Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 072036 AAA
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
236 PM MDT TUE JUL 7 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...

SATELLITE VIS IMAGERY CLEARLY REVEALS WILDFIRE SMOKE COMING IN
WAVES FROM TWO DIRECTIONS...FROM THE NORTH AND FROM THE WEST. SO
WILL MAINTAIN AREAS OF SMOKE IN THE WX GRIDS TONIGHT.

THE FORECAST PERIOD BEGINS WITH THE PERSISTENT HIGH PRESSURE IN
THE WEST AND A BROAD TROUGH ACROSS CANADA ANCHORED BY A CLOSED
LOW PRESSURE SYSTEM NEAR HUDSON BAY. THEN OFF THE WEST COAST OF
CALIFORNIA IS ANOTHER CLOSED LOW THAT WILL MOVE INLAND BY
TOMORROW. THE BASE OF THAT TROUGH WILL BE PICKING UP PACIFIC
MOISTURE AND EJECTING IT INTO THE GREAT BASIN REGION AND THE
CENTRAL ROCKY MOUNTAINS.

THE UPPER FLOW PATTERN THIS EVENING WILL BE GENERALLY ZONAL WITH A
SLIGHT NORTHWEST COMPONENT. THE CANADIAN LOW NUDGES A SECONDARY
COLD FRONT SOUTH THROUGH NORTHEAST MONTANA THAT WILL MAINLY KEEP
THE HOT AIR OF THE WESTERN HIGH PRESSURE FROM MOVING INTO THE
LOCAL AREA ON WEDNESDAY. THE INITIAL COLD FRONT THAT PASSED
THROUGH EARLIER TODAY WILL BE THE MAIN FOCAL POINT OF THE SHOWERS
AND THUNDERSTORMS THIS EVENING...WHICH WILL MAINLY OCCUR TO OUR
EAST...WEST AND SOUTH. THE SPC SSEO SHOWS THE BEST OPPORTUNITY FOR
STRONG THUNDERSTORMS TO BE IN A NE-TO-SW ORIENTATED AREA JUST TO
THE EAST AND SOUTH OF OUR YELLOWSTONE RIVER VALLEY REGION. A FEW
THUNDERSTORMS MIGHT BEGIN IN OUR AREA THEN GROW AS THEY MOVE EAST
INTO THE DAKOTAS.

THURSDAY...THE FRONTAL BOUNDARY MOVES OFF WELL TO THE NORTH AND
THE WESTERN RIDGE SPREADS HOT AIR INTO MONTANA. EXPECT
TEMPERATURES TO RISE ABOVE NORMAL...AT LEAST 10F ABOVE NORMAL. BY
00Z FRIDAY THE CALIFORNIA TROUGH WILL BE SENDING MORE MOISTURE
THAT WILL REACH INTO SOUTHERN MONTANA BUT WILL NOT QUITE REACH THE
LOCAL AREA.

SCT


.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
AFTERNOON UPDATE...MOSTLY TWEAKS MADE WITH NO SIGNIFICANT CHANGES.
THE TWO BIGGEST CONCERNS IN THE EXTENDED IS THE RETURN TO WARMER
AND DRIER CONDITIONS AS WE GET DEEPER INTO FIRE SEASON. THE OTHER
CONCERN FOR PUBLIC AND FIRE WEATHER FORECASTING IS THE TIMING ON
THE BROAD AREA SURFACE LOW COMING THROUGH FRIDAY NIGHT INTO
SATURDAY. THIS IS A SIGNIFICANT LOW SIMILAR TO THE ONE ON THE
4TH OF JULY AND WE COULD SEE A SIMILAR SITUATION WITH THE LOW IN
THE AREA KICKING OFF SOME AIR MASS THUNDERSTORMS AHEAD OF THE
FRONT AND THEN MORE SIGNIFICANT STORMS AS THE FRONT MOVES THROUGH.
AT THIS TIME I`M NOT SURE THE WINDS IN THE FORECAST PORTRAY THE
SITUATION REAL WELL BUT EVERY MODEL IS SHOWING SOMETHING SLIGHTLY
DIFFERENT WITH THE FRONTAL PASSAGE. WITH A TIGHT GRADIENT...THE
WINDS WILL BE AN ISSUE AT TIMES...AND THAT IS OF CONCERN WITH A
LARGE FISHING TOURNAMENT ON FORT PECK THIS WEEKEND AS WELL AS THE
NON-TOURNAMENT OUTDOOR RECREATIONALISTS WHO WILL BE CAMPING OUT
THERE. FRANSEN

PREVIOUS DISCUSSION...SOUTHWEST FLOW ALOFT WITH AN UPPER TROUGH
TO THE WEST WILL PREVAIL FROM THURSDAY NIGHT THROUGH SUNDAY. THIS
FLOW WILL ALLOW MOISTURE FROM THE PACIFIC TO MOVE TOWARDS MONTANA.
COMBINE THIS MOISTURE WITH SOME SHORTWAVES AND UNSTABLE AIR MASS
TO BRING CHANCES FOR SHOWERS AND THUNDERSTORMS. ONE OF THESE WAVES
IS TIMED FOR FRIDAY AFTERNOON AND EVENING WITH A LOW PRESSURE AND
FRONTAL SYSTEM. A SOMEWHAT STRONGER SHORTWAVE IS FORECASTED BY
BOTH THE GFS AND ECMWF TO MOVE THROUGH NORTHEAST MONTANA SATURDAY
AFTERNOON AND EVENING WITH THE LOW PRESSURE SYSTEM STILL IN THE
AREA. THIS WAVE WILL BRING A COLD FRONT THROUGH THE AREA SATURDAY
NIGHT.

UPPER RIDGE BUILDS OVER EASTERN MONTANA ON SUNDAY AND REMAINS IN
PLACE MONDAY AND TUESDAY. HOT AND DRY WEATHER CAN BE EXPECTED MOST
OF THE TIME. HOWEVER...WEAK SHORTWAVE TROUGH ARE EXPECTED TO MOVE
ACROSS THE RIDGE AT TIMES THAT COULD BRING AN ISOLATED
THUNDERSTORM. FORRESTER


&&

.AVIATION...
FLIGHT CATEGORY: MAINLY VFR...BUT SOME MVFR MIXED IN AT TIMES DUE TO
SMOKE/HAZE FROM CANADIAN FIRES. THE SITE WITH THE GREATEST
POTENTIAL FOR REDUCED VISIBILITY IS KGGW.

SKY: A COLD FRONT IS APPROACHING THE REGION AND WE HAVE A CU FIELD
ACROSS THE AREA. SOME WIDELY SCATTERED SHOWERS OR THUNDERSTORMS
ARE POSSIBLE WITH KSDY HAVING THE BEST CHANCE OF ACCUMULATING
PRECIP. SKIES WILL CLEAR AFTER MIDNIGHT (06Z) TONIGHT.

WINDS: WINDS WILL BECOME NORTH TO NW THIS AFTERNOON 10 TO 15 KNOTS
BEHIND THE COLD FRONT AND BECOME FAIRLY LIGHT BY MORNING.


&&

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

&&

$$

WEATHER.GOV/GLASGOW




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