712
FXUS65 KTFX 190539
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1139 PM MDT SAT JUL 18 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON AND EVENING,
CAPABLE OF PRODUCING STRONG WIND GUSTS AND LARGE HAIL.
- AFTER SOMEWHAT OF A LULL SUNDAY AND MONDAY, SHOWERS AND
THUNDERSTORMS BECOME MORE SCATTERED AGAIN TUESDAY ONWARD.
- NEAR TO ABOVE AVERAGE TEMPERATURES THIS WEEK.
DISCUSSION
/ISSUED 151 PM MDT SAT JUL 18 2026/
METEOROLOGICAL OVERVIEW:
SOUTHWESTERLY FLOW ALOFT AHEAD OF COMPACT UPPER TROUGHING TO THE
WEST AND BROAD UPPER LEVEL RIDGING TO THE EAST WILL SUPPORT ANOTHER
DAY OF SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE REGION. DEEP
MIXING (LARGELY GREATER THAN 10K FT) AND ASSOCIATED INVERTED-V
PROFILES BY MID-AFTERNOON HOURS WILL SUPPORT THUNDERSTORMS CAPABLE
OF STRONG WIND GUSTS THROUGH THE EVENING. WHILE LARGE HAIL CANNOT BE
RULED OUT, THE PRIMARY THREAT TODAY WILL BE FOR WIND GUSTS.
AFOREMENTIONED TROUGHING LIFTS NORTHEASTWARD FROM WA TONIGHT AND
THEN SHIFTS EAST ACROSS AB/SK SUNDAY AFTERNOON. A ZONAL FLOW ALOFT
ENSUES AS A RESULT, WITH AN EVER SO SLIGHTLY ANTI-CYCLONIC NATURE TO
THE FLOW DEVELOPING BY THE AFTERNOON. THIS LOOKS TO INHIBIT SHOWER
AND THUNDERSTORM FORMATION IN MANY AREAS BY THE AFTERNOON. AREAS
NEAR THE IDAHO BORDER BETWEEN MONIDA PASS AND WEST YELLOWSTONE WILL
HAVE THE GREATEST PROBABILITY TO SEE A SHOWER OR THUNDERSTORM SUNDAY
AFTERNOON.
UPPER LEVEL RIDGING ACROSS THE CENTRAL US EXTENDING NORTHWESTWARD
TOWARD THE NORTHERN ROCKIES LOOKS TO RESULT IN AN ANTICYCLONIC FLOW
ALOFT ACROSS THE REGION MUCH OF THE UPCOMING WEEK. THAT SAID,
MONSOONAL MOISTURE REBUILDS INTO THE REGION THROUGH THE WESTERN
PERIPHERY OF THE RIDGING BY TUESDAY, WHICH WILL RESULT IN AT LEAST
SCATTERED SHOWERS AND THUNDERSTORMS EACH AFTERNOON TUESDAY ONWARD
THROUGH AT LEAST FRIDAY. THESE LOOKS TO BE INITIALLY TERRAIN
BASED BEFORE MAKING INROADS TOWARD LOWER ELEVATIONS. GUSTY WINDS
AND HEAVY RAIN WHICH COULD LEAD TO LOCALIZED FLASH FLOODING WILL
BE THE PRIMARY CONCERN WITH THESE THUNDERSTORMS.
UNCERTAINTY GROWS FOR THE UPCOMING WEEKEND, THOUGH WITH AT LEAST
SOME VARIETY OF SOUTHWESTERLY FLOW ALOFT FAVORED, SCATTERED SHOWERS
AND THUNDERSTORMS LOOK TO CONTINUE, PRIMARILY IN THE AFTERNOON AND
EVENING HOURS. -AM
UNCERTAINTY:
THERE IS CONDITIONAL RISK FOR STRONG TO SEVERE THUNDERSTORMS SUNDAY
AFTERNOON, MOSTLY ACROSS CENTRAL MONTANA AND VICINITY. THIS AREA
LOOKS TO SEE THE MOST ROBUST COMBINATION OF INCREASED SHEAR FROM THE
PASSING TROUGH TO THE NORTH AS WELL AS THE BEST SURFACE MOISTURE
WHICH WOULD RESULT IN INCREASED INSTABILITY AND ABILITY TO BREAK THE
CAP. ALTHOUGH SOME WEAK CAPPING LOOKS TO KEEP MOST OF THIS
THUNDERSTORM ACTIVITY AT BAY, SHOULD A THUNDERSTORM DEVELOP IN THIS
ENVIRONMENT (PERHAPS INITIALLY FORMING OVER TERRAIN), IT WOULD BE
CAPABLE OF PRODUCING LARGE HAIL AND STRONG WIND GUSTS. THE RISK FOR
THIS SCENARIO WILL LARGELY DEPEND ON HOW WELL SURFACE DEW POINTS ARE
ABLE TO HOLD ON INTO SUNDAY. LINGERING HIGHER DEW POINTS WOULD FAVOR
A GREATER RISK OF BREAKING THE CAP WHILE LOWER DEW POINTS WOULD
AVIATION
19/06Z TAF PERIOD
VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE TAF PERIOD.
THERE IS AROUND A 30% CHANCE FOR SOME ISOLATED SHOWERS AND
THUNDERSTORMS DEVELOPING SOUTH OF THE I-90 CORRIDOR SUNDAY
AFTERNOON WHICH MAY IMPACT KWYS AND KEKS. THE MAIN CONCERN WOULD
BE LIGHTNING AND GUSTY, ERRATIC WINDS. ACROSS THE REST OF THE
REGION, WINDS ARE EXPECTED TO PICK UP OUT OF THE WEST/NORTHWEST BY
LATE MORNING INTO EARLY AFTERNOON WITH WIDESPREAD GUSTS UP TO
25KTS POSSIBLE AND HIGHER GUSTS POSSIBLE ALONG THE ROCKY MOUNTAIN
FRONT. MINOR AMOUNTS OF WILDFIRE SMOKE FROM THE WEST MAY START TO
INFILTRATE INTO CENTRAL MONTANA SUNDAY AFTERNOON/EVENING. THERE
MAY BE SOME VERY MINOR REDUCTIONS TO SLANTWISE VISIBILITY BUT
OVERALL NO MAJOR VISIBILITY OR AIR QUALITY IMPACTS ARE EXPECTED
AT THIS TIME. -THOR
PRELIMINARY POINT TEMPS/POPS
GTF 61 93 57 84 / 10 0 0 0
CTB 57 85 56 80 / 0 0 0 0
HLN 60 93 57 87 / 40 20 0 0
BZN 57 93 57 91 / 30 20 10 0
WYS 49 87 49 91 / 20 40 20 20
DLN 55 90 55 88 / 20 20 10 10
HVR 63 93 58 87 / 40 0 0 0
LWT 57 89 55 82 / 20 20 10 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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