Tornado Warning 4, NWS Riverton, WY

000 
WWUS55 KRIW 251959
SVSRIW

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
159 PM MDT FRI AUG 25 2006

WYC037-252009-
/O.EXP.KRIW.TO.W.0004.000000T0000Z-060825T2000Z/
SWEETWATER WY-
159 PM MDT FRI AUG 25 2006

...THE TORNADO WARNING FOR SOUTHWESTERN SWEETWATER COUNTY EXPIRES AT
200 PM MDT...

THE STORM HAS DECREASED IN INTENSITY AND IS NO LONGER SEVERE.
THEREFORE...THE WARNING WILL BE ALLOWED TO EXPIRE.

REPORT SEVERE WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.

LAT...LON 4122 10996 4105 10990 4112 10924 4138 10932

$$

C. BAKER

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
300 AM MDT FRI AUG 25 2006

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
VERY INTERESTING WEATHER SITUATION SHAPING UP OVER WYOMING THE NEXT
COUPLE OF DAYS.  EARLY THIS MORNING...A JET MAX MOVING THROUGH
NORTHERN UTAH IS ALLOWING CONVECTION TO FIRE OFF AND MOVE INTO SW
WYOMING.  00Z NAM/WRF HANDLES THIS FEATURE FAIRLY WELL...WHEN
PREVIOUSLY ON SHIFT THOUGHT THAT IT WOULDNT MATERIALIZE.  HAVE
ADJUSTED EARLY MORNING FORECAST TO REFLECT ISOLATED THUNDERSTORMS
THROUGH SW INTO SOUTH CENTRAL WYOMING. MID TO HIGH LEVEL CLOUDINESS
IS COVERING NW WY IN RESPONSE TO FIRST SHORTWAVE TROUGH APPROACHING
FROM PACIFIC NORTHWEST.  GFS AND NAM APPEAR TO BE IN FAIRLY GOOD
AGREEMENT THROUGH THE NEXT FEW DAYS...AND BASED ON PREVIOUS
FORECAST...HAVE BOTH SLOWED DOWN THE PROGRESSION OF THE OVERALL
STORM SYSTEM THROUGH THE WEEKEND.  WHILE FIRST SHORTWAVE TROUGH MOW
IN CENTRAL IDAHO AND SW MT BEGINS THE APPROACH...ANOTHER SHORTWAVE
TROUGH IS DROPPING SOUTH OUT OF BRITISH COLUMBIA.  SATELLITE
IMAGERY THROUGH MIDNIGHT PICKS THIS FEATURE UP WELL WITH LATE EVENING
MID LEVEL CLOUDINESS.  MODEL GUIDANCE INDICATES THAT BY 9 AM...
CLOSED UPPER LEVEL LOW DEVELOPS OVER SE IDAHO...AND SURFACE LOW
BEGINS DEVELOPING OVER CENTRAL UTAH.  WITH RELATIVELY HIGH PRESSURE
STILL OVER THE NW PLAINS...AND LOW PRESSURE TO THE SOUTH AND WEST...
GRADIENT NORTH AND EAST WINDS WILL BE SUSTAINED FOR MUCH OF THE
FORECAST AREA TOMORROW...WITH THE EXCEPTION OF WESTERLY FLOW
THROUGH SW WYOMING.  MID LEVEL MOISTURE AND INSTABILITY SHOULD BE
AMPLE ENOUGH TODAY FOR ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS...WITH THE BETTER CHANCES IN NW WY.  SOMETHING OF A
DRY SLOT SHOULD ADVECT INTO SOUTHERN WYOMING LATE IN THE DAY AS
NORTHERLY FLOW IN THE NORTHERN AND CENTRAL BASINS PROVIDES FOR
DECENT UPSLOPE TYPE CONDITIONS INTO FRIDAY NIGHT.  WHILE MOS GUIDANCE
FOR SEVERAL LOCATIONS IS OVER 50 PERCENT FOR POPS FRIDAY NIGHT...
PERSONAL CONFIDENCE IS NOT HIGH ENOUGH YET GIVEN STILL DRY BOUNDARY
LAYER AND SURFACE CONDITIONS.  CLOSED LOW THEN MIGRATES TOWARD
NORTHERN UTAH BY SATURDAY AFTERNOON...WITH WESTERN WYOMING In GOOD
POSITION FOR CONTINUED CHANCES OF PRECIPITATION WITH INSTABILITY AND
MOISTURE.  BY THIS TIME...EASTERLY FLOW WILL DEVELOP THROUGH
SWEETWATER COUNTY AS WELL.  AS LOW CONTINUES TO THE EAST AND HIGH
PRESSURE BUILDS TO THE NORTH...NORTHERLY SURGE WILL PUSH THROUGH
MUCH OF THE FORECAST AREA SATURDAY NIGHT....AND MID LEVEL TEMPS WILL
BEGIN WARMING ONCE AGAIN TO REDUCE POPS AND CLEAR OUT SKIES BY
SUNDAY AFTERNOON.  ISOLATED SHOWERS ARE STILL POSSIBLE FROM JOHNSON
THROUGH EASTERN SWEETWATER COUNTY LATE SUNDAY.  TEMPERATURES WILL
COOL CONSIDERABLY THROUGH THE WEEKEND...WITH MANY MOUNTAIN
LOCATIONS ABOVE 10K FT EXPERIENCING FREEZING TEMPS FOR A COUPLE OF
NIGHTS IN A ROW.  SOME SNOW SHOWERS AND NOT OUT OF THE QUESTIONS IN
THE NW MOUNTAINS DURING THE NEXT COUPLE OF NIGHTS AS WELL. BASIN MAX
TEMPS WILL DROP TO THE MID TO UPPER 70S ON SATURDAY AND THEN REBOUND
TO THE LOW 80S ON SUNDAY.  OVERALL...THIS APPEARS TO BE THE BEST
CHANCE IN MONTHS FOR WESTERN AND CENTRAL WYOMING TO RECEIVE MUCH
NEEDED PRECIPITATION.  WOULD NOT BE SURPRISED IN THE LEAST IF SOME
LOCATIONS END UP WITH CONVECTIVE AND OR STRATIFORM RAIN AMOUNTS OF
NEARLY AN INCH...JUST CANT PINPOINT GENERAL AREAS AT THIS TIME
GIVEN UNSEASONAL SYSTEM AND PERSISTENT DRY CONDITIONS.

