Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 010314
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
914 PM MDT TUE JUN 30 2015

.DISCUSSION...
THE MAIN CHANGE TO THE FORECAST WAS TO ADD AREAS OF SMOKE TO
NORTHERN HILL AND NORTHERN BLAINE COUNTIES FOR THE REST OF TONIGHT.
VISIBILITIES HAVE BEEN REPORTED TO BE BELOW A MILE IN SPOTS THIS
EVENING. OTHERWISE DROPPED ANY MENTION OF PRECIPITATION FOR THE
REST OF THIS EVENING. SOME GUIDANCE INDICATES THAT
SHOWERS AND THUNDERSTORMS COULD MOVE INTO THE FAR NORTHWEST PLAINS
BEFORE MIDNIGHT BUT COMPARING THEIR FORECASTS FOR MID-EVENING WITH
WHAT WAS OBSERVED IT APPEARS THEY ARE SPREADING PRECIPITATION TOO
FAR SOUTH. THERE IS STILL A CHANCE FOR SHOWERS OR THUNDERSTORMS
NEAR THE CANADIAN BORDER AFTER MIDNIGHT WHICH IS IN LINE WITH THE
INHERITED FORECAST. FORECAST LOWS FOR TONIGHT LOOK ESPECIALLY
GOOD. BLANK

&&

.AVIATION
UPDATED 2350Z.

SKIES ARE EXPECTED TO BE CLEAR TONIGHT. A WEATHER DISTURBANCE
TUESDAY WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS N OF A KGTF-
KLWT LINE WEDNESDAY AFTERNOON. LOCAL MVFR CONDITIONS IN HEAVIER RAIN
ARE POSSIBLE WITH THE THUNDERSTORMS. WEDNESDAY MORNING THERE COULD
ALSO BE A FEW SHOWERS NEAR THE CANADIAN BORDER BUT AGAIN THE MAIN
SHOWER AND THUNDERSTORM ACTIVITY WILL BE DURING THE AFTERNOON. BLANK

&&

.PREV DISCUSSION...
/ISSUED 550 PM MDT TUE JUN 30 2015/
TONIGHT THROUGH THURSDAY NIGHT...AS ONE SMALL WEATHER SYSTEM MOVES
OFF TO THE EAST...ANOTHER IS APPROACHING FROM THE NORTHWEST AND
WILL SKIRT ACROSS THE HI-LINE AREA OF NORTH-CENTRAL MONTANA DURING
THE DAY WEDNESDAY. MEANTIME, THE AREA IS COVERED WITH A DRY AIR
MASS BRINGING LITTLE CHANCE OF ANY PRECIPITATION TONIGHT...AND THE
GUSTY WINDS THIS AFTERNOON WILL BE DECREASING WITH SUNSET.
WEDNESDAY WILL START WITH GENERALLY LIGHT WINDS...HOWEVER...AS THE
SYSTEM SWEEPS THROUGH WEDNESDAY AFTERNOON...WINDS WILL INCREASE
SOMEWHAT AND SHIFT AROUND TO THE NORTH. WIND GUSTS OF 20 TO 25 MPH
ARE POSSIBLE AS THE SYSTEM PASSES. WHILE SHOWERS AND THUNDERSTORMS
MAY DEVELOP WITH THE SYSTEM PASSAGE...IT APPEARS THE BEST CHANCE
OF ANY PRECIPITATION IS GENERALLY ACROSS THE HI-LINE. TEMPERATURES
WILL BE A FEW DEGREES COOLER WEDNESDAY AND THURSDAY...THOUGH STILL
WELL ABOVE NORMAL...AS THIS SYSTEM HELPS IN KEEPING THE DOMINATING
HIGH PRESSURE RIDGE FLATTENED AND PUTS THE AREA UNDER MORE OF A
NORTHWEST FLOW ALOFT.

THURSDAY NIGHT THROUGH TUESDAY. WESTERLY FLOW ALOFT WILL KEEP
CONDITIONS WARM AND DRY ACROSS MOST OF CENTRAL/SOUTHWEST MT ON
FRI/SAT. BOTH GFS AND ECMWF MODELS STILL DEPICTING A SHORTWAVE
TROF AND ASSOCIATED SURFACE COLD FRONT TO MOVE THROUGH THE HILINE
AND CENTRAL COUNTIES ON SAT, BUT FRONT`S ARRIVAL IS A BIT LATER
(NOW EXPECTED SAT AFTN/EVE) THAN YESTERDAY`S MODELS RUNS
SUGGESTED. COVERAGE OF SHOWERS AND THUNDERSTORMS WITH THE FRONT
REMAINS SCATTERED AT BEST AND CONCENTRATED OVER
LIBERTY/HILL/BLAINE COUNTIES. MODEL SOLUTIONS BEGIN TO DIVERGE ON
SUN WITH THE DIFFERENCES CONTINUING INTO EARLY NEXT WEEK. ALTHOUGH
RAW MODEL AND ENSEMBLES SHOW A HIGH PRESSURE CENTER PARKED OVER
THE FOUR CORNERS REGION, AGREEMENT IS CURRENTLY POOR ON HOW THE
RIDGE WILL EVOLVE IN OUR REGION. THE GFS GENERALLY KEEPS TO ITS
EARLIER SOLUTION IN EXPANDING THE RIDGE AXIS THROUGH MT AND INTO
SW CANADA WHILE BRINGING MONSOONAL MOISTURE NORTHWARD FOR
SCATTERED AFTN/EVE THUNDERSTORMS PRIMARILY OVER SOUTHWEST MT FOR
SUN-TUE. THE ECMWF IS CONSIDERABLY DRIER, LIMITING THE INFLUENCE
OF THE RIDGE BY KEEPING THE REGION IN THE SOUTHWEST FLANK OF A
DEEP UPPER-LEVEL TROF IN SOUTH-CENTRAL CANADA. GIVEN THE
REASONABLE CONTINUITY OF THE GFS RUNS, CURRENT GRIDS INCLUDE A
MENTION OF THUNDER ACROSS SOUTHWEST MT AND TREND TEMPERATURES
WARMER (BACK INTO THE UPPER 80S AND LOW 90S) FOR THE START OF NEXT
WEEK. WARANAUSKAS

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  59  87  57  87 /   0  20  10  10
CTB  54  81  52  84 /  10  30  20  10
HLN  64  93  61  93 /   0   0  10  10
BZN  53  89  51  88 /   0   0  10  10
WEY  45  81  42  81 /  10  10  10  10
DLN  57  88  53  88 /  10   0   0   0
HVR  59  86  56  88 /  10  50  20  10
LWT  57  85  55  83 /   0  20  20  10

&&

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

$$

WEATHER.GOV/GREATFALLS



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