101
FXUS65 KTFX 040531
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1131 PM MDT FRI APR 3 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- FOG LOOKS TO DEVELOP TONIGHT ALONG AND NORTHEAST OF A
LEWISTOWN, TO GREAT FALLS, TO CUT BANK LINE, ESPECIALLY WITHIN
THE MILK RIVER VALLEY OF HILL AND BLAINE COUNTIES.
- OVERALL DRY CONDITIONS ARE EXPECTED THIS WEEKEND, BUT A FEW
SHOWERS CAN'T BE RULED OUT OVER THE PLAINS AND MOUNTAINS OF
CENTRAL AND NORTH CENTRAL MONTANA SATURDAY NIGHT AND SUNDAY AS
A WEAK FRONT MOVES SOUTH.
- WINDY CONDITIONS LOOK TO RETURN ON TUESDAY.
UPDATE
/ISSUED 644 PM MDT FRI APR 3 2026/
A FEW SHOWERS ACROSS CENTRAL AND NORTH-CENTRAL MONTANA WILL
DIMINISH WITH LOSS OF DAYTIME HEATING THIS EVENING. THE MAIN
CONCERN THEN TURNS TO DEVELOPMENT OF FOG TONIGHT AND INTO SATURDAY
MORNING. NO MENTIONABLE CHANGES WERE NEEDED THIS EVENING WITH THE
UPDATE. -AM
DISCUSSION
/ISSUED 644 PM MDT FRI APR 3 2026/
- METEOROLOGICAL OVERVIEW:
UPPER LEVEL TROUGH AND ASSOCIATED CLOSED LOW RESPONSIBLE FOR
WIDESPREAD PRECIPITATION ACROSS THE NORTHERN ROCKIES YESTERDAY AND
TODAY WILL LIFT NORTHEAST AND OVER THE UPPER MISSISSIPPI RIVER
VALLEY THROUGH TONIGHT, WITH QUASI-NORTHWEST FLOW REMAINING IN PLACE
OVER SOUTHWEST THROUGH NORTH CENTRAL MONTANA. SKIES BENEATH THIS
DRY, NORTHWEST FLOW ALOFT WILL CLEAR THROUGH THE EVENING HOURS
TONIGHT, WHICH COMBINED WITH RECENT PRECIPITATION AND/OR SNOW COVER
WILL SET THE STAGE FOR FOG DEVELOPMENT, ESPECIALLY WHERE WINDS
REMAIN LIGHT. LOW TEMPERATURES TONIGHT WILL FALL QUICKLY WHERE SNOW
COVER EXIST, WITH LOCATIONS ALONG THE IMMEDIATE EASTERN SLOPES OF
THE ROCKY MOUNTAIN FRONT WARMING BEYOND THE MIDNIGHT HOUR AS
SOUTHWEST TO WESTERLY SURFACE WINDS INCREASE. TEMPERATURES LOOK TO
REBOUND THROUGH THE DAY ON SATURDAY AS SOUTHWEST TO WEST WINDS
ACROSS THE REGION; HOWEVER, A WEAK COLD FRONT DROPPING SOUTHEAST AND
ACROSS THE PLAINS OF NORTH CENTRAL AND CENTRAL MONTANA LATE SATURDAY
WILL HELP TO COOL TEMPERATURES SLIGHTLY FOR THE DAY ON SUNDAY. WHILE
A FEW LIGHT RAIN/SNOW SHOWERS CAN'T BE RULED OUT ALONG AND BEHIND
THIS FRONT SATURDAY NIGHT AND INTO THE DAY ON SUNDAY MOST AREAS WILL
REMAIN DRY THROUGH THE WEEKEND AS UPPER LEVEL RIDGING AMPLIFIES OVER
THE WESTERN CONUS/CANADA. - MOLDAN
AN UPPER LEVEL SYSTEM THEN LOOKS TO BREAK DOWN THE RIDGE ON TUESDAY,
INITIALLY BRINGING GUSTY WESTERLY WINDS TO THE PLAINS AHEAD OF A
COLD FRONT. UPPER LEVEL TROUGHING HANGS AROUND IN SOME CAPACITY FROM
THE MIDDLE TO LATE PORTION OF NEXT WEEK, WHICH WILL AT THE VERY
LEAST COOL TEMPERATURES ACROSS THE REGION. UNCERTAINTY BUILDS WITH
RESPECT TO HOW MUCH PRECIPITATION RESULTS FROM THIS STRETCH OF
