FXUS65 KTFX 061745
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1145 AM MDT MON OCT 6 2008
...UPDATE TO AVIATION...
.UPDATE...
UPPER TROUGH OVER CENTRAL MONTANA AS OF MID-MORNING WILL CONTINUE
TO PUSH EAST THE REST OF TODAY. ASSOCIATED WITH THIS RADAR WAS
INDICATING SCATTERED SHOWERS OVER HILL COUNTY WHICH WILL MOVE INTO
BLAINE COUNTY THE REST OF THE MORNING. HAVE ADJUSTED THE CHANCE OF
PRECIPITATION FORECAST TO BETTER REFLECT RADAR TRENDS. ALSO WILL
ADJUST THE CLOUD FORECAST OVER MUCH OF THE FORECAST AREA TO BETTER
REFLECT WHAT WAS BEING OBSERVED ON SATELLITE IMAGERY. IN LINE WITH
THIS DROPPED THE MENTION OF PRECIPITATION FOR A SMALL PORTION OF
MEAGHER COUNTY. FORECAST HIGHS AND ALSO WINDS FOR TODAY LOOK
REASONABLE SO LEFT THOSE FORECASTS AS IS. BLANK
&&
.AVIATION...
UPDATED 1745Z.
VFR CONDITIONS TO CONTINUE ACROSS MOST OF NORTH
CENTRAL...CENTRAL...AND SOUTHWEST MONTANA THROUGH AT LEAST 18Z
TUESDAY. A BAND OF MID LEVEL CLOUDS AND ISOLATED RAIN SHOWERS OVER
FAR NORTH CENTRAL MONTANA (INCLUDING THE KHVR TERMINAL) WILL
DISSIPATE THROUGH 21Z TODAY. OTHERWISE...AN UPPER LEVEL RIDGE OF
HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE SOUTHWEST THROUGH
THE PERIOD...AS MID LEVEL CLOUDS WITH ISOLATED RAIN/SNOW SHOWERS
WILL OBSCURE MOUNTAIN TOPS ACROSS WESTERN AND SOUTHWEST MONTANA.
GUSTY WEST SURFACE WINDS WILL ALSO PERSIST ACROSS THE AREA THROUGH
THE DAY...BEFORE DECREASING OVERNIGHT. MID LEVEL CLOUDINESS AND
MAINLY MOUNTAIN SHOWERS WILL INCREASE OVERNIGHT INTO TUESDAY MORNING
AS A DISTURBANCE APPROACHES THE AREA FROM THE WEST...WHICH IN TURN
WILL OBSCURE MOUNTAINS AT TIMES. WESTERLY WINDS WILL ALSO INCREASE
AGAIN TUESDAY MORNING...ESPECIALLY ALONG THE EAST SLOPES OF THE
ROCKIES...AS THE DISTURBANCE MOVES THROUGH THE AREA.
&&
.PREV DISCUSSION...
/ISSUED 615 AM MDT MON OCT 6 2008/
TODAY THROUGH WEDNESDAY...A FLAT UPPER LEVEL HIGH PRESSURE RIDGE
OVER THE WEST COAST WILL MOVE EAST OVER THE ROCKIES BY MONDAY
EVENING. STRONG UPPER LEVEL WINDS WILL CROSS THE ROCKIES TUESDAY AS
THIS RIDGE MOVES EAST OF THE AREA. AFTERNOON MIXING AND PASSAGE OF A
COLD FRONT SHOULD PRODUCE GUSTS WELL OVER 50 KNOTS ACROSS THE
ROCKIES AND ADJACENT PLAINS. WILL CONTINUE THE CURRENT HIGH WIND
WATCH...AND ADD TETON COUNTY. TEMPS WILL CLIMB ABOVE NORMALS BY
TUESDAY UNDER THE HIGH PRESSURE RIDGE BUT DROP AGAIN NEAR OR BELOW
NORMALS AS THE TROF MOVES EAST ON WEDNESDAY. ZELZER
WEDNESDAY NIGHT THROUGH THURSDAY...A PACIFIC COOL FRONT WILL
CONTINUE TO PUSH THROUGH THE REGION RESULTING IN COOLER AIR MOVING
INTO THE REGION FOR THURSDAY AFTERNOON. A WEAK UPPER LEVEL
DISTURBANCE ALSO MOVING THROUGH WILL ALLOW FOR A FEW MOUNTAIN
SHOWERS...ESPECIALLY OVER THE ROCKY MOUNTAIN FRONT.
