High Wind in Wyoming, June 5 to 6, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1225 PM MDT TUE JUN 5 2012

.SHORT TERM...TUESDAY THROUGH THURSDAY NIGHT
UPDATED TO UPGRADE THE HIGH WIND WATCHES TO WARNINGS AND ALSO
EXTEND THE CODY FOOTHILLS ONE BY 3 HOURS UNTIL 12Z. EVERYTHING
POINTS TO HIGH WINDS IN THESE AREAS WITH THE DECENT POTENTIAL OF A
ABOVE NORMAL HIGH WIND EVENT FOR LANDER...CODY AND CLARK. THE GAP
FLOW SIGNATURE FOR THE CODY FOOTHILLS IS ALSO VERY IMPRESSIVE.

RADAR STILL HAS SOME LIGHT SHOWERS ACROSS PORTIONS OF THE CWA AS OF
1 AM...MAINLY ACROSS THE WESTERN MOUNTAINS. MOST OF THESE ARE IN THE
PROCESS OF WEAKENING AND SHOULD BE GONE BY SUNRISE IN MOST
LOCATIONS. WITH THE REGION IN THE WARM SECTOR THIS MORNING MOST
AREAS SHOULD RAIN FREE THIS MORNING WITH THE EXCEPTION OF SOME
ISOLATED SHOWERS IN THE FAR WEST.

HOWEVER...ACTIVE WEATHER WILL RETURN THIS AFTERNOON AS A POTENT COLD
FRONT MOVES INTO WESTERN WYOMING FROM IDAHO LATER THIS AFTERNOON AND
PLOWS ACROSS THE AREA THROUGH THE EVENING. OF FIRST ISSUE WILL BE
THE WIND. AS THE COLD FRONT APPROACHES A RATHER TIGHT PRESSURE
GRADIENT WILL DEVELOP. THE FIRST AREA WILL LIKELY BE ACROSS EASTERN
SWEETWATER COUNTY AS WELL AS THE GREEN MOUNTAINS THIS AFTERNOON SO
WE HAVE UPGRADED THE HIGH WIND WATCH TO A HIGH WIND WARNING. OTHER
AREAS WILL SEE HIGHER WINDS WITH THE COLD FRONTAL PASSAGE WITH A
VERY QUICK PRESSURE DROP AND RISE WITH A PERIOD OF STRONG PRE AND
POST FRONTAL WINDS. SINCE MOST OF THIS WIND WILL OCCUR IN THE SECOND
PERIOD OF THE FORECAST WE WILL LET THE HIGH WIND WATCHES RIDE FOR
NOW AND LET THE DAY SHIFT UPGRADE IF NEEDED.

THE NEXT CONCERN IS FOR FIRE WEATHER. EXPECT ANOTHER VERY WARM TO
HOT DAY ACROSS MOST AREAS TODAY COMBINED WITH GUSTY WINDS ALONG WITH
RELATIVE HUMIDITY FALLING BELOW 15 PERCENT FOR MANY AREAS AND UNDER
10 PERCENT IN SOME AREAS. WITH CRITICAL FUELS ACROSS EASTERN
PORTIONS OF OUR AREA WE HAVE DECIDED TO UPGRADE THE FIRE WEATHER
WATCH TO A RED FLAG WARNING.

ANOTHER CONCERN IS FOR POTENTIAL STRONG THUNDERSTORMS IN PARTS OF
THE AREA. MUCH OF THE REGION EAST OF THE DIVIDE AS WELL AS
SWEETWATER COUNTY WILL LIKELY ESCAPE ANY CONVECTION.
HOWEVER...MODELS CONTINUE TO SHOW A THIN BAND OF MOISTURE SNEAKING
INTO FAR EASTERN PORTIONS OF JOHNSON AND NATRONA COUNTIES SO WE HAVE
MAINTAINED ISOLATED CONVECTION THERE ALTHOUGH MOST PLACES SHOULD
STAY STORM FREE. THERE WILL BE A BETTER CHANCE ACROSS WESTERN
WYOMING AS WELL. SOUNDINGS SHOW SOME INVERTED V SOUNDINGS SO SOME
STRONGER WIND GUSTS ARE POSSIBLE WITH ANY STORM AS WELL AS SOME
SMALL HAIL.

