305 
FXUS65 KTFX 131555
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
955 AM MDT FRI JUL 13 2012

.UPDATE...
MADE ONLY MINOR CHANGES TO POPS..SKIES..AND WIND. THE MAIN CHANGE IN 
THIS UPDATE WAS TO MENTION THE THREAT OF SEVERE THUNDERSTORMS OVER 
THE NORTHERN ROCKY MOUNTAIN FRONT AND EASTERN GLACIER COUNTY. THE 
ENVIRONMENT WILL BE FAVORABLE FOR SEVERE THUNDERSTORMS BUT AM 
CONCERNED THAT BETTER LIFT AND MOISTURE MIGHT NOT ARRIVE UNTIL  
LATE IN THE EVENING. WILL CONTINUE TO MONITOR THE SITUATION. BLANK

&&

.AVIATION...
UPDATED 1200Z.
VFR CONDITIONS WILL GENERALLY CONTINUE ACROSS THE AREA THROUGH AT 
LEAST 12Z SATURDAY...UNLESS OTHERWISE SPECIFIED BELOW. THE UPPER 
LEVEL RIDGE OF HIGH PRESSURE OVER THE AREA WILL GRADUALLY SHIFT EAST 
DURING THE PERIOD AS AN UPPER LEVEL TROUGH OF LOW PRESSURE MOVES 
INTO THE PACIFIC NORTHWEST. THIS WILL BRING AN INCREASINGLY MOIST 
AND UNSTABLE SOUTHWESTERLY FLOW ALOFT TO THE AREA. ISOLATED SHOWERS 
AND THUNDERSTORMS DEVELOPED ACROSS THE AREA OVERNIGHT...BUT THEY 
HAVE BEEN WEAK AND HAVE AVOIDED THE TFX TERMINALS. HOWEVER...AM 
EXPECTING A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE 
AREA TODAY...MAINLY BETWEEN 18Z AND 06Z. SURFACE MOISTURE IS 
GREATEST ALONG THE ROCKY MOUNTAIN FRONT NEAR THE CANADIAN BORDER 
(INCLUDING KCTB)...WHICH WILL KEEP THE GREATEST CHANCE FOR STRONG 
THUNDERSTORMS WITH GUSTY WINDS IN THAT AREA.  COULSTON

&&

.FIRE WEATHER...
THE AIRMASS WILL BECOME UNSTABLE THIS AFTERNOON WITH SCATTERED
SHOWERS AND THUNDERSTORMS DEVELOPING MAINLY OVER THE WESTERN
MOUNTAINS AND SPREADING EAST DURING THE AFTERNOON. THE AIRMASS HAS
BECOME MORE MOIST AND THUNDERSTORMS ARE EXPECTED TO BE A MIX OF
DRY AND WET THUNDERSTORMS. THE AIRMASS WILL CONTINUE TO MOISTEN
TONIGHT AND SATURDAY. 

&&

.PREV DISCUSSION...
/ISSUED 749 AM MDT FRI JUL 13 2012/
FXUS65 KTFX 131349
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
749 AM MDT FRI JUL 13 2012

UPDATE...
HAVE UPDATED FOR A FEW SHOWERS AND ISOLATED THUNDERSTORMS OVER
CENTRAL MONTANA FOR THE REST OF THIS MORNING. ALSO INCREASED
WINDS IN THE CUT BANK AREA FOR THE REST OF TODAY. BLANK

