651
FXUS65 KTFX 080501
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1101 PM MDT THU AUG 7 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE LATE TONIGHT, WITH
A FEW STORMS CAPABLE OF PRODUCING GUSTY WINDS AND HAIL.
- SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE THROUGH FRIDAY, WITH
COOLER TEMPERATURES.
- WARMER AND DRIER FOR THE WEEKEND.
UPDATE
/ISSUED 837 PM MDT THU AUG 7 2025/
STOUT UPPER LEVEL TROUGHING CONTINUES TO PIVOT THROUGH THE NORTHERN
ROCKIES THIS EVENING. AT THE SURFACE MOST WARMER AIR HAS ALREADY
BEEN SCOURED OUT BY THE COMBINATION OF THUNDERSTORMS, OUTFLOW, AND
JUST OUTRIGHT COOLER AIR MOVING IN WITH THE TROUGHING. THAT SAID,
THE COOLER AIR ALOFT IS STILL RESULTING IN SOME ELEVATED INSTABILITY
ACROSS THE REGION THIS EVENING. FORCING FROM THE TROUGH SWINGING
THROUGH WILL BE MORE THAN SUFFICIENT TO TAP INTO THIS INSTABILITY
AND AS A RESULT, SHOWERS AND THUNDERSTORMS LOOK TO CONTINUE THROUGH
THE NIGHT, BUT SHIFT FOCUS NORTHWARD TOWARD THE PLAINS. THE THREAT
FOR STRONG TO SEVERE THUNDERSTORMS HAS LARGELY WANED, BUT A BRIEFLY
STRONGER GUST OR INSTANCE OF SMALL HAIL CANNOT BE RULED OUT THIS
EVENING.
THE COOLEST AIR ALOFT MOVES THROUGH TONIGHT AND TOMORROW MORNING
ASSOCIATED WITH THE CORE OF THE UPPER LEVEL DISTURBANCE. A FEW
INSTANCES OF LIGHT SNOW ON THE HIGHER PEAKS OF THE LITTLE BELTS,
BIG BELTS, TOBACCO ROOTS SEEMS REASONABLE LATE TONIGHT AND EARLY
FRIDAY MORNING GIVEN THE COLDEST OF THE SUB-ZERO H7 TEMPERATURES
SWINGING THROUGH IN THESE AREAS. COLD PRONE VALLEYS TONIGHT, SUCH
AS THE BIG HOLE VALLEY, ARE LIKELY TO SEE OVERNIGHT LOWS IN THE
20S AND 30S.
INCREASED WESTERLY TO NORTHWESTERLY MID LEVEL FLOW IN THE MID LEVELS
BEHIND THE DEPARTING TROUGHING FRIDAY WILL ALLOW FOR A BREEZY DAY.
BY THE AFTERNOON, MIXING SHOULD SUPPORT SUSTAINED WINDS NEAR OR IN
EXCESS OF 20 MPH FOR MOST AREAS, WITH GUSTS IN TO THE 30S. ALTHOUGH
MUCH COOLER AIR WILL LINGER AT THE SURFACE, SUFFICIENTLY COOL AIR
ALOFT OVER THE PLAINS AND ADJACENT AREAS WILL SUPPORT AFTERNOON AND
EVENING SHOWERS AND A FEW THUNDERSTORMS. FORECAST SOUNDINGS SHOW
LITTLE IN WAY OF INSTABILITY OVER MOST AREAS, WITH AREAS NEAR BLAINE
COUNTY HAVING THE BEST CHANCE TO EXCEED 500 M2/S2 SFC-BASED CAPE IN
THE AFTERNOON. DCAPE APPEARS MINIMAL THOUGH IN THIS AREA, SO SMALL
HAIL IS THE PRIMARY CONCERN SHOULD A STRONGER THUNDERSTORM FORM.
GIVEN THE CORE OF THE UPPER DISTURBANCE NEARBY IN THE AFTERNOON
FRIDAY, I CANNOT RULE OUT AN INSTANCE OR TWO OF A COLD AIR FUNNEL.
