146
FXUS65 KTFX 091416
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
816 AM MDT SAT AUG 9 2025
KEY MESSAGES
- ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL
CONTINUE OVER MAINLY THE PLAINS OF CENTRAL AND NORTH CENTRAL
MONTANA, WITH CONTINUED GUSTY WEST TO NORTHWEST SURFACE WINDS
ACROSS THESE SAME LOCATIONS.
- TEMPERATURES MODERATE THROUGH THE WEEKEND, WITH THE WARMEST
DAY OF THE UPCOMING WEEK OCCURRING ON TUESDAY.
- OVERALL DRY CONDITIONS FROM THE SECOND HALF OF THE WEEKEND
THROUGH TUESDAY WILL GIVE WAY TO INCREASING CHANCES FOR SHOWERS
AND THUNDERSTORMS FOR THE SECOND HALF OF THE UPCOMING WORK
WEEK.
UPDATE
THE ONLY CHANGE OF NOTE WITH THE MORNING UPDATE WAS ADDING HAZE TO
THE FORECAST BASED ON HRRR SMOKE GUIDANCE. WILDFIRE SMOKE FROM
CANADA IS EXPECTED TO ARRIVE THIS AFTERNOON AND IMPACT PORTIONS OF
THE HI-LINE EAST OF CHESTER. THE WORST OF THE IMPACTS ARE EXPECTED
EAST OF MALTA BUT SOME DEGRADATION IN AIR QUALITY IS POSSIBLE
ACROSS NORTHERN BLAINE AND HILL COUNTIES THROUGH TOMORROW
MORNING.
OTHERWISE THE REST OF THE FORECAST REMAINS ON TRACK. -THOR
DISCUSSION
/ISSUED 431 AM MDT SAT AUG 9 2025/
- METEOROLOGICAL OVERVIEW:
H500 SHORTWAVE, WITH A CLOSED LOW CENTERED OVER SOUTHEAST
SASKATCHEWAN, WILL SLOWLY LIFT TO THE NORTHEAST AND OVER MANITOBA
AND THE UPPER MISSISSIPPI VALLEY THROUGH THE DAY TODAY. NORTHWEST
FLOW OVER THE NORTHERN ROCKIES ON THE BACK SIDE OF THE DEPARTING
SHORTWAVE WILL HELP TO MAINTAIN GUSTY WINDS OVER THE PLAINS OF
CENTRAL AND NORTH CENTRAL MONTANA, ISOLATED TO WIDELY SCATTERED
SHOWERS NORTH OF THE US HWY 12 CORRIDOR, AND CONTINUED BELOW NORMAL
TEMPERATURES ACROSS ALL OF SOUTHWEST THROUGH NORTH CENTRAL MONTANA.
PREDOMINATELY NORTHWEST FLOW ALOFT LOOKS TO PREVAIL OVER THE
NORTHERN ROCKIES ON SUNDAY AND MONDAY; HOWEVER, WITH 1000-500MB
THICKNESSES CLIMBING ~60M ON SUNDAY AND AN ADDITIONAL 20M ON MONDAY
SURFACE TEMPERATURES WILL RESPOND BY MODERATING BACK TO NEAR NORMAL.
WHILE A NARROW REGION OF MID-LEVEL (GENERALLY BETWEEN H700-600)
MOISTURE WILL EXIST THROUGHOUT THE PERIOD, WHICH WILL LIKELY SUPPORT
AFTERNOON CUMULUS DEVELOPMENT, OVERALL DRY CONDITIONS CAN BE
EXPECTED THANKS TO DRY AIR BOTH ABOVE AND BLOW THIS NARROW CORRIDOR
OF MOISTURE.
