000 
FXUS65 KTFX 012349 AAA
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
450 PM MST SUN FEB 1 2009

UPDATE AVIATION SECTION...

.DISCUSSION...
TONIGHT THROUGH TUESDAY...EXPECT NORTHWEST FLOW ALOFT OVER THE 
FORECAST AREA THROUGH TUESDAY. MODELS ARE ON THE SAME PAGE IN 
SPREADING INCREASING MOISTURE OVER THE FORECAST AREA TONIGHT INTO
EARLY MONDAY. OROGRAPHIC EFFECTS WILL LEAD TO SNOW OVER THE
MOUNTAINS. A LITTLE MORE TRICKY AS TO WHETHER THERE WILL BE
PRECIPITATION FOR THE PLAINS AND VALLEYS. DO SEE AT LEAST SOME
WEAK LIFT FOR THE LOWER ELEVATIONS SO WILL GO WITH SLIGHT CHANCE
TO CHANCE POPS THERE. MODELS ARE ALSO ON THE SAME PAGE IN
DECREASING MOISTURE MONDAY NIGHT SO WILL CONTINUE THE IDEA OF A
DECREASING TREND WITH THE CHANCES OF PRECIPITATION. TUESDAY A
STRONG UPPER RIDGE WILL BE APPROACHING THE FORECAST AREA FROM THE
WEST AND WILL CONTINUE WITH THE DRY FORECAST. AS FOR THE HIGH
WIND WATCH HAVE DECIDED TO CONTINUE IT. THERE ARE SOME INDICATIONS
THAT THE FLOW ALOFT WILL BE WEAKER THAN ORIGINALLY EXPECTED.
HOWEVER THE FLOW ALOFT IS STILL STRONG ENOUGH THAT WINDS WOULD NOT
HAVE TO INCREASE MUCH FOR A HIGH WIND EVENT TO OCCUR. WILL LET
EVENING SHIFT LOOK AT LATER MODEL DATA AND OBSERVATIONS AND MAKE A
FINAL DECISION ON WHETHER TO UPGRADE THE WATCH TO A WARNING OR TO
DROP THE WATCH. BLANK

TUESDAY NIGHT THROUGH FRIDAY NIGHT...A LARGE UPPER LEVEL HIGH
PRESSURE RIDGE SITS OVER THE ROCKIES AND THE AIRMASS WILL BE WARM
AND DRY. AN UPPER LEVEL SHORTWAVE WILL BE MOVING THROUGH THE
RIDGE IN ALBERTA AND THIS WILL DEVELOP A SURFACE TROF ALONG THE
LEE OF THE ROCKIES IN ALBERTA. THIS LEE TROF WILL DEVELOP
SOUTHWARD AND KEEP BREEZY CONDITIONS THROUGH WEDNESDAY ALONG THE
ROCKIES AND ADJACENT PLAINS. ANOTHER SHORTWAVE WILL FLATTEN THE
RIDGE ON WEDNESDAY. MOISTURE WILL MOVE OVER THE NORTHERN ROCKIES
AND A CHANCE OF PRECIP WILL RESULT. ELSEWHERE CONDITIONS WILL
REMAIN TOO DRY FOR PRECIP. BY LATE WEDNESDAY...A SPLIT UPPER
LEVEL LOW PRESSURE TROF OVER THE EASTERN PACIFIC WILL APPROACH
THE WEST COAST. THE SOUTHERN PORTION WILL MOVE OVER THE COAST OF
NORTHERN CALIFORNIA ON THURSDAY. UPPER LEVEL FLOW OVER THE ZONES
WILL SWITCH TO THE SOUTHWEST DURING THE DAY AND MOISTURE AHEAD OF
THE LOW PRESSURE CENTER WILL BEGIN TO MOVE INTO SOUTHWEST MONTANA
AND WORK ITS WAY NORTH. FALLING HEIGHTS WILL BEGINS TO LOWER MAX
TEMPS. POPS WILL BE INCREASED THURSDAY NIGHT OVER SOUTHWEST
MONTANA...AND HIGHER POPS WILL BE REQUIRED ACROSS THE CENTRAL CWA
AND PERHAPS EVEN INTO THE NORTHEAST ZONES. THIS SYSTEM WILL
REMAIN QUITE WEAK AND SIGNIFICANT PRECIPITATION AMOUNTS ARE NOT
EXPECTED. TEMPS WILL CONTINUE TO TREND DOWNWARDS AS A COLD FRONT
PASSAGE ASSOCIATED WITH THE NORTHERN PORTION OF THE LOW PRESSURE
TROF MOVES ACROSS THE NORTHERN ROCKIES EARLY FRIDAY. THIS WILL
ALSO INCREASE THE CHANCE OF PRECIP OVER THE NORTHERN ZONES
HOWEVER TEMPS WILL REMAIN ABOVE NORMALS THROUGH FRIDAY NIGHT.
ZELZER

SATURDAY AND SUNDAY...MODELS CONTINUE TO BRING A BROAD PACIFIC
LOW PRESSURE TROUGH INTO MONTANA OVER THE WEEKEND. MAINTAINED
CLIMATOLOGY FOR PRECIPITATION CHANCES. A TIGHT PRESSURE GRADIENT
WILL WILL CREATE GUSTY WINDS ALONG THE FRONT RANGE AND THE NORTH
CENTRAL PLAINS THROUGH THE PERIOD. TEMPERATURES ARE EXPECTED TO
BE SLIGHTLY ABOVE SEASONAL AVERAGES. SAUCIER

&&

.AVIATION...
MODERATE TO STRONG NW FLOW ALOFT WILL CONTINUE THROUGH THE NEXT 
24HRS AS AN UPPER LEVEL RIDGE OF HIGH PRESSURE CONTINUES TO BUILD IN 
FROM THE WEST. INCREASING MOISTURE IN THE FLOW WILL BRING INCREASING 
CLOUDS WITH BASES LOWERING TO 6000-12000 FT AGL BY LATE 
TONIGHT...AND EVEN TO MVFR LEVELS DURING THE DAY ON MONDAY. COULD 
SEE SOME LIGHT PRECIPITATION AFTER 10Z TONIGHT AS A WEAK DISTURBANCE 
MOVES THROUGH THE FLOW. PRECIP WILL INITIALLY BE CONFINED TO THE 
HIGHER TERRAIN...THEN SPREAD EAST AFTER 15Z. VFR CONDITIONS WILL 
PREVAIL...WITH LOCAL MVFR CONDITIONS IN AREAS OF PRECIPITATION ON
MONDAY. SURFACE WINDS WILL INCREASE LATE TONIGHT THROUGH 
MONDAY MORNING OVER WESTERN PORTIONS OF NORTH CENTRAL MT AS THE 
DISTURBANCE APPROACHES WITH GUSTS IN EXCESS OF 50KTS POSSIBLE  ALONG 
THE IMMEDIATE EAST SLOPES OF THE ROCKIES. DB 

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  27  47  33  54 /  20  20  10   0 
CTB  23  42  31  51 /  20  20  10   0 
HLN  24  46  31  48 /  10  20  10   0 
BZN  18  43  23  47 /  10  30  10   0 
WEY   7  29   8  32 /  20  50  20   0 
DLN  20  40  23  45 /  10  20  10   0 
HVR  14  37  16  39 /  10  20  10   0 
LWT  18  41  27  49 /  10  20  10   0 

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM MIDNIGHT MST TONIGHT THROUGH MONDAY 
AFTERNOON FOR MTZ009-048.

&&

$$

SHORT TERM...BLANK
LONG TERM...HOENISCH
AVIATION...DB

WEATHER.GOV/GREATFALLS