Winter Storm in Montana, November 24 to 25, 2015

Name: Winter Storm in Montana, November 24 to 25, 2015
Start: 2015-11-24T11:00
End: 2015-11-25T08:00
Location: Montana

November 24 to 25, 2015 · NWS TFX · 16 events in 14 counties and zones

A deep plume of Pacific moisture overran a cold airmass east of the Continental Divide resulting in areas of heavy snow just before the Thanksgiving holiday. Snow amounts in excess of 6 inches were common.

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 16

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS TFX wrote it up.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Great Falls, MT wrote its last area forecast discussion before the first event at Nov 24, 9:40 AM MST, 1 hour 20 minutes earlier.

Area forecast discussion, Nov 24, 9:40 AM MST, 1 hour 20 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
940 AM MST TUE NOV 24 2015

.UPDATE... LIGHT SNOW HAS BEGUN ACROSS THE NORTHWEST PORTION OF THE
FORECAST AREA, WITH REPORTS OF SNOW IN FAIRFIELD/HEART BUTTE/PENDROY
AND FLURRIES OBSERVED AT THE GREAT FALLS AIRPORT.  THE COLD FRONT,
WHICH CROSSED THE US/CAN BORDER AROUND 1:00 AM, IS CURRENTLY LOCATED
FROM NEAR SIEBEN (NORTH OF HELENA) TO LEWISTOWN.  THE FRONT WILL
CONTINUE TO TRACK SOUTHWARD TODAY, WITH STEADILY FALLING TEMPS AND
SNOW BECOMING MORE WIDESPREAD BEHIND THE FRONT. GOING FORECAST IS ON
TRACK; ONLY CHANGES WERE TO ADJUST TODAY'S HIGH TEMPERATURES DOWN A
FEW DEGREES FOR THE HILINE AND CENTRAL COUNTIES TO BETTER MATCH THE
DECREASING TEMPS.
WARANAUSKAS

&&

.DISCUSSION...

TODAY AND TONIGHT...
MODELS REMAIN IN EXCELLENT AGREEMENT WITH THE WINTER WEATHER
SYSTEM TO EFFECT THE REGION TODAY AND TONIGHT. VIGOROUS SHORTWAVE
DIGGING SOUTH ALONG THE WA COAST EARLY THIS MORNING WILL CONTINUE
SOUTH WITH A CLOSED MID TO UPPER LEVEL CIRCULATION CENTER
DEVELOPING AND MOVING INTO THE NORTHERN GREAT BASIN TONIGHT.
MOISTURE ADVECTING N/NE AHEAD OF THIS FEATURE WILL INTERACT WITH
A COLD AIRMASS SURGING SOUTH OUT OF CANADA TO PRODUCE WIDESPREAD
SNOW ACROSS ALL OF THE FORECAST AREA BY LATE THIS AFTERNOON, WHICH
CONTINUES THROUGH MUCH OF TONIGHT BEFORE DECREASING WEDNESDAY.
SURFACE COLD FRONT HAS ALREADY PASSED THROUGH GLACIER COUNTY AND
SHOULD REACH CENTRAL MT BY MID-MORNING AND SW MT THIS AFTERNOON.
TEMPERATURES FALL INTO THE 20S INITIALLY BEHIND THE FRONTAL
PASSAGE WITH FORECAST MAX TEMPS TODAY OCCURRING EARLY BEFORE THE
FRONT BRINGS FALLING TEMPS. SNOW DEVELOPS FROM NW TO SE ACROSS THE
REGION TODAY AFTER THE INITIAL FRONTAL PASSAGE. GUSTY NORTH WINDS
FOLLOWING THE FRONT WILL CONTINUE THROUGH MUCH OF TONIGHT AS
SURFACE PRESSURE CONTINUES TO RISE PRODUCING AREAS OF
BLOWING/DRIFTING SNOW. PERIOD OF GREATEST IMPACT TO TRAVEL STILL
LOOKS TO BE LATE THIS AFTERNOON THROUGH THIS EVENING WHEN SNOWFALL
RATES ARE GREATEST IN COMBINATION WITH GUSTY NORTH WINDS.

WEDNESDAY THROUGH THANKSGIVING DAY...
SNOW WILL GRADUALLY DECREASE FROM NORTH TO SOUTH WEDNESDAY, ENDING
IN THE NORTH WEDNESDAY AFTERNOON AND IN THE SOUTH WEDNESDAY NIGHT.
TEMPERATURES CONTINUE TO FALL UNDER COLD ADVECTION TUESDAY NIGHT
WITH LITTLE CHANGE ON WEDNESDAY. COLDEST TEMPERATURES OF THE
SEASON THUS FAR ARE LIKELY WEDNESDAY NIGHT, PARTICULARLY ACROSS
CENTRAL AND NORTH CENTRAL MT WHERE SOME CLEARING IS LIKELY AND
WIND WILL BE RELATIVELY LIGHT WITH FRESH SNOW COVER. BY THURSDAY,
COLD SURFACE HIGH PRESSURE WILL BE CENTERED OVER MT WITH UPPER
LEVEL RIDGING BUILDING IN FROM THE NW FOR DRY BUT COLD CONDITIONS.
HOENISCH

