465
FXUS65 KMSO 270905
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
305 AM MDT MON APR 27 2026
DISCUSSION
KEY MESSAGES:
- FROST POSSIBLE EACH MORNING THROUGH MID WEEK
- SLOW WARMING TREND WITH LINGERING SHOWERS, ESPECIALLY DURING
THE AFTERNOON AND EVENING
A BROAD UPPER LEVEL TROUGH REMAINS THE DOMINANT FEATURE ACROSS
THE NORTHERN ROCKIES, MAINTAINING NORTH TO NORTHWESTERLY FLOW
THROUGH MIDWEEK. THIS REGIME WILL SUSTAIN UNSEASONABLY COOL
CONDITIONS AND PERSISTENT SHOWER ACTIVITY ACROSS WESTERN MONTANA
AND NORTH CENTRAL IDAHO. DIURNAL CLEARING WILL FACILITATE
EFFICIENT RADIATIONAL COOLING, PUSHING OVERNIGHT LOWS BELOW
FREEZING FOR MOST VALLEYS, WHILE HIGH-ELEVATION TERRAIN WILL
LIKELY DROP INTO THE LOW 20S. WITHIN THIS FLOW, A SERIES OF
SUBTLE SHORTWAVES WILL TRIGGER ISOLATED TO SCATTERED SHOWERS,
WITH COVERAGE AND INTENSITY PEAKING DURING THE AFTERNOON HOURS AS
MODEST INSTABILITY DEVELOPS. ACTIVITY SHOULD DIMINISH RAPIDLY
AFTER SUNSET EACH EVENING.
THE SYNOPTIC PATTERN SHIFTS SIGNIFICANTLY THURSDAY INTO FRIDAY
AS AN AMPLIFIED RIDGE OF HIGH PRESSURE BUILDS OVER THE REGION.
THIS TRANSITION WILL INITIATE A ROBUST WARMING AND DRYING TREND,
WITH FRIDAY'S MAX TEMPERATURES PROJECTED TO REACH APPROXIMATELY 10
DEGREES ABOVE SEASONAL NORMALS. WHILE THE RIDGE REMAINS THE
PRIMARY DRIVER, A WEAK DISTURBANCE TRAVERSING THE CANADIAN BORDER
MAY INTRODUCE LOCALIZED CLOUD COVER AND LIGHT PRECIPITATION ACROSS
FAR NORTHWEST MONTANA FRIDAY AFTERNOON.
LOOKING INTO THE WEEKEND AND BEYOND, LONG-TERM GUIDANCE CONTINUES
TO ADVERTISE A SIGNIFICANT LOW PRESSURE SYSTEM IMPACTING THE
WESTERN U.S., THOUGH MODEL DIVERGENCE PERSISTS REGARDING ITS EXACT
TRAJECTORY. CURRENT ENSEMBLE MODELS FAVOR A MORE SOUTHERLY TRACK
(80% PROBABILITY), KEEPING THE PRIMARY ENERGY AND DEEPER MOISTURE
WELL SOUTH OF WESTERN MONTANA AND NORTH-CENTRAL IDAHO. UNDER THIS
SCENARIO, THE REGION WOULD LIKELY SEE INCREASED SHOWER ACTIVITY
ASSOCIATED WITH THE SYSTEM'S NORTHERN PERIPHERY, THOUGH HIGH SNOW
LEVELS SHOULD MITIGATE ANY SNOW IMPACTS.
AVIATION
NORTH TO NORTHWESTERLY FLOW ALOFT WILL MAINTAIN A
REGIME OF DIURNALLY DRIVEN SHOWER ACTIVITY ACROSS WESTERN MONTANA
AND NORTH-CENTRAL IDAHO THROUGH MIDWEEK. PREDOMINANT VFR
CONDITIONS ARE EXPECTED TO PREVAIL, THOUGH LOCALIZED MVFR/IFR
REDUCTIONS IN VISIBILITY AND CEILINGS ARE POSSIBLE WITHIN MORE
ROBUST AFTERNOON SHOWERS, PARTICULARLY OVER TERRAIN WHERE MOUNTAIN
OBSCURATIONS MAY OCCUR. ANY CONVECTIVE ACTIVITY WILL DIMINISH
RAPIDLY AFTER SUNSET AS THE BOUNDARY LAYER STABILIZES. SURFACE
WINDS WILL SEE THE CURRENT EASTERLY GRADIENT GRADUALLY RELAX
THROUGH THE REMAINDER OF THE MORNING HOURS, TRANSITIONING TO A
LIGHT AND VARIABLE OR TERRAIN-DRIVEN FLOW BY THE AFTERNOON.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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