187
FXUS65 KTFX 281142
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
542 AM MDT WED MAY 28 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- WARM AND MOSTLY DRY CONDITIONS ARE EXPECTED THROUGH THE
WEEKEND WITH THE WARMEST TEMPERATURES EXPECTED ON THURSDAY AND
SATURDAY.
- A PACIFIC FRONT WILL BRING SCATTERED SHOWERS AND
THUNDERSTORMS LATE THURSDAY AFTERNOON AND EVENING, SOME MAY
CONTAIN LOCALIZED STRONG, GUSTY WINDS, BRIEF DOWNPOURS, AND
SMALL HAIL.
- ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ARE EXPECTED
LATE SATURDAY INTO SUNDAY BEFORE COOLER AND WETTER CONDITIONS
MOVE IN EARLY NEXT WEEK.
DISCUSSION
/ISSUED 212 AM MDT WED MAY 28 2025/
- METEOROLOGICAL OVERVIEW:
RIDGING ALOFT WILL MAINTAIN MOSTLY DRY CONDITIONS THROUGH
THURSDAY WITH MERELY A RISK FOR A STRAY MOUNTAIN SHOWER OR STORM.
LOWER ELEVATION HIGH TEMPERATURES WARM WELL INTO THE 80S TO NEAR
90 BY THURSDAY. THERE WILL ONLY BE A BRIEF AND MODEST COOL DOWN ON
FRIDAY FOLLOWING A COLD FRONTAL PASSAGE BEFORE THE RIDGING
REORGANIZES AND BRINGS A RETURN OF VERY WARM TO HOT TEMPERATURES
ON SATURDAY.
AN OPEN SHORTWAVE AND ATTENDANT COLD FRONT WILL PASS THROUGH THE
REGION LATE THURSDAY AFTERNOON AND EVENING AND BRING A QUICK ROUND
OF SCATTERED SHOWERS AND THUNDERSTORMS. THIS SYSTEM LOOKS TO HAVE
DECENT DYNAMICS WITH H700/H500 TEMPERATURES AROUND 5C/-10C AND
WIND SPEED ALOFT GENERALLY RUNNING IN THE 30 TO 50 KT RANGE.
STRONG AND GUSTY WINDS WILL BE A CONCERN WITH ANY SHOWER OR
THUNDERSTORM DEVELOPMENT GIVEN THE AVAILABILITY OF WINDS ALOFT
TRANSFERRING TO THE SURFACE AND THE WARM AND DRY SURFACE
CONDITIONS PRIOR TO THE FRONT'S ARRIVAL. INITIALLY THIS SYSTEM
APPEARED TO BE LACKING MOISTURE, BUT NEWER MODEL GUIDANCE NOW
BRING A STRIPE OF 'JUST IN TIME' MOISTURE WITH PRECIPITABLE WATER
VALUES APPROACHING THE THREE QUARTERS TO ONE INCH MARK. BRIEF
DOWNPOURS AND HAIL WILL ALSO BE ADDED TO THE EQUATION SHOULD THIS
MOISTURE AVAILABILITY COME TO FRUITION.
A DEEP TROUGH DIGS INTO THE PACIFIC NORTHWEST AND FORCES
SOUTHWESTERLY FLOW ALOFT OVER THE NORTHERN ROCKIES DURING THE
SECOND HALF OF THE WEEKEND. ALTHOUGH THERE ARE STILL SOME TIMING
STORM EVOLUTION UNCERTAINTIES TO WORKOUT, A COLD FRONTAL PASSAGE
LATE SATURDAY INTO SUNDAY LOOKS TO USHER IN A PERIOD OF COOLER AND
WETTER CONDITIONS EARLY NEXT WEEK WHILE THE MOISTURE LADEN
PACIFIC TROUGH CHURNS AND HEADS INTO THE NORTHERN ROCKIES. - RCG
- FORECAST CONFIDENCE & SCENARIOS:
SHOWERS AND THUNDERSTORMS THURSDAY EVENING INTO EARLY FRIDAY...
