Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 102044
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
244 PM MDT THU JUL 10 2014

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

SYNOPTIC SET UP... A LARGE HOT HIGH PRESSURE DOME EXISTS OVER THE
INTERMOUNTAIN WEST AND ROCKY MOUNTAINS. TWO RIDGES EXTEND UP FROM
THIS DOME... ONE RUNS UP THROUGH WYOMING... THE DAKOTA... AND
MANITOBA WHILE THE OTHER RIDGE RUNS UP THROUGH BRITISH COLUMBIA
INTO EASTERN ALASKA. A LARGE TROUGH RESIDES OVER ALBERTA AND
SASKATCHEWAN WITH COOLER INFLUENCE REACHING OVER THE INTERNATIONAL
BORDER INTO NORTHERN MONTANA. FARTHER WEST... A CLOSED LOW EXISTS
OVER THE ALEUTIANS WITH A WEAK TROUGH EXTENDING DOWN TO OFF THE
COAST OF CALIFORNIA.

THIS AFTERNOON AND EVENING... CLEAR SKIES AND DRY CONDITIONS ARE
ANTICIPATED AS A COLD FRONT MOVES THROUGH THE AREA AND STABILIZES
OUT THE SURFACE LAYER. MEANWHILE... A SHORTWAVE DISTURBANCE WILL
MAKE ITS WAY ACROSS THE PACIFIC NORTHWEST.

FRIDAY MORNING... PAC NORTHWEST DISTURBANCE WILL HIT THE HIGH
PLAINS OFF THE FRONT RANGE AND FORM A FEW ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS. THESE ARE EXPECTED TO REACH PHILLIPS
AND PETROLEUM COUNTY BORDER AROUND MIDNIGHT AND THEN PASS OVER THE
REST OF THE CWA DURING THE MORNING HOURS.

FRIDAY AFTERNOON THROUGH SATURDAY... TROUGH TO THE NORTH WILL FORM
INTO A CLOSED LOW AND CONSISTENTLY DRAG DOWN COOLER AIR OVER THE
AREA. THIS AIR WILL IN CONFLICT WITH AN INTENSIFYING HEAT DOME
OVER THE INTERMOUNTAIN WEST. DUE TO THE COMPACT THERMAL GRADIENT
TEMPERATURES COULD EASILY SWING WARMER OR COOLER THAN ANTICIPATED
DURING THIS TIME. SO... HAVE GONE WITH A CENTER OF THE ROAD APPROACH.

GAH


.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...

THE GOING FORECAST WAS IN OVERALL GOOD SHAPE...AND MODEL
CONSISTENCY REMAINS GOOD THROUGHOUT THE EXTENDED. WITH NO BIG
SYSTEMS ON THE HORIZON...THE ONLY CHANGE WAS TO CONTINUE TO TREND
THE FORECAST TOWARD THE MODEL CONSENSUS WHICH IS A BIT COOLER ON
MONDAY AND TUESDAY AS A COOL UPPER TROUGH REMAINS OVERHEAD.
OTHERWISE NO OTHER NOTEWORTHY CHANGES WERE MADE. GILCHRIST


PREVIOUS LONG TERM DISCUSSION...
NORTHEAST MONTANA REMAINS SETUP BETWEEN A PERSISTENT CLOSED LOW
NEAR HUDSON BAY AND AN UPPER RIDGE OVER THE WEST ANCHORED BY
DESERT HIGH PRESSURE ACROSS THE GREAT BASIN. THE NORTHWEST FLOW
ALOFT SATURDAY NIGHT AND SUNDAY IS A DRY PATTERN. THE MAIN
QUESTION WILL BE TEMPERATURE. BOTH THE GFS AND THE EC HAVE
NORTHEAST MONTANA ON THE BOUNDARY BETWEEN THE NORTHERN COOLER AIR
AND THE HOT SOUTHWEST AIR. GUIDANCE SUGGESTS CLOSE TO NORMAL
TEMPERATURES FOR SUNDAY. HOWEVER ON MONDAY AN EMBEDDED DISTURBANCE
KNOCKS DOWN THE THE RIDGE AND LOCAL THICKNESS HEIGHTS DROP
SIGNIFICANTLY. THE WIND PROFILE ALOFT TO THE SURFACE IS FOR
NORTHERLY WIND. SO GUIDANCE SUGGESTS BELOW AVERAGE TEMPERATURES
FOR MONDAY.

BY TUESDAY THE EMBEDDED DISTURBANCE MOVES SOUTHEAST OUT OF MONTANA
TO ALLOW THE UPPER RIDGE TO REBOUND. THIS TAKES ANY STORM ENERGY
AWAY FROM EASTERN MONTANA AND WILL ONCE AGAIN ESTABLISH A DRY
NORTHWEST FLOW ALOFT PATTERN FOR WEDNESDAY AND THURSDAY.

OVERALL THE MODELS ARE IN AGREEMENT WITH A MOSTLY DRY PERIOD WITH
TEMPERATURES THAT DO NOT DEVIATE FAR FROM NORMAL. THERE WILL BE NO
PERIODS OF STRONG WIND. CONVECTIVE PARAMETERS WILL ALSO REMAIN
WEAK FOR LIMITED SHOWER THUNDERSTORM ACTIVITY. AS SUCH...POP GRIDS
ARE DRY. SCT


&&

.AVIATION...
FLIGHT CATEGORY: MAINLY VFR. ISOLATED IFR POSSIBLE.

OVERNIGHT SHOWERS AND THUNDERSTORMS: A WEAK DISTURBANCE IS
ANTICIPATED TO PASS OVER THE AREA AFTER MIDNIGHT AND WILL GENERATE
SCATTERED SHOWERS AND THUNDERSTORMS AGAIN WITH AN ISOLATED CHANCE
AT IFR DUE TO VISIBILITY REDUCTIONS FROM BRIEF INTENSE SHOWERS.
CHANCES ARE BELOW 50 PERCENT AND HAVE THEREFORE GONE WITH VCSH
UNTIL THE STORMS DEVELOP LATER TONIGHT.

AREA WINDS: VEERING TO THE NORTHWEST AND INCREASE 10 TO 20 KTS THIS
AFTERNOON... THEN CALMING TO LESS THAN 10 KTS AND VEERING FARTHER
TO THE NORTH TO NORTHEAST AFTER SUNSET.

GAH


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 6 PM MDT THIS EVENING FOR FORT PECK
LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.

&&

$$

WEATHER.GOV/GLASGOW




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