Winter Storm in Montana, December 2, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1100 PM MST MON DEC 1 2008

AVIATION SECTION UPDATED

.UPDATE...
COLD FRONT WAS NEAR THE CANADIAN BORDER AS OF 830 PM THIS EVENING.
FRONT WILL BE IN HAVRE AND CUT BANK BEFORE MIDNIGHT THEN REACH
GREAT FALLS AND LEWISTOWN BETWEEN 1 AND 2 AM. WILL MAKE
SIGNIFICANT CHANGES TO THE WIND FORECASTS TO REFLECT THIS FASTER
TIMING. ALSO PUSHED THE FRONT FARTHER SOUTH OVER SOUTHWEST
MONTANA DURING THE DAY TOMORROW. HAVE ALSO LOWERED MOST HIGHS FOR
TUESDAY AND INDICATED SLOWLY FALLING TEMPERATURES DURING THE DAY
EXCEPT OVER FAR SOUTHWEST MONTANA. WITH THE FASTER TIMING OF THE
FRONT BROUGHT LIKELY POPS FARTHER SOUTH LATER TONIGHT. AS FOR THE
HIGHLIGHTS..THE WINTER WEATHER ADVISORY LOOKS GOOD. WINDS HAVE
TENDED TO DECREASE THIS EVENING. HOWEVER THE ROCKY MOUNTAIN FRONT
STILL WAS GUSTING ABOVE 60 KNOTS EARLY THIS EVENING. SO WILL
CONTINUE THE HIGH WIND WARNING THERE. DOUBT THAT OTHER AREAS WILL
SEE HIGH WINDS BUT THERE APPEARS TO BE JUST ENOUGH OF A CHANCE NOT
TO DROP THE HIGH WIND WARNING FOR THOSE OTHER AREAS. BLANK

&&

.AVIATION...
UPDATED 0600Z.
A CANADIAN COLD FRONT CONTINUES TO PUSH SOUTHWARD THROUGH THE
REGION. A SURFACE WIND SHIFT TO THE NORTH CAN BE EXPECTED BEHIND THE
FRONT. THE FRONT WILL MOVE THROUGH GTF BY 08Z...THRU LWT BY
10Z...AND THRU SOUTHWEST MONTANA FROM 11Z TO 17Z. EXPECT LOW
CLOUDS...SNOW AND IFR CONDITIONS TO DEVELOP A FEW HOURS AFTER
FRONTAL PASSAGE. MOUNTAINS WILL BE OBSCURED OVER MUCH OF THE REGION
THRU THE PERIOD. EXPECT SLOWLY IMPROVING CONDITIONS AFTER 00Z
WEDNESDAY. THERE IS THE POTENTIAL FOR FOG TO DEVELOP AFTER 03Z
WEDNESDAY OVER THE WESTERN PORTIONS OF THE REGION...THIS WILL
EVALUATED FURTHER TONIGHT AND TOMORROW MORNING. BRUSDA

&&

.PREV DISCUSSION...
/ISSUED 445 PM MST MON DEC 1 2008/

TONIGHT THROUGH WEDNESDAY...HIGH PRESSURE DOMINATES THE AREA
ALTHOUGH THE UPPER LEVEL RIDGE HAS BEEN FLATTENED BY A SHORTWAVE.
STRONG WINDS CONTINUE ALOFT AS THE SHORTWAVE MOVES EAST BUT WILL
DECREASE THIS EVENING. THE NEXT LOW PRESSURE SYSTEM IS OVER THE
EASTERN PACIFIC APPROACHING THE WEST COAST OF WA/BC....BUT THE NEXT
WEATHER WILL ARRIVE FROM THE NORTH. SURFACE HEIGHT RISES ARE VISIBLE
OVER NORTHERN BC AND ALBERTA. COLD AIR MOVING SOUTH OUT OF CANADA
WILL CROSS THE BORDER AFTER MIDNIGHT AND MOVE THROUGH CTB SEVERAL
HOURS LATER. THE COLD AIR WILL MOVE QUICKLY THROUGH NORTH CENTRAL
MONTANA...THROUGH GREAT FALLS BEFORE SUNRISE AND INTO SOUTHWEST
MONTANA BY NOON. SNOWFALL AMOUNTS WILL NOT BE HEAVY BUT STRONG WINDS
WILL CREATE AREAS OF BLOWING SNOW AND VERY LOW VISIBILITIES.
CONDITIONS WILL IMPROVE FROM THE NORTH LATE TUESDAY AND TUESDAY
NIGHT AS THE FRONT CONTINUES SOUTH. NORTHWEST FLOW ALOFT WILL BE IN
PLACE BY TUESDAY NIGHT. THIS WILL CONTINUE TO BRING COLD AIR INTO
THE AREA AS WELL AS KEEP THE AIRMASS UNSETTLED. TEMPERATURES TONIGHT
WILL BE WELL ABOVE NORMALS BUT THEY WILL TAKE A SHARP DROP TUESDAY
AND STAY BELOW NORMALS THROUGH WEDNESDAY. ZELZER