YET ANOTHER CONCERN WILL BE THE POTENTIAL FOR SNOW AFTER THE FRONT
PASSES ACROSS THE WESTERN MOUNTAINS. SNOW LEVELS ARE EXPECTED TO
DROP QUICKLY AFTER THE FRONTAL PASSAGE. EVEN PLACES LIKE JACKSON
COULD SEE SOME WET SNOWFLAKES AFTER MIDNIGHT BEFORE THE
PRECIPITATION ENDS. ACROSS HIGHER ELEVATIONS INCLUDING PORTIONS OF
YELLOWSTONE PARK AS WELL AS SOME OF THE MOUNTAIN PASSES THERE COULD
BE A QUICK INCH OF SNOW AS WELL THAT COULD MAKE FOR SLICK DRIVING
CONDITIONS AT TIMES.

MUCH MORE SETTLED WEATHER LOOKS TO RETURN ON WEDNESDAY AS HIGH
PRESSURE BUILDS INTO THE AREA. WITH MOISTURE IN THE EAST NOW
EXPECTED TO STAY EAST OF THE AREA...WE HAVE REMOVED SHOWERS FROM
EASTERN PORTIONS OF THE CWA. THE BIG CHANGE WILL BE COOLER
TEMPERATURES WITH MANY AREAS SEEING HIGH TEMPERATURES AROUND 20
DEGREES COOLER THAN ON TUESDAY. WITH FLOW TURNING MORE SOUTHWESTERLY
ON THURSDAY...EXPECT WARMER TEMPERATURES WITH CONTINUED SETTLED
WEATHER.

LONG TERM...FRIDAY THROUGH TUESDAY

FRIDAY...WINDY AND UNSEASONABLY WARM SOUTH AND CENTRAL...ELEVATED
TO CRITICAL FIRE WEATHER CONDITIONS. CHANCE OF AFTERNOON/EVENING
THUNDERSTORMS WEST AND FAR NORTH.

SATURDAY...COLD FRONTAL PASSAGE.  COOLER WEST WITH SCATTERED SHOWERS
AND THUNDERSTORMS.  CONTINUED WARM AND WINDY CENTRAL WITH ISOLATED
TO SCATTERED THUNDERSTORMS...MORE NUMEROUS NORTH.  ISOLATED STRONG
THUNDERSTORMS.

SUNDAY...COOLER. BREEZY TO WINDY.  CHANCE OF SHOWERS AND ISOLATED
THUNDERSTORMS NORTH.

MONDAY AND TUESDAY...WARMING TREND.  SLIGHT CHANCES OF AFTERNOON AND
EVENING THUNDERSTORMS.

