138
FXUS65 KTFX 290534
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1134 PM MDT WED MAY 28 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- MOSTLY DRY TODAY WITH A FEW SHOWERS AND A THUNDERSTORM BY THE
MONTANA AND IDAHO BORDER.
- A PACIFIC COLD FRONT WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS
THURSDAY EVENING WITH STORMS CAPABLE OF PRODUCING STRONG WINDS,
BRIEF DOWNPOURS, AND SMALL HAIL.
- TEMPERATURES REMAIN WELL ABOVE AVERAGE THROUGH THE WEEKEND,
BEFORE A COOLER AND WETTER PATTERN SETTLES IN FOR THE FIRST
HALF OF NEXT WEEK.
UPDATE
/ISSUED 831 PM MDT WED MAY 28 2025/
SATELLITE IMAGERY THIS EVENING SHOWS THE CUMULUS FIELD ACROSS THE
AREA RAPIDLY DIMINISHING WITH MAINLY CLEAR SKIES EXPECTED ACROSS
MUCH OF THE AREA OVERNIGHT. SURFACE PRESSURE GRADIENT BETWEEN
HIGH PRESSURE ACROSS THE DAKOTAS AND LOW PRESSURE ACROSS THE
INTERIOR NW US WILL SUPPORT SOME BREEZY EAST TO SOUTHEAST WINDS
LATER THIS EVENING ACROSS EASTERN PORTIONS OF NORTH-CENTRAL AND
SOUTHWEST MT. NO SIGNIFICANT CHANGES TO THE FORECAST. HOENISCH
DISCUSSION
/ISSUED 831 PM MDT WED MAY 28 2025/
- METEOROLOGICAL OVERVIEW:
AN UPPER-LEVEL RIDGE AND HIGH PRESSURE TODAY WILL MAINTAIN A MOSTLY
DRY DAY TODAY. THE EXCEPTION IS A FEW SHOWERS/THUNDERSTORM OVER THE
HIGHER TERRAIN ALONG THE MT/ID BORDER AND SOUTHERN FERGUS COUNTY THIS
AFTERNOON. THURSDAY, A SHORTWAVE TROUGH AND A PACIFIC COLD FRONT
WILL SLIDE EAST ACROSS THE REGION IN THE EVENING. THE MAIN UPPER
WAVE/FRONT WON'T ARRIVE UNTIL LATE AFTERNOON/EARLY EVENING, BUT
STRONG DAY TIME HEATING (HIGH TEMPERATURES OF LOW TO UPPER 80S AT
LOWER ELEVATIONS, AND UP TO 70 IN HIGHER TERRAIN) MAY ALLOW FOR
EARLIER INITIATION IN PRECIPITATION BY REACHING CONVECTIVE
TEMPERATURE. DEEP, INVERTED V VERTICAL PROFILE SOUNDINGS WILL HAVE
STORMS CAPABLE OF PRODUCING GUSTY TO STRONG WINDS. MODELS HINT AT
MOISTURE INCREASING AHEAD OF THE FRONT, WHICH IN ADDITION TO WIND CAN
ALSO PRODUCE SMALL HAIL WITH BRIEF HEAVY DOWNPOURS WITH STORMS
LATER IN THE DAY. THE FRONT LINGERING AROUND IN THE MORNING CAN
KEEP ISOLATED SHOWERS EARLY FRIDAY MORNING IN THE NORTH-CENTRAL
MT PLAINS. WELL ABOVE AVERAGE TEMPERATURES CONTINUE THROUGH
SATURDAY, WITH THURSDAY AND SATURDAY BEING THE WARMEST. THE RIDGE
AXIS MOVING OVERHEAD SATURDAY WILL HELP PARTS OF NORTH-CENTRAL MT
REACH 90 DEGREES.
SUNDAY, A TROUGH DIGS INTO THE PACIFIC NORTHWEST. THIS WILL BRING
THE FIRST WAVE OF SHOWERS AND THUNDERSTORMS IN THE AFTERNOON.
A BETTER SHEARED ENVIRONMENT WILL BRING THE POTENTIAL FOR A FEW
STRONGER STORMS. ENSEMBLES HAVE BEEN CONSISTENT ON THIS TROUGH TO
SPLIT INTO AN OCCLUDING LOW ALOFT. THIS WILL KEEP A COOLER AND
WETTER PATTERN FOR THE FIRST HALF OF THE WEEK. LOWERING SNOW
LEVELS WILL ALLOW FOR HIGH TERRAIN MOUNTAIN SNOW AS WELL.
