Tornadoes and Hail in Montana, August 10, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
212 PM MDT FRI AUG 10 2007

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
SEE-SAW CONDITIONS ARE EXPECTED WITH THE TEMPERATURES THROUGH SUNDAY
AS COOLER TEMPS ARE EXPECTED SATURDAY WITH THE WARMER CONDITIONS
EXPECTED TO MAKE A RETURN FOR SUNDAY.

WATER VAPOR SHOWING AN UPPER DISTURBANCE LIFTING OUT OF THE PACIFIC
NORTHWEST TOWARD THE PRAIRIE PROVINCES. THUNDERSTORMS ARE EXPECTED
TO CONTINUE DEVELOPING OVER SW AND CENT MT THROUGH THE REMAINDER OF
THE AFTERNOON. SURFACE LOW PRESSURE OVER SE MT HAS HELPED TO ADVECT
LOW LEVEL MOISTURE INTO THE CWA THIS AFTERNOON FROM THE MUCH WETTER
CONDITIONS THAT ARE OCCURRING IN CENTRAL NORTH DAKOTA.

MODELS SEEM TO BE IN GOOD AGREEMENT WITH BRINGING CONVECTION
EAST-NORTHEAST INTO THE CWA THIS EVENING. A HIGHLY UNSTABLE AIRMASS
OVER THE DAKOTAS THIS AFTERNOON SHOULD BE CUT OFF THIS EVENING AS
THE SURFACE LOW MOVES EAST...SO STORMS SHOULD NOT BE WIDESPREAD
SEVERE (BUT A FEW IN THE EASTERN ZONES STILL MAY COME CLOSE).
THEREFORE REMOVED THE MENTION OF DAMAGING WIND MENTION.

NORTHWEST WILL BE BREEZY FOR A TIME TONIGHT AS A SECOND SURGE OF
COLD AIR ADVECTION MOVES IN LATE TONIGHT. ATMOSPHERE LOOKS TO BE
DECOUPLED AT THAT POINT...SO GOING LAKE WIND ADVISORY MAY BE
CANCELLED THIS EVENING AS WINDS SHOULD DROP OFF (WILL LET EVENING
SHIFT GET A BETTER LOOK AT THIS THOUGH).

CANADIAN SURFACE HIGH THEN BRINGS SOME OF THE COOLER AIR THAT HAS
RESIDED ACROSS THE PRAIRIE PROVINCES INTO NORTHEAST MONTANA
SATURDAY. WITH 850 MB TEMPS BEING CLOSE TO 10-14C (ABOUT 10-12
DEGREES COOLER THAN TODAY)...HIGH TEMPS WILL BE 10-15 DEGREES COOLER.

UPPER RIDGE BEGINS TO BUILD BACK OVER THE REGION SATURDAY NIGHT AND
SUNDAY. ALONG WITH A RETURN FLOW AROUND THE SURFACE HIGH THAT MOVES
INTO NORTHERN MINNESOTA...TEMPERATURES WILL START TO WARM BACK UP
FOR SUNDAY. READINGS SHOULD TOP OUT FROM THE UPPER 80S TO THE MIDDLE
90S. JAMBA

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
MOST OF THE 12Z MODELS AND ENSEMBLES ARE ON THE SAME PAGE THAT
THE COLD FRONTAL PASSAGE WILL TAKE PLACE SUNDAY NIGHT AND NOT
MONDAY...ALTHOUGH THE OPERATIONAL GFS AND IT/S ENSEMBLES ARE
FASTER THAN THE ECMWF.  THE FRONT DOES NOT LOOK AS STRONG AS THE
FRONTAL PASSAGE THIS EVENING...BUT MAY BE ENOUGH TO KNOCK
TEMPERATURES BACK DOWN INTO THE 80S ON MONDAY. AFTER REVIEWING ALL
THE GFS ENSEMBLES THE OPERATIONAL/CONTROL MEMBER IS THE MOST
AGGRESSIVE OF THE BUNCH IN LOWERING HEIGHTS AND 850MB
TEMPERATURES. GIVEN THAT THE UKMET AND ECMWF ALSO DO NOT LOWER
HEIGHTS NEARLY AS MUCH AS THE OPERATIONAL GFS WILL NOT MAKE ANY
CHANGES TO THE TEMPERATURES AT THIS TIME. IF LATER RUNS DO START
TO TREND TOWARD A STRONGER SHORTWAVE WOULD CERTAINLY NEED TO
CONSIDER LOWERING TEMPERATURES SOME ON MONDAY...BUT PREFER TO
HOLD OFF FOR NOW AS THE OPERATIONAL GFS LOOKS TO BE OUT IN IT/S
OWN.

IN THE WAKE OF THE FRONTAL PASSAGE A MODERATELY STRONG CANADIAN HIGH
PRESSURE SYSTEM BUILDS INTO THE NORTHERN PLAINS THROUGH THE MIDDLE
OF THE WEEK.  THIS SHOULD KEEP ANY PRECIPITATION FOCUSED TO OUR
SOUTH ALONG A WAVY FRONTAL BOUNDARY THAT WILL EXTEND FROM THE
MIDWEST INTO THE CENTRAL ROCKIES.

