Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 231506
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
906 AM MDT SAT MAY 23 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...

MORNING UPDATE...
CHANGES TO THE FORECAST FOCUSED AROUND POPS THROUGH TODAY. TRENDS
ON RADAR HAVE A FEW ISOLATED TO SCATTERED SHOWERS IN SOUTHWESTERN
ZONES THIS MORNING. SO POPS WERE BUMPED UP IN ACCORDANCE. WHEN
LOOKING AT REGIONAL RADAR TRENDS... LIMITED ECHOS ARE EXITING
SOUTH DAKOTA INTO SOUTHERN MONTANA AND SEEM TOO LIGHT ON THE DBZ
SCALE TO BE IMPACTING THE GROUND. MODELS FOR THE AFTERNOON AND
EVENING HOURS SEEM TO CONFIRM THIS WITH ONLY A SMALL PLACEMENT OF
QPF OVER WIBAUX COUNTY DURING THAT TIME. SO HAVE CUT BACK POPS TO
ISOLATED OVER THE YELLOWSTONE VALLEY. WIND AND SKY FIELDS WERE
ALSO MANIPULATED BRIEFLY ALONG WITH WETTING RAINS AND QPF. NO
CHANGE TO AREA TEMPERATURES ARE EXPECTED.  GAH


PREVIOUS SHORT TERM DISCUSSION...
A LARGE UPPER LOW CURRENTLY CENTERED OVER UTAH WILL SLOWLY MOVE
NORTHEAST OVER THE WEEKEND. MONTANA WILL BE ON THE NORTHERN
FRINGES OF THIS LOW CYCLONIC CIRCULATION TODAY. AS A RESULT MOST
OF THE SHOWERS AND THUNDERSTORMS WILL BE TO THE SOUTH OF THE
FORECAST AREA. WITH THE AIRMASS EXPECTED TO BE SOMEWHAT
UNSTABLE...A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE TODAY
MAINLY SOUTH OF THE MISSOURI RIVER. MEANWHILE...EAST WINDS WILL BE
STRONG ENOUGH TO REQUIRE A LAKE WIND ADVISORY OVER FORT PECK LAKE.

MONTANA WILL REMAIN IN THE NORTHERN FRINGES OF THE UPPER LOW
CIRCULATION TONIGHT. MOST OF THE SHOWERS AND THUNDERSTORMS WILL
REMAIN TO THE SOUTH OF THE FORECAST AREA ALTHOUGH THE SOUTHEAST
ZONES WILL SEE SOMEWHAT DEEPER MOISTURE WITH A SOUTHERLY FLOW
ALOFT. WILL MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS THERE.

THE UPPER LOW WILL MOVE NORTHEAST THROUGH EASTERN WYOMING ON
SUNDAY AND EASTERN MONTANA WILL BE SOMEWHAT DEEPER INTO THE
SYSTEM`S CIRCULATION AND MOISTURE. HOWEVER...MODELS STILL DIFFER
ON HOW MUCH OF NORTHEAST MONTANA WILL SEE RAIN. NAM SPREADS RAIN
OVER MOST OF THE AREA EXCEPT ALONG CANADIAN BORDER... GFS KEEPS IT
IN THE EAST HALF OF THE FORECAST AREA AND ECMWF KEEPS IT SOUTH OF
THE YELLOWSTONE RIVER. WILL HAVE HIGHEST POPS...LIKELY...IN THE
SOUTHEAST AND LOWEST POPS...EITHER SLIGHT CHANCE OR DRY...IN THE
NORTH. WITH SOMEWHAT UNSTABLE AIRMASS MAY SEE THUNDERSTORMS AT TIMES.

THE UPPER LOW MOVES INTO SOUTH DAKOTA SUNDAY NIGHT AND NORTH
DAKOTA. THE BEST CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE IN
THE EAST CLOSER TO THE LOW. PRECIP CHANCES WILL BE LESS TO THE
WEST. FORRESTER


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

THE UPPER FLOW PATTERN WILL CONTINUE TO BE RATHER UN-FOCUSED
THROUGH THE PERIOD. MONDAY NIGHT BEGINS WITH A MEDIUM WAVE TROUGH
FORMING OVER THE PACIFIC NORTHWEST THAT WILL SLOWLY DRIFT ACROSS
THE DIVIDE AND OVER THE NORTHERN PRAIRIE THROUGH THE REST OF NEXT
WEEK. SO THROUGH THIS PERIOD WITH NO DISTINCT FRONT OR STRONG
UPPER FLOW PATTERN.  IT WILL BE A PERIOD OF ISOLATED TO SCATTERED
RAIN SHOWERS AND A FEW THUNDERSTORMS.

GUIDANCE SUGGESTS THE PERIOD WILL CONTINUE INITIALLY WITH NORMAL
TO ABOVE NORMAL TEMPERATURES. THEN LATE IN THE PERIOD A POOL OF
COLD AIR FORMS UP A COLD FRONT IN CANADA THAT WILL BEGIN TO WORK
ITS WAY SOUTH. WINDS WILL BE ON THE QUIET SIDE UNTIL LATE IN THE
PERIOD WHEN THE TROUGH MOVES THROUGH THE LOCAL REGION THAT
PRODUCES BRISK SOUTHEAST WINDS. THERE DOES NOT APPEAR TO BE ANY
PERIOD WITH STRONG INSTABILITY...SO STRONG THUNDERSTORMS ARE
UNLIKELY DURING THIS TIME.  SCT


&&

.AVIATION...
A LONG-WAVE TROUGH CENTERED OVER THE CENTRAL ROCKIES OCCUPIES
MOST OF THE WEST...BRINGING ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS. MOST STORM ENERGY WILL REMAIN SOUTH OF NORTHEAST
MONTANA TODAY AND TONIGHT. HOWEVER A FEW WEAK STORMS MAY DRIFT
INTO THE AREA...MAINLY NEAR THE YELLOWSTONE RIVER VALLEY TO AFFECT
KGDV AND KSDY. ALL TERMINALS GENERALLY EXPECT MID-TO-LOW LEVEL
BROKEN CLOUDS.

PERSISTENT EASTERLY TO SOUTHEASTERLY WINDS TO CONTINUE AT 10-20KT
WITH THE STRONGEST WINDS IN THE AFTERNOON. SCT


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 9 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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