Severe Thunderstorm Warning 71, NWS Glasgow, MT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
654 PM MDT SAT JUL 20 2013

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
MADE ANOTHER UPDATE TO POPS AND WX GRIDS BASED ON THE LATEST
MOVEMENT OF THE THUNDERSTORMS. THESE STORMS ARE PRODUCING BRIEF
HEAVY RAIN...GUSTY WIND AND HAIL RANGING IN SIZE FROM DIME TO
QUARTER. THEY ARE EXPECT TO DEPART THE AREA BY MID EVENING. SCT

PREVIOUS UPDATE...
MADE A QUICK UPDATE TO CHANGE AFTERNOON WX TO COVERAGE AND
INCREASE POPS. A COUPLE OF STRONG STORMS HAVE POPPED UP WITH
REPORTS OF HEAVY RAIN...SMALL HAIL...AND GUSTY WIND. SCT

PREVIOUS DISCUSSION...
CONVECTIVE ACTIVITY THIS AFTERNOON WILL CONTINUE TO DEVELOP OVER
THE NEXT COUPLE OF HOURS BUT SHOULD DIMINISH PRETTY QUICK WITHOUT
THE SHEAR IN PLACE. HRRR MODEL SHOWING JUST SCATTERED ACTIVITY AT
BEST OVER THE NORTHEASTERN HALF OF THE CWA THIS EVENING.

WITH AN UPPER TROUGH OVER THE EASTERN STATES AND A RIDGE TO OUR
WEST...THE AREA IS UNDER A WEST-NORTHWEST FLOW. A DISTURBANCE...BOTH
AT THE SURFACE AND ALOFT MOVES INTO SOUTHERN SASK LATER
TONIGHT...KEEPING SHOWERS/THUNDERSTORMS GOING OVERNIGHT MAINLY TO
THE NORTHEAST ZONES.

SUNDAY...DISTURBANCE MOVES SOUTHEAST AND THROUGH THE CWA BRINGING AN
INCREASE IN WEST WINDS DURING THE AFTERNOON. THEY SHOULD BE STRONG
ENOUGH TO CAUSE PROBLEMS FOR FORT PECK LAKE FROM NOON UNTIL 9
PM...SO ISSUED A LAKE WIND ADVISORY.

ON MONDAY...BACKDOOR FRONT THAT LIES NW TO SE ACROSS MONTANA SUNDAY
NIGHT HELPS TO FIRE UP THUNDERSTORMS AS A VORT MAX MOVES IN FROM THE
WEST. ACTIVITY MOVES IN FROM THE WEST WITH MORE ACTIVITY EXPECTED
DURING THE EVENING.  TFJ

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
AN UPPER LEVEL RIDGE IN THE WEST AND A PERSISTENT UPPER TROUGH
CENTERED OVER NORTHERN QUEBEC WILL MAINTAIN A NORTHWEST FLOW OVER
NORTHEAST MONTANA THROUGH MOST OF THE PERIOD. WEAK EMBEDDED
DISTURBANCES IN THE UPPER FLOW WILL BRING ISOLATED TO SCATTERED
THUNDERSTORMS TO THE REGION THROUGHOUT THE PERIOD.

MONDAY EVENING AND OVERNIGHT GFS SENDS A DISTURBANCE FLOWING
ALONG THE STATIONARY BOUNDARY THAT WILL INITIATE THUNDERSTORMS
ACROSS NEMONT. WITH SOME AGREEMENT FROM THE 00Z EC...WENT AHEAD
AND ADJUSTED POPS TO CHANCE.

TUESDAY THROUGH SATURDAY THE FLUCTUATING STATIONARY BOUNDARY AND
WEAK DISTURBANCES WILL GENERATE A FEW STORMS EACH DAY. THIS IS
REFLECTED IN THE INHERITED GRIDS AND NO CHANGES ARE PLANNED HERE.
SCT

SYNOPTIC SET UP... A LARGE HIGH PRESSURE HEAT DOME IS CENTERED
OVER THE LOWER INTER-MOUNTAIN WEST. A RIDGE SPUR RUNS NORTH OF THIS
DOME INTO BRITISH COLUMBIA. A LARGE TROUGH EXTENDS FROM THE
NORTHERN US PLAINS INTO MANITOBA AND UP THROUGH NUNAVUT. NORTHEAST
MONTANA LIES BETWEEN THESE TWO FEATURES IN A ZONAL TO NORTHWEST
FLOW PATTERN. ANOTHER LARGE TROUGH LIES OFF THE COAST OF BRITISH
COLUMBIA.