LATER IN THE WEEK THE UPPER RIDGE BEGINS TO REBOUND ACROSS THE AREA
WITH ABOVE AVERAGE TEMPERATURES.  SOME MONSOONAL MOISTURE MAY START
TO CREEP NORTHWARD LATE IN THE WEEK...BUT THE BEST CHANCE OF
CONVECTION WILL LIKELY REMAIN SOUTH OF THE LOCAL AREA.  SOME
INDICATION THAT THE RIDGE AXIS MAY START TO NUDGE EAST TOWARD NEXT
WEEKEND WHICH MAY ALLOW ANOTHER COLD FRONT TO WORK ACROSS THE
AREA. CB
PREVIOUS LONG TERM...
LITTLE CHANGE IN THE OVERALL PATTERN EARLY IN THE EXTENDED PERIOD.
UPPER TROF OFF THE PACIFIC NORTHWEST WITH UPPER HIGH OVER THE
SOUTHERN STATES. UPPER LOW NORTHWEST OF HUDSON BAY MIGRATES
SOUTHEAST INTO QUEBEC EARLY NEXT WEEK. THIS WILL HELP BUILD UP
RIDGE OVER MONTANA ALTHOUGH MORE MODELS DIFFERENCES TOWARD THE
END OF THE PERIOD. SOME SOLUTIONS SUGGEST MORE PROGRESSIVE FLOW
OVER CANADA TO SUPPRESS THE RIDGE...WHILE OTHERS BUILD THE RIDGE
OVER THE HIGH PLAINS AND SLOWLY SHIFT IT EASTWARD.

MAIN CHANGE EARLY IN THE PERIOD IS SLIGHTLY FASTER COLD FRONT
INDICATED FOR EARLY NEXT WEEK...COMING THROUGH SUNDAY NIGHT RATHER
THAN MONDAY. THUS HAVE COOLED TEMPERATURES SLIGHTLY FOR MONDAY.
CANADIAN HIGH PRESSURE SLIDES INTO THE NORTHERN PLAINS AND
INFLUENCES THE WEATHER THROUGH THE REMAINDER OF THE WEEK.

MONSOONAL MOISTURE STARTS A RETURN SURGE NORTHWARD WITH THE
BUILDING RIDGE. WITH RIDGE AXIS REMAINING TO THE WEST OF THE
CWA...FOR NORTHWEST FLOW INTO NORTHEAST MONTANA...EXPECT MOISTURE
TO BE DEFLECTED EASTWARD OVER SOUTHERN MONTANA. THUS WILL KEEP
POPS LOW THROUGH THE PERIOD. EBERT

&&

.AVIATION...
A STRONG COLD FRONT WILL SWEEP ACROSS THE AREA FROM THE NORTHWEST
THIS EVENING. ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE
THIS EVENING WITH BRIEF STRONG AND ERRATIC WIND GUSTS. THERE WILL
ALSO LIKELY BE A PERIOD OF STRONG N-NW WIND IN THE WAKE OF THE
FRONT FOR A FEW HOURS TONIGHT. CB

&&

.FIRE WEATHER...
THUNDERSTORMS ARE STILL SCHEDULED TO MOVE THROUGH THE FIRE DISTRICTS
THIS EVENING. MANY OF THESE STORMS WILL CONTAIN RAINFALL...BUT WITH
THE DRY FUELS...FIRE STARTS ARE GOOD POSSIBILITY. ERRATIC WINDS ARE
THE SECONDARY THREAT. SUNDAY MAY FEATURE ANOTHER DAY FOR CRITICAL
FIRE WEATHER AS SOUTHEAST WINDS WILL BE BUSY WHILE HUMIDITIES LOOK
TO DROP AT OR BELOW 20 PERCENT. JAMBA

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL MIDNIGHT MDT TONIGHT FOR MTZ119-MTZ120-
MTZ121-MTZ122.

LAKE WIND ADVISORY FROM 6 PM THIS EVENING TO 4 AM MDT SATURDAY
FOR FORT PECK LAKE.

&&

WEATHER.GOV/GLASGOW

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE GLASGOW MT
441 AM MDT FRI AUG 10 2007

MTZ016>027-059>062-111045-
CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-
DANIELS-SHERIDAN-WESTERN ROOSEVELT-PETROLEUM-GARFIELD-MCCONE-
RICHLAND-DAWSON-PRAIRIE-WIBAUX-NORTHERN PHILLIPS-
SOUTHWEST PHILLIPS-NORTHERN VALLEY-EASTERN ROOSEVELT-
441 AM MDT FRI AUG 10 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...TODAY AND TONIGHT

ISOLATED SEVERE THUNDERSTORMS ARE EXPECTED TONIGHT. THESE WILL
HAVE LITTLE RAINFALL...BUT SOME WITH WIND POTENTIAL OF UP TO 60
MPH. A RED FLAG WARNING IS ALSO IN EFFECT THROUGHOUT NORTHEAST
MONTANA BETWEEN NOON AND MIDNIGHT FOR LOW RELATIVE HUMIDITY...
FOLLOWED BY WINDY WEATHER AND ISOLATED SEVERE...DRY THUNDERSTORMS
THIS EVENING.

THERE IS ALSO A LAKE WIND ADVISORY IS IN EFFECT FOR FORT PECK
LAKE FROM 6 PM UNTIL MIDNIGHT.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.