FRIDAY THROUGH TUESDAY...MAINLY DRY CONDITIONS ARE EXPECTED
THROUGH THE FIRST HALF OF THE HOLIDAY WEEKEND. FORECAST MODELS
CONTINUE TO REMAIN IN GENERAL AGREEMENT WITH DEVELOPING A BLOCKING
PATTERN AS A CLOSED LOW MOVES OVER THE GREAT BASIN REGION AND AN
UPPER RIDGE BUILDS ACROSS THE EASTERN PACIFIC. HOWEVER...THERE ARE
SOME DIFFERENCES BETWEEN THE GFS AND ECMWF REGARDING THE TRACK OF
THE CLOSED LOW AND EMBEDDED SHORTWAVES. BOTH MODELS INDICATE
INCREASING MOISTURE AND POSSIBLE PRECIPITATION INTO CENTRAL AND
EASTERN MONTANA ON SUNDAY AND MONDAY AS WEAK ENERGY BREAKS OFF FROM
THE MAIN CLOSED LOW. HAVE INCREASED POPS TO SLIGHT CHANCE FOR
CENTRAL AND EASTERN PORTIONS OF THE FORECAST AREA DURING THIS TIME
PERIOD BUT LITTLE PRECIPITATION IS EXPECTED.

THOUGH TEMPERATURES WILL GRADUALLY WARM THROUGH THE FORECAST
PERIOD...HIGHS WILL REMAIN BELOW SEASONAL AVERAGES THROUGH EARLY
NEXT WEEK. HIGHS ON FRIDAY WILL BE IN THE 20S...LOW TO MID 30S ON
SATURDAY AND SUNDAY...THEN 30S TO LOW 40S EARLY NEXT WEEK. OVERNIGHT
LOWS WILL BE IN THE SINGLE DIGITS AND TEENS. MLV

&&

.AVIATION...
UPDATED 1200Z.
SURFACE COLD FRONT WILL PUSH SOUTH THROUGH THE REGION REACHING KGTF
AND KHVR BY 14Z, KHLN AND KLWT BY 17Z AND KBZN BY 22Z. WIND SHIFT TO
THE NORTH WILL FOLLOW THE FRONTAL PASSAGE WITH GUSTS 20-30KTS
CONTINUING THROUGH THIS EVENING. IFR/LIFR WILL FOLLOW THE FRONT AS
WELL, INITIALLY DUE TO LOW CIGS WITH SNOW DEVELOPING SEVERAL HRS
BEHIND THE FRONTAL PASSAGE BRINGING ADDITIONAL VIS REDUCTIONS.
WIDESPREAD LOW CIGS/VIS...MOUNTAIN OBSCURATION AND IFR/LIFR
CONDITIONS WILL PERSIST ACROSS THE AREA INTO WEDNESDAY MORNING WITH
GRADUAL IMPROVEMENT FROM N TO S WEDNESDAY AFTERNOON. HOENISCH

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  11  14  -2 / 100 100  60  10
CTB  28   5  12   1 / 100  80  30  10
HLN  37  14  18   0 /  90 100  60  30
BZN  40  17  24   3 /  50  80  70  40
WEY  33  16  21   2 /  10  60  70  70
DLN  39  14  19   3 /  20  80  60  50
HVR  35  15  20   4 /  60  70  30   0
LWT  36  14  17  -1 /  70 100  80  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 11 AM THIS MORNING TO 11 PM MST
WEDNESDAY FOR MTZ009-010-012>014-046-048>054.

WINTER WEATHER ADVISORY FROM 11 AM THIS MORNING TO 8 AM MST
WEDNESDAY FOR MTZ011-044-045-047.

WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO 11 PM MST
WEDNESDAY FOR MTZ008-015-055.

&&

WEATHER.GOV/GREATFALLS

Event by event

16 winter storm. Local standard time, as filed.

Winter Storm, Jefferson

When: November 24, 11:00 AM MST to November 25, 8:00 AM MST
Where: Jefferson forecast zone
Reported by: Trained Spotter

Nine inches of snow fell at Clancy 2N.

Winter Storm, Cascade

When: November 24, 11:00 AM MST to November 25, 8:00 AM MST
Where: Cascade forecast zone
Reported by: Public

Eight inches of snow fell at Great Falls 4S. Also, eight inches of snow fell at Ulm 11SSE.

Winter Storm, Fergus

When: November 24, 11:00 AM MST to November 25, 8:00 AM MST
Where: Fergus forecast zone
Reported by: Other Federal Agency

Six inches of snow fell at Lewistown 1SW.

Winter Storm, Southern Lewis and Clark

When: November 24, 11:00 AM MST to November 25, 8:00 AM MST
Where: Southern Lewis and Clark forecast zone
Reported by: Law Enforcement

Numerous vehicle accidents due to icy and snow-covered roads between Wolf Creek and Helena as well as low visibility in heavy snow. KHLN reported less than 0.50 mile visibility between 1100 and 1600 LST.

Winter Storm, Beaverhead

When: November 24, 11:00 AM MST to November 25, 8:00 AM MST
Where: Beaverhead forecast zone
Reported by: CoCoRaHS

Measured snowfall 3.5 inches. Roads were snow-covered and icy causing difficult travel conditions.

Winter Storm, Gallatin

When: November 24, 11:00 AM MST to November 25, 8:00 AM MST
Where: Gallatin forecast zone
Reported by: CoCoRaHS

Observer 1.5 miles SSE of Bozeman measured 5.5 inches of snow. Roads were snow-covered and icy causing difficult travel conditions during a high-impact period of the Thanksgiving holiday travel period.