494
FXUS65 KMSO 172144
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
244 PM MST MON FEB 17 2020
DISCUSSION
NORTHWEST FLOW AND COLD AIR ALOFT WILL CONTINUE TO PRODUCE BANDED
SNOW FEATURES AT TIMES ACROSS WEST CENTRAL MONTANA THROUGH AT LEAST
TUESDAY AFTERNOON. HIGH-RESOLUTION MODELS SUGGEST A PERIOD OF
STRENGTHENED SNOW BANDS BOTH THIS EVENING THROUGH TONIGHT, AND AGAIN
TUESDAY MIDDAY THROUGH TUESDAY LATE AFTERNOON. THERE IS REASONABLE
CONFIDENCE IN THE SNOW BANDS DEVELOPING, HOWEVER THERE IS MUCH LESS
CONFIDENCE IN THE FORECAST SNOW ACCUMULATION. BE AWARE THAT THIS
TYPE OF SCENARIO IS CAPABLE TO PRODUCE FAST SNOW ACCUMULATIONS AND
CAN HAVE A PROFOUND IMPACT ON CHANGING ROAD CONDITIONS FROM
COMPLETELY DRY TO NEARLY IMPASSIBLE IN UNDER 15 MINUTES.
TEMPERATURES WILL COOL INCREDIBLY OVERNIGHT TONIGHT FOR AREAS THAT
CLEAR OUT, SUCH AS SOUTHERN IDAHO COUNTY (E.G., DIXIE) AND SOUTHERN
LEMHI COUNTY (E.G., LEADORE). FOR THE REST OF THE NORTHERN ROCKIES
TONIGHT, CLOUD COVER AND THE UNSTABLE AIR ALOFT WILL PREVENT
TEMPERATURES FROM COOLING RAPIDLY OVER THE RECENT SNOW COVER.
A RIDGE OF HIGH PRESSURE WILL BUILD OVER THE NORTHERN ROCKIES FOR
THE LATTER PART OF THE WORK WEEK. THIS RIDGE SHOULD ALLOW FOR
CLEAR SKIES AT NIGHT WHICH IN TURN WILL ALLOW SNOW COVERED VALLEYS
TO COOL OFF DRAMATICALLY. HIGH ELEVATION VALLEYS HAVE A HIGH
POTENTIAL OF EXPERIENCING TEMPERATURES TO DROP BELOW ZERO BY
WEDNESDAY AND THURSDAY MORNING. THE DEVELOPMENT OF PATCHY FOG OR
LOW STRATUS EACH MORNING. THE FOG COULD HINDER ON HOW COLD AN AREA
COULD POTENTIALLY GET. THE VALLEY INVERSIONS COULD LINGER
THROUGHOUT THE DAY KEEPING TEMPERATURES FROM WARMING DRAMATICALLY
EACH DAY.
THE MODELS ARE TRENDING TOWARDS THE NORTHERN ROCKIES MOVING BACK
TO AN ACTIVE WEATHER PATTERN BY SUNDAY INTO NEXT WEEK.
AVIATION
NORTHERN ROCKIES AIR SPACE WILL EXPERIENCE HIGHLY
VARIABLE CLOUD AND VISIBILITY CONDITIONS THROUGH TUESDAY. BANDED
SNOW FEATURES WILL EXIST AT TIMES, LOWERING CEILINGS AND
VISIBILITY RAPIDLY. THE MAJORITY OF SNOW FEATURES WILL BE SITUATED
NEAR KMSO, KBTM, AND ALONG THE CONTINENTAL DIVIDE NORTH OF KBTM.
KGPI MAY ALSO EXPERIENCE BRIEF VISIBILITY AND CEILING REDUCTIONS
THROUGH 18/0000Z DUE TO SNOW, HOWEVER ACTIVITY IS ANTICIPATED TO
LESSEN NEARBY THEREAFTER. ALSO, ANY SNOW FEATURES OCCURRING
THROUGH 18/0200Z WILL PRODUCE WIND GUSTS TO 25 KNOTS AT TIMES.
MOST HIGH TERRAIN WILL BE OBSCURED, HOWEVER NOT CONTINUOUSLY,
THROUGH TUESDAY.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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