TRANSIENT RIDGING LOOKS TO SLIDE EAST FROM THE PACIFIC NORTHWEST AND
OVER THE NORTHERN ROCKIES FROM MONDAY NIGHT THROUGH TUESDAY MORNING
AHEAD OF A SHORTWAVE DIGGING SOUTH FROM THE YUKON TO OVER BRITISH
COLUMBIA, WHICH WILL ALLOW SURFACE TEMPERATURES TO WARM TO THE
"HOTTEST" VALUES OF THE UPCOMING WEEK ON TUESDAY WITH MOST LOCATIONS
PEAK IN THE MID-80S TO LOW 90S. FROM WEDNESDAY THROUGH THE REMAINDER
OF THE UPCOMING WORK WEEK THE AFOREMENTIONED SHORTWAVE WILL SLOWLY
BEGIN TO SLIDE/LIFT EAST AND OVER THE CANADIAN ROCKIES TO THE PRAIRIE
PROVINCES, WITH FALLING HEIGHTS OVER THE NORTHERN ROCKIES THROUGHOUT
THE PERIOD. TEMPERATURES LOOK TO COOL THROUGH THE SECOND HALF OF THE
WORK WEEK, WITH READINGS FALLING BACK INTO THE 70S ON THURSDAY OVER
THE PLAINS OF CENTRAL AND NORTH CENTRAL MONTANA AND THEN THE VALLEYS
AND PLAINS OF CENTRAL AND NORTH CENTRAL MONTANA ON FRIDAY WHILE
VALLEYS OF SOUTHWEST MONTANA LOOK TO REMAINS IN THE LOW TO MID-80S
ON BOTH DAYS. PRECIPITATION, WHILE ONLY ISOLATED TO SCATTERED IN
COVERAGE, WILL ALSO RETURN BENEATH THIS INCREASINGLY "TROUGHY"
PATTERN. - MOLDAN
- FORECAST CONFIDENCE & SCENARIOS:
GUSTY WINDS THROUGH THIS AFTERNOON :
WHILE HIGH WINDS ARE NOT SUPPORTED BY EITHER CLIMATE ANOMALY
INDICATOR (NAEFS OR ECMWF EFIS) THERE REMAINS STRONG SUPPORT WITHIN
BOTH INDICATORS FOR UNUSUALLY GUSTY WEST TO NORTHWEST OVER PORTIONS
OF THE CENTRAL AND NORTH CENTRAL MONTANA PLAINS, GENERALLY ALONG AND
EAST OF A JUDITH GAP, TO GREAT FALLS, TO SHELBY LINE. H850-700 WIND
SPEEDS OF 25-35KTS, WHICH ARE 1 TO NEARLY 3 STANDARD DEVIATIONS
ABOVE NORMAL FOR EARLY AUGUST PER NAEFS ANALYSIS, WILL SLOWLY PULL
EAST OF THE NORTHERN ROCKIES AS THE ATTENDANT UPPER LEVEL LOW MOVES
OVER THE NORTHERN HIGH PLAINS THROUGH THE DAY TODAY. DIURNAL MIXING,
PARTICULARLY FROM THE LATE MORNING THROUGH LATE AFTERNOON HOURS,
WILL HELP TO TRANSLATE THESE "STRONGER" LOW TO MID-LEVEL WINDS TO
THE SURFACE, WITH NBM PROBABILITIES FOR WIND GUSTS OF 40 MPH OR
GREATER GENERALLY RANGING FROM A 60-90% CHANCE EAST OF A HAVRE TO
STANFORD LINE. ECMWF EFI VALUES OF 0.8 TO NEARLY 0.9 FOR WIND GUSTS
IN LEE OF THE ISLAND RANGES OF FERGUS AND BLAINE COUNTIES SUPPORT
THE POTENTIAL FOR VERY UNUSUAL GUSTS WITH RESPECT TO CLIMATOLOGY,
WITH NBM PROBABILITIES FOR GUSTS OF 50 MPH OR GREATER GENERALLY
RANGING FROM A 20-50% CHANCE. - MOLDAN
AVIATION
09/12Z TAF PERIOD
ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL
CONTINUE TO MOVE SOUTHEAST OVER THE PLAINS OF CENTRAL AND NORTH
CENTRAL MONTANA THROUGH 03-06Z SUNDAY, WITH THE KCTB, KHVR, KGTF,
AND KLWT TERMINALS POTENTIALLY SEEING PRECIPITATION THROUGH THIS
TIMEFRAME. CONFIDENCE, HOWEVER, IN ANY ONE SHOWER OR THUNDERSTORM
IMPACTING A TERMINAL REMAINS TOO LOW TO MENTION WITH THIS TAF
PACKAGE, WITH THE EXCEPTION OF THE KHVR TERMINAL WHERE A PROB30
GROUP WAS USED THROUGH 18Z THIS AFTERNOON. OTHERWISE, MVFR
CONDITIONS ARE EXPECTED AT THE KHVR TERMINAL DUE TO LOW CIGS
THROUGH 20Z THIS AFTERNOON, WITH IMPROVING CONDITIONS THEREAFTER.
VFR CONDITIONS WILL PREVAIL AT ALL REMAINING SITES. MOUNTAIN
OBSCURATION WHILE NOT WIDESPREAD WILL CONTINUE TO OCCUR AT TIMES,
ESPECIALLY OVER THE CENTRAL AND NORTH CENTRAL MONTANA. - MOLDAN
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 76 54 84 54 / 20 20 0 0
CTB 73 52 80 54 / 10 20 0 0
HLN 78 53 84 53 / 10 0 0 0
BZN 77 48 83 49 / 0 0 0 0
WYS 70 34 76 34 / 0 0 0 0
DLN 73 44 79 46 / 0 0 0 0
HVR 75 53 84 55 / 30 10 0 0
LWT 70 50 78 51 / 20 20 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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