOW CONTINUES TO MOVE A BIT FURTHER 
EAST...WITH MODELS SPEEDING UP THE PROGRESSION OF THE LOW A BIT. THE 
COOLING ALOFT WILL MAKE IT EASIER FOR THE ATMOSPHERE TO 
DESTABILIZE...AGAIN MOISTURE WILL BE LACKING ACROSS THE SOUTH BUT 
THERE COULD BE A FEW SHOWERS IN THE NORTHERN BIG HORN BASIN AND 
ACROSS THE NORTHWEST WITH A SHORTWAVE BRUSHING BY. BREEZY SOUTHWEST 
WINDS AGAIN RETURN TO SWEETWATER AND NATRONA COUNTIES ALONG WITH LOW 
HUMIDITY...LOOKING BORDERLINE FOR CRITICAL FIRE WEATHER 
CONDITIONS...SO WILL HOLD OFF ON EXTENDING THE WARNING INTO FRIDAY 
FOR NOW.

THE UPPER LOW EVENTUALLY OPENS UP INTO A TROUGH WITH SOME 
DISAGREEMENT STILL EXISTING WITH RESPECT TO HOW FAR SOUTH THE TROUGH 
DIGS. MOST OF THE MOIST AIR REMAINS TO THE NORTH BUT COULD DIP AS 
FAR SOUTH AS THE WIND RIVER RANGE...HAVE BROAD BRUSHED ISOLATED POPS 
DOWN INTO CENTRAL WYOMING. THERE IS NOT A LOT OF MOISTURE WITH THIS 
SYSTEM...SO NO HEAVY RAIN IS EXPECTED...BUT IT COULD BE ENOUGH TO 
PRODUCE SHOWERS AND CLOUD COVER OVER MUCH OF THE STATE.  

.LONG TERM...SUNDAY THROUGH THURSDAY

SUNDAY LOOKS DRY WITH A SW FLOW ALOFT OVER THE REGION. SW FLOW 
CONTINUES MONDAY AND TUESDAY WITH A FEW WEATHER DISTURBANCES IN THE 
FLOW. THIS WOULD BRING A SLIGHT CHANCE OF SHOWERS AND STORMS TO THE 
NW MOUNTAINS AND ACROSS THE NORTH. THE CENTRAL AND SOUTH LOOK TO BE 
DRY AT THIS POINT AS MOISTURE LOOKS LOW. WEDNESDAY AND THURSDAY OF 
NEXT WEEK LOOK VERY WARM TO HOT AS UPPER LEVEL RIDGE BUILDS OVER THE 
ROCKIES. THE CENTER OF THE HIGH MOVES TO THE VICINITY OF THE FOUR 
CORNERS NEXT THURSDAY. FOR NOW DRY WEATHER AS MID OR UPPER LEVEL 
MOISTURE IS NOT SHOWN BY THE MODELS MOVING AROUND THE HIGH INTO WY. 
WILL WATCH THIS OVER THE COMING DAYS. AS FOR TEMPS...GRADUAL WARMING 
IS EXPECTED SUNDAY THROUGH THURSDAY. THIS WILL CONTINUE TO RAISE 
FIRE WEATHER CONCERNS AS FUELS WILL CONTINUE TO DRY ESPECIALLY AT 
LOWER ELEVATIONS. 

&&

.AVIATION.../12Z ISSUANCE/

A DRY START WILL BE PRESENT THIS MORNING...WITH WIDESPREAD VFR 
CONDITIONS. HOWEVER... A WEAK DISTURBANCE WILL MOVE ACROSS NORTHERN 
WYOMING. THIS SYSTEM MAY BE ENOUGH TO GENERATE SOME HIGHER TERRAIN 
SHOWERS AND THUNDERSTORMS...MAINLY IMPACTING THE NORTHERN AND 
NORTHWESTERN MOUNTAINS. SHOWERS ARE NOT ANTICIPATED TO IMPACT THE 
TERMINALS...THOUGH SOME STRONGER WIND MAY NOT BE OUT OF THE QUESTION 
FOR NEARBY AIRPORTS. WIDESPREAD VFR CONDITIONS EXPECTED OTHERWISE. 
AN INCREASE IN WIND IS ANTICIPATED AFTER 18Z...WITH SOME GUSTY WIND 
POSSIBLE. WIND WILL WEAKEN THROUGH THE EVENING. GENERALLY LIGHT WIND 
EXPECTED BY 07Z ACROSS THE AREA. 

&&

.FIRE WEATHER...

...RED FLAG WARNING FOR NATRONA COUNTY TODAY...

RH RECOVERY OVERNIGHT WAS VERY POOR EVEN WITH THE COLD FRONTAL 
PASSAGE...ACROSS THE EAST. THE UPPER LOW RESPONSIBLE FOR THE COLD 
FRONT CONTINUES TO APPROACH FROM THE WEST TODAY...INCREASING 
SOUTHWEST FLOW AHEAD OF IT AND MAINTAINING AN UNSTABLE 
ATMOSPHERE...RAISING CONCERN FOR AREAS WITH CRITICAL FUELS. A RED 
FLAG WARNING HAS BEEN ISSUED FOR NATRONA COUNTY AS THE WARMEST AIR 
IS EXPECTED TO BE FROM NATRONA COUNTY SOUTHWARD. CONDITIONS COULD 
STILL MEET CRITERIA IN THE BIGHORNS AND JOHNSON COUNTY...BUT THEY 
WILL BE MORE MARGINAL. THESE CONDITIONS WILL ALSO BE PRESENT ACROSS 
RAWLINS AND CODY DISPATCH WHERE FUELS ARE A LITTLE LESS 
CRITICAL...NO HIGHLIGHTS FOR THESE AREAS BUT THE WIDESPREAD 
HOT...DRY...WINDY AND UNSTABLE CONDITIONS WILL STILL RAISE SOME 
CONCERN. CONTINUED DRY AND BREEZY CONDITIONS EXPECTED ON 
FRIDAY...BUT MORE MARGINAL.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...

RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 8 PM MDT THIS 
EVENING WYZ280-300.

&&

$$

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