Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 242022
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
222 PM MDT THU APR 24 2014

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

SYNOPTIC SET UP...TO THE EAST A WEAK TROUGH IS EXITING THE
NORTHERN AND CENTRAL PLAINS. TO THE WEST A WEAK RIDGE RUNS UP THE
SPINE OF THE ROCKY MOUNTAINS FROM COLORADO THROUGH MONTANA AND
SOUTHERN ALBERTA. THIS PLACES MONTANA IN NORTHWEST FLOW THROUGH
TODAY WITH WARM FRONT READYING TO PASS THROUGH THE AREA TONIGHT.
MEANWHILE FARTHER WEST... A LARGE POTENT TROUGH EXISTS OFF THE
COAST OF THE US AND CANADA OVER THE GULF OF ALASKA.

THIS AFTERNOON THROUGH TONIGHT...NORTHWEST FLOW FROM THIS MORNING
CLEARED OUT A LARGE CHUNK OF THE CWA/S SKY COVER ALLOWING ENOUGH
SURFACE HEATING TO GENERATE AFTERNOON CUMULUS. AS A RIDGE MOVE
INTO THE AREA IT WILL BRING IN A WARM FRONT ALOFT WHICH IN HIGHER
TERRAIN TO THE SOUTHWEST MAY DESTABILIZE THE ATMOSPHERE DURING THE
AFTERNOON AND EVENING HOURS BUT SHOULD KEEP A TIGHT LID/INVERSION
OVER THE COOLER SURFACE BOUNDARY ACROSS THE NORTHEAST. A LEE
SURFACE TROUGH IS ALSO EXPECTED TO ENHANCE ANY ISOLATED RAIN
SHOWER ACTIVITY OVERNIGHT TO THE SOUTHWEST.

FRIDAY... WARMER AIR WILL BE IN PLACE WITH THE RIDGE AMPLIFYING AND
DRY CONDITIONS ARE EXPECTED THROUGH THE MORNING HOURS. HOWEVER
THE TROUGH OFF THE WEST COAST SHORE WILL MOVE INLAND ALLOWING A
STREAM OF PACIFIC MOISTURE TO FEED INTO THE REGION. HIGH CLOUDS
WITH INCREASING CHANCE FOR RAIN SHOWERS SHOULD BEGIN SHOWING UP
DURING THE LATE AFTERNOON.

FRIDAY NIGHT THROUGH SATURDAY... BASE OF THE TROUGH WILL DIG INTO
THE DESERT SOUTHWEST. HOWEVER... PLENTY OF PACIFIC MOISTURE ALREADY
IN THE PIPE WILL STREAM UP FROM THE SOUTH AND FEED INTO A LOW
DEVELOPING OVER SOUTHEAST MONTANA AND NORTHEAST WYOMING. THIS WILL
PLACE NORTHEAST MONTANA IN THE NORTH TO NORTHWEST QUADRANT OF THE
LOW AND PROVIDE INCREASING CHANCES FOR PRECIPITATION IN THE FORM
OF RAIN. A BRIEF DRY SLOT MAY BE POSSIBLE STRETCHING FROM WIBAUX
TO CIRCLE TO GLASGOW DURING THE AFTERNOON HOURS BUT AS JET LIFT
KICKS IN AROUND 6PM MUCH OF THE CLEAR AREAS WILL FILL RIGHT BACK
IN. PLACEMENT OF THE DRY SLOT COULD ALSO MOVE NORTH OR SOUTH BY
ABOUT 50 TO 100 MILES EASILY TRENDING TOWARDS LOWER CONFIDENCE FOR
THIS MESOSCALE WINDOW. GAH


.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
GOING FORECAST IN GOOD SHAPE AS 12Z MODELS ARE NOT SHOWING ANY
NEEDED CHANGES TODAY. MOST OF THE PRECIP CONTINUES TO LOOK TO BE
RAIN BUT A COLD POOL MAY BRIEFLY BRING A MIX OF SNOW EARLY NEXT
WEEK. WITH TEMPS ABOVE FREEZING...NOT ANTICIPATING ANY ACCUMULATION
MOST PLACES. TFJ


PREVIOUS DISCUSSION...
DEEP UPPER TROF MOVING THROUGH THE GREAT BASIN THIS WEEKEND IS
FORECAST TO DEVELOP INTO A STACKED CLOSED LOW OVER THE CENTRAL
PLAINS EARLY NEXT WEEK. BLOCKING PATTERN CAUSED BY LOWS OVER THE
NORTH ATLANTIC WILL KEEP THE STORM SYSTEM OVER THE CENTRAL STATES
FOR MUCH OF THE WEEK WHILE AN UPPER RIDGE BUILDS ALONG THE WEST
COAST.

AS THE LOW DEVELOPS OFF THE CENTRAL ROCKIES SATURDAY NIGHT...
MOISTURE AND WARM AIR WILL BE DRAWN NORTHWARD FROM THE GULF OF
MEXICO TO WRAP INTO THE STORM SYSTEM. AN INVERTED TROF WILL EXTEND
NORTHWARD FROM THE LOW INTO EASTERN MONTANA...AND WITH A LITTLE
COLD AIR FILTERING IN FROM THE WEST TO PROVIDE ADDITIONAL LIFT...
SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH SUNDAY...AND MAINLY
NEAR THE NORTH DAKOTA BORDER ON MONDAY. INITIALLY THE WARM AIR IN
THE SOUTHEASTERLY FLOW WILL KEEP THE AIRMASS WARM ENOUGH FOR RAIN
BUT AS THE SYSTEM SLIDES EAST...COULD SEE SOME SNOW IN THE HIGHER
ELEVATIONS ON SUNDAY NIGHT.

BEYOND PRECIPITATION TYPE...THEN OTHER FORECAST PROBLEM IS HOW
QUICKLY WILL THE PRECIPITATION END AND THE WEST RIDGE BUILD INTO
THE REGION. GENERAL CONSENSUS IS FOR SCATTERED LIGHT SHOWERS TO
LINGER INTO TUESDAY WITH LOW CONFIDENCE ON THE FORECAST BEYOND
THAT POINT. EBERT


&&

.AVIATION...
FLIGHT CATEGORY: VFR

CLOUDS: SCTTERED TO BROKEN BASES AT ABOUT 8K MOVE THROUGH FROM SW
TO NE TONIGHT. A FEW SHOWERS ARE POSSIBLE.

WINDS: LIGHT AND VARIABLE WINDS TONIGHT ARE EXPECTED TO BE LIGHT
W-NW AT LESS THAN 10 KTS FRIDAY. TFJ


&&

.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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