Hail and Damaging Winds in Montana, July 3, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
238 PM MDT FRI JUL 3 2009

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
A SHORTWAVE TROUGH WILL SWEEP ACROSS NORTHEAST MONTANA OVERNIGHT
BRINGING A ROUND OF THUNDERSTORMS...SOME OF WHICH COULD BE SEVERE
IN THE EVENING. PRECIPITABLE WATER VALUES WILL BE NEAR ONE
INCH...SO HEAVY RAIN IS POSSIBLE IN ANY STORMS. FLASH FLOOD
GUIDANCE IS HIGH ACROSS MOST OF THE AREA. HOWEVER...IT IS MUCH
LOWER IN RICHLAND...WIBAUX...AND EASTERN DAWSON COUNTIES AS
THEY RECENTLY RECEIVED SEVERE THUNDERSTORMS WITH HEAVY RAIN.
FLASH FLOODING COULD BE A THREAT THERE OVERNIGHT IF THEY RECEIVE
HEAVY RAIN.

A DRIER NORTHERLY PUSH OF CANADIAN AIR DEVELOPS BEHIND THE
DEPARTING SHORTWAVE TROUGH SATURDAY. THIS WILL REDUCE INSTABILITY
ACROSS THE AREA...EXCEPT FOR THE FAR SOUTHWEST CORNER OF THE CWA.
12Z MODEL SUITE CASTS DOUBT ON THUNDERSTORM POTENTIAL. HOWEVER...RECENT
MODEL RUNS HAVE BEEN...AND TYPICALLY ARE...FICKLE WITH
MOISTURE...SO A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WILL BE
MAINTAINED WITH ENERGETIC WEST-SOUTHWEST FLOW ALOFT. MAXIMUM
TEMPERATURES WILL RANGE FROM THE UPPER 70S TO MID 80S ACROSS THE
AREA...WHICH IS NEAR AVERAGE FOR EARLY JULY.

A WEAK SHORTWAVE TRAVERSES ACROSS NORTHEAST MONTANA SATURDAY NIGHT
RESULTING IN STEEPENING MID-LEVEL LAPSE RATES. THIS COULD RESULT
IN A FEW ELEVATED NOCTURNAL THUNDERSTORMS. 500MB HEIGHTS AND
1000-500MB THICKNESS VALUES BEGIN TO CLIMB ON SUNDAY AS AN UPPER
RIDGE BUILDS OVER THE NORTHERN HIGH PLAINS. THIS WILL SEND MAXIMUM
TEMPERATURES WELL INTO THE 80S...AND PERHAPS LOW 90S. THE LEE-SIDE
SURFACE TROUGH BECOMES RE-INVIGORATED OVER CENTRAL MONTANA IN A
WARMING AIRMASS ALLOWING SOUTHEASTERLY FLOW TO EXPAND OVER THE
REGION...AND HENCE...REFRESH LOW LEVEL MOISTURE IN THE AREA. THE
MID AND UPPER LEVELS WILL BE MORE STABLE SUNDAY...BUT A SLIGHT
CHANCE OF THUNDERSTORMS WILL BE MAINTAINED WITH INCREASING
INSTABILITY. AJZ

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
LITTLE CHANGE FOR THE EXTENDED FORECAST AS MODELS IN GOOD
AGREEMENT WITH MAIN PATTERN...OF UPPER FLOW BACKING TO THE
SOUTHWEST EARLY NEXT WEEK. MADE SLIGHT ADJUSTMENT TO POPS FOR
COLLABORATIVE PURPOSES...WHILE THE REMAINDER OF THE FORECAST LOOKS
ON TRACK. EBERT

PREVIOUS LONG TERM FORECAST DISCUSSION...THE UPPER LEVEL RIDGE
WILL PASS OVER THE AREA SUNDAY NIGHT AND MONDAY BACKING THE
INITIAL NW FLOW ALOFT TO THE WEST. UPPER FLOW WILL CONTINUE
BACKING TO THE SOUTHWEST THROUGH THE REMAINDER OF THE WEEK AS
STRONG HIGH PRESSURE BUILDS UP OVER THE SOUTHWESTERN STATES WHILE
AN UPPER LEVEL TROUGH MOVES INTO THE PACNW.

MONDAY AND MONDAY NIGHT...A THERMAL RIDGE PUSHES INTO THE
AREA...RAMPING UP TEMPERATURES. INSTABILITY COULD INITIATE TS
ACTIVITY BY AFTERNOON. TIMING DIFFERENCES BETWEEN GFS AND EC
CONTINUE...WITH THE EC PUSHING THE RIDGE AXIS EAST OF THE AREA BY
AFTERNOON...ALLOWING MORE MOISTURE INTO THE UNSTABLE AREA. THE GEM
SIDES WITH THE EC...SO IT SEEMS REASONABLE TO INCLUDE AT LEAST
SLIGHT CHANCE POPS. AN INVERTED SURFACE TROUGH WILL PUSH THE BEST
AREA FOR POPS INTO THE NORTHERN ZONES AND CANADA.

TUESDAY AND TUESDAY NIGHT...THERMAL RIDGE MOVES EAST OF THE AREA
AND SW FLOW ALOFT SENDS MORE CLOUDS OUR WAY...LOWERING
TEMPERATURES A BIT CLOSER TO NORMAL. OTHERWISE UNSTABLE CONDITIONS
WILL CONTINUE TO CREATE AT LEAST A SLIGHT CHANCE FOR
THUNDERSTORMS.

WEDNESDAY AND WEDNESDAY NIGHT...THE UPPER LEVEL LOW CONTINUES TO
SPIN OVER WASHINGTON STATE SENDING A STRONG UPPER JET OVER
CENTRAL MONTANA. THE RESULT WILL BE CONTINUED INJECTION OF
MOISTURE. BOTH EC AND GFS SHOW A COLD FRONT NUDGING CLOSE TO OUR
WESTERN BORDER. THE RESULT COULD BE HEAVIER SHOWERS PUSHING INTO
THE CWA. THERE WILL BE A TREND TOWARDS TEMPERATURES NEAR NORMAL
THROUGH THE REMAINDER OF THE EXTENDED PERIOD.

THURSDAY THE UPPER LOW LIFTS INTO THE CENTRAL CANADIAN PRAIRIE
TAKING MOST OF THE SHOWER ACTIVITY WITH IT. THE RESULT LOCALLY
WILL BE NEAR NORMAL TEMPERATURES. SCT

&&

.AVIATION...
ISOLATED TO SCATTERED RAIN SHOWERS AND THUNDERSTORMS WILL MOVE
ACROSS THE REGION TODAY AND THE INCREASINGLY UNSTABLE AFTERNOON
CONDITIONS COULD PRODUCE SOME SEVERE THUNDERSTORMS...MAINLY TO THE
SOUTHWEST OF THE TAF SITES...INTO EARLY EVENING WITH STRONG GUSTY
WINDS AND POSSIBLY LARGE HAIL. OTHERWISE GENERALLY VFR THROUGH
TONIGHT WITH SOUTHEAST WINDS DIMINISHING AROUND SUNSET. RAE

&&

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

&&

WEATHER.GOV/GLASGOW

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GLASGOW MT
242 PM MDT FRI JUL 3 2009

MTZ016>027-059>062-041000-
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-
242 PM MDT FRI JUL 3 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED TO SCATTERED THUNDERSTORMS WILL AFFECT THE AREA THIS
AFTERNOON AND TONIGHT. A FEW STORMS MAY BECOME SEVERE WITH LARGE
HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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