Severe Thunderstorm Warning 11, NWS Riverton, WY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
308 PM MDT TUE JUN 12 2001

SURFACE LOW SPINNING UP OVER SOUTHEAST WYOMING/NORTHEAST COLORADO.
UPPER LOW DIGGING SOUTHEAST ACROSS THE PACIFIC NORTHWEST.  SEVERAL
SHORTWAVES AROUND THIS LOW SPINNING OUT AHEAD...ONE OF WHICH IS
CROSSING THE AREA AT PRESENT.  ALREADY SOME SEVERE WEATHER IN
SOUTHWEST WYOMING...AND EXPECT A DECENT EVENING OF SUCH ACROSS THE
AREA.  MODELS SHOWING SURFACE TROF TO SET UP ALONG MONTANA/WYOMING
BORDER TONIGHT AND TOMORROW...PROVIDING A FOCUS FOR PRECIPITATION
ALONG AND MAINLY NORTH OF IT.  HIGHLY UNCERTAIN FORECAST DUE TO WHAT
HAPPENS WITH SURFACE LOW AND ASSOCIATED TROF.  MODELS NOT DEPICTING
ANY UPSLOPE FLOW FOR US AROUND SURFACE LOW...BUT HAVE A HARD TIME
BELIEVING EASTERN COUNTIES WILL NOT SEE AT LEAST SOME OVERNIGHT...SO
BETTER CHANCES OF RAIN THERE.  COLD AIR FILTERS IN THIS EVENING AND
TONIGHT WITH FRONT FROM THE WEST.  NOT EXPECTING COLD ENOUGH AIR
EAST OF DIVIDE FOR MUCH...IF ANY SNOW.  TOMORROW A DIFFERENT STORY
AS COLD AIR CONTINUES TO BARGE IN ALOFT WITH ARRIVAL OF STRONG UPPER
LOW WHICH TRACKS ACROSS WYOMING TOMORROW/TOMORROW EVENING.  LOOKS TO
BE A COLD AND WINDY DAY WITH RAIN/SNOW SHOWERS AND LATE AFTERNOON
AND EVENING THUNDERSTORMS.  IN THE INTERIM...WILL POST SNOW ADVISORY
FOR NORTHWEST MOUNTAINS DUE TO PROXIMITY OF SURFACE BOUNDARY AND
UPPER LEVEL DYNAMICS.  IMPROVING THURSDAY...AND LOOKING DECENT FOR
THE END OF WEEK AND WEEKEND WITH A BIT OF WARMING.  BEHIND THE CURVE
SO THATS IT.

.RIW...SNOW ADVISORY TONIGHT AND WEDNESDAY YELLOWSTONE...TETONS
...ABSAROKAS...AND SALT RANGE.

VALONE