000 
FXUS65 KTFX 290450
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1050 PM MDT TUE JUL 28 2009

.UPDATE...

THE CANADIAN COLD FRONT HAS PUSHED THROUGH THE REMAINDER OF CENTRAL
AND SW MT THIS EVENING WITH SHOWER AND THUNDERSTORM ACTIVITY ON
THE DECREASE AS SOMEWHAT DRIER AIR MOVES IN ALOFT AND THE AIRMASS
BECOMES LESS UNSTABLE. UPDATED POPS FOR THE REMAINDER OF THIS
EVENING BASED ON LATEST RADAR TRENDS. EXPECT BEST CHANCE FOR
ADDITIONAL PRECIP ACROSS THE CENTRAL AND SW MT MTNS WHERE UPSLOPE
AND OROGRAPHIC EFFECTS ENHANCE PRECIP. HAVE DECREASED COVERAGE TO
SCATTERED OR ISOLATED NORTH OF A LINE FROM GREAT FALLS TO
LEWISTOWN WHERE DRIER AIR IS MOVING IN. HOWEVER...WILL STILL HAVE
AT LEAST ISOLATED POPS ACROSS MUCH OF THE AREA THROUGH THE
REMAINDER OF TONIGHT AS MOISTURE LINGERS IN THE LOW LEVELS AND THE
ATMOSPHERE ONLY MARGINALLY STABILIZES UNDER A CYCLONIC NW FLOW
ALOFT. REMAINDER OF THE FORECAST IS IN GOOD SHAPE. HOENISCH

&&

.AVIATION...
UPDATED 0447Z.
A WEAK CANADIAN COLD FRONT HAS MOVED THROUGH SOUTHWEST MONTANA 
COOLER BUT ISOLATED SHOWERS ARE POSSIBLE THROUGH THE NIGHT.  LOCAL 
MVFR/IFR CIGS AND VSBYS WILL DEVELOP AFTER MIDNIGHT AND DISSIPATE 
AFTER SUNRISE. THE AIRMASS BECOMES SLIGHTLY UNSTABLE WEDNESDAY 
AFTERNOON AND ISOLATED SHOWERS OR THUNDERSTORMS ARE AGAIN POSSIBLE. 

&&

.PREV DISCUSSION...
/ISSUED 523 PM MDT TUE JUL 28 2009/

TONIGHT THROUGH THURSDAY NIGHT...NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS ARE CONTINUING TO DEVELOP ALONG A WEAK CANADIAN COLD
FRONT THAT IS ASSOCIATED WITH AN UPPER-LEVEL LOW PRESSURE SYSTEM.
WHILE SEVERE WEATHER IS NOT ANTICIPATED...THERE IS ENOUGH COOL AIR
ALOFT TO SUPPORT STRONG GUSTY WINDS AND SMALL HAIL BUT HEAVY RAIN
IS THE MAIN CONCERN. BREEZY CONDITIONS ALONG AND BEHIND THE FRONT
WILL HELP TO PUSH THE STORMS QUICKER THAN HAS BEEN THE CASE OVER
THE PAST SEVERAL DAYS. AS OF EARLY AFTERNOON THE FRONT WAS PASSING
THROUGH CENTRAL MONTANA NORTH OF A LINE FROM GTF-LWT. COOLER AND
CONTINUED UNSTABLE AIR BEHIND THE FRONT OVER NORTH- CENTRAL
MONTANA WILL ALLOW FOR WIDESPREAD RAIN SHOWERS TO PERSIST THROUGH
THIS EVENING. AS DAYTIME HEATING AND INSTABILITY WANE THIS
EVENING...ANY THUNDERSTORM ACTIVITY SHOULD QUICKLY DIMINISH WITH
ONLY SCATTERED SHOWERS EXPECTED THROUGH MIDNIGHT. DRIER AND
CONTINUED COOL NORTHWEST FLOW WILL PERSIST THROUGH THURSDAY WITH
ONLY ISOLATED MOUNTAIN SHOWERS OR THUNDERSTORMS EXPECTED AND
TEMPERATURES WILL CONTINUE TO STAY BELOW AVERAGE FOR THIS TIME OF
YEAR. MLS

FRIDAY NIGHT THROUGH TUESDAY...NORTHWEST FLOW ALOFT WILL DOMINATE 
DURING THE PERIOD. FRIDAY AND SATURDAY EXPECT A COUPLE DISTURBANCES 
ALOFT AND ASSOCIATED MOISTURE TO AFFECT THE AREA WITH A CHANCE FOR 
SHOWERS AND AFTERNOON THUNDERSTORMS. STARTING SUNDAY BOTH THE GFS 
AND ECMWF HAVE AN UPPER RIDGE BEGINNING TO EXERT ITS INFLUENCE ON 
OUR AREA. THUS AGREE WITH THE MODELS DRY FORECAST OVER THE NORTHERN 
AND EASTERN ZONES. ANY SHOWER ACTIVITY LOOKS TO BE CONFINED TO THE 
SOUTHWEST DURING THIS TIME. MODELS AGREE IN BRINGING COOLER AIR DOWN 
FROM CANADA OVER THE WEEKEND KEEPING HIGH TEMPS A LITTLE BELOW 
NORMAL BEFORE RISING A LITTLE EARLY NEXT WEEK. EG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  49  72  46  78 /  80  20  10  10 
CTB  46  71  44  76 /  50  10  10  10 
HLN  53  73  48  81 /  60  20  10  10 
BZN  50  71  42  80 /  80  30  10  10 
WEY  41  65  34  70 /  30  20  10  20 
DLN  48  68  42  74 /  50  20  10  10 
HVR  48  76  46  81 /  40  10  10  10 
LWT  47  66  42  74 /  80  30  10  20 

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

WEATHER.GOV/GREATFALLS