Severe Thunderstorm Warning 33, NWS Missoula, MT

000 
WWUS55 KMSO 310602
SVSMSO

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
1202 AM MDT SUN AUG 31 2008

MTC023-039-077-310630-
/O.CON.KMSO.SV.W.0033.000000T0000Z-080831T0630Z/
DEER LODGE MT-GRANITE MT-POWELL MT-
1202 AM MDT SUN AUG 31 2008

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1230 AM MDT
FOR SOUTHEASTERN POWELL...EASTERN GRANITE AND NORTHERN DEER LODGE
COUNTIES...

* AT 1154 PM MDT...TRAINED WEATHER SPOTTERS REPORTED A SEVERE
  THUNDERSTORM CAPABLE OF PRODUCING DIME SIZE HAIL.  THIS STORM WAS
  LOCATED NEAR WEST VALLEY...OR ABOUT 9 MILES NORTHWEST OF
  ANACONDA...AND WAS MOVING NORTHEAST AT 44 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  GALEN AROUND 1210 AM MDT...
  RACETRACK AROUND 1215 AM MDT...
  DEER LODGE AND GARRISON AROUND 1225 AM MDT.

LAT...LON 4601 11304 4626 11341 4667 11278 4639 11243
TIME...MOT...LOC 0602Z 226DEG 38KT 4626 11300

$$

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
908 PM MDT SAT AUG 30 2008

.UPDATE...MINOR ADJUSTMENTS TO THE PROBABILITY OF PRECIPITATION
AND CLOUD COVER FOR TONIGHT.

&&

.DISCUSSION...A DISTURBANCE HAS MADE ITS WAY INTO THE SOUTHERN
CLEARWATER MOUNTAINS THIS EVENING. THIS DISTURBANCE IS EXPECTED TO
KEEP SHOWER AND A FEW THUNDERSTORMS GOING THROUGH OUT THE NIGHT.
THE BEST CHANCE FOR SHOWERS WILL BE SOUTH OF THE LINE FROM LOWELL
IDAHO TO MISSOULA MONTANA. THE RED FLAG WARNING WAS ALLOWED TO
EXPIRE SINCE THE WINDS HAVE DECREASED WHILE HUMIDITIES HAVE RISEN. THE
FORECAST WILL HAVE TO BE MONITORED FOR FURTHER UPDATES.

&&

.AVIATION...THUNDERSTORM DEVELOPMENT WILL ALSO MAKE ERRATIC WINDS
POSSIBLE IN THESE LOCATIONS THROUGH THE NIGHT WITH KSMN AND KBTM
BEING PRIMARILY IMPACTED. CLOUD COVER WILL INCREASE OVERNIGHT THROUGH
SUNDAY AS AN UPPER LEVEL TROUGH APPROACHES THE NORTHERN ROCKIES.
BIGGEST AVIATION IMPACT WILL BE GUSTY WINDS ACROSS NORTH CENTRAL
IDAHO AND SOUTHWEST MONTANA WITH MOUNTAIN PEAKS INCREASINGLY
OBSCURED THROUGH SUNDAY NIGHT.

&&

.PREV DISCUSSION... /ISSUED 303 PM MDT SAT AUG 30 2008/

DISCUSSION...WATER VAPOR IMAGERY SHOWS A PLUME OF MID/HIGH LEVEL
MOISTURE BEING PUMPED NORTHEASTWARD ACROSS SOUTHERN IDAHO AND
MONTANA. A SURFACE-BASED BOUNDARY RESIDES OVER LEMHI COUNTY AND
SOUTHWEST MONTANA AND WILL BE A FOCUS FOR HIGH-BASED CONVECTION
THROUGH THE REMAINDER OF THE AFTERNOON AND INTO TONIGHT. THE
COMBINATION OF WINDS ALOFT AND A WESTERLY SURFACE PRESSURE
GRADIENT WILL CREATE BREEZY CONDITIONS FARTHER NORTH ONLY WITH A
BIT MORE LOW LEVEL MOISTURE PRESENT. UPPER LEVEL SYNOPTIC LIFT
WILL BE ENHANCE OVERNIGHT AND SUNDAY AS AN UPPER LEVEL TROUGH OF
LOW PRESSURE DIGS SOUTH ALONG THE WEST COAST. AN INCREASING TREND
IN THE CHANCE OF PRECIPITATION WILL BE REPRESENTED IN THE FORECAST
FOR MUCH OF WESTERN MONTANA AND NORTH-CENTRAL IDAHO...EXCEPT FOR
RIGHT ALONG THE WASHINGTON BORDER. TEMPERATURES WILL ALSO BE
COOLING OFF AS CLOUDS/PRECIPITATION INCREASE SUNDAY AND MONDAY.
SNOW OVER THE HIGHEST MOUNTAINS WILL BE A GOOD POSSIBILITY ONCE
THE UPPER LEVEL TROUGH MOVES OVER THE NORTHERN ROCKIES LATE SUNDAY
NIGHT THROUGH MONDAY NIGHT.

THE AREA WILL DRY OUT FROM WEST TO EAST EARLY TUESDAY AS THE SYSTEM
MOVES EAST. ANOTHER SHORTWAVE WILL DROP SOUTH OUT OF CANADA INTO THE
NORTHERN ROCKIES TUESDAY NIGHT. MOISTURE APPEARS TO BE LIMITED AS
THIS SYSTEM INITIALLY ARRIVES SO THE POTENTIAL FOR SHOWERS WILL BE
LIMITED UNTIL A DEEPER LAYER OF MOISTURE ARRIVES WEDNESDAY
AFTERNOON.

