FXUS65 KTFX 102350
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
450 PM MST THU DEC 10 2009
...UPDATE TO AVIATION...
.DISCUSSION...
TONIGHT THROUGH SATURDAY...THE ZONES ARE UNDERNEATH NORTHWEST FLOW
ALOFT WHICH IS ASSOCIATED WITH A LOW PRESSURE SYSTEM IN CANADA.
WESTERLY FLOW TO THE SOUTH OF THE ZONES IS ASSOCIATED WITH A
SHORTWAVE OVER THE PACIFIC. HIGH PRESSURE ALOFT WILL CONTINUE TO
BUILD OVER THE REGION AND SEVERAL DISTURBANCES WILL MOVE THROUGH THE
NORTHWEST FLOW ALOFT. THE UPPER LEVEL FLOW GRADUALLY SHIFTS TO THE
WEST THROUGH THE PERIOD AND MID LEVEL WINDS REMAIN STRONG. LIGHT
SNOW ASSOCIATED WITH THE CURRENT UPPER LEVEL DISTURBANCE WILL AFFECT
MOSTLY THE SOUTHWEST ZONES DURING THE EVENING. THE CHANCE FOR PRECIP
WILL REMAIN SLIGHT FRIDAY BUT THE CHANCE BEGINS TO INCREASE LATE
FRIDAY AS A BOUNDARY SETS UP ACROSS THE HILINE. A SECOND SOURCE OF
PRECIP WILL MOVE UP TOWARDS THE SOUTHWEST THAT IS ASSOCIATED WITH
THE PACIFIC SHORTWAVE. HIGHEST CHANCE OF PRECIP WILL BE OVER THE
EXTREME SOUTHERN MOUNTAINS WHERE SNOW SHOULD BE ACCUMULATING BY
SATURDAY. TEMPS WILL REMAIN AT OR BELOW SEASONAL NORMALS BUT BEGIN
TO APPROACH NORMALS BY SATURDAY. ZELZER
SATURDAY NIGHT THROUGH THURSDAY...MEDIUM RANGE MODELS CONTINUE TO
EXHIBIT GENERAL SIMILARITIES DURING THE PERIOD. A CLOSED UPPER LOW
OVER CENTRAL CANADA WILL PUSH A LARGE AREA OF MOISTURE SOUTH ACROSS
THE CANADIAN BORDER ON SUNDAY MERGING WITH MOISTURE WORKING ITS WAY
NORTH FROM THE SOUTHWEST US. THE RESULT WILL BE ACCUMULATING
SNOWFALL OVER THE ROCKY MOUNTAIN FRONT AND SCATTERED SNOW OVER MOST
OF THE REST OF COUNTY WARNING AREA. A SURFACE COLD FRONT WILL MOVE
ACROSS THE AREA SUNDAY BRINGING MUCH COLDER AIR AS FAR SOUTH AS
GREAT FALLS WHILE ONLY COOLING SOUTHWEST MONTANA A BIT. SCATTERED
SNOW AND COLD TEMPS WILL CONTINUE MONDAY AS THE AREA REMAINS UNDER
NORTHWEST FLOW ALOFT. THE REMAINDER OF THE PERIOD WILL SEE A DRYING
AND WARMING TREND AS A WEAK UPPER RIDGE MOVES ACROSS THE CONTINENTAL
DIVIDE BY THURSDAY. ISOLATED SNOW SHOWERS WILL REMAIN A POSSIBILITY
FOR THE WESTERN MOUNTAINS AS WELL AS THE MOUNTAINS OF SOUTHWEST
MONTANA. TEMPS WILL REMAIN BELOW SEASONAL AVERAGES UNTIL THE MIDDLE
OF NEXT WEEK WHEN IT APPEARS A STRONGER WARMING TREND MAY BEGIN.
&&
.AVIATION...
UPDATED 2350Z.
MOIST NORTHWEST FLOW ALOFT CONTINUES ACROSS MONTANA TONIGHT AND
FRIDAY. ISOLATED MOUNTAIN SNOW SHOWERS ARE EXPECTED AT TIMES ALONG
WITH LOCAL MOUNTAIN OBSCURATIONS...BUT LOWER ELEVATIONS AND
TERMINALS ARE EXPECTED TO REMAIN DRY WITH VFR CONDITIONS.
SOUTHWEST TO WEST SURFACE WINDS WILL REMAIN BREEZY ACROSS THE
ENTIRE FORECAST AREA. MPJ
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 9 29 16 31 / 10 10 10 20
CTB 6 24 8 24 / 10 10 30 30
HLN 4 24 8 28 / 10 10 10 20
BZN -3 22 2 30 / 10 10 20 30
WEY -10 17 3 24 / 10 10 60 60
DLN -1 23 7 30 / 10 10 20 30
HVR 1 22 4 22 / 10 10 30 20
LWT 1 27 6 29 / 10 10 10 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
