000
FXUS65 KRIW 140522
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1122 PM MDT THU JUN 13 2013

.SHORT TERM...TONIGHT THROUGH FRIDAY

HIGH BASED CONVECTION...SOUTH OF A TOWER JUNCTION TO CODY TO
GREYBULL TO BARNUM WY LINE...WILL BE PROBLEMATIC THE REST OF TODAY
AND THROUGH THE EVENING PERIOD...WITH SEVERE WIND GUSTS POSSIBLE
FROM ANY OF THE STORMS THAT FORM. STORM MOTION IS FROM SOUTHWEST TO
NORTHEAST AT AROUND 40 MPH TO BEGIN WITH...ALONG WITH STRONG UPPER
LEVEL SUPPORT NOW OVER-RIDING THE WESTERN CWA AND TEMP/DEWPOINT
SPREADS APPROACHING 50 DEG WILL YIELD DCAPE VALUES BETWEEN 1000 AND
1500 J/KG ACROSS VIRTUALLY THE ENTIRE CWA. NORTH OF THE LINE
MENTIONED ABOVE...PARTICULARLY BIG HORN AND JOHNSON COUNTIES...MORE
MOISTURE WILL BE AVAILABLE FOR MORE STANDARD SUPERCELLULAR
MODE...WITH POSSIBLE SEVERE HAIL IN ADDITION TO SEVERE WINDS AND
PERHAPS AN ISOLATED TORNADO IN NORTHERN JOHNSON COUNTY. THROUGH THE
EVENING...SHOWERS AND CONVECTION SHOULD CLEAR THE CWA MOSTLY BY
MIDNIGHT.

FRIDAY...FINALLY BEHIND COLD FRONT WITH WIDESPREAD DRY WEST TO
SOUTHWEST FLOW MOST AREAS EXCEPT FOR THE VERY EXTREME NORTHWEST
CORNER OF THE CWA WHICH WILL HAVE THE BENEFIT OF AT LEAST MID-LEVEL
MOISTURE AND UPPER FORCING...KEEPING SHOWERS AND ISOLATED THUNDER
THROUGH MOST OF THE DAYTIME PERIOD TOMORROW...ENDING BY LATE
AFTERNOON. HIGH TEMPERATURES WILL BE RUNNING SOME 10 TO 12 DEG
COOLER FRIDAY THAN TODAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

FRIDAY NIGHT THROUGH SUNDAY...

FRIDAY`S ISOLATED CONVECTION WILL
LIKELY BE GONE BY THE BEGINNING OF THIS PERIOD AND MAINLY BE
CONFINED TO MONTANA. A DRIER MORE STABLE AIRMASS MOVES IN FOR
SATURDAY FOR DRIER AND COOLER DAY BEHIND A COLD FRONT. ANOTHER
DISTURBANCE PASSES ACROSS SRN CANADA ON SUNDAY WITH A WEAK COLD
FRONT PUSHING INTO THE NRN ZONES. SOME CONVECTION MAY FIRE ALONG
THE FRONT OVER THE HIGHER TERRAIN LATE IN THE DAY BUT NOT SURE
THERE WILL BE ENOUGH INSTABILITY AT THE LOWER ELEVATIONS BEHIND
THE FRONT. OTHERWISE IT WILL BE DRY. THE NORTH WILL BE COOL TO
MILD AT BEST WITH MILD TO WARM CONDITIONS IN THE SOUTH HALF.

SUNDAY NIGHT THROUGH THURSDAY NIGHT...

NO MAJOR CHANGES FROM THE PREVIOUS FORECAST. DECREASED POPS A BIT
FROM SUNDAY NIGHT THROUGH TUESDAY...OTHERWISE NO OTHER CHANGES. THE
UPPER RIDGE OF HIGH PRESSURE REMAINS THE DOMINANT FEATURE FOR MOST
OF THE EXTENDED PERIOD. THE UPPER LOW OFF THE NORTHWEST COAST...WILL
MOVE ONSHORE TUESDAY NIGHT...MOVING NORTHEAST UP THE BACKSIDE OF THE
RIDGE AND OVER THE NORTHERN ROCKIES BY THURSDAY. OVERALL...DRY
CONDITIONS ACROSS THE FORECAST AREA WILL RESULT IN HEIGHTENED FIRE
WEATHER CONCERNS.

ON MONDAY...SURFACE HIGH PRESSURE BUILDING INTO THE PLAINS WILL
RESULT IN AN EASTERLY FLOW BRINGING IN BETTER MOISTURE AND
INSTABILITY/CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS...MAINLY
ACROSS NATRONA AND JOHNSON COUNTIES.

TUESDAY AND WEDNESDAY...A DRY AND WARM SW FLOW WILL PREVAIL ACROSS
MOST OF THE AREA...BREEZY TO WINDY CONDITIONS ALONG WITH INCREASING
FIRE WEATHER CONCERNS ACROSS THE SOUTH AND CENTRAL.  ISOLATED
THUNDERSTORMS WILL BE POSSIBLE ACROSS THE NORTH.

THURSDAY...COLD FRONTAL PASSAGE.  COOLER HIGH TEMPERATURES WITH A
CONTINUED SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE NORTH.



&&

.AVIATION.../06Z ISSUANCE/

SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH 12Z
FRIDAY...ESPECIALLY ACROSS NORTHERN AND WESTERN WYOMING. STORMS
MAY BRING PERIODS OF STRONG WIND TO AREA TERMINALS. BRIEF PERIODS
OF MVFR TO IFR CONDITIONS WILL BE POSSIBLE IN THE STRONGEST STORMS
THROUGH 12Z FRIDAY. SHOWER INTENSITY WILL WEAKEN THROUGH THE
OVERNIGHT HOURS...WITH GENERALLY BENIGN CONDITIONS EXPECTED BY 18Z
FRIDAY. GUSTY WIND OF 15G30KT WILL RETURN TO THE AREA AFTER 16Z
FRIDAY...AND WILL CONTINUE THROUGH MUCH OF THE AFTERNOON. WIND IS
EXPECTED TO RELAX AFTER 03Z SATURDAY.

&&

.FIRE WEATHER...

SEVERAL UPPER LEVEL DISTURBANCES CONTINUE TO SWING UP THROUGH THE
REGION TODAY AND TONIGHT...WITH THE POSSIBILITY OF PRODUCING SOME
STRONG TO SEVERE STORMS ACROSS NEARLY THE ENTIRE CWA TODAY...WITH
HIGH BASED STORMS PRODUCING BRIEF BUT VERY STRONG WINDS IN EXCESS OF
50 MPH AT TIMES. FOR ZONES IN THE NORTHEAST...INCLUDING ZONES 275
AND 281...SEVERE STORMS WITH LARGE HAIL...HIGH WINDS...HEAVY
RAIN...ALL AND FREQUENT LIGHTNING CAN BE EXPECTED THIS EVENING.
TEMPERATURES HIGH TEMPERATURES WILL COOL OFF SOME 10 DEGREES FRIDAY
BEHIND A COLD FRONT.

&&

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

$$

SHORT TERM...BRAUN
LONG TERM...SKRBAC/LAVOIE
AVIATION...BRANHAM
FIRE WEATHER...BRAUN