OVERALL THE CHANGES WITH THE FORECAST WERE MINIMAL THIS EVENING,
JUST NUDGING TOWARD LATEST TRENDS. -AM
DISCUSSION
/ISSUED 837 PM MDT THU AUG 7 2025/
- METEOROLOGICAL OVERVIEW:
THERE LOOKS TO BE TWO DIFFERENT WAVES OF PRECIPITATION TODAY. A
SHORTWAVE THIS AFTERNOON HAS PRODUCED THE FIRST WAVE OF SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. LATER IN THE EVENING,
THE CORE OF THE UPPER-LEVEL TROUGH MOVES THROUGH. CAPE BETWEEN
500-1,000 J/KG AND MODEST SHEAR OF 40-50KTS WILL BRING AN ISOLATED
RISK FOR STRONG TO SEVERE THUNDERSTORMS THROUGH THE EVENING. THE
UPPER-LEVEL LOW BRINGING IN COOLER AIR ALOFT LATER THIS EVENING
WILL KEEP A LITTLE BIT OF ELEVATED INSTABILITY AND ISOLATED STORMS INTO
THE OVERNIGHT HOURS.
HEADING INTO THE OVERNIGHT HOURS, THIS OCCLUDING LOW ALOFT LOOKS
TO TRANSVERSE OVER NORTH-CENTRAL MT. THIS WILL BRING A WIDESPREAD
BAND OF WETTING RAIN TO PORTIONS OF NORTH-CENTRAL MT THROUGH
FRIDAY MORNING. THAT MAIN WAVE WILL EXIT OFF TO THE EST IN THE
AFTERNOON, BUT MOISTURE WRAPPING AROUND THAT LOW PRESSURE SYSTEM
WILL KEEP SHOWERS AND THUNDERSTORMS ACROSS THE REGION (MAINLY
NORTH OF I-90) THROUGHOUT FRIDAY AND OVERNIGHT INTO SATURDAY
MORNING. THE LOW PRESSURE SYSTEM WILL MOVE OFF TO THE EAST BY
SATURDAY AFTERNOON. WE THEN TRANSITION TO NORTHWEST FLOW ALOFT FOR
THE WEEKEND AS AN UPPER- LEVEL RIDGE BUILDS OFF THE PACIFIC
NORTHWEST COAST. ALTHOUGH THE WEEKEND WILL STAY ON THE DRIER SIDE
OVERALL, AS FEW DISTURBANCES TRIES TO "ROUND OUT THE RIDGE" AND
DIVE SOUTH FROM CANADA INTO MONTANA. THIS WILL KEEP LOW END
CHANCES FOR PRECIPITATION THIS WEEKEND, PARTICULARLY ON SATURDAY.
FRIDAY LOOKS TO BE THE COOLEST DAY OF THE FORECAST PERIOD WITH
HIGH TEMPERATURES FORECASTED TO REACH ONLY THE 60S TO LOW 70S AT
LOWER ELEVATIONS. A WARMUP TREND IS EXPECTED THROUGH THE BEGINNING
OF NEXT WEEK, BUT STILL TEMPERATURES DON'T LOOK IMPRESSIVE. IT'LL
REMAIN NEAR TO SLIGHTLY BELOW AVERAGE.
MODELS NEXT WEEK ARE UNCERTAIN HOW LONG THIS NORTHWEST FLOW ALOFT
PATTERN LASTS. ENSEMBLES INDICATE A SMALL SHORTWAVE TROUGH
DEVELOPING IN BRITISH COLUMBIA, BUT ARE UNSURE HOW TO PROGRESS
THIS TROUGH. SOME HAVE THIS TROUGH DIGGING INTO THE PACIFIC
NORTHWEST, BRINGING BETTER CHANCES FOR PRECIPITATION, WHILE SOME
KEEP IT CONFINED TO CANADA WHICH WILL KEEP THINGS ON THE DRIER
SIDE. TIMING OF THIS WAVE IS ALSO INCONSISTENT, WHICH LOWERS THE
CONFIDENCE OF THE FORECAST FOR NEXT WEEK.
