Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 042038
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
238 PM MDT SAT JUL 4 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
THE UPPER RIDGE THAT BROUGHT QUIET WEATHER TO NORTHEAST MONTANA
THE LAST COUPLE OF DAYS IS BEING BROKEN DOWN BY AN UPPER TROUGH
AND ITS ASSOCIATED COLD FRONT. THE RESULT OF THIS BREAKDOWN
ARE SHOWERS AND THUNDERSTORMS...SOME OF WHICH ARE SEVERE THIS AFTERNOON EAST
OF A WOLF POINT TO TERRY LINE. THESE STORMS SHOULD LIFT INTO NORTH
DAKOTA WITH THE SURFACE TROUGH BY EARLY IN THE EVENING. HOWEVER
LATER ON THIS EVENING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS
IS EXPECTED AS ANOTHER DISTURBANCE PUSHES OUT OF SOUTHERN BRITISH
COLUMBIA...INTO NORTHERN MONTANA. THIS WILL BRING MOST OF
NORTHEAST MONTANA GOOD CHANCES FOR PRECIPITATION TONIGHT INTO
SUNDAY MORNING.

SUNDAY COOLER WEATHER WILL PREVAIL...WITH BELOW NORMAL
TEMPERATURES...AS AN UPPER TROUGH EXTENDING SOUTHWARD FROM HUDSON
BAY TO WESTERN MONTANA THE DOMINANT FEATURE. INSTABILITY UNDER THE
UPPER TROUGH WILL KEEP SCATTERED TO WIDESPREAD SHOWERS GOING
ACROSS THE REGION...WITH SHOWERS TAPERING OFF DURING THE
AFTERNOON.

SUNDAY NIGHT INTO MONDAY SHOWER ACTIVITY WILL CONTINUE TO RAMP
DOWN AS HIGH PRESSURE AT THE SURFACE RETURNS TO THE AREA.
TEMPERATURES WILL WARM SOME...HOWEVER BELOW NORMAL TEMPS WILL
CONTINUE. GILCHRIST


.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...

THE PERIOD BEGINS WITH AN UPPER TROUGH ROTATING AROUND THE HUDSON
BAY LOW. THE BASE OF THE TROUGH WILL BE TO OUR EAST MONDAY NIGHT
RESULTING IN NORTHWEST FLOW ALOFT LOCALLY. HOT HIGH PRESSURE
COVERS THE FAR WEST AS A CLOSED LOW SPINS OFF THE COAST OF
NORTHERN CALIFORNIA. THIS RELATIVELY COOL PATTERN FOR NORTHEAST
MONTANA WILL RESULT IN TMINS RANGING FROM THE MID 40S ACROSS THE
NORTH AND THE MID 50S ACROSS THE SOUTHERN COUNTIES. THE TROUGH
MOVES FARTHER EAST ON TUESDAY ALLOWING THE STATIONARY BOUNDARY TO
WEAKEN. HIGHS ON TUESDAY WILL BEING TO REBOUND CLOSER TO
NORMAL...AND CONTINUE WARMING THROUGH MID-WEEK.

BEGINNING AROUND THURSDAY...FLOW ALOFT BEGINS TO BACK AROUND TO
ZONAL FLOW AS THE CALIFORNIA CLOSED LOW FINALLY DECIDE TO MOVE
ASHORE. THIS LOW WILL TRAVEL ACROSS THE GREAT BASIN THAN MOVE INTO
THE NORTHERN ROCKIES BY SATURDAY AND ACROSS NORTHEAST MONTANA BY
SATURDAY NIGHT. THE EVENTUAL SOUTHWEST FLOW WILL BRING IN MOISTURE
FOR A ROUND OF SHOWERS AND THUNDERSTORMS NEXT WEEKEND. THERE ARE
STRENGTH DIFFERENCES BETWEEN THE EC AND THE GFS BUT TIMING IS
SIMILAR.

