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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1147 AM MDT WED JUL 1 2015

.DISCUSSION...

A WEAK COLD FRONT IS PUSHING SOUTH ACROSS THE NORTHERN TIER.
ISOLATED SHOWERS AND THUNDERSTORMS ARE EXPECTED. UPDATED TO
FRESHEN FIRST PERIOD POPS, WX, AND QPF. CURRENT FORECAST ON TRACK.
ZELZER

&&

.AVIATION 
UPDATED 1746Z.

AREAS OF SMOKE WILL CONTINUE TO AFFECT AREAS ALONG THE CANADIAN 
BORDER, INCLUDING KCTB AND KHVR. SOME IMPROVEMENT IS EXPECTED DURING 
THE AFTERNOON BUT VISIBILITIES WILL LOWER AGAIN DURING THE NIGHT. 
LOCAL MVFR/IFR CONDITIONS ARE POSSIBLE. ELSEWHERE VFR CONDITIONS 
WILL PREVAIL THROUGH THE NEXT 24 HOURS. SCATTERED THUNDERSTORMS ARE 
EXPECTED THIS AFTERNOON AND EVENING MAINLY ACROSS NORTH PORTIONS OF 
THE REGION, MAINLY NORTH OF A KGTF-KLWT LINE. GUSTY AND ERRATIC 
WINDS ARE EXPECTED NEAR THUNDERSTORMS. 

&&

.PREV DISCUSSION...
/ISSUED 514 AM MDT WED JUL 1 2015/

TODAY THROUGH FRIDAY...SMOKE FROM CANADIAN WILD FIRES SPREAD ACROSS
MUCH OF THE NORTH CENTRAL PLAINS LATE TUESDAY NIGHT. VISIBILITY
RANGES FROM 2.5 MILES AT HAVRE TO 7 MILES AT GREAT FALLS. SMOKE IS
EXPECTED TO LINGER UNDER CLEAR AND STABLE CONDITIONS THROUGH THE
MORNING.

A WEAK WEATHER SYSTEM WILL TRAVERSE THE HILINE TODAY WITH A NEARLY
ZONAL FLOW ALOFT. FORECAST MODELS ADVERTISE SCATTERED SHOWERS AND
THUNDERSTORMS THIS AFTERNOON ACROSS NORTHERN PORTIONS OF THE
CENTRAL PLAINS. WEST TO NORTHWEST WINDS WILL FOLLOW THE SYSTEM AND
CLEAR REMAINING SMOKE FROM THE AREA. SOUTHWEST MONTANA REMAINS
MOSTLY SUNNY TODAY WITH SUBSIDENCE AND DRY AIR ALOFT. HIGH PRESSURE
YIELDS FAIR AND DRY CONDITIONS ON THURSDAY. ISOLATED MOUNTAIN
SHOWERS ARE POSSIBLE LATE THURSDAY AND FRIDAY WITH ADDITIONAL
RIPPLES PASSING THROUGH THE NORTHWEST FLOW ALOFT. TEMPERATURES
WILL MOVE A FEW DEGREES COOLER TODAY AND THURSDAY FOR NORTHERN
ZONES...BUT OVERALL REMAIN WELL ABOVE AVERAGE GOING INTO JULY.
NUTTER

FRIDAY NIGHT THROUGH WEDNESDAY...AN UPPER LEVEL LOW CURRENTLY 
LOCATED OVER THE GULF OF AK WILL MOVE INTO FAR NW CANADA LATE THIS 
WEEK THEN TRACK EAST ACROSS AB/SK THIS WEEKEND. ASSOCIATED SHORTWAVE 
ENERGY DIGGING SE THROUGH BC FRIDAY NIGHT WILL HELP PUSH A 
MODERATELY STRONG COLD FRONT SOUTH INTO NORTH CENTRAL MT 
SATURDAY/SATURDAY NIGHT WITH SOME DIFFERENCES REMAINING AMONG MODELS 
WITH REGARD TO TIMING. HAVE INCREASED POPS FOR SAT/SAT NIGHT WITH 
GFS/ECMWF MODELS BOTH BRINGING SOME SHORTWAVE AND UPPER LEVEL JET 
DYNAMICS ACROSS NORTHERN PORTIONS OF THE STATE ALONG WITH THE 
FRONTAL PASSAGE, THOUGH MOISTURE IS SOMEWHAT LIMITING. COOLER 
AIRMASS MOVES SOUTH BEHIND THE FRONT SATURDAY NIGHT AND SUNDAY WITH 
SUNDAY AFTERNOON TEMPERATURES COOLING BACK TO NEAR OR EVEN SLIGHTLY 
BELOW SEASONAL AVERAGES. THE FRONTAL BOUNDARY WILL STALL OVER SW MT 
SUNDAY WHERE SHOWERS AND THUNDERSTORMS WILL BE MAINLY LIMITED TO 
AREAS NEAR THE ID/WY BORDER. MODELS DIVERGE WITH THE OVERALL UPPER 
LEVEL PATTERN EVOLUTION NEXT WEEK WITH THE ECMWF MODEL MAINTAINING A 
MORE NW FLOW ALOFT OVER THE FORECAST AREA UNDER THE INFLUENCE OF 
BROAD TROUGHING OVER CENTRAL CANADA WHILE THE GFS QUICKLY REBUILDS 
UPPER LEVEL RIDGING OVER THE INTERIOR WESTERN US. BOTH SCENARIOS 
WOULD BRING WARMING CONDITIONS THOUGH THE ECMWF SOLUTION WOULD BE 
SLOWER. HOENISCH

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  86  57  86  58 /  20  10   0  10 
CTB  81  52  84  53 /  40  10  10  10 
HLN  93  61  92  62 /  10   0   0   0 
BZN  89  51  88  52 /   0   0   0   0 
WEY  82  43  80  43 /  10  10   0   0 
DLN  89  53  88  54 /   0   0   0   0 
HVR  85  56  88  57 /  50  20  10  10 
LWT  84  55  83  57 /  20  20  10  10 

&&

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

$$

WEATHER.GOV/GREATFALLS

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