- FORECAST CONFIDENCE & SCENARIOS:
MORNING CLOUD COVER HAS LIMITED INSTABILITY ACROSS THE REGION THIS
AFTERNOON TO GENERALLY 1,000 J/KG OR LESS. THIS WILL KEEP THE
THREAT FOR STRONG TO SEVERE THUNDERSTORMS ISOLATED, TO MAINLY
AREAS EAST OF THE LITTLE BELTS REGION THIS AFTERNOON. LATER THIS
EVENING WITH THE ARRIVAL OF THE UPPER-LEVEL CLOSED LOW, ANOTHER
CORRIDOR ALONG THE BOULDER HILL, BROADWATER COUNTY, AND THE
MISSOURI HEADWATERS AREA, WHERE GOOD DEEP LAYER SHEAR AND LOWER
AMOUNTS OF HELICITY WILL BRING AN ISOLATED CHANCE FOR A FEW STRONG
TO SEVERE STORMS.
FOR FRIDAY, THERE ARE SUBTLE DIFFERENCES IN THE LOCATION OF THE
WIDESPREAD OF PRECIPITATION OVERNIGHT. AREAS THAT DO GET THIS
STEADY, CONSISTENT RAIN CAN SEE AMOUNTS HIGHER END AMOUNTS OF 0.75"-
1". BEING ON THE WESTERN SIDE OF THE LOW PRESSURE SYSTEM NOW, THE
SYNOPTICS AND MESOSCALE DYNAMICS LOOK TO KEEP THUNDERSTORMS
RELATIVELY WEAK ON FRIDAY. AN INCREASE IN THE LOW LEVEL JET
HOWEVER, WILL BRING BREEZY WEST TO NORTHWEST WINDS TO THE REGION
FOR FRIDAY. -WILSON
AVIATION
08/06Z TAF PERIOD
A MIX OF STRATIFORM RAIN AND RAIN SHOWERS WILL CONTINUE LIFTING
NORTH AND NORTHEASTWARD ACROSS THE REGION OVERNIGHT. A FEW INSTANCES
OF GUSTY WINDS WHERE SHOWERS INITIALLY DEVELOP DURING THE OVERNIGHT
WILL BE POSSIBLE. MOST RAIN SHOULD EXIT EASTWARD LATE THIS MORNING.
ATTENTION THEN TURNS TO THE LATE MORNING AND AFTERNOON TIMEFRAME
FRIDAY. INITIAL CONCERNS WILL BE FOR GUSTY WINDS MIXING TO THE
SURFACE ACROSS THE REGION BEGINNING LATE MORNING. AS BETTER
SURFACE HEATING ENSUES, SHOWERS AND A FEW THUNDERSTORMS WILL
BECOME MORE NUMEROUS ACROSS THE PLAINS IN THE AFTERNOON. SURFACE
WINDS GENERALLY DIMINISH ENTIRELY AFTER SUNSET FRIDAY (ASIDE FROM
MOST OF THE PLAINS), WHICH MAY BRING ABOUT A BRIEF INSTANCES OF
LLWS WHERE WINDS OFF THE DECK REMAIN BREEZY.
REFRAINED FROM LLWS MENTION IN TAFS FOR FRIDAY EVENING FOR
NOW GIVEN LOWER CONFIDENCE. MOUNTIAN OBSCURATION WILL BE COMMON
THROUGH MUCH OF THE TAF PERIOD. -AM
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 50 72 53 77 / 80 50 20 10
CTB 49 67 51 73 / 30 60 30 10
HLN 49 73 52 79 / 60 30 10 10
BZN 44 73 45 78 / 80 20 10 0
WYS 34 67 32 71 / 20 10 0 0
DLN 39 70 40 75 / 60 10 0 0
HVR 51 70 54 76 / 90 80 60 30
LWT 46 67 49 70 / 60 60 40 20
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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