Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 220146
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
746 PM MDT TUE OCT 21 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...
UPDATE...THE COLD FRONT HAS MOVED THROUGH THE AREA THIS
EVENING...A FEW SHOWERS AND SOME RUMBLES OF THUNDER REMAIN BEHIND
THE FRONT. EXPECT THE THREAT OF THUNDER TO END SHORTLY THEN A FEW
SCATTERED SHOWERS OVERNIGHT ACROSS THE AREA. OTHERWISE NO CHANGES.
HAVE DECIDED THAT THE FRONTAL WINDS ARE NOT ENOUGH TO JUSTIFY THE
LAKE WIND ADVISORY AT THIS TIME. PROTON

PREVIOUS DISCUSSION...THE UPPER RIDGE THAT BROUGHT WELL ABOVE NORMAL TEMPS AND
DRY CONDITIONS TO NORTHEAST MONTANA OVER THE LAST SEVERAL DAYS IS
CURRENTLY BEGIN BROKEN DOWN BY A PACIFIC TROUGH CURRENTLY OVER
WESTERN MONTANA. A WIND SHIFT TO THE WEST...INDICATIVE OF THE COLD
FRONT...IS ALREADY OCCURRING ACROSS THE WEST. MOST NOTABLY AT
MALTA WHERE WEST WINDS AROUND 20 MPH HAVE DEVELOPED. EXPECT THIS
FRONT TO CONTINUE TO PUSH THROUGH THIS EVENING AS THE UPPER TROUGH
LIFTS NORTHEASTWARD TOWARD SOUTHERN SASKATCHEWAN. ISOLATED TO
SCATTERED POPS WILL ALSO PUSH EASTWARD WITH THE MOVEMENT OF THE
UPPER TROUGH THIS EVENING AND OVERNIGHT TONIGHT. WINDS WILL ALSO
DEVELOP WITH AND BEHIND THE FRONT BUT SPEEDS LOOK TO BE JUST BELOW
LAKE WIND CRITERIA. WITH THAT SAID IT WILL NEED TO BE CLOSELY
MONITORED.

BREEZY CONDITIONS WILL CONTINUE INTO WEDNESDAY...BUT PRECIPITATION
POTENTIAL WILL BE LIMITED TO AREAS ROUGHLY NORTH AND EAST OF A
MALTA TO WIBAUX LINE DURING THE MORNING...THEN JUST FAR NORTHEAST
MONTANA NEAR THE NORTH DAKOTA BORDER DURING THE AFTERNOON AS THE
UPPER TROUGH PUSHES TOWARD LAKE MANITOBA AND WEAK RIDGING BEGINS
TO BUILD IN FROM THE WEST. CLOUD COVER WILL BEGIN TO TAPER OFF
FROM WEST TO EAST ON WEDNESDAY AS WELL.

WEDNESDAY NIGHT AND THURSDAY DRY CONDITIONS WILL RULE AS THE AREA
ONCE AGAIN COMES UNDER THE INFLUENCE OF AN UPPER RIDGE OF HIGH
PRESSURE. SOUTHWEST WINDS ON THURSDAY WILL HELP WARM TEMPS AGAIN
TO UNSEASONABLY WARM READINGS IN THE MID 60S TO LOW 70S.


.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
A GULF OF ALASKA LOW WILL MAINTAIN A SOUTHWEST FLOW INTO MONTANA
THURSDAY NIGHT. THIS STRONG UPPER FLOW VEERS MORE TO THE WEST ON
FRIDAY AND FRIDAY NIGHT BEFORE BACKING TO THE SOUTHWEST AGAIN WHEN
THE TROUGH MOVES INTO THE PACIFIC NORTHWEST.