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG
AN EASTWARD ADVANCING COLD FRONT BY THURSDAY EVENING. THE PRIMARY
CONCERN WILL BE GUSTY THUNDERSTORM WINDS WITH VERY WARM AND DRY
SURFACE CONDITIONS AHEAD OF THE FRONT (DCAPE > 1,000 J/KG), ALONG
WITH COLD AIR ADVECTION AND A STRONGER WIND PROFILE ALOFT BEHIND
THE FRONT. PROBABILISTIC GUIDANCE AND OTHER ANOMALY INDICATOR
INDICES ARE STILL NOT YET ON BOARD WITH MERELY A 40 TO 60% CHANCE
FOR GUSTS EXCEEDING 45 MPH ALONG THE NORTHERN ROCKY MOUNTAIN FRONT
AND THE ADJACENT HIGH PLAINS WEST OF I15. NORTH-CENTRAL LOCATIONS
WILL BE MOST SUSCEPTIBLE TO THE STRONGER GUSTS DUE TO THE
SHORTWAVE'S FORCING BEING GREATEST OVER THE PLAINS. NEWER MODEL
GUIDANCE INCLUDING THE NAEFS STATISTICAL ANOMALY INDEX HAVE
INCREASED MOISTURE AVAILABILITY WITH THIS SYSTEM WITH PRECIPITABLE
WATER VALUES AS HIGH AS THREE QUARTERS TO ONE INCH; HOWEVER, CAPE
SEEMS TO BE A LIMITING FACTOR AT AROUND 500 J/KG OR LESS. STILL
THE STRONGER STORMS MAY CONTAIN BRIEF DOWNPOURS AND SMALL HAIL IN
ADDITION TO WIND GUSTS. A FEW SHOWERS AND THUNDERSTORMS MAY LINGER
OR REDEVELOP ON FRIDAY VIA A MOIST NORTHWESTERLY FLOW ALOFT ON
THE BACK SIDE OF THE SYSTEM. - RCG
COOL AND WET CONDITIONS EARLY NEXT WEEK...
VERY WARM AND DRY CONDITIONS MORE OR LESS PERSIST THROUGH LATE
SATURDAY INTO SUNDAY BEFORE A TROUGH DIGS INTO THE PACIFIC
NORTHWEST AND SENDS A COLD FRONT MOVING THROUGH THE STATE. A ROUND
OF SHOWERS AND THUNDERSTORMS CAN BE EXPECTED DURING THE
TRANSITION. MOST ENSEMBLE MEMBERS STILL SUPPORT THE PACIFIC
NORTHWEST TROUGH MOVING EASTWARD INTO THE INTERIOR WEST AND
BRINGING WIDESPREAD RAIN, HIGH MOUNTAIN SNOW, AND WELL BELOW
AVERAGE TEMPERATURES DURING THE FIRST PART OF NEXT WEEK; HOWEVER,
THERE ARE FINER POSITIONING AND TIMING SOLUTIONS TO SORT OUT GIVEN
THE HIGHER UNCERTAINTY PREDICTING THE EVOLUTION OF CLOSED LOW
PRESSURE SYSTEMS.
THE NBM PROBABILISTIC GUIDANCE HAS INCREASED SOME OVER THE LAST
24 HOURS WITH SUPPORT FOR WIDESPREAD RAINFALL AMOUNTS BETWEEN A
QUARTER AND ONE INCH BETWEEN MONDAY AND WEDNESDAY, HEAVIEST OVER
CENTRAL AND SOUTHWEST MONTANA. WHILE PROBABILISTIC GUIDANCE HAS
BEEN TARGETING CENTRAL AND SOUTHWEST MONTANA FROM THE BEGINNING,
IT HAS BEEN EVEN MORE EVIDENT WITH THE LATEST MODEL RUNS. MOST OF
THESE AREAS NOW HAVE A 60 TO 80% CHANCE FOR EXCEEDING A HALF INCH
OF RAINFALL DURING THIS TIMEFRAME AND A 40 TO 70% CHANCE FOR ONE
INCH OR MORE. AREAS ALONG THE NORTHERN ROCKY MOUNTAIN FRONT AND
THE HI- LINE HAVE DROPPED OFF TO 20 TO 40% CHANCE FOR A HALF INCH
AND LESS THAN 20% CHANCE FOR ONE INCH TOTALS. - RCG
AVIATION
28/12Z TAF PERIOD
RIDGING ALOFT BUILDS IN OVER THE NEXT 24 HOURS FOR VFR CONDITIONS;
HOWEVER, LINGERING NORTHWESTERLY FLOW ALOFT WILL MAINTAIN PASSING
MID- AND HIGHER LEVEL CLOUDS FOR THE FIRST HALF OF THE PERIOD.
WINDS WILL BECOME EASTERLY FOR MOST CENTRAL/NORTH-CENTRAL
LOCATIONS AND WILL MOSTLY BE LIGHT AND VARIABLE IN THE SOUTHWEST.
- RCG
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL
AVIATION WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 78 50 88 54 / 0 0 10 20
CTB 78 49 87 52 / 0 0 10 20
HLN 80 52 87 55 / 10 0 10 20
BZN 77 46 83 50 / 0 0 10 10
WYS 71 38 75 41 / 20 10 30 10
DLN 75 48 81 50 / 10 10 10 10
HVR 81 51 88 56 / 0 0 0 30
LWT 73 47 79 54 / 10 10 0 20
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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