.LONG TERM...MONDAY THROUGH FRIDAY
MEDIUM RANGE MODELS IN AGREEMENT MON THROUGH WED. NORTHWEST FLOW
ALOFT BEHIND THE DEPARTING STORM SYSTEM MON. LOOKS TO BE A DRY DAY
WITH WEAK INSTABILITY. WITH MORE SUNSHINE EXPECTED HIGHS WILL WARM
UP ON MONDAY...BUT DID TRIM THEM A BIT AS 700MB TEMPS A LITTLE SLOWER
TO WARM THAN WHAT WAS INDICATED LAST NIGHT. UPPER RIDGE STILL
EXPECTED TO BUILD BACK OVER THE REGION TUE. THIS LEADS TO A DRY AND
WARMER DAY. SW FLOW ALOFT FOR WED AS TROUGH EVOLVES OVER SW CANADA
AND THE PACIFIC NW STATES. SOME INDICATION OF ENOUGH MID LEVEL
MOISTURE INTO WESTERN WY FOR ISOLATED STORMS WED PM INTO WED EVENING.
ALSO POSSIBLE WEAK SHORTWAVE IN THE SW FLOW MOVES THROUGH IDAHO WED
EVE WHICH MAY AID THINGS SOME. WARM TO HOT DAY ON WED. SW FLOW ALOFT
THU WITH SOME MID LEVEL MOISTURE IN THE FLOW. POTENTIAL FOR WEAK
SHORTWAVE IN THE FLOW AND SOME UPPER JET INTERACTION THU PM/EVE...
WHICH COULD AID CONVECTION. LEFT ISOLATED STORMS IN NW WY THU PM/EVE.
STILL WARM TO HOT THU. GFS WISHES TO BRING TROUGH CLOSER TO AREA FRI
WITH SW FLOW ALOFT AHEAD OF IT. TIMING MAY BE AN ISSUE THAT FAR OUT
AND ONLY WENT WITH ISOLATED STORMS IN THE FAR WEST MOUNTAINS AND
VALLEYS NEXT FRI. WENT JUST A LITTLE COOLER FRI OVER REGION. PLENTY
OF TIME TO WATCH MODEL TRENDS.

&&

RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

SHORT TERM...MCDONALD
LONG TERM...AR

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RIVERTON WY
400 AM MDT FRI AUG 25 2006

WYZ001>020-022>030-261200-
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-
400 AM MDT FRI AUG 25 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING.

.DAY ONE...TODAY AND TONIGHT

SHOWERS AND A FEW THUNDERSTORMS WILL MAINLY IMPACT SWEETWATER COUNTY
THIS MORNING. THEN AFTERNOON SHOWERS AND THUNDERSTORMS WILL DEVELOP
OVER THE AREA. GUSTY WIND TO 40 MPH WILL BE THE MAIN THREAT FROM
STORMS. EXPECT SHOWERS AND SOME THUNDERSTORMS TONIGHT OVER THE AREA
AS A STORM SYSTEM FORMS OVER IDAHO.

AREAS OF SMOKE WILL AGAIN BE AN ISSUE FOR SOME OF THE VALLEY
LOCATIONS TODAY...AS WELL AS NEAR THE MAJOR FIRES THAT ARE BURNING IN
WESTERN WYOMING. VISIBILITY WILL BE REDUCED AT TIMES.  AIR QUALITY
MAY BE OF SOME CONCERN AS WELL NEAR THE FIRES.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE STORM WILL MOVE INTO NORTHERN UTAH SATURDAY AND THEN INTO
NORTHERN COLORADO ON SUNDAY. THIS WILL PROVIDE THE CHANCE OF SHOWERS
AND STORMS OVER MUCH OF THE REGION SATURDAY INTO SATURDAY NIGHT.
THERE IS THE POTENTIAL FOR SOME PLACES TO RECEIVE UP TO ONE HALF INCH
OF RAIN FROM THIS STORM SYSTEM. STAY TUNED FOR UPDATES.

SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT RAINFALL AMOUNTS AND STRONG WIND
GUSTS TODAY AND TONIGHT. THANK YOU.

TEAM RIVERTON