WEDNESDAY NIGHT THROUGH MONDAY NIGHT...MEDIUM RANGE MODELS HAVE COME
INTO FAIRLY GOOD AGREEMENT ON THE LARGE SCALE UPPER LEVEL FEATURES
THIS PERIOD BUT SOME SMALLER DIFFERENCES REMAIN IN LOWER TO MID
LEVEL FEATURES...ESPECIALLY BY LATER THIS WEEKEND INTO EARLY NEXT
WEEK...LEADING TO LOWER CONFIDENCE IN DETAILS LATE IN THE FORECAST.
WED NIGHT AND TUES WILL REMAIN COOL UNDER A NNW FLOW ALOFT WITH A
COOL SURFACE HIGH EAST OF THE ROCKIES. SOME LIGHT SNOW SHOWERS MAY
LINGER THROUGH WED NIGHT AND THURS...MAINLY OVER WESTERN AND
SOUTHERN ZONES AS A WEAK SHORTWAVE SLIDES BY TO THE W AND SW OF THE
REGION...PROVIDING SOME LIGHT OVERRUNNING. GRADUAL WARMING IS
EXPECTED IN THE THURS NIGHT THROUGH SAT PERIOD AS AN UPPER LEVEL
RIDGE BUILDS ONTO THE WEST COAST WITH THE SURFACE HIGH BEING
REPLACED BY A LEE-SIDE TROUGH WHICH WILL ALSO MEAN AN INCREASE IN
WINDS FRI AND SAT. MOISTURE IS FAIRLY LIMITED...BUT CANNOT RULE
OUT A FEW SHOWERS OVER THE HIGHER TERRAIN THROUGH THE PERIOD. MODELS
INDICATE THAT THE RIDGE WILL BEGIN TO BREAK DOWN IN THE SUN THROUGH
MON PERIOD AS A SERIES OF SHORTWAVES RIDE OVER THE RIDGE EVENTUALLY
CARVING OUT ANOTHER BROAD TROUGH OVER THE CENTRAL CONUS. NO
SIGNIFICANT COLD SURFACE AIRMASS IS SEEN AT THIS POINT TO MOVE IN AS
THE TROUGH DEVELOPS...SO HAVE ONLY TRENDED TEMPS DOWN BACK TOWARDS
SEASONAL NORMS BY EARLY NEXT WEEK WITH POPS NEAR CLIMATOLOGICAL

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  28  29  14  24 /  70  80  20  10
CTB  23  24  11  21 /  80  70  10  10
HLN  33  34  21  31 /  40  80  30  10
BZN  31  36  18  32 /  20  70  30  10
WEY  26  34  17  29 /  10  80  50  10
DLN  32  40  21  32 /  10  60  20  10
HVR  25  26  13  23 /  70  70  10  10
LWT  27  28  13  22 /  40  90  40  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 2 AM TO 5 PM MST TUESDAY FOR
MTZ009>014-044>051-054.

HIGH WIND WARNING UNTIL 2 AM MST TUESDAY FOR MTZ009-010-012-044-
046-048>051.

&&

SHORT TERM...BLANK
LONG TERM...BRUSDA
AVIATION...BRUSDA

WEATHER.GOV/GREATFALLS

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GREAT FALLS MT
530 PM MST MON DEC 1 2008

MTZ009-010-044-046-048-049-021200-
NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-TOOLE-
EASTERN PONDERA-SOUTHERN ROCKY MOUNTAIN FRONT-EASTERN TETON-
530 PM MST MON DEC 1 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
MONTANA.

.DAY ONE...TODAY AND TONIGHT

A HIGH WIND WARNING IS IN EFFECT TODAY. EXPECT WEST WINDS 25 TO 40
MPH WITH GUSTS TO 70 MPH.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE HIGH WIND WARNING CONTINUES UNTIL 2 AM MST TUESDAY.
ADDITIONALLY...A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW
IS IN EFFECT FROM 2 AM MST TUESDAY UNTIL 5 PM MST TUESDAY EVENING.

INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

MTZ012-050-051-021200-
CASCADE-JUDITH BASIN-FERGUS-
530 PM MST MON DEC 1 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MONTANA.

.DAY ONE...TODAY AND TONIGHT

A HIGH WIND WARNING IS IN EFFECT BEGINNING AT NOON MST TODAY.
EXPECT WEST WINDS 25 TO 35 MPH WITH GUSTS TO 60 MPH.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE HIGH WIND WARNING REMAINS IN EFFECT UNTIL 2 AM MST TUESDAY.
ADDITIONALLY... A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING AND
SNOW IS IN EFFECT FROM 2 AM MST TUESDAY UNTIL 5 PM MST TUESDAY
EVENING.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

MTZ011-013-014-045-047-054-021200-
HILL-CHOUTEAU-CENTRAL AND SOUTHERN LEWIS AND CLARK-LIBERTY-BLAINE-
MEAGHER-
530 PM MST MON DEC 1 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
MONTANA AND SOUTHWEST MONTANA.

.DAY ONE...TODAY AND TONIGHT

THERE IS A LOW PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW IS IN EFFECT
FROM 2 AM MST TUESDAY UNTIL 5 PM MST TUESDAY EVENING.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

MTZ008-015-052-053-055-021200-
BEAVERHEAD-MADISON-JEFFERSON-BROADWATER-GALLATIN-
530 PM MST MON DEC 1 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST
MONTANA.

.DAY ONE...TODAY AND TONIGHT

THERE IS A LOW PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A CANADIAN COLD FRONT WILL MOVE THROUGH SOUTHWEST MONTANA ON TUESDAY
MORNING. EXPECT FALLING TEMPERATURES DURING THE LATE MORNING AND
AFTERNOON HOURS. ADDITIONALLY...LIGHT SNOW WILL ALSO DEVELOP. BY
TUESDAY EVENING...EXPECT NEW SNOW ACCUMULATIONS OF 1 TO 2 INCHES AT
LOWER ELEVATIONS...AND 6 TO 12 INCHES IN THE MOUNTAINS.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.