Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 031746
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1146 AM MDT WED JUN 3 2015

.UPDATE...SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS
MUCH OF THE AREA ONCE AGAIN THIS AFTERNOON AND EVENING. HAVE
UPDATED POPS, WEATHER AND QPF TO BE IN BETTER ALIGNMENT WITH
LATEST MODEL RUNS AND NEIGHBORING WFO FORECASTS. HAVE ALSO
INCREASED TEMPERATURES FOR MANY LOCATIONS BY 2 TO 3 (OR MORE)
DEGREES BASED ON MORNING MODELS AND YESTERDAYS OBSERVED HIGHS. MPJ

&&

.AVIATION...
UPDATED 1745Z.

MOIST SOUTHWEST FLOW ALOFT WILL CONTINUE TO KEEP THE AIR MASS
UNSETTLED AND A CHANCE OF AFTER SHOWERS AND THUNDERSTORMS WILL
CONTINUE ACROSS THE REGION INTO THIS EVENING. LOCAL MVFR CONDITIONS
ARE POSSIBLE NEAR SHOWERS AND THUNDERSTORMS. ALSO, KBZN COULD SEE
MVFR VSBYS AND CIGS NEAR SUNRISE. ELSEWHERE, VFR CONDITIONS ARE
EXPECTED THROUGH UPDATED 1130Z.

&&

.PREV DISCUSSION...
/ISSUED 530 AM MDT WED JUN 3 2015/

LITTLE CHANGE IN CONDITIONS EXPECTED OVER THE NEXT FEW DAYS AS MOIST
SOUTHWEST FLOW ALOFT WILL CONTINUE ACROSS MONTANA, RESULTING IN
PARTLY TO MOSTLY CLOUDY SKIES WITH PERIODS OF SCATTERED SHOWERS AND
THUNDERSTORMS. THESE CONDITIONS ARE PRIMARILY DRIVEN BY A PERSISTENT
LONGWAVE TROF CENTERED OVER THE EASTERN PACIFIC THAT HAS A NUMBER OF
EMBEDDED SHORTWAVES/LOW PRESSURE DISTURBANCES WITHIN THE FLOW.
LATEST SATELLITE IMAGERY SHOWS THE NEXT SHORTWAVE STEADILY
APPROACHING THE WEST COAST TODAY. FORECAST MODELS PUSH THIS SYSTEM
INTO SOUTHERN CALIFORNIA BY MIDDAY FRIDAY WITH SOUTHWEST WINDS AHEAD
OF THE TROF AXIS CARRYING SEVERAL PLUMES OF PACIFIC MOISTURE TOWARD
THE NORTHERN ROCKIES. THOUGH THERE ARE A FEW DIFFERENCES IN THE
VARIOUS MODEL SOLUTIONS ON THE TIMING AND COVERAGE OF THESE PLUMES,
THE OVERALL PATTERNS ARE SIMILAR FOR OUR REGION, MEANING MORE RAIN
IN THE DAYS AHEAD. A FEW OF THE AFTN/EVE THUNDERSTORMS MAY GET
STRONG ENOUGH TO PRODUCE SMALL HAIL AND OUTFLOW WIND GUSTS OF 40 TO
50 MPH, BUT NO SEVERE WEATHER IS EXPECTED THROUGH THIS FORECAST
PERIOD. WITH WIDESPREAD PARTLY TO MOSTLY CLOUDY SKIES, TEMPERATURES
WILL REMAIN CLOSE TO SEASONAL AVERAGES, WITH HIGHS IN THE MID 60S TO
LOW 70S EACH DAY. WARANAUSKAS

FRIDAY NIGHT THROUGH TUESDAY...MEDIUM RANGE MODELS CONTINUE TO BE IN
GOOD AGREEMENT WITH THE OVERALL PATTERN THROUGH THIS PERIOD.
HOWEVER, THEY ARE INDICATING STRONGER HIGH PRESSURE MOVING IN FROM
THE PACIFIC NORTHWEST AFTER SATURDAY, SO HAVE GENERALLY DECREASED
THE CHANCE FOR SHOWERS AND THUNDERSTORMS UNTIL THE END OF THE
PERIOD. A DISTURBANCE EJECTING FROM AN UPPER LOW PRESSURE AREA OVER
THE SOUTHWESTERN CONUS WILL BRING A GOOD CHANCE OF SHOWERS AND
THUNDERSTORMS TO THE FORECAST AREA FRIDAY EVENING, BUT THE CHANCE
WILL DECREASE OVERNIGHT AS THE DISTURBANCE EXITS THE AREA. THE LOW
WILL THEN WEAKEN AND MOVE SLOWLY EAST OVER THE CENTRAL ROCKIES
SATURDAY THROUGH MONDAY. THIS WILL KEEP THE CHANCE FOR SHOWERS AND
THUNDERSTORMS OVER SOUTHERN MONTANA DURING THIS TIME AND MAINLY
DURING THE PEAK INSTABILITY PERIOD OF THE AFTERNOONS AND EVENINGS.
HIGH PRESSURE ALOFT WILL CONTINUE TO BUILD OVER THE AREA INTO
TUESDAY, BUT WEAK ENERGY AND MOISTURE WILL COMBINE WITH THE
INCREASINGLY UNSTABLE AIRMASS TO BRING A CHANCE OF SHOWERS AND
THUNDERSTORMS TO THE MOUNTAIN AREAS. OVERALL, THE BUILDING HIGH
PRESSURE ALOFT WILL CAUSE TEMPERATURES TO BE AROUND 10 DEGREES ABOVE
NORMAL THROUGH THE PERIOD, WITH HIGHS IN THE 70S TO LOWER 80S AND
LOWS MOSTLY IN THE 50S.
COULSTON

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  70  48  70  51 /  40  50  40  20
CTB  68  44  68  44 /  20  30  40  20
HLN  71  48  73  53 /  40  50  40  30
BZN  72  45  71  49 /  30  40  30  30
WEY  67  37  67  39 /  30  30  30  30
DLN  69  43  69  48 /  40  50  40  30
HVR  72  50  70  47 /  20  50  70  30
LWT  66  49  68  50 /  40  70  60  40

&&

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

$$

WEATHER.GOV/GREATFALLS



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