Hail in Montana, August 15, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
250 PM MDT TUE AUG 15 2006

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...
UPPER RIDGE OVER THE NORTHERN PLAINS TO BE KNOCKED DOWN BY A
SERIES OF SHORTWAVES PUSHING OUT OF THE PACIFIC NORTHWEST OVER THE
NEXT FEW DAYS.

FRONTAL SYSTEM OVER MONTANA THIS AFTERNOON AS FIRST OF THE
SHORTWAVES LIFTS OUT OF SOUTHERN IDAHO. THUNDERSTORMS DEVELOPING
INTO SOUTHWEST MONTANA AND EXPECTED TO SPREAD EAST...MAINLY IN
SOUTHERN MONTANA AHEAD OF COLD FRONT PUSHING OUT OF CANADA
OVERNIGHT.

STRONGER UPPER TROF/SHORTWAVE LIFTS INTO MONTANA FOR THURSDAY.
GOOD AREA OF DIVERGENCE OVER CENTRAL MONTANA WEDNESDAY NIGHT TO
BRING INCREASED CHANCE OF THUNDERSTORMS. A SOMEWHAT WINTER TIME
SITUATION WITH SURFACE LOW DEVELOPING OVER NORTHEASTERN WYOMING
WITH PRECIPITATION TO THE NORTH AND WEST AS WARM AIR LIFTS OVER
COLDER AIR ASSOCIATED WITH THE TROF. WILL KEEP POPS LOW AS EVEN
WITH GOOD LIFT...NORTH PACIFIC SOURCE OF MOISTURE RATHER THAN
MONSOONAL TAP WILL KEEP STORMS HIGH BASED AND MOSTLY DRY.

SLIGHTLY COOLER TEMPERATURES WEDNESDAY WITH CANADIAN HIGH PRESSURE
PUSHING SOUTHWARD. EVEN COOLER ON THURSDAY WITH UPPER TROF MOVING
INTO THE STATE. EBERT

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
MINOR UPDATES...MAINLY TO EARLY PERIOD SKY...POP...AND WEATHER
GRIDS TO PROMOTE INTER-OFFICE COORDINATION. ELSE...FORECAST
REMAINS ON TRACK.

ECMWF...CANADIAN...AND GFS ALL FORECAST AN UPPER TROUGH OVER
MONTANA EARLY IN PERIOD...BUT HAVE DIFFERENT TRANSLATION SPEEDS
AND SHEAR OUT THE TROUGH DIFFERENTLY. GFS IN PARTICULAR FOR FRIDAY
AND FRIDAY EVENING HAS SHOWN POOR RUN-TO-RUN CONTINUITY BY
ALTERNATING SOLUTIONS PLACING CLOUDS/POPS OVER SOUTHEAST CORNER OF
CWA...OR AT LEAST 100 MILES FURTHER SOUTH. GIVEN THIS LACK OF
CONTINUITY...OPTING TO KEEP AREA PARTLY CLOUDY WITHOUT MENTION OF
PRECIPITATION AFTER 12Z FRIDAY. ELSE...MINOR TWEAKS TO TEMPERATURE
AND WIND GRIDS TO ENHANCE COORDINATION DUE TO MINOR CHANGES MADE
AT ADJACENT OFFICES.

PREVIOUS LONG TERM...
WILL HOLD THE COURSE THIS FORECAST PERIOD AND MAKE VERY FEW
CHANGES. WEAKENING SHORTWAVE TROF THURSDAY EVENING MAY PROVIDE
A FEW THUNDERSTORMS...WITH BEST CHANCES FOR THE SOUTHEAST ZONES.
FOR NOW WILL STICK WITH THIS TIMING AND LEAVE FORECAST DRY AFTER
MIDNIGHT AND MAKE ADJUSTMENTS...IF NECESSARY...AT A LATER TIME.
UPPER FLOW THEN MORE OR LESS FLATTENS OUT WITH WAY TOO MANY
WEAK SHORTWAVE TROFS AND RIDGES IN THE FAST FLOW TO MAKE MUCH OUT
OF WITH RESPECT TO PRECIPITATION. SO WILL LEAVE THE REMAINDER OF
THE FORECAST DRY FOR THE WEEKEND INTO EARLY NEXT WEEK.
TEMPERATURES WILL START OFF ON FRIDAY ON THE RELATIVELY COOLER
SIDE WITH HIGHS MAINLY UPPER 70S TO MIDDLE 80S. TEMPERATURES WILL
THEN WARM BACK TO MAINLY MIDDLE 80S TO LOWER 90S FOR SATURDAY THRU
TUESDAY. RIGHT NOW MONDAY LOOKING THE WARMEST WITH LOW LEVEL
THERMAL RIDGE EXPECTED OVER NORTHEAST MONTANA.

&&

.AVIATION...
VFR CONDITIONS EXPECTED INTO THIS EVENING. A FEW HIGH-BASED
THUNDERSTORMS POSSIBLE LATE THIS AFTERNOON AND EARLY EVENING. BY
LATE EVENING AND OVERNIGHT MAY SEE ISOLATED TO WIDELY SCATTERED
THUNDERSTORMS...SOME OF WHICH MAY PROVIDE SOME RAIN WHICH COULD
BRIEFLY PROVIDE MVFR CONDITIONS. GENERALLY LIGHT WIND WILL BECOME
WEST AROUND 10KT DURING EVENING...VEERING NORTH...THEN NORTHEAST
...OVERNIGHT AND WEDNESDAY. LOCALLY STRONG AND GUSTY WIND NEAR ANY
THUNDERSTORM.

&&

.FIRE WEATHER...
SERIES OF WEATHER SYSTEM WILL MOVE ACROSS THE REGION OVER THE NEXT
TWO DAYS BRINGING A CHANCE OF THUNDERSTORMS. WITHOUT THE TAP OF
MONSOONAL MOISTURE EXPECT THE STORMS TO BE MOSTLY DRY WITH ERRATIC
GUSTY WINDS. COOLER TEMPERATURES ARE EXPECTED BY LATE THURSDAY. RAE

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

WEATHER.GOV/GLASGOW