MEDIUM RANGE GLOBAL MODELS IN GOOD OVERALL AGREEMENT THIS MORNING
WITH NEXT UPPER LOW MOVING ALONG 50N NEAR 160W THIS MORNING MOVING
INTO THE NORTHWEST U.S. ON FRIDAY.  PORTION OF DOWNSTREAM UPPER LOW
LIFTING ACROSS AREA IN THE SHORT TERM GETS CAUGHT UP IN
FUJIWARA-TYPE CIRCULATION...MAKING ONE FULL ORBIT AROUND THIS NEXT
SYSTEM...RETURNING TO THE NORTHERN GREAT BASIN ON SATURDAY WHILE
DOMINANT UPPER LOW LIFTS INTO SOUTH CENTRAL CANADA.  THE TWO SYSTEMS
THEN MERGE TOGETHER OVER THE NORTHERN PLAINS ON SUNDAY.  BOTH GFS
AND ECMWF LEAVE SOME DEGREE OF TROUGHINESS OVER THE INTERMOUNTAIN
WEST/GREAT BASIN UNDERNEATH UPPER RIDGE OVER THE NORTHERN ROCKIES
MONDAY WITH SLOW PROGRESSION OF THIS PATTERN THROUGH TUESDAY.  GFS
SHOWS DEEPER TROUGH OVER THE GREAT BASIN THAN ECMWF...WHILE ECMWF
HAS DEEPER UPPER LOW NEAR 50N/130W BY 00Z WED.  EITHER WAY...BOTH
AGREE ON SOME PERTURBATIONS IN SW FLOW TO WARRANT AT LEAST SLIGHT
CHANCES OF AFTERNOON/EVENING THUNDERSTORMS ACROSS MOST AREAS MONDAY
AND TUESDAY.

AVIATION.../18Z ISSUANCE/

THUNDERSTORMS WILL DEVELOP ALONG AND WEST OF A KEVW TO KCOD LINE
THIS AFTERNOON.  SOME CONVECTION COULD BE STRONG TO SEVERE AT TIMES
AS THEY WILL BE FAST MOVING FROM SOUTH TO NORTH. PERIODS OF MVFR/IFR
POSSIBLE AS STORMS MAY IMPACT KBPI...KPNA...KAFO...AND KJAC. MOST
OTHER AIRPORTS WILL SEE VFR CONDITIONS. HOWEVER...EXPECT STRONG WIND
AHEAD OF A FRONTAL PASSAGE THIS AFTERNOON AND EVENING. THESE STRONG
WINDS WILL IMPACT MUCH OF THE AREA TODAY THROUGH THE FORECAST
PERIOD. VERY STRONG WIND IS POSSIBLE THIS AFTERNOON ACROSS MUCH OF
THE AREA...INCLUDING THE MAJORITY OF TERMINALS. HIGH WIND WARNINGS
ARE IN EFFECT FOR MANY AREAS EAST OF THE CONTINENTAL DIVIDE. THE
COLD FRONT WILL MOVE THROUGH THE AREA LATE THIS AFTERNOON THROUGH
THIS EVENING FROM WEST TO EAST...CAUSING WIND SHIFTS. THIS FRONT SHOULD
BE THROUGH KJAC BY 22Z...KRIW BY 03Z...AND APPROACHING KCPR BY 12Z.

FIRE WEATHER...

A STRONG COLD FRONT WILL APPROACH FROM THE WEST AND MOVING THROUGH
THE AREA DURING THE AFTERNOON AND EVENING. STRONG SOUTHERLY WINDS
WILL DEVELOP AHEAD OF THE FRONT AND THIS COMBINED WITH HOT
TEMPERATURES AND LOW RELATIVE HUMIDITY WILL MAKE FOR ELEVATED FIRE
DANGER...ESPECIALLY ACROSS EASTERN PORTIONS OF THE REGION. RED FLAG
WARNINGS HAVE BEEN ISSUED FOR PORTIONS OF NATRONA AND JOHNSON
COUNTIES.

WEDNESDAY LOOKS TO BE A MUCH COOLER DAY WITH SOMEWHAT HIGHER
HUMIDITY ALTHOUGH STILL BELOW 20 PERCENT FOR MANY AREAS. WINDS WILL
STILL BE BREEZY AT TIMES BUT MUCH LIGHTER THAN ON TUESDAY. DRY
WEATHER WILL CONTINUE ON THURSDAY WITH SOMEWHAT WARMER TEMPERATURES
AND LIGHT TO MODERATE WINDS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 3 PM THIS AFTERNOON TO MIDNIGHT MDT
TONIGHT WYZ005-018-019-030.

RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING WYZ280-281-285.

HIGH WIND WARNING FROM 6 PM THIS EVENING TO 3 AM MDT WEDNESDAY
WYZ016-017.

