High Wind Watch 9, NWS Riverton, WY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
242 AM MDT TUE OCT 2 2007

.MAJOR WEATHER PATTERN CHANGE IN STORE FOR WYOMING BEGINNING
THURSDAY AFTERNOON...

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ISOLATED LIGHT SHOWERS IN A SOMEWHAT MOIST NORTHWESTERLY FLOW
ALOFT MOVING THROUGH THE NORTHERN WIND RIVER MOUNTAINS
NORTHEASTWARD INTO THE SOUTHERN ABSAROKA MOUNTAINS EARLY THIS MORNING.
ISOLATED LIGHT SHOWERS WILL CONTINUE OVER THE MOUNTAINS OF
NORTHWEST WYOMING THROUGH THE DAY AS PACIFIC MOISTURE NEAR
MOUNTAIN TOP LEVEL RIDES IN ON A STRONG 150KT JET STREAM NOSING
INTO THE PACIFIC NORTHWEST. 12Z LOCALLY RUN WRF NUMERICAL MODEL
SUGGESTING WINDS IN THE CODY AREA MAY REACH HIGH WIND WARNING
CRITERIA TONIGHT INTO EARLY WEDNESDAY MORNING. WILL ISSUE A HIGH
WIND WATCH FOR THIS AREA DUE TO THE POTENTIAL FOR A MOUNTAIN WAVE
TO DEVELOP IN THE LEE OF THE ABSAROKAS MIXING WINDS DOWN TO CODY
FOOTHILL AREA. THE MAIN CORE OF THE JET STREAM SAGS SLOWLY
SOUTHWARD TONIGHT INTO WEDNESDAY GRADUALLY INCREASING THE
POTENTIAL FOR OROGRAPHIC RAIN AND SNOW SHOWERS OVER THE
NORTHWESTERN MOUNTAINS ON WEDNESDAY THROUGH WEDNESDAY NIGHT. AS
SEVERAL TYPHOONS IN THE WEST PACIFIC BEGIN TO TRANSITION FROM WARM
CORE TO COLD CORE SYSTEMS...A HIGH AMPLITUDE UPPER LEVEL RIDGE
BEGINS TO DEVELOP LATER TODAY OVER THE GULF OF ALASKA AND BEGINS
TO DRIVE THE JET STREAM SOUTHWARD ALONG THE WEST COAST TONIGHT
INTO THURSDAY. AS THE MID AND UPPER LEVEL FLOW BACKS OVER THE AREA
ON THURSDAY...MID-LEVEL SUBTROPICAL MOISTURE SURGES NORTHWARD
THROUGH THE EASTERN GREAT BASIN AND CONVERGES WITH RELATIVELY COLD
AIR OVER NORTHWEST WYOMING...BEGINNING A GOOD FRONTOGENETIC EVENT
OVER WESTERN AND CENTRAL WYOMING THURSDAY NIGHT ALONG WITH THE
POTENTIAL FOR WIDESPREAD SIGNIFICANT SNOWFALL IN THE MOUNTAINS AND
POSSIBLY IN MANY VALLEYS OF NORTHWEST AND WEST-CENTRAL WYOMING.

.LONG TERM...FRIDAY THROUGH TUESDAY
PACIFIC LOW PRESSURE TROUGH SHOWING MORE SIGNS OF DEEPENING AND
CUTTING OFF IN NORTHERN UTAH ON FRIDAY WITH WIDESPREAD PRECIPITATION
INCREASING ACROSS WESTERN AND CENTRAL WYOMING. TEMPERATURES
CONTINUE TO COOL AND WILL LIKELY CONTINUE THIS TREND AS THE STORM
APPROACHES AND THE MODELS SETTLE IN MORE ON A CONSENSUS FORECAST.
AT THIS TIME PLENTY OF DIVERGENCE IN MODEL SOLUTIONS WITH DEPTH OF
LOW...AMOUNT OF CUTTING OFF IF ANY AND TIMING OF THE LOW MOVING EAST.
AT THIS TIME CONSENSUS OF SURROUNDING FORECASTS IS FOR SLOWER AND DEEPER
MOVING LOW. FRIDAY NIGHT SNOW LEVEL MOVES INTO VALLEYS AND BASINS.
SNOWFALL AMOUNTS ARE HIGHLY SPECULATIVE AT THIS TIME FRAME AND
COULD BE SIGNIFICANTLY HIGHER WITH A STRONGER SLOWER COLDER CUT
OFF LOW. CONTINUE SNOW/RAIN SNOW ON SATURDAY WITH DECREASING
CHANCE OF PRECIPITATION IN THE WEST.  COLDER LOWS FOR SATURDAY NIGHT
WITH CLEARING FROM WEST TO EAST. DEPENDING ON PRECIPITATION
AMOUNTS AND STATE...COULD SEE CONSIDERABLE AREAS OF FOG SATURDAY
NIGHT BUT TOO MUCH UNCERTAINTY TO BE THAT SPECIFIC AT THIS TIME.
IMPROVING CONDITIONS SUNDAY THROUGH TUESDAY WITH DRY AND WARMER
CONDITIONS. STILL MAY BE SOME FOG AROUND LATE SUNDAY NIGHT AND MONDAY
MORNING.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL OVER THE ROUTES UNTIL 00Z WEDNESDAY.
WIND SPEED WILL INCREASE AGAIN TUESDAY AFTERNOON AT MOST TAF SITES
AS THE PRESSURE GRADIENT TIGHTENS ONCE MORE.