- FORECAST CONFIDENCE & SCENARIOS:
THERE'S A LITTLE UNCERTAINTY IN THE THUNDERSTORM POTENTIAL FOR
THURSDAY SINCE IT WILL BE DEPENDENT ON THE TIMING OF THE COLD
FRONT. STORMS THAT FIRE EARLIER IN THE AFTERNOON FROM CONVECTIVE
TEMPERATURE WILL MAINLY BE A WIND THREAT WITH DEEP MIXING FROM
DAYTIME HEATING. HI-RES MODELS DEPICT AN INCREASE OF MOISTURE
AHEAD OF THE COLD FRONT. THIS ALONG WITH BETTER FORCING ALONG THE
FRONT CAN PRODUCE SMALL HAIL AND BRIEF HEAVY DOWNPOURS WITH
STORMS. CURRENT TIMING OF THE FRONT HAS IT REACHING THE
CONTINENTAL DIVIDE DURING THE LATE AFTERNOON/EARLY EVENING. THIS
CAN SUPPORT SOME STRONGER STORMS ALONG THE ROCKY MOUNTAIN FRONT
AND I-15 CORRIDOR. THE SLOW PROGRESSION OF THE FRONT ONCE IT
REACHES THE DIVIDE WILL DECREASE THE STRONG STORM POTENTIAL EAST
OF I-15. ANOTHER LIMITING FACTOR IS LOW CAPE (~500 J/KG) AND SHEAR
(20KTS WITH ISOLATED 30KTS) DON'T SUPPORT ROBUST THUNDERSTORM
DEVELOPMENT. OVERALL THINKING IS THERE ARE SOME STORMS THAT CAN
BECOME STRONG (50-55MPH WIND GUSTS) BUT CHANCES FOR SEVERE STORMS
ARE LOW (CAN'T RULE OUT A ROGUE SEVERE STORM THOUGH, ESPECIALLY
ONE THAT GET ENHANCED DOWNSLOPING WINDS WHEN MOVING LEEWARDS OF
THE CONTINENTAL DIVIDE).
CONFIDENCE IS INCREASING FOR A COOLER AND WETTER PATTERN NEXT WEEK.
CURRENT FORECAST HAS A FEW ROUNDS OF WIDESPREAD PRECIPITATION
MONDAY THROUGH WEDNESDAY MORNING FROM THE CUT OFF LOW. THERE
REMAINS UNCERTAINTY IN HOW MUCH PRECIPITATION AND WHERE THE MAIN
PRECIPITATION AXIS WILL BE. THIS WILL MAINLY DEPEND ON HOW THIS
CUT OFF LOW EVOLVES. ENSEMBLES HAVE BEEN HINTING AT CENTRAL AND
PARTS OF SOUTHWEST MT BEING THE MAIN CORRIDOR OF PRECIPITATION.
THERE IS AT LEAST A 70-80% CHANCE FOR 0.5" OF PRECIPITATION
THERE. THERE IS ALSO A 40-60% CHANCE FOR 1" OF RAIN, AND A 20-30%
CHANCE FOR 2", MAINLY AT HIGHER TERRAIN. HEADING TOWARDS THE HI-
LINE, THERE'S A 50-70% CHANCE FOR 0.25" OF RAIN AND A 30-50%
CHANCE FOR 0.5". SINCE THIS SYSTEM IS TRENDING COOLER, FALLING
SNOW LEVELS SHOULD ALLOW FOR MOUNTAIN SNOW OVER THE HIGHER
TERRAIN. THIS WILL ALSO HELP REDUCE THE RISK FOR RIVER FLOODING
FROM RAIN ON SNOW MELT. SOME SOLUTIONS THAT TREND COOLER EVEN DROPS
SNOW LEVELS DOWN TO THE HIGHER MOUNTAIN PASSES. -WILSON
AVIATION
29/06Z TAF PERIOD
RIDGING ALOFT WILL MAINTAIN MOSTLY CLEAR SKIES THROUGH 29/18Z
BEFORE SCATTERED SHOWERS AND THUNDERSTORMS BEGIN TO INITIATE OVER
THE HIGHER TERRAIN WEST AND SOUTHWESTERN MONTANA IN RESPONSE TO
AN APPROACHING PACIFIC COLD FRONT. THIS ACTIVITY WILL MOVE OFF TO
THE EAST LATER IN THE AFTERNOON AND EVENING, MOSTLY IMPACTING THE
TERMINALS AFTER 30/00Z. THE PRIMARY HAZARD WITH THIS HIGH BASED
CONVECTION WILL BE LOCALIZED WIND GUSTS IN EXCESS OF 35 KTS WITH
THE STRONGER STORMS. - RCG
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL
AVIATION WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 51 87 54 77 / 0 20 30 0
CTB 49 86 51 78 / 0 20 20 0
HLN 53 86 54 81 / 0 20 20 0
BZN 46 82 49 77 / 0 20 20 0
WYS 38 74 41 74 / 10 40 20 10
DLN 47 81 49 77 / 0 30 10 0
HVR 51 86 56 79 / 0 0 30 0
LWT 45 79 53 72 / 0 0 20 20
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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