CHANCES FOR PRECIPITATION WILL REMAIN IN THE FORECAST THROUGH
FRIDAY NIGHT WHEN THE REMNANTS OF THE MID-WEEK TROUGH FINALLY EXITS
TO THE EAST. CONDITIONS WILL REBOUND WITH A DRYING TREND ON
SATURDAY BUT TEMPERATURES WILL REMAIN BELOW NORMAL UNDER
NORTHWESTERLY FLOW PATTERN.

AVIATION...BREEZY CONDITIONS WILL CONTINUE ACROSS NORTH CENTRAL
IDAHO AND WEST CENTRAL MONTANA THROUGH EARLY EVENING...MAINLY
IMPACTING TERMINALS KMSO...KBTM AND KSMN. THUNDERSTORM DEVELOPMENT
WILL ALSO MAKE ERRATIC WINDS POSSIBLE IN THESE LOCATIONS THROUGH
THIS EVENING. CLOUD COVER WILL INCREASE OVERNIGHT THROUGH SUNDAY
AS AN UPPER LEVEL TROUGH APPROACHES THE NORTHERN ROCKIES. BIGGEST
AVIATION IMPACT WILL BE GUSTY WINDS ACROSS NORTH CENTRAL IDAHO AND
SOUTHWEST MONTANA WITH MOUNTAIN PEAKS INCREASINGLY OBSCURED
THROUGH SUNDAY NIGHT.

FIRE WEATHER...A TIGHTENING SURFACE PRESSURE GRADIENT COMBINED
WITH DRY SOUTHWEST WINDS ALOFT HAS CREATED POTENTIALLY DANGEROUS
FIRE WEATHER CONDITIONS ACROSS SOUTHWEST MONTANA THROUGH THIS
EVENING. ALTHOUGH BREEZY CONDITIONS CAN BE FOUND ELSEWHERE...
HIGHER HUMIDITIES ARE EXPECTED TO OFFSET THE NEGATIVE EFFECTS OF
THE WINDS.

&&

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

SHORT TERM...SMITH
PREV DISCUSSION....MSJ/LOEFFELBEIN/DEROSA
AVIATION...SMITH/DE ROSA

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MISSOULA MT
237 PM MDT SAT AUG 30 2008

MTZ006-007-043-311200-
BITTERROOT/SAPPHIRE MOUNTAINS-BUTTE/BLACKFOOT REGION-
POTOMAC/SEELEY LAKE REGION-
237 PM MDT SAT AUG 30 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WEST CENTRAL
MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A RELATIVELY DRY COOL FRONT WILL PASS THROUGH THE REGION TODAY
CREATING A TIGHTENING SURFACE PRESSURE GRADIENT. GUSTY WINDS UP TO
30 MPH MAY BE EXPERIENCED DURING THE AFTERNOON AND EVENING HOURS.
IN ADDITION...ISOLATED THUNDERSTORMS MAY ENHANCE WIND GUST
POTENTIAL FOR HIGHER GUSTS POSSIBLE THIS AFTERNOON AND EVENING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A COLD UPPER LOW PRESSURE SYSTEM WILL ENTER THE NORTHERN ROCKIES
SUNDAY NIGHT INTO MONDAY. WIDESPREAD PRECIPITATION AND COOL
TEMPERATURES...MAINLY FROM THE BITTERROOT AND SAPPHIRE MOUNTAINS
TO WEST GLACIER...ARE POSSIBLE. SNOW LEVELS MAY LOWER TO 5500 FEET BY
SUNDAY NIGHT WITH MODERATE SNOW AMOUNTS POSSIBLE OVER HIGHER
TERRAIN. TRAVELLERS PLANNING TO USE MCDONALD PASS AND OTHER HIGHER
PASSES OF THE REGION SHOULD BE PREPARED FOR POSSIBLE WINTRY
DRIVING CONDITIONS. BACK-COUNTRY HIKERS SHOULD ALSO BE PREPARED FOR
MUCH COLDER CONDITIONS WITH TERRAIN OBSCURATIONS...SNOW AND COLD
RAIN.

.SPOTTER INFORMATION STATEMENT...

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

MTZ002-311200-
WEST GLACIER REGION-
237 PM MDT SAT AUG 30 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST
MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A COLD UPPER LOW PRESSURE SYSTEM WILL ENTER THE NORTHERN ROCKIES
SUNDAY NIGHT INTO MONDAY. WIDESPREAD PRECIPITATION AND COOL
TEMPERATURES ARE POSSIBLE. SNOW LEVELS MAY LOWER TO 5500 FEET BY
SUNDAY NIGHT WITH MODERATE SNOW AMOUNTS POSSIBLE OVER HIGHER
TERRAIN. TRAVELLERS PLANNING TO USE LOGAN PASS AND OTHER HIGHER
PASSES OF THE REGION SHOULD BE PREPARED FOR POSSIBLE WINTRY
DRIVING CONDITIONS. BACK-COUNTRY HIKERS SHOULD ALSO BE PREPARED
FOR MUCH COLDER CONDITIONS WITH TERRAIN OBSCURATIONS...SNOW AND
COLD RAIN.

.SPOTTER INFORMATION STATEMENT...

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