High Wind in Montana, May 9, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
225 PM MDT FRI MAY 9 2008

.DISCUSSION...A TROUGH WILL CONTINUE TO SWING THROUGH THE NORTHERN
ROCKIES THIS AFTERNOON AND EVENING. THE ATMOSPHERE WILL REMAIN
UNSTABLE ENOUGH TO KEEP WIDESPREAD CONVECTION GOING UNTIL SUNSET.
THE SHOWERS WILL BE MAINLY CONFINED TO THE MOUNTAINS...BUT CANNOT
RULE OUT A SHOWER MAKING IT OVER THE WIDER VALLEYS. SOUTHWEST
MONTANA COULD SEE A LIGHTNING STRIKE OR TWO THIS EVENING...BUT
FELT IT WOULD NOT BE ENOUGH COVERAGE TO WARRANT MENTION IN THE
FORECAST. THEN A RIDGE OF HIGH PRESSURE WILL BUILD OVER THE AREA
LATER TONIGHT INTO SATURDAY. WITH COLDER AIRMASS IN PLACE AND
CLEARING...THIS RIDGE WILL ALLOW TEMPERATURES TO COOL WELL BELOW
NORMAL TONIGHT. HIGH TEMPERATURES ON SATURDAY SHOULD BE NEAR
NORMAL.

ANOTHER SYSTEM IS EXPECTED TO MAKE ITS WAY ACROSS THE NORTHERN
ROCKIES LATE SATURDAY NIGHT INTO SUNDAY. THE BEST MOISTURE AND
DYNAMICS ASSOCIATED WITH THIS SYSTEM WILL BE ACROSS EXTREME
NORTHWEST MONTANA. THE WESTERLY WINDS SHOULD BECOME FAIRLY GUSTY
SUNDAY AFTERNOON AND EVENING. ONCE AGAIN THE SNOW LEVELS APPEAR TO
REMAIN FAIRLY HIGH...SO RAIN WILL BE THE PRIMARY PRECIPITATION
TYPE FOR THIS EVENT.

PROGRESSIVE FLOW WILL KEEP TEMPERATURES BELOW NORMAL WITH CHANCE
OF PRECIPITATION MONDAY THROUGH WEDNESDAY.

THE BIG WEATHER STORY IN THE EXTENDED IS AN INCREDIBLY STRONG
RIDGE BEING FORECAST AND BECOMING MORE CONSISTENT BY THE EXTENDED MODELS
FOR THE END OF THE WEEK. IF THE HEIGHTS THAT ARE CURRENTLY BEING
FORECAST BY THE MODELS MATERIALIZE...THE INTERMOUNTAIN REGION
COULD SEE TEMPERATURES WELL ABOVE NORMAL BY FRIDAY.
HOWEVER...ANTICIPATE SOME MODERATING IN LATER RUNS SO HAVE
INCREASED TEMPERATURES ABOVE GOING GUIDANCE...BUT BELOW FULL
POTENTIAL. STILL TEMPERATURES WILL BE WELL ABOVE SEASONAL LEVELS
INCREASING SNOW MELT. THIS COULD CAUSE SOME HYDROLOGY ISSUES.
PLEASE SEE DISCUSSION BELOW FOR DETAILS.

&&

.AVIATION...THE ATMOSPHERE WILL REMAIN UNSTABLE THROUGH THE
EVENING HOURS. SO WIDESPREAD CONVECTION WILL CONTINUE WITH A
DECREASE IN COVERAGE AFTER SUNSET. THE MOUNTAINS AND PASSES WILL
BE OBSCURED AT TIMES THIS EVENING. SINCE SNOW AND GRAUPEL WILL BE
THE PRIMARY PRECIP TYPES...EXPECT VISIBILITIES TO BE REDUCED. ALL
TERMINALS IN THE NORTHERN ROCKIES WILL BE AFFECTED BY THESE
SHOWERS.

&&

.HYDROLOGY...TEMPERATURES FORECAST WELL ABOVE AVERAGE FOR THE END
OF NEXT WEEK. WITH PLENTY OF SNOW REMAINING IN THE HIGHER
ELEVATIONS...EXPECT INCREASED SNOWMELT WITH HIGHER FLOWS INTO AREA
CREEKS AND RIVERS. WITH WARM OVERNIGHT LOWS...MAINLY ABOVE
FREEZING...RIVER LEVELS MAY CONTINUE TO RISE OVERNIGHT. KEEP ALERT
TO LATTER FORECAST FOR POSSIBLE RIVER STATEMENTS OR WATCHES.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&

SHORT TERM...SMITH
LONG TERM....MEAD
AVIATION...SMITH