985
FXUS65 KTFX 181113
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
513 AM MDT SUN OCT 18 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- THE BEGINNING OF THE WEEK WILL FEATURE NEAR NORMAL HIGH TEMPERATURES,
WITH ABOVE NORMAL TEMPERATURES PUSHING IN WEDNESDAY THROUGH
FRIDAY.
- SOUTHWEST FLOW WILL BRING DAILY INCREASED CHANCES OF PRECIPITATION
DURING THE AFTERNOON HOURS TUESDAY AND WEDNESDAY.
- PRECIPITATION CHANCES INCREASE AREA WIDE TOWARDS THE END OF
THE WORK WEEK WITH TEMPERATURES RETURNING TO NEAR OR SLIGHTLY
BELOW NORMAL.
DISCUSSION
/ISSUED 1204 AM MDT SUN OCT 18 2026/
- METEOROLOGICAL OVERVIEW:
IN THE WAKE OF SATURDAYS HIGH WIND EVENT, A MUCH CALMER REGIME TAKES
HOLD AS UPPER-LEVEL RIDGING BUILDS OVERHEAD. GENERALLY CALMER, LIGHT
WINDS WILL TAKE HOLD AS NEAR NORMAL TEMPERATURES SETTLE IN ACROSS
THE AREA SUNDAY THROUGH TUESDAY.
BY MIDWEEK, SPLIT FLOW ESTABLISHES OVER THE WESTERN CONUS, LEAVING A
CUTOFF LOW CENTERED OFF THE COAST OF CALIFORNIA AND ALLOWING
STRONGER RIDGING TO EXPAND WESTWARD ACROSS THE NORTHERN ROCKIES AND
NORTHERN PLAINS. THIS PATTERN INDUCES SOUTHWESTERLY FLOW ALOFT OVER
MONTANA, DRIVING A WARMING TREND WEDNESDAY THROUGH THE END OF THE
WORKWEEK. THE SOUTHWESTERLY FLOW WILL ALSO CHANNEL INCREASED
MOISTURE INTO THE AREA, RESULTING IN THE RETURN OF DAILY CHANCES OF
AFTERNOON SHOWERS LARGELY FOCUSED ACROSS SOUTHWEST MONTANA TUESDAY
THROUGH THURSDAY.
HEADING INTO NEXT WEEKEND, THE CUTOFF LOW OFF THE CALIFORNIA COAST
BEGINS TO RE-MERGE WITH THE MAIN JET STREAM THANKS TO A DIGGING
TROUGH THAT ORIGINATES FROM ALASKA DIPS SOUTHWARD OVER THE
PACIFIC NORTHWEST. MODEL CONSENSUS FAVORS THIS FEATURE
TRANSITIONING INTO AN OPEN SHORTWAVE AS IT PUSHES EAST ACROSS THE
REGION. THIS PROGRESSION WILL BRING INCREASED CHANCES FOR MORE
WIDESPREAD PRECIPITATION ALONGSIDE A DROP IN HIGH TEMPERATURE BACK
DOWN TO NEAR OR SLIGHTLY BELOW SEASONAL AVERAGES. WINDS THROUGH
THE ENTIRE FORECAST PERIOD ARE EXPECTED TO REMAIN GENERALLY LIGHT,
WITH THE EXCEPTION OF WEDNESDAY WHICH WILL SEE SLIGHTLY BREEZIER
CONDITIONS AS WE ADVECT WARMER AIR IN FROM THE SOUTH/SOUTHEAST.
-JR
-FORECAST CONFIDENCE & SCENARIOS:
CONFIDENCE IS HIGH FOR LIGHT WINDS AND NEAR-NORMAL TEMPERATURES
THROUGH TUESDAY UNDER WEAK RIDGING, FOLLOWED BY ABOVE-NORMAL
TEMPERATURES WEDNESDAY THROUGH FRIDAY AS THE RIDGE AXIS EXPANDS
FURTHER WEST. CONFIDENCE IS ALSO MODERATE TO HIGH FOR SCATTERED,
DIURNALLY DRIVEN AFTERNOON SHOWERS REMAINING LARGELY CONFINED TO
SOUTHWEST MONTANA TUESDAY THROUGH THURSDAY.
CONFIDENCE IS LOW REGARDING NEXT WEEKENDS SYSTEM DUE TO DIVERGENCE
AMONG BOTH DETERMINISTIC AND ENSEMBLE GUIDANCE ON HOW THE CUTOFF
LOW INTERACTS WITH THE BROADER JET:
-SCENARIO 1 (OPEN PROGRESSIVE SHORTWAVE - FAVORED): THE
CUTOFF LOW PHASES SMOOTHLY INTO THE NORTHERN BRANCH AS AN
OPEN WAVE, BRINGING A FAIRLY QUICK ROUND OF MORE WIDESPREAD
PRECIPITATION AND COOLING TEMPERATURES BACK NEAR OR SLIGHTLY
BELOW AVERAGE.
-SCENARIO 2 (SLOWER/DEEPER PHASING): IF THE CUTOFF LOW LINGERS
LONGER OFF THE COAST, OR PHASES MORE AGGRESSIVELY WITH
INCOMING NORTHER-STREAM ENERGY, PRECIPITATION TIMING COULD
SLOW DOWN, POTENTIALLY PROLONGING MOISTURE STREAMING FROM THE
SOUTHWEST AND BRINGING A SHARPER DROP IN TEMPERATURES ONCE
THE EVENTUAL TROUGHING PUSHES THROUGH.
-JR
AVIATION
18/12Z TAF PERIOD
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE 1812/1912 TAF PERIOD,
WITH PERIODS OF BROKEN TO SCATTERED UPPER LEVEL CLOUDINESS. -
MOLDAN
PRELIMINARY POINT TEMPS/POPS
GTF 60 38 71 41 / 0 0 0 0
CTB 57 32 61 36 / 0 0 0 0
HLN 62 34 67 38 / 0 0 0 0
BZN 60 31 66 34 / 0 0 0 0
WYS 57 23 59 25 / 0 0 0 0
DLN 60 32 63 34 / 0 0 0 0
HVR 62 35 66 36 / 0 0 0 0
LWT 58 35 71 40 / 0 0 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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