Area Forecast Discussion
Issued by NWS Glasgow, MT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KGGW 261628
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
928 AM MST WED NOV 26 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY...
UPDATE...GOING FORECAST IN EXCELLENT SHAPE. ONLY TWEAK WAS TO
INCREASE POPS GIVEN ONGOING LIGHT SNOW ACROSS THE LOWER
YELLOWSTONE VALLEY THIS MORNING. THE REMAINDER OF THE FORECAST
STANDS. GILCHRIST

PREVIOUS DISCUSSION...THERE WILL BE A SLOW MOVING WARM FRONT TODAY ACROSS
CENTRAL AND WESTERN MONTANA. MEANWHILE...A BAND OF MOISTURE WILL
OVERRUN THIS FRONT AND BRING SNOW TO A LARGE PORTION OF CENTRAL
MONTANA AND INTO THE SOUTHWEST PARTS OF THE FORECAST AREA. FOR
NORTHEAST MONTANA... THE SNOW TODAY WILL FALL MAINLY WEST OF MALTA
AND JORDAN. SNOW FALL TOTALS OF 4 TO 6 INCHES ARE LIKELY ACROSS
PETROLEUM...SOUTHWEST PHILLIPS AND WESTERN GARFIELD COUNTY. WILL
KEEP CURRENT WINTER STORM WARNING IN EFFECT. WILL ALSO MAINTAIN
THE ADVISORY FOR ONE ZONE NORTHEAST OF THE WARNING TODAY AS IT
WILL BE ON THE FRINGES OF THE ACCUMULATING SNOW.

THE WARM FRONT WILL CONTINUE TO MOVE SLOWLY NORTHEAST TONIGHT AND
THURSDAY TAKING THE AREA OF OVERRUNNING PRECIP WITH IT.
TEMPERATURES ALOFT WILL WARM ENOUGH OVER THE SOUTHWEST ZONES THAT
THE SNOW WILL MIX WITH OR CHANGE TO FREEZING RAIN BEFORE IT MOVES
TO THE EAST THURSDAY MORNING.

THURSDAY MORNING... THE AREA OF OVERRUNNING MIXED PRECIP MOVES
INTO THE NORTHEAST HALF OF THE FORECAST AREA. TEMPERATURES ALOFT
WILL LIKELY STAY COLD ENOUGH FOR ALL SNOW IN THE FAR NORTHEAST
CORNER OF THE STATE. ELSEWHERE... WARMING ALOFT WILL ALLOW FOR
SLEET AND FREEZING RAIN... POSSIBLY RAIN IN AREAS WHERE SURFACE
TEMPERATURES RISE ABOVE FREEZING. HOWEVER... MOST OF THE PRECIP
WILL OCCUR ON THURSDAY IN AREAS THAT WILL BE WARM ALOFT BUT IN THE
20S AT THE SURFACE. THERE IS A POTENTIAL FOR A TENTH OF AN INCH OR
MORE OF ICING. WILL KEEP WINTER STORM WATCH IN EFFECT FOR THURSDAY
IN THE EAST FOR NOW.

THAT BAND OF MIXED PRECIP FINALLY MOVES TO THE NORTH THURSDAY
NIGHT. WILL MAINTAIN A CHANCE OF MIXED PRECIP AS ATMOSPHERE
REMAINS MOIST. SURFACE LOW MOVES ACROSS THE AREA ON FRIDAY.
NORTHEAST MONTANA WILL BE ON THE DRY SIDE OF THE SYSTEM. WILL
LIMIT POPS TO CHANCE OR LESS. MOST OF THE FORECAST AREA WILL BE IN
THE WARM SECTOR MOST OF THE DAY. A COLD FRONT WILL START MOVING
SOUTH ON THE BACK SIDE OF THE LOW LATE IN THE AFTERNOON. FORRESTER


.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
SYNOPTIC SET UP...A STRONG BROAD ARCTIC AIR-MASS EXISTS OVER THE
MAJORITY OF CANADA. AN ESPECIALLY DEEP AND VIGOROUS TROUGH
EXTENSION SETS OVER BRITISH COLUMBIA AND ALBERTA. A RELATIVELY
WARMER BROAD RIDGE SETS OVER THE WESTERN HALF OF THE US. NORTHEAST
MONTANA SETS AT THE EDGE OF THESE TWO LARGE AIR-MASSES IN ZONAL
FLOW ALOFT WITH THE SHARPENED FRONTAL GRADIENT JUST NORTH OF THE
INTERNATIONAL BORDER. OVER THE NORTHEAST PACIFIC SPLIT FLOW HAS
SET UP CENTERED OFF THE COAST OF THE PACIFIC NORTHWEST WITH THE
TROUGH OFF SHORE OF CALIFORNIA AND A WEAK RIDGE OVER THE GULF OF
ALASKA.