MONDAY NIGHT THROUGH THURSDAY NIGHT... NORTHWEST FLOW WILL END UP
ALLOWING HIGH POP CHANCE ACROSS THE NORTHEAST DRYING TOWARD THE
SOUTHWEST. THIS GRADIENT WILL BEGIN A BIT MORE SHARP MONDAY NIGHT
BUT WILL SLOWLY DIFFUSE OUT TOWARD THURSDAY NIGHT AS JETS AND
SHORTWAVES BECOME MORE FUZZY IN TIME. ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS DO EXIST ALMOST EVERY PERIOD.

FRIDAY ONWARD... THE PATTERN WILL BECOME A LITTLE MORE PROGRESSIVE
AS THE RIDGE TO THE WEST SETTLES OVER THE MONTANA HIGH PLAINS.
THIS SHOULD EDGE TEMPERATURES UP BUT POPS WILL PROBABLY REMAIN AS
THE ATMOSPHERE BECOMES MORE DESTABILIZED. HOWEVER... QPF IS
EXPECTED TO LOWER AS PLANTS BEGIN TO STRESS FROM PROGRESSIVELY
DRIER HOTTER DAYS AND SOILS FOLLOWED BY THE SURFACE LAYER OF THE
ATMOSPHERE DRY OUT. GAH

&&

.AVIATION...
GENERALLY VFR. HOWEVER A WEAK UPPER LEVEL DISTURBANCE FLOWING
OVER A STATIONARY SURFACE BOUNDARY WILL INITIATE ISOLATED TO
SCATTERED AFTERNOON/EVENING THUNDERSTORMS THAT COULD AFFECT ANY OF
THE TAF SITES. SCT

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM NOON TO 9 PM MDT SUNDAY 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
449 PM MDT SAT JUL 20 2013

MTZ016>027-059>062-211100-
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-
449 PM MDT SAT JUL 20 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND TONIGHT...
MOSTLY NEAR THE CANADIAN AND NORTH DAKOTA BORDERS. STRONGER STORMS
WILL LIKELY HAVE SOME BRIEF HEAVY RAIN...SMALL HAIL...GUSTY WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A COLD FRONT MOVING THROUGH THE REGION ON SUNDAY WILL GENERATE
GUSTY NORTHWEST WIND. THEREFORE A LAKE WIND ADVISORY IS IN EFFECT
FOR FORT PECK LAKE FROM NOON UNTIL 9 PM SUNDAY.

.SPOTTER INFORMATION STATEMENT...

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
657 PM MDT SAT JUL 20 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0654 PM     HAIL             11 NNE CIRCLE           47.56N 105.51W
07/20/2013  E2.75 INCH       MCCONE             MT   TRAINED SPOTTER

            GOLF BALL TO BASE BALL SIZED HAIL WITH HEAVY RAIN.

&&

MATTM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
742 PM MDT SAT JUL 20 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0646 PM     TSTM WND GST     10 S VIDA               47.69N 105.49W
07/20/2013  M67 MPH          MCCONE             MT   MESONET

            COW CREEK DOT WEATHER STATION

&&

PROTON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
749 PM MDT SAT JUL 20 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0615 PM     HAIL             12 NE WOLF POINT        48.21N 105.46W
07/20/2013  E1.75 INCH       ROOSEVELT          MT   PUBLIC

            NICKEL TO GOLF BALL SIZED HAIL.

0650 PM     TSTM WND GST     7 N CIRCLE              47.52N 105.60W
07/20/2013  M78 MPH          MCCONE             MT   PUBLIC

0650 PM     TSTM WND DMG     7 N CIRCLE              47.52N 105.60W
07/20/2013                   MCCONE             MT   PUBLIC

            METAL FENCING TWISTED AND BLOWN DIFFERENT DIRECTIONS.

&&

MATTM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
759 PM MDT SAT JUL 20 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0745 PM     HAIL             LINDSAY                 47.22N 105.15W
07/20/2013  E1.75 INCH       DAWSON             MT   CO-OP OBSERVER

            PEA TO GOLF BALL SIZED HAIL...HEAVY RAIN.

&&

MATTM

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