176
FXUS65 KTFX 181951
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
151 PM MDT SAT JUL 18 2026
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
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
FAVOR THE CAP REMAINING IN PLACE. -AM
AVIATION
18/18Z TAF PERIOD
INITIAL CONCERN THIS TAF PERIOD WILL BE FOR DEVELOPMENT OF SHOWERS
AND THUNDERSTORMS THIS AFTERNOON AND EVENING, CAPABLE OF PRODUCING
STRONG WINDS GUSTS, SMALL HAIL, AND LIGHTNING. SHOULD ANY OF THESE
SHOWERS OR THUNDERSTORMS PRODUCE BRIEFLY HEAVY RAIN, THERE WILL BE
THE RISK FOR SOME FOG BY SUNDAY MORNING. THE CONFIDENCE IN THIS
OCCURRING WAS TOO LOW TO WARRANT MENTION IN ANY TAF AT THIS POINT,
HOWEVER. LOOKING AHEAD TOWARD SUNDAY DURING THE DAY, BREEZY WEST
TO NORTHWEST WINDS LOOK TO DEVELOP IN MOST AREAS BY LATE MORNING. -AM
PRELIMINARY POINT TEMPS/POPS
GTF 61 93 57 85 / 20 0 0 0
CTB 57 85 55 80 / 10 0 0 0
HLN 60 92 56 87 / 50 20 10 0
BZN 57 94 56 91 / 30 20 20 0
WYS 49 88 49 89 / 30 20 20 0
DLN 55 90 54 88 / 30 20 20 0
HVR 63 93 57 87 / 40 0 0 0
LWT 57 89 54 82 / 20 20 20 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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