&&


.PREV DISCUSSION...
/ISSUED 600 AM MDT FRI JUL 13 2012/

TODAY THROUGH SUNDAY...THE OVERALL WEATHER PATTERN DURING THE NEXT 
FEW DAYS WILL SEE MONSOONAL MOISTURE MOVING INTO THE CWA FROM THE 
SOUTH WHILE A LOW PRESSURE TROF OVER THE WEST COAST APPROACHES THE 
ROCKIES. WATER VAPOR INDICATES MONSOONAL MOISTURE ALREADY MOVING 
INTO SOUTHWEST MONTANA....SOMEWHAT AHEAD OF WHAT THE NAM INDICATES. 
INSTABILITY ACROSS PORTIONS OF THE ZONES TODAY WILL REACH CAPE 
VALUES GREATER THAN 2000. STRONG HELICITY...CAPE...AND EHI WILL 
DEVELOP OVER THE NORTHERN ROCKIES...AND SPREAD EAST ACROSS THE 
HILINE TONIGHT. CURRENTLY...EXPECT CONVECTION TO BEGIN OVER THE 
ROCKIES AND SPREAD EASTWARD INTO THE PLAINS. SURFACE HIGH PRESSURE 
IN ALBERTA SHOULD PROVIDE A PUSH OF SLIGHTLY COOLER AIR INTO THE 
NORTHERN ZONES TODAY AND CREATE A BOUNDARY WHICH ADD ANOTHER AID FOR 
CONVECTIVE DEVELOPMENT ACROSS THE NORTHERN PLAINS. ALONG WITH THE 
STRONG INSTABILITY...LOWER LEVELS WILL REMAIN DRY AND THE BEST 
CHANCE FOR SEVERE THUNDERSTORMS WILL LIKELY COME IN THE FORM OF 
STRONG GUSTS. A SHORTWAVE WILL BE MOVING THROUGH THE FLOW ALOFT THIS 
EVENING AND COULD KEEP CONVECTION WELL INTO THE NIGHT. BY 
SATURDAY...THE LOW PRESSURE TROF WILL DEVELOP A CLOSED LOW AND 
MOVEMENT WILL BECOME QUITE SLOW. THIS WILL GIVE TIME FOR MOISTURE TO 
INCREASE OVER THE ZONES...AND ESPECIALLY OVER NORTHWEST PORTIONS OF 
THE CWA WHERE THE AIRMASS SHOULD BECOME QUITE MOIST BY NOON. A SHORT 
WAVE IS FORECAST BY THE NAM TO MOVE THROUGH THE FLOW AHEAD OF THE 
LOW PRESSURE TROF. THIS SHOULD ENHANCE CHANCE OF CONVECTION AND 
PROVIDE LIFT FOR SOME WIDESPREAD PRECIPITATION FOR SATURDAY. AT THE 
SURFACE...A AREA OF LOW PRESSURE WILL BE OVER THE ROCKIES SATURDAY 
MORNING AND AND DRIFT EAST DURING THE DAY. THIS WILL BRING A 
NORTHERLY FLOW OF CANADIAN AIR INTO THE ZONES. THIS AREA WILL SEE 
WIDESPREAD CAPES ABOVE 1000 AS WELL AS STRONG DCAPES. THE UPPER 
LEVEL TROF WILL MOVE OVER THE IDAHO PANHANDLE SUNDAY AND GOOD 
SOUTHWEST FLOW ALOFT OVER THE ZONES. THE AIRMASS WILL REMAIN MOIST 
AND SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED. 
ZELZER

SUNDAY NIGHT THROUGH FRIDAY NIGHT...THE MEDIUM RANGE MODELS APPEAR 
TO BE IN DECENT AGREEMENT WITH THE GENERAL TREND FOR THIS PERIOD. 
THE UPPER LEVEL LOW PRESSURE TROUGH EXTENDING FROM SOUTHERN CANADA 
INTO THE PACIFIC NORTHWEST WILL KEEP A GOOD CHANCE OF SHOWERS AND 
THUNDERSTORMS OVER THE TFX CWA THROUGH SUNDAY NIGHT. THE UPPER LEVEL 
RIDGE OF HIGH PRESSURE OVER THE CENTRAL CONUS WILL THEN GRADUALLY 
BUILD NORTHWEST BACK INTO THE AREA THROUGH THE WEEK AND FORCE THE 
TROUGH BACK TO THE PACIFIC NORTHWEST COAST. THE RESULTING WEAK 
MONSOONAL FLOW WILL THEN BRING A CHANCE OF MAINLY AFTERNOON/EVENING 
SHOWERS/THUNDERSTORMS TO THE AREA THROUGH THE REMAINDER OF THE 
PERIOD...FOR A SIMILAR PATTERN TO THAT OF THE LAST WEEK OR SO. THERE 
DOES NOT APPEAR TO BE ANY SIGNIFICANT DISTURBANCE IN THE FLOW TO 
WARRANT GOING ANY HIGHER THAN CLIMATOLOGICAL POPS FOR THIS TIME OF 
YEAR. TEMPERATURES ON MONDAY WILL REMAIN NEAR NORMAL AS THE UPPER 
RIDGE BEGINS BUILDING BACK INTO THE AREA...BUT TEMPERATURES OVERALL 
WILL WARM UP TO AT LEAST 5 TO 10 DEGREES ABOVE SEASONAL AVERAGES FOR 
THE REMAINDER OF THE WEEK AS THE RIDGE STRENGTHENS. THE WEAK 
DISTURBANCES IN THE FLOW ALOFT APPEAR AT THIS TIME TO PREVENT A 
SIGNIFICANT WARM-UP SIMILAR TO THE PAST WEEK OR SO (HIGHS IN THE 90S 
FOR MOST AREAS)...BUT IT IS A POSSIBILITY THAT CANNOT BE RULED OUT 
AT THIS TIME AND THE POTENTIAL FOR ANOTHER HOT/DRY SPELL WILL 
CONTINUE TO BE MONITORED.  COULSTON

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  93  65  83  61 /  20  40  60  40 
CTB  86  61  75  57 /  30  40  60  50 
HLN  93  65  88  61 /  30  40  60  50 
BZN  94  59  88  55 /  30  50  50  50 
WEY  83  52  74  48 /  40  50  50  50 
DLN  88  57  83  54 /  40  50  60  60 
HVR  99  67  87  62 /  10  20  40  50 
LWT  93  64  84  59 /  20  30  50  50 

&&

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

$$

SHORT TERM...BLANK
LONG TERM...MPJ
AVIATION...LANGLIEB

WEATHER.GOV/GREATFALLS