HIGH WIND WARNING FROM 6 PM THIS EVENING TO 6 AM MDT WEDNESDAY
WYZ003.

&&

SHORT TERM...SKRBAC
LONG TERM...HATTINGS
AVIATION...BERC
FIRE WEATHER...SKRBAC

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RIVERTON WY
1012 AM MDT TUE JUN 5 2012

WYZ001>020-022>030-061200-
ABSAROKA MOUNTAINS-BIGHORN MOUNTAINS SOUTHEAST-
BIGHORN MOUNTAINS WEST-CASPER MOUNTAIN-CODY FOOTHILLS-
EAST SWEETWATER COUNTY-FLAMING GORGE-
GREEN MOUNTAINS AND RATTLESNAKE RANGE-JACKSON HOLE-LANDER FOOTHILLS-
NATRONA COUNTY LOWER ELEVATIONS-NORTH BIG HORN BASIN-
NORTHEAST JOHNSON COUNTY-OWL CREEK AND BRIDGER MOUNTAINS-
ROCK SPRINGS AND GREEN RIVER-SALT RIVER AND WYOMING RANGES-
SOUTH LINCOLN COUNTY-SOUTHEAST BIG HORN BASIN-
SOUTHEAST JOHNSON COUNTY-SOUTHWEST BIG HORN BASIN-STAR VALLEY-
TETON AND GROS VENTRE MOUNTAINS-UPPER GREEN RIVER BASIN-
UPPER GREEN RIVER BASIN FOOTHILLS-UPPER WIND RIVER BASIN-
WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST-WIND RIVER MOUNTAINS WEST-
YELLOWSTONE NATIONAL PARK-
1012 AM MDT TUE JUN 5 2012

...HIGH WIND WARNINGS IN EFFECT FOR MUCH OF CENTRAL WYOMING
LATER THIS AFTERNOON THROUGH MUCH OF TONIGHT...

...RED FLAG WARNING IN EFFECT FOR JOHNSON AND NATRONA COUNTIES
FOR THIS AFTERNOON AND EARLY THIS EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING.

.DAY ONE...TODAY AND TONIGHT

NEAR BANKFULL CONDITIONS EXPECTED ALONG THE NORTH AND SOUTH FORK OF
SHOSHONE RIVER WEDNESDAY MORNING AND ALONG THE WIND RIVER NEAR
RIVERTON WEDNESDAY NIGHT AND THURSDAY MORNING. PLEASE VIEW OUR
HYDROLOGY PRODUCTS FOR ADDITIONAL INFORMATION.

WIDESPREAD ELEVATED FIRE WEATHER BEHAVIOR WHERE FUELS ARE CRITICAL.
PLEASE SEE RED FLAG WARNING PRODUCT FOR MORE INFORMATION.

AREAS OF STRONG TO HIGH WIND WILL DEVELOP ACROSS CENTRAL AND SOUTHERN
WYOMING DURING THE AFTERNOON HOURS AND CONTINUE THROUGH EARLY
WEDNESDAY MORNING.  PLEASE SEE HIGH WIND WARNING PRODUCTS FOR MORE
INFORMATION.

ISOLATED SEVERE THUNDERSTORMS WITH HAIL AND DAMAGING WIND
GUSTS POSSIBLE FROM THE STAR VALLEY NORTH TO YELLOWSTONE NATIONAL
PARK.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

FRIDAY AND SATURDAY...ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS
POSSIBLE SOUTH AND CENTRAL.  CHANCES OF AFTERNOON AND EVENING
THUNDERSTORMS...WEST AND FAR NORTH FRIDAY AND ACROSS MOST AREAS
ON SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER...
INCLUDING HAIL...STRONG WINDS...ANY DAMAGE...AS WELL AS ANY FLOODING
ALONG ANY CREEK OR RIVER. THANK YOU.

TEAM RIVERTON