THEN SUNDAY NIGHT AN ASSOCIATED COLD FRONT MOVES ACROSS NORTHEAST
MONTANA TO BRING ABOUT A GENERAL COOLING PATTERN. THERE IS PLENTY
OF MOISTURE ASSOCIATED WITH THIS WAVE BUT MOST OF IT SPLITS AROUND
NEMONT. SO WILL KEEP POPS LOW...CLOSE TO CLIMO. BOTH THE GFS AND
THE EC BRING IN 850MB TEMPERATURES BELOW 0C FOR A FROSTY SUNDAY
NIGHT. FEW CHANGES WERE NECESSARY. SCT

PREVIOUS DISCUSSION... SYNOPTIC SET UP...LONG TERM BEGINS WITH A
RIDGE OVER THE GREAT PLAINS. THIS RIDGE TRANSITIONS TO SOUTHWEST
TO SEMI-ZONAL FLOW ACROSS THE MONTANA AND THE PACIFIC NORTHWEST
AND TERMINATES IN A TROUGH WELL OFF OF THE PACIFIC NORTHWEST`S
COASTLINE. BEHIND THAT TROUGH THERE IS A ANOTHER RIDGE LOCATED
WELL SOUTH OF THE ALEUTIANS. MEANWHILE THE COLDEST AIR OF THE
NORTHERN HEMISPHERE IS REMAINING BOTTLED UP OVER THE ARCTIC.

PATTERN SHOULD REMAIN PROGRESSIVE WITH EACH FEATURE MENTIONED
ABOVE MARCHING THROUGH NORTHEAST MONTANA AS THE FORECAST READS
ON. WHILE ISOLATED SHOWERS MAY BE POSSIBLE...NO PERIODS STAND OUT
AS BEING DEFINITIVE FOR RAIN AND THEREFORE HAVE GONE CLOSE TO
CLIMO OR JUST BELOW IT WITH POPS. ARCTIC AIR IS EXPECTED TO
INTRUDE INTO THE PASSING TROUGH SATURDAY NIGHT/SUNDAY AND WILL
LOWER TEMPERATURES 10 TO 20 DEGREE OVERALL BY MONDAY. THE
CONFIDENCE DROP OFF POINT APPEARS TO BE MONDAY NIGHT/TUESDAY IN
THE WAKE OF THIS ARCTIC INTRUSION. ANY FORECAST FROM THAT POINT ON
IS CURRENTLY SUSPECT WITH THE RIDGE AT THE END OF THE CHAIN
MENTIONED ABOVE POSSIBLY NEVER ARRIVING AT ALL. GAH

&&

.AVIATION...

EXPECT A CHANGE IN THE WEATHER PATTERN OVERNIGHT WHEN A SHORT-WAVE
TROUGH AND COLD FRONT MOVE THROUGH NORTHEAST MONTANA. THE FRONT
SHOULD REACH THE NORTH DAKOTA BORDER AROUND MIDNIGHT. THERE WILL
BE RAIN SHOWERS ASSOCIATED WITH THIS WAVE BUT THE CHANCE FOR
SHOWERS WILL BE LOW AT ANY PARTICULAR TERMINAL. SO LOOK FOR
AMENDMENTS IF SHOWERS DEVELOP NEAR ANY TERMINAL. THE MAIN EFFECTS
OF THE WAVE WILL BE WINDS SHIFTING TO THE WEST AND INCREASING TO
AROUND 15-25 KT...AND CLOUDS THICKENING AND LOWERING. VFR
CONDITIONS WILL GENERALLY PREVAIL...HOWEVER MVFR CEILINGS ARE
POSSIBLE TONIGHT AND WEDNESDAY MORNING. BRIEF SHOWERS MAY ALSO
PRODUCE IFR CEILINGS/VISIBILITIES.

THE TROUGH WILL MOSTLY BE THROUGH THE AREA BY WEDNESDAY AFTERNOON.
THEREFORE WIND WILL CONTINUE WESTERLY AND STRONG UNTIL LATE
AFTERNOON. THEN A NARROW RIDGE OF HIGH PRESSURE MOVES OVER THE
AREA WEDNESDAY EVENING ALLOWING SKIES TO CLEAR AND WIND TO SLACKEN
TO AROUND 10 KT. SCT/BLM

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

WEATHER.GOV/GLASGOW





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