FXUS65 KTFX 021007
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
307 AM MST WED DEC 2 2009
.DISCUSSION...
TODAY THROUGH FRIDAY...AN UPPER LEVEL HIGH PRESSURE RIDGE HAS
BUILT OVER THE WEST COAST. THIS WILL PLACE THE ZONES UNDERNEATH
NORTH FLOW ALOFT. A LOW PRESSURE CENTER WILL BE OVER CENTRAL
CANADA AND MOISTURE ASSOCIATED WITH THIS SYSTEM SHOULD CLIP THE
EASTERN ZONES....AND MOVE INTO THE CENTRAL ZONES BY EVENING.
INCREASED SKY COVER...AND PERHAPS A FLURRY OR TWO OVER THE EASTERN
ZONES...WILL BE THE ONLY EFFECTS. OTHERWISE...THE AIRMASS WILL
STAY DRY THROUGH FRIDAY. AT LOWER LEVELS...SURFACE HIGH PRESSURE
WILL KEEP SURFACE WINDS LIGHT TODAY. THE UPPER LEVEL RIDGE WILL
FINALLY MOVE OVER THE ROCKIES BUT WARMING OF THE AIRMASS WILL BE
MARGINAL AS A SHORTWAVE QUICKLY MOVES INTO THE RIDGE AND OVER THE
ROCKIES BY MID DAY FRIDAY. ZELZER
FRIDAY NIGHT THROUGH MONDAY NIGHT...A RATHER VERY COLD AND WINTRY
WEATHER PATTERN SETTING UP OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. BOTH THE EC/GFS MODELS CONTINUE TO INDICATE SOME FAIRLY COLD
AIR TO MOVE INTO THE REGION OVER THE WEEKEND...AND THEN CONTINUE TO
RESIDE OVER THE REGION FOR SEVERAL DAYS. AS THE COLD FRONT MOVES
THROUGH LATE FRIDAY NIGHT AND THROUGH THE DAY ON SATURDAY...EXPECT
ANOTHER ROUND OF LIGHT SNOW TO ACCOMPANY THE FRONTAL PASSAGE. SNOW
AMOUNTS AND AREA OF SNOWFALL FOR SATURDAY LOOK TO BE FAIRLY SIMILAR
TO TUESDAY MORNINGS SNOW EVENT...IN WHICH GENERALLY 1 TO 2 INCHES
FELL AT LOWER ELEVATIONS AND 3 TO 5 INCHES FELL IN THE
MOUNTAINS...WITH LITTLE/NO SNOW FALL EXPECTED IN THE HAVRE AREA AND
NORTHEAST OF LEWISTOWN. AFTER THIS COLD FRONT MOVES
THROUGH...MODIFIED ARCTIC AIR WILL MOVE INTO THE REGION...AND THE
ONLY THING STOPPING WIDESPREAD MORNING TEMPERATURES FROM BEING
AROUND 20 BELOW WILL BE CLOUD COVER. THUS OVERNIGHT LOWS HAVE BEEN
LOWERED A BIT...BUT BECAUSE OF THE EXPECTED CLOUD COVER...ONLY THE
COLDEST LOCATIONS HAVE FORECASTED TEMPERATURES NEAR 20 BELOW RIGHT
NOW...BUT THIS SITUATION WILL NEED TO BE MONITORED CLOSELY OVER THE
NEXT FEW DAYS. THERE WILL BE A FEW ISOLATED SNOW SHOWERS SUNDAY AND
MONDAY...BUT ANY SNOWFALL WILL BE LIGHT. BRUSDA
TUESDAY AND WEDNESDAY...MODELS CONTINUE TO SHOW A COLD UPPER LEVEL
LOW OVER CENTRAL CANADA...BRINGING COLD ARCTIC AIR INTO THE REGION
UNDER A NORTHERLY FLOW ALOFT. TEMPERATURES WILL CONTINUE TO BE WELL
BELOW AVERAGE WITH ISOLATED SNOW SHOWERS. WILLIAMSON DC
&&
.AVIATION...
UPDATED 0500Z.
NORTHERLY FLOW ALOFT WILL CONTINUE OVER THE REGION THROUGH THE NEXT
24 HRS WITH COLD SURFACE HIGH PRESSURE REMAINING OVER THE REGION
THROUGH THE PERIOD. AN AREA OF LOWER TO MID LEVEL CLOUDS/MOISTURE
EMBEDDED WITHIN THE NORTHERLY FLOW CURRENTLY ROTATING SOUTH FROM
SASKATCHEWAN/ALBERTA INTO EASTERN MT WILL GRADUALLY BACK TO THE WEST
LATER TONIGHT THROUGH WEDNESDAY. THIS WILL LIKELY BRING A BROKEN
DECK OF LOWER TO MID LEVEL CLOUDS TO THE KHVR AND KLWT TERMINALS BY
WEDNESDAY MORNING WITH THE WESTERN EDGE OF THESE CLOUDS POSSIBLY
REACHING AS FAR WEST AS THE KGTF...KHLN AND KBZN TERMINALS FOR A
PERIOD WEDNESDAY AFTERNOON. VFR CONDITIONS WILL GENERALLY PREVAIL
THROUGH THROUGH THE PERIOD WITH LOCAL MVFR CONDITIONS POSSIBLE IN
LOWER CLOUDS AT EASTERN TERMINALS WEDNESDAY AFTERNOON. HOENISCH
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 22 2 23 6 / 0 0 0 10
CTB 21 -1 25 4 / 0 0 0 10
HLN 23 12 26 7 / 0 0 0 10
BZN 22 -6 20 -7 / 10 10 0 0
WEY 17 -14 14 -7 / 10 10 10 10
DLN 22 0 20 2 / 0 0 0 0
HVR 22 2 23 1 / 10 0 0 10
LWT 19 -7 18 -1 / 10 10 0 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
