AREA FORECAST DISCUSSION

 
 FXUS65 KTFX 250021
 AFDTFX
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE GREAT FALLS MT
 521 PM MST TUE NOV 24 2009
 
 .DISCUSSION...
 
 TONIGHT THROUGH THANKSGIVING DAY...STRONG NORTHWESTERLY FLOW WILL
 PERSIST ACROSS THE AREA AS AN UPPER-LEVEL RIDGE CONTINUES TO BUILD
 INTO THE REGION. SOME LINGERING MOISTURE WILL KEEP ISOLATED
 SHOWERS IN THE MOUNTAINS THROUGH MIDNIGHT...THEN DRY CONDITIONS
 ARE EXPECTED. WINDS WILL DECREASE ACROSS THE FORECAST AREA TONIGHT
 BEFORE INCREASING ONCE AGAIN BY WEDNESDAY EVENING AS RIDGE AXIS
 MOVES EASTWARD. ON WEDNESDAY EVENING...AN UPPER-LEVEL SHORTWAVE
 WILL HELP TO BREAK DOWN THE RIDGE RESULTING IN PREDOMINANT
 WESTERLY FLOW. THIS MAY RESULT IN HIGH WINDS ONCE AGAIN ALONG THE
 ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS WITH STRONG DOWNSLOPING
 EXPECTED. HAVE DECIDED TO HOLD OFF ON HIGHLIGHTS FOR NOW BUT THIS
 WILL CONTINUE TO BE MONITORED. TEMPERATURES ARE EXPECTED TO REACH
 5 TO 10 DEGREES ABOVE AVERAGE ON WEDNESDAY AND AROUND 15 DEGREES
 ABOVE AVERAGE ON THANKSGIVING DAY. EVEN THOUGH WINDS WILL BE
 STRONG OVER THE AREA...PRECIP CHANCES WILL BE QUITE LOW UNTIL NEXT
 SHORTWAVE TROUGH MOVES INTO THE PACIFIC NORTHWEST. MLS
 
 
 THURSDAY NIGHT THROUGH TUESDAY NIGHT...PROGRESSIVE PATTERN TO
 CONTINUE. AN UPPER TROUGH WILL MOVE THROUGH THE FORECAST AREA
 LATE THIS WEEK OR EARLY IN THE WEEKEND. MODELS DIFFER ON THE
 TIMING OF THIS UPPER TROUGH BUT IT APPEARS THE MOST LIKELY TIMING
 WILL BRING IT THROUGH FRIDAY NIGHT. THIS FEATURE MOVES THROUGH
 FAIRLY QUICKLY AND IS NOT ALL THAT STRONG SO INHERITED CHANCES OF
 PRECIPITATION IN THE SLIGHT CHANCE TO CHANCE CATEGORY FOR THE
 LOWER ELEVATIONS LOOKS FINE. BEST THREAT FOR PRECIPITATION WITH
 THIS SYSTEM APPEARS TO BE OVER THE MOUNTAINS OF THE ROCKY
 MOUNTAIN FRONT SO WENT WITH CHANCES OF PRECIPITATION IN THE
 LIKELY CATEGORY THERE. AFTER THE PASSAGE OF THE UPPER TROUGH
 THERE COULD BE SOME LINGERING MOISTURE AND POSSIBLY A WEAK
 WEATHER DISTURBANCE OR TWO IN THE NORTHWEST TO NORTH FLOW ALOFT
 SATURDAY AND SATURDAY NIGHT SO WILL CONTINUE WITH A MENTION OF
 PRECIPITATION. THEN ANOTHER UPPER TROUGH IS EXPECTED TO MOVE
 THROUGH THE AREA EARLY NEXT WEEK. THE PREVIOUS RUN OF THE GFS
 COMPUTER MODEL WAS QUITE A BIT FASTER THAN THE ECMWF COMPUTER RUN
 WITH THE UPPER TROUGH BUT THE LATEST GFS RUN IS NOW IN RELATIVELY
 BETTER AGREEMENT WITH THE ECMWF COMPUTER RUN. WHEREAS THE UPPER
 TROUGH OF LATE THIS WEEK WILL BE OF PACIFIC ORIGIN THE UPPER
 TROUGH OF EARLY NEXT WEEK WILL COME FROM THE GULF OF ALASKA AND
 WILL LIKELY BE COLDER. AS MODELS HAVE NOT BEEN CONSISTENT ON THIS
 COOL DOWN DID NOT GO REALLY COLD BUT THERE IS THE POTENTIAL FOR
 TEMPERATURES TO BE 10 DEGREES COLDER THAN CURRENT FORECASTS.
 BLANK
 
 &&
 
 .AVIATION...
 UPDATED 2310Z. 
 AN UPPER LEVEL LOW PRESSURE TROF OVER EASTERN MONTANA WILL CONTINUE 
 TO MOVE EAST WHILE HIGH PRESSURE ALOFT BUILDS OVER CENTRAL MONTANA. 
 LOW TO MID LEVEL MOISTURE WILL CAUSE LOW LEVEL CLOUDS AND LOCAL MVFR 
 CONDITIONS DUE TO CIGS ACROSS THE KLWT REGION. THESE LOW CLOUDS WILL 
 BECOME SCATTERED AROUND MIDNIGHT. VFR CONDITIONS WILL PREVAIL 
 ELSEWHERE DURING THE NEXT 24 HOURS HOWEVER STRONG...GUSTY WINDS WILL 
 CONTINUE ACROSS THE NORTHERN ROCKIES AND ADJACENT PLAINS.
 
 &&
 
 .PRELIMINARY POINT TEMPS/POPS...
 GTF  30  53  39  58 /  10   0   0   0 
 CTB  28  52  37  55 /  10   0   0   0 
 HLN  24  48  28  50 /  10   0   0   0 
 BZN  17  42  18  44 /  20   0   0   0 
 WEY  10  34  13  36 /  20   0   0   0 
 DLN  20  42  24  44 /  10   0   0   0 
 HVR  17  52  31  61 /  10   0   0   0 
 LWT  19  49  30  57 /  20   0   0   0 
 
 &&
 
 .TFX WATCHES/WARNINGS/ADVISORIES...
 NONE.
 &&
 
 $$
 
 
 WEATHER.GOV/GREATFALLS