Severe Thunderstorm Warning 73, NWS Glasgow, MT

Area Forecast Discussion
National Weather Service GLASGOW MT
419 PM MDT FRI JUN 24 2016

.SHORT TERM...for northeast Montana...tonight through Sun...
Update: Updated for severe thunderstorm watch issuance. Gilchrist

The initial longwave pattern across CONUS this evening consists
of storm system/upper trough rotating and pushing across the
Divide, and an upper ridge moving east across the Central Plains.
The trough/low center will move across Northeast Montana on
Saturday and into Quebec Province on Sunday. So the short-term
will see active weather, beginning with thunderstorms tonight,
strong winds on Saturday, and showers on Sunday. The trough will
bring cooler than normal temperatures for the weekend.

Tonight: At 00Z a moderately strong cold front begins to plow
through Northeast Montana. It will meet up in the forecast area
with a moist and unstable airmass. Thunderstorms and rain showers
will likely intensify, becoming severe. Strong winds aloft suggest
the potential for damaging winds and large hail. SPC has placed
most of the CWA in its Convective Outlook for a Slight Risk for
Severe Thunderstorms. Diminishing storms and rain showers may
not totally exit the area until around sunrise.

Saturday: The closed upper low/storm center will move through the
local region, but mainly keeping showers to the north in Canada
and near or north of the Hi-Line. The main issue will be the wind
strength. Mid-morning westerly winds may reach 25g40kt. Afternoon
northwesterly winds may reach 30g50kt. Will go ahead and issue an
NPW for Fort Peck Lake from 15Z to 03Z.

Saturday night through Sunday: Showers wrapping around behind the
storms will create a chance for rain showers, mainly north of the
Missouri River.

Templer

.LONG TERM...Sun night through Fri...

not too many changes were made today. subtle disturbances
occasionally will move through the upper ridge. upper flow will be
weaker so severe thunderstorm chances should be lower. TFJ

previous discussion...
Synoptic Setup: Long range begins with a large trough over the
Canadian Prairies and northern US Plains. A second large trough
resides over the northeast Pacific centered around or just south
of the Gulf of Alaska. A large airmass of hot high pressure
resides over the Desert Southwest and runs as far north as
southern Idaho. A slightly cooler ridge juts out of the high
pressure through western Montana and through Alberta.

Sunday night through Monday: Northeast Montana lies on the stable
side of a developing ridge to the west. conditions will warm but
remain mostly dry.

Monday night through Wednesday: A shortwave will move around the
edges of the hot high pressure and through eastern Montana.
Tuesday and Tuesday night look to be the prime impact times with
showers being scattered.

Wednesday onward: Hot air from down south will fill in the
ridge into southern Alberta and then slowly move it over Montana.
This will increase temperatures and lower chances for showers and
thunderstorms slightly until the ridge axis hits. The only other
chance for showers and thunderstorms will be during night time
when the K-boundary from the desert air passes over the region.
GAH

&&

.AVIATION...

SYNOPSIS: Upper low system moving in from the Pacific NW will
bring unsettled conditions through Saturday.

SEVERE WX: Evening severe thunderstorms still look on tap with
damaging winds being the main threat. Gusts over 60 kts are
possible with some storms. Making sure aircraft are tied down or
in sheltered locations is recommended.

WINDS: Winds will turn clockwise to the east ahead of the
thunderstorms then punch in from the northwest for a couple hours
in the wake of the storms. Expect them to increase saturday with
gusts to 40 kts during the afternoon. They will diminish Saturday
evening. TFJ

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory from 9 AM to 9 PM MDT Saturday For Fort Peck
Lake for Central and Southeast Phillips...Central and Southern
Valley...Garfield...McCone...Petroleum.

&&

weather.gov/glasgow

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GLASGOW MT
221 PM MDT FRI JUN 24 2016

MTZ016>027-059>062-251200-
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-
221 PM MDT FRI JUN 24 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A STRONG FRONTAL SYSTEM WILL MOVE ACROSS THE REGION TONIGHT.
THUNDERSTORMS ARE EXPECTED FROM LATE THIS AFTERNOON THROUGH
TONIGHT AND SOME STORMS MAY BECOME SEVERE WITH LARGE HAIL AND
DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

STRONG WEST TO NORTHWEST WINDS 25 TO 40 MPH WITH GUSTS TO 50 MPH
ARE EXPECTED ON SATURDAY BEHIND THE FRONTAL PASSAGE. THESE WINDS
WILL MAKE BOATING EXTREMELY HAZARDOUS ON FORT PECK LAKE AND TRAVEL
DIFFICULT FOR HIGH PROFILE VEHICLES. THEREFORE A LAKE WIND
ADVISORY IS IN EFFECT FOR FORT PECK LAKE FROM 9 AM SATURDAY
MORNING THROUGH 9 PM SATURDAY EVENING.

.SPOTTER INFORMATION STATEMENT...

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GLASGOW MT
320 PM MDT FRI JUN 24 2016

MTZ017-018-020-242215-
DANIELS MT-CENTRAL AND SOUTHERN VALLEY MT-WESTERN ROOSEVELT MT-
320 PM MDT FRI JUN 24 2016

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN VALLEY...
NORTHWESTERN ROOSEVELT AND CENTRAL DANIELS COUNTIES UNTIL 415 PM
MDT...

AT 319 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 12
MILES SOUTHEAST OF PEERLESS...OR 17 MILES SOUTHWEST OF
SCOBEY...MOVING NORTHEAST AT 45 MPH.

DIME SIZE HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
SCOBEY...FLAXVILLE...MADOC AND FOUR BUTTES.

LAT...LON 4879 10510 4846 10582 4849 10595 4900 10559
      4900 10556
TIME...MOT...LOC 2119Z 227DEG 39KT 4863 10570

TFJ

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GLASGOW MT
347 PM MDT FRI JUN 24 2016

MTZ021-022-060-242245-
SOUTHWEST PHILLIPS MT-PETROLEUM MT-GARFIELD MT-
347 PM MDT FRI JUN 24 2016

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN GARFIELD...PETROLEUM
AND SOUTH CENTRAL PHILLIPS COUNTIES UNTIL 445 PM MDT...

AT 346 PM MDT...DOPPLER RADAR WAS TRACKING STRONG THUNDERSTORMS ALONG
A LINE EXTENDING FROM 11 MILES NORTHEAST OF ROY TO 15 MILES NORTHWEST
OF ROUNDUP. MOVEMENT WAS EAST AT 45 MPH.

WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE WITH THESE STORMS.

LOCATIONS IMPACTED INCLUDE...
WINNETT...MOSBY...FLATWILLOW...CROOKED CREEK REC AREA...CAT CREEK...
TIEGEN AND PETROLIA LAKE.

LAT...LON 4727 10872 4732 10831 4759 10832 4759 10843
      4760 10839 4762 10820 4758 10818 4759 10797
      4751 10790 4745 10791 4745 10788 4685 10771
      4685 10789 4677 10784 4676 10783 4675 10863
      4710 10861 4710 10874
TIME...MOT...LOC 2146Z 260DEG 38KT 4747 10883 4664 10870

TFJ

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