FRIDAY NIGHT THROUGH SATURDAY...COLD FRONT NORTH OF THE
INTERNATIONAL BORDER WILL DROP THROUGH THE REGION BRING IN WITH
IT SNOW SHOWERS FOLLOWED BY VERY COLD AIR. 850 MB TEMPERATURES
NEGATIVE 20S CELSIUS. TOTAL SNOWFALL WITH THIS PASSAGE CURRENTLY
LOOKS TO BE AROUND 1 TO 4 INCHES.

SUNDAY THROUGH MONDAY NIGHT...CENTER OF THE COLD AIR-MASS SHOULD
SLUMP OFF TO THE EAST MONDAY NIGHT AS THE RIDGE OVER THE GULF OF
ALASKA IS FLATTENED SLIGHTLY AND MOVES ACROSS THE REGION IN THE
FLOW. TEMPERATURES WILL RISE HERE SLIGHTLY AND DECREASE THE
CHANCES FOR POPS TO BELOW CLIMATOLOGY AND THEREFORE MENTION.
MONDAY ITSELF WILL SEE A SMALL CHANCE FOR CHINOOK WARMING WITH
HIGHS IN THE 20S.

TUESDAY ONWARD...CONFIDENCE AT THIS POINT BREAKS DOWN. MODELS
HINT AT A TROUGH MOVING THROUGH DURING THIS TIME BUT HAVE A 24
HOURS DISCREPANCY IN TIMING. BY WEDNESDAY...A LARGER AND
THEREFORE HIGHER CONFIDENCE RIDGE MOVES THROUGH THE REGION
BEGINNING YET ANOTHER WARM-UP. GAH


&&

.AVIATION...
FLIGHT CATEGORY: LOW MVFR TO IFR.

SYNOPSIS: THE NW TO SE ORIENTATED FRONTAL BOUNDARY...NOW
SITUATED TO OUR SOUTHWEST...IS SLOWLY MOVING NORTHEAST AS A WARM
FRONT. OVERRUNNING MOISTURE FROM THE NW WILL FLOW ALONG THIS
BOUNDARY TO BRING ABOUT CONTINUOUS PRECIPITATION. THIS BOUNDARY
SHOULD REMAIN WEST OF THE TAF SITES THROUGH THE MORNING. BY THE
AFTERNOON LIGHT SNOW WILL MOVE FAR ENOUGH NORTHEAST TO BEGIN
AFFECTING KGGW AND KGDV. ALL TERMINALS SHOULD BE AFFECTED BY
WEDNESDAY NIGHT WITH PERSISTENT IFR POSSIBLE.

CEILINGS: BETWEEN 1 TO 2 KFT WITH FUEL LOADING FOR MOST SITES.
BRIEF IFR WITH DROPS BELOW 1KFT WILL BE POSSIBLE EARLY ON. MORE
PERSISTENT CEILINGS BELOW 1K FEET ARE LIKELY NEAR THE END OF THE
CYCLE WITH CONTIGUOUS SNOW FALL.

VSBY: BRIEF OBSTRUCTIONS TO VISIBILITY DOWN TO 3SM ARE POSSIBLE
WITH SNOW SHOWERS...BUT SHOULD RISE BACK TO P6SM QUICKLY WITH
PASSAGE. NEAR THE END OF THE CYCLE SNOW AND VSBY REDUCTION WILL
LIKELY BECOME SUSTAINED FOR KGGW AND KGDV.

AREA WINDS: FROM THE NORTHEAST AROUND OR UNDER 10KT...VEERING TO
THE EAST BY NOON...AND THEN FURTHER TO THE SOUTHEAST OVERNIGHT.

FREEZING RAIN: THURSDAY BEYOND THE TAF CYCLE THERE IS A
SIGNIFICANT THREAT FOR FREEZING RAIN WHICH CAN ACCUMULATE ICE ON
RUNWAYS AND AIRCRAFT WINGS.

GAH/SCT

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 5 PM MST THURSDAY FOR GARFIELD...
PETROLEUM...SOUTHWEST PHILLIPS.

WINTER WEATHER ADVISORY UNTIL 5 PM MST THURSDAY FOR CENTRAL AND
SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...MCCONE...
NORTHERN PHILLIPS...PRAIRIE.

WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURSDAY AFTERNOON
FOR DANIELS...DAWSON...EASTERN ROOSEVELT...NORTHERN VALLEY...
RICHLAND...SHERIDAN...WESTERN ROOSEVELT...WIBAUX.

&&

$$

WEATHER.GOV/GLASGOW





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.