&&

.FIRE WEATHER...
A STRONG WESTERLY FLOW ALOFT WILL MOVE OVER THE DISTRICT TODAY WITH
SOME RAIN AND SNOW SHOWERS LINGERING OVER THE NORTHWEST MOUNTAINS
THROUGH WEDNESDAY NIGHT. A MUCH STRONGER PACIFIC STORM SYSTEM WILL
DIG INTO THE GREAT BASIN ON THURSDAY BRINGING SUBTROPICAL MOISTURE
NORTHWARD INTO THE SOUTHERN AND SOUTHEAST PORTIONS OF THE AREA WITH
THE POTENTIAL FOR SIGNIFICANT SNOWFALL OVER THE HIGHER TERRAIN OF WESTERN
AREAS THURSDAY NIGHT INTO FRIDAY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM THIS EVENING THROUGH WEDNESDAY MORNING FOR
WYZ003.

&&

SHORT TERM...CHURCH
LONG TERM...C.BAKER
AVIATION...AR
FIRE WEATHER...CHURCH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RIVERTON WY
536 AM MDT TUE OCT 2 2007

WYZ001>020-022>030-031200-
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-
536 AM MDT TUE OCT 2 2007

...STRONG WEST WINDS POSSIBLE IN THE CODY FOOTHILLS THIS EVENING
THROUGH WEDNESDAY MORNING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING.

.DAY ONE...TODAY AND TONIGHT

A HIGH WIND WATCH FOR THE CODY FOOTHILLS HAS BEEN ISSUED FOR
TONIGHT FOR THE POTENTIAL OF STRONG WEST WINDS DEVELOPING AFTER
SUNSET AND CONTINUING UNTIL ABOUT SUNRISE WEDNESDAY. SUSTAINED WEST
WINDS OF 40 TO 50 MPH WITH GUSTS TO 55 MPH ARE POSSIBLE. LIGHT RAIN
AND SNOW SHOWERS WILL OCCUR IN THE MOUNTAINS OF NORTHWEST WYOMING
TODAY AND TONIGHT. ROADS OVER THE MOUNTAIN PASSES MAY BE SLICK AT
TIMES TONIGHT DUE TO LIGHT SNOW ACCUMULATION.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

AN ACTIVE WEATHER PATTERN IS THEN EXPECTED TO DEVELOP AROUND MIDWEEK
AND CONTINUE INTO THE WEEKEND. A FAVORABLE PATTERN FOR SNOW IN THE
NORTHWEST MOUNTAINS IS EXPECTED TO DEVELOP WEDNESDAY NIGHT AND
CONTINUE THROUGH THURSDAY. AS THIS STORM SYSTEM GATHERS STRENGTH IN
THE GREAT BASIN THURSDAY AND MOVES TOWARDS WESTERN WYOMING...THE
CHANCES OF PRECIPITATION WILL BE ON THE INCREASE ACROSS ALL OF
WESTERN AND CENTRAL WYOMING THURSDAY NIGHT. COLDER AIR WILL FILTER
INTO AREAS EAST OF THE DIVIDE FRIDAY WHICH COULD TURN THE EXPECTED
RAIN INTO SNOW ABOVE ABOUT 6000 FEET.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT RAINFALL AMOUNTS AND STRONG WINDS.
THANK YOU.

TEAM RIVERTON