THE MAIN CHANGE WAS TO DRY OUT MID WEEK. OTHERWISE THERE WERE FEW
OTHER SIGNIFICANT CHANGES TO THE 12Z MODELS. SCT

PREVIOUS DISCUSSION...
THE EXTENDED PERIOD KICKS OFF ON MONDAY NIGHT WITH NORTHWEST FLOW
ALOFT OVER THE NORTHERN HIGH PLAINS WITH AN UPSTREAM RIDGE ACROSS
BRITISH COLOMBIA. DO EXPECT A COLD FRONTAL PASSAGE SOMETIME
TUESDAY WHICH COULD RESULT IN AN ISOLATED SHOWER OR THUNDERSTORM.

WEDNESDAY INTO FRIDAY...UPPER RIDGE WILL AMPLIFY OVER THE HIGH
PLAINS ALLOWING FOR DRY WEATHER CONDITIONS AND WARMING
TEMPERATURES. WILL HAVE HIGHS ONCE AGAIN APPROACHING 90 DEGREES BY
WEDNESDAY OR THURSDAY.

TOWARD THE WEEKEND...MODEL SOLUTIONS POINT TOWARD A PACIFIC TROUGH
DEVELOPING...ALLOWING FOR SOUTHWEST FLOW ALOFT TO BECOME
ESTABLISHED ACROSS THE REGION AS THE RIDGE AXIS SLIDES EAST.
TIMING OF THESE DEVELOPMENTS REMAIN SOMEWHAT UNCERTAIN AND
ENSEMBLE SPREAD IN THE 500MB HEIGHTS INCREASES CONSIDERABLY TOWARD
THE END OF THE PERIOD...HOWEVER...BROAD AGREEMENT ON UNSETTLED
WEATHER CONDITIONS RETURNING TO NORTHEAST MONTANA EXISTS AND SO
INTRODUCED SLIGHT CHANCE TO LOW END CHANCE POPS TO FINISH OUT THE
PERIOD. WITH UPPER LEVEL DIFFLUENT SOUTHWEST FLOW ALOFT...ANY
SHORTWAVE APPROACHING THE AREA COULD EASILY ASSIST IN CONVECTION
INITIATION AND SO WILL MENTION SHOWERS AND THUNDERSTORMS ON
SATURDAY FOR NOW. MALIAWCO

&&

.AVIATION...

SMOKEY HAZE CONTINUES...WITH SOME MVFR AS A RESULT. VISUAL SATELLITE
IMAGERY OF SOUTHERN ALBERTA SHOWS MORE SMOKE BEHIND THE COLD
FRONT COMING IN FROM THE NORTHWEST.

SATELLITE IMAGERY AND THE LIGHTNING DETECTION NETWORK ARE ALSO
SHOWING SCATTERED THUNDERSTORMS MOVING EAST ACROSS SOUTHERN
SASKATCHEWAN.

AS THE COLD FRONT PASSES THROUGH THE LOCAL AREA...EXPECT ISOLATED
TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND
EVENING. SOME STRONGER STORMS MAY ALSO PRODUCE TEMPORARY MVFR
VISIBILITY. EXPECT SOUTHEAST WINDS AT 5-10 KTS THIS MORNING TO
INCREASE AND TURN VEER NORTH TO NORTHEASTERLY BY THIS EVENING AT
10 TO 20 KTS BEHIND THE COLD FRONTAL PASSAGE.

SPC HAS PLACED MOST OF NORTHEAST MONTANA IN A SLIGHT RISK FOR
SEVERE WEATHER AREA FOR TODAY AND EVENING. SO THERE IS THE
POSSIBILITY OF SUPER-CELL DEVELOPMENT RESULTING IN LARGE HAIL
AND DAMAGING WINDS. SINCE IT IS TOO ISOLATED TO PREDICT...EXPECT
TAF AMENDS IF AND WHEN STORMS DEVELOP THAT WOULD AFFECT THE
TERMINALS.

SCT



&&

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

&&

$$

WEATHER.GOV/GLASGOW





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