FOR THURSDAY NIGHT THROUGH SATURDAY NIGHT...BOTH THE GFS AND ECMWF
CONTINUE TO DISAGREE ON THE POTENTIAL SNOW STORM THAT COULD AFFECT
THE REGION. THE GFS HAS A BAND OF SNOW SHOWERS MOVING THROUGH THE
AREA THURSDAY NIGHT INTO FRIDAY MORNING...THEN PRETTY MUCH DRY AND
MILDER CONDITIONS FOR SATURDAY. THE ECMWF HOWEVER HAS A CLOSED UPPER
LEVEL LOW OVER THE REGION FRIDAY AND SATURDAY...ALONG WITH MUCH
COLDER TEMPERATURES...AND A STRONG SURFACE LOW DEVELOPING OVER THE
CENTRAL ROCKIES. THIS SCENARIO WOULD RESULT IN HEAVY SNOW OVER
PORTIONS OF CENTRAL AND SOUTHWEST MONTANA. FOR NOW HAVE TRENDED
TOWARDS THE GFS BUT KEPT IN A SMALL CHANCE FOR SHOWERS AND KEPT
TEMPERATURES BELOW GFS GUIDANCE...AND ON THE COOL SIDE. HOWEVER THIS
SYSTEM NEEDS TO BE WATCHED CLOSELY OVER THE NEXT FEW DAYS...BECAUSE
IF THE ECMWF PANS OUT...THE FIRST SIGNIFICANT SNOW STORM WILL AFFECT
PORTIONS OF CENTRAL AND SOUTHWEST MONTANA THIS WEEKEND...WITH HEAVY
SNOW AND MUCH BELOW NORMAL TEMPERATURES. BRUSDA
SUNDAY AND MONDAY...MODELS NOT IN VERY GOOD AGREEMENT.
HOWEVER...MOST MODELS DO SHOW A LONG WAVE TROUGH OVER THE UPPER
MIDWEST WITH UPPER LEVEL RIDGE ACROSS THE PACIFIC NORTHWEST.
WILL GO WITH THE GFS MODEL...BUT KEEP TEMPERATURES LOWER ON SUNDAY
AS GFS MODEL GENERALLY MOVE SYSTEMS OUT TOO FAST. THUS...WILL DELAY
THE WARMUP UNTIL MONDAY. IT WILL BE MOSTLY DRY WITH ONLY SCATTERED
RAIN OR SNOW SHOWERS ACROSS THE CONTINENTAL DIVIDE. SUNDAY WILL
STILL BE COOL WITH TEMPERATURES WARMING TO NEAR SEASONAL AVERAGE BY
MONDAY. WILLIAMSON DC
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 60 40 67 38 / 10 0 10 10
CTB 58 38 63 37 / 10 0 10 20
HLN 62 38 67 40 / 10 0 10 10
BZN 62 34 71 37 / 10 0 10 10
WEY 52 29 56 34 / 20 0 10 10
DLN 58 36 65 36 / 10 0 10 10
HVR 61 33 69 39 / 20 0 10 10
LWT 57 34 67 36 / 10 0 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING FOR
MTZ009-010-044-046-048-049.
&&
$$
SHORT TERM...BLANK
LONG TERM...BRUSDA/WILLIAMSON DC
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
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