Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 231058
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
358 AM MST SUN NOV 23 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
SURFACE LOW OVER SOUTHEAST SASKATCHEWAN WITH TIGHT GRADIENT AND
COLD AIR ADVECTION OVER NORTHEAST MONTANA PRODUCING VERY STRONG
WINDS OVER THE REGION THIS MORNING. SOME BANDS OF LIGHT SNOW ARE
ALSO BEGINNING TO WRAP INTO THE NORTHEAST FOR THE POTENTIAL FOR
BLOWING SNOW TO INCREASE. WILL THUS CONTINUE THE BLOWING SNOW
ADVISORY ALONG WITH THE LAKE WIND ADVISORY.

SYSTEM MOVES QUICKLY EAST TODAY WITH SNOWFALL ENDING BY LATE
AFTERNOON. TOTAL ACCUMULATION IS EXPECTED TO BE AROUND AN INCH OR
LESS. NEXT UPPER WAVE DROPS THROUGH THE NORTHERN ROCKIES TONIGHT
SENDING AN IMPULSE ALONG THE BOUNDARY OVER CENTRAL MONTANA. AS THE
BOUNDARY FLEXES EAST COULD SEE A LITTLE LIGHT SNOW OVER THE
SOUTHWEST ZONES TONIGHT INTO MONDAY MORNING.

A WEAK CHINOOK PUSHES THE BOUNDARY EASTWARD MONDAY NIGHT BEFORE
ANOTHER CLIPPER DROPS OUT OF ALBERTA. A LITTLE SNOW IS POSSIBLE AS
THE SYSTEM CROSSES NORTHEAST MONTANA ON TUESDAY. EBERT


.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
HUDSON BAY LOW WILL ESTABLISH ITSELF BY TUESDAY AND WILL ALLOW
SEVERAL SUB-TROUGH TO JOG DOWN FROM THE NORTHERN PRAIRIE
PROVINCES AND PINWHEEL AROUND IT. TO THE WEST A LARGE RIDGE HAS
DEVELOPED OVER THE NORTHEAST PACIFIC AND ALLOWS ITS INFLUENCE TO
BE FELT OVER THE COAST OF CALIFORNIA... THE PACIFIC NORTHWEST...
AND BRITISH COLUMBIA. NORTHEAST MONTANA WILL BE CAUGHT BETWEEN
THE INFLUENCE OF THESE TWO FEATURES THROUGHOUT THE LONG RANGE.
SEVERAL MESO-TROUGH WILL PASS THROUGH THE AREA AND ALLOW THE ARCTIC
BOUNDARY TO WAFFLE BACK AND FORTH ACROSS THE CWA. TIMING OF THE
BOUNDARY WILL BE ALMOST IMPOSSIBLE AS RELATIVE MEASURE OF
PREDICTABILITY IS NEAR ZERO THROUGHOUT THE LONG RANGE AND STANDARD
DEVIATION OF THE 500 MB HEIGHT ENSEMBLE IS REACHING 80 TO 100
METERS AT TIMES. EVEN AMONG MULTI MODEL MEMBERS CONSISTENCY IS
POOR IN ALL BUT THE LARGEST OF FEATURES.

THIS BEING SAID... THERE DOES LOOK TO BE SUFFICIENT MOISTURE IN
AN ATMOSPHERIC RIVER OVERRUNNING THE FRONTAL BOUNDARY TUESDAY
NIGHT THROUGH ROUGHLY THURSDAY TO OVERSPREAD A WIDE AREA AND GRAZE
AT LEAST A PART OF THE CWA. OVERRUNNING EVENTS OF THESE KINDS CAN
BE TRICKY AND PRESENT VARIOUS PRECIPITATION TYPE CHALLENGES. SO...
WHILE THE DOMINANT PRECIPITATION TYPE WILL LIKELY BE SNOW... RAIN
AND FREEZING RAIN CAN NOT RULED OUT YET AND WILL NEED TO BE
FURTHER INVESTIGATED DURING LATER SHIFTS. GAH

&&

.AVIATION...
FLIGHT CATEGORY: VFR TO MVFR

SYNOPSIS: A FAST MOVING CLIPPER WILL SWEEP ACROSS THE REGION
THIS MORNING. BOTH AN UPPER AND LOWER LEVEL LOWS CLOSE OFF AND
QUICKLY EXIT TO MANITOBA. THE COMPACT CYCLONE HAS BECOME RATHER
EFFICIENT IN PRODUCING STRONG WINDS. WRAP-AROUND SNOW COULD
INCREASE THE CHANCES FOR HEAVIER... MEASURABLE SNOW THROUGH THE
MORNING... AND TAPERING OFF IN THE AFTERNOON.

AREA WINDS: NORTHWEST WINDS COULD RANGE FROM 20KT TO 30KT
SUSTAINED WITH GUSTS TO 45KT. WIND WILL TAPER OFF TO AROUND 15KT
DURING THE LATE AFTERNOON.

VSBY: WITH LIGHT SNOW EXPECTED... VISIBILITY COULD EASILY LOWER
WITH SHOWERS. BLOWING SNOW WITH DRIFTING ACROSS RUNWAYS IS ALSO A
POSSIBILITY. ANY TERMINAL WITH FALLING SNOW COULD TEMPORARILY SEE
MVFR VISIBILITY.

CEILINGS: EXPECT OVERCAST WITH BOUNCING BETWEEN ROUGHLY 5 TO 1.5
KFT CEILINGS.

GAH

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 2 PM MST THIS AFTERNOON FOR
CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...
DANIELS...DAWSON...EASTERN ROOSEVELT...GARFIELD...MCCONE...
NORTHERN PHILLIPS...NORTHERN VALLEY...PRAIRIE...RICHLAND...
SHERIDAN...SOUTHWEST PHILLIPS...WESTERN ROOSEVELT...WIBAUX.

LAKE WIND ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR FORT PECK
LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.

&&

$$

WEATHER.GOV/GLASGOW




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