TROUGHING. -AM
- FORECAST CONFIDENCE & SCENARIOS:
REDUCED VISIBILITY THIS EVENING THROUGH SATURDAY MORNING :
HI-RES ENSEMBLE FORECAST (HREF) GUIDANCE INDICATES A 30-70% CHANCE
FOR VISIBILITIES TO FALL BELOW 3 MILES DUE TO FOG WITHIN THE MILK
RIVER VALLEY OF HILL AND BLAINE COUNTIES, WITH EVEN A 10-30% CHANCE
FOR VISIBILITIES TO FALL BELOW 0.5 MILE. ONE LIMITING FACTOR WILL BE
MID-LEVEL CLOUD COVER, WHICH COULD HOLD BACK VISIBILITIES FROM
FALLING TOO LOW. - MOLDAN
WINDS ON TUESDAY:
THE EUROPEAN EXTREME FORECAST INDEX CONTINUES TO HIGHLIGHT TUESDAY
AS A DAY FOR GUSTY WINDS, MOSTLY ACROSS THE PLAINS AND ADJACENT
AREAS. FORECAST SOUNDINGS OVER THIS TIMEFRAME DO NOT SHOW MUCH
RIDGETOP STABILITY, WHICH WILL MAKE THIS A PRESSURE GRADIENT AND
DIURNALLY DRIVEN MIXING TYPE OF EVENT. THERE IS QUITE A BIT OF
UNCERTAINTY ASSOCIATED WITH IT HOWEVER, AS COOLER AIR SINKING
SOUTHWARD FROM CANADA LATE TUESDAY AFTERNOON OR TUESDAY EVENING
WOULD SHUT DOWN THE WINDS RATHER QUICKLY. SHOULD THIS FRONT ARRIVE A
BIT QUICKER THE THREAT FOR STRONGER WINDS TUESDAY WOULD BE SHORTER
IN DURATION AND MORE LOCALIZED.
UNSETTLED WEDNESDAY THROUGH FRIDAY:
CLUSTER GUIDANCE FAVORS TROUGHING ACROSS THE REGION OVER THIS
TIMEFRAME, BUT STRUGGLES MIGHTILY WITH RESPECT TO TIMING AND
STRENGTH OF THE TROUGHING. THIS RESULTS IN A LOWER CONFIDENCE FROM A
PRECIPITATION PERSPECTIVE. CONFIDENCE IS HIGHER WITH RESPECT TO
COOLING TEMPERATURES HOWEVER. THE MAIN TAKEAWAY OVER THIS TIMEFRAME
WILL BE FOR OVERALL COOLER AND UNSETTLED CONDITIONS AT TIMES. -AM
AVIATION
04/06Z TAF PERIOD
A NORTHWESTERLY FLOW ALOFT WILL MAINTAIN SCATTERED TO BROKEN LOW
VFR CLOUDS THROUGH AROUND 04/12Z. ONCE THESE CLOUDS BEGIN TO CLEAR
OUT, PATCHY FOG WILL BEGIN DEVELOPING OVER THE WIND PROTECTED
PLAINS AND SOUTHWEST VALLEYS. THE PROBABILITIES FOR IMPACTFUL FOG
ARE GENERALLY LESS THAN 20% FOR ALL TERMINALS; HOWEVER, THE
METEOROLOGICAL SET UP FAVORS LOCALIZED INSTANCES OF MVFR/IFR FOG
OVER KBZN, KHVR, AND KLWT BETWEEN 04/10 AND 04/16Z. ON SATURDAY,
A WEAK FRONT WILL MOVE THROUGH THE PLAINS AND BRING A NORTHERLY
WIND SHIFT. A MOIST EASTERLY LOW LEVEL BECOMES MORE ESTABLISHED
OVER CENTRAL/NORTH-CENTRAL MT AFTER 05/06Z AND GRADUALLY INCREASES
MVFR/IFR STRATUS FROM NORTH TO SOUTH. - RCG
PRELIMINARY POINT TEMPS/POPS
GTF 27 57 28 50 / 10 0 10 10
CTB 27 55 26 47 / 0 0 10 10
HLN 24 58 27 58 / 0 0 0 10
BZN 19 58 24 61 / 10 0 0 0
WYS 13 48 17 56 / 0 10 10 0
DLN 21 57 26 63 / 0 0 0 0
HVR 24 57 29 47 / 10 0 10 10
LWT 23 51 28 49 / 10 0 10 10
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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