Low pressure moving across Southern Canada combined with high pressure over Idaho and Utah resulted in a tight pressure gradient along the east slopes of the Rocky Mountain Divide. High winds were observed in Stillwater, Sweet Grass and Wheatland Counties.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
The episode as NWS BYZ wrote it up.
Low pressure moving across Southern Canada combined with high pressure over Idaho and Utah resulted in a tight pressure gradient along the east slopes of the Rocky Mountain Divide. High winds were observed in Stillwater, Sweet Grass and Wheatland Counties.
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 Billings, MT wrote its last area forecast discussion before the first event at Jan 5, 8:43 PM MST, 3 hours 16 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
843 PM MST WED JAN 5 2011
.SHORT TERM...VALID FOR THU AND FRI...
UPDATE TO FORECAST FOR TONIGHT. BIGGEST CHANGE FOR TONIGHT WAS TO
LOWER MINIMUM TEMPERATURES ACROSS THE FORECAST AREA AS A FEW
LOCATIONS HAD ALREADY EXCEEDED FORECAST LOWS. ONLY LOWERED
TEMPERATURES 4 TO 5 DEGREES WITH CLOUD COVER AND WINDS PROVIDING
GOOD MIXING THROUGH THE NIGHT. WINDS HITTING ADVISORY CRITERIA IN
LIVINGSTON THIS EVENING WITH SUSTAINED WINDS OF 42 MPH. CURRENT
ADVISORY FOR THAT AREA IN GOOD SHAPE AND NO CHANGES MADE. WINDS
20 TO 30 MPH NEAR NYE BUT EXPECT THEM TO INCREASE BY 06Z AS THE
PRESSURE GRADIENT CONTINUES TO TIGHTEN. WILL ALSO CONTINUE HIGH
WIND WARNING FROM BIG TIMBER NORTH TO HARLOWTON TONIGHT. CROSS
SECTIONS SHOWING 50KT WINDS NEAR MOUNTAIN TOP LEVEL OVER THE
CRAZIES. STRONG SUBSIDENCE ALONG THE EAST SLOPES SHOULD ALLOW
SUSTAINED WINDS TO INCREASE TO 40KTS OVERNIGHT AND THURSDAY.
CALLS TO LOCAL LAW ENFORCEMENT OVER THE WESTERN AND NORTHERN
ZONES INDICATE STRONG WINDS BUT NO VISIBILITY RESTRICTIONS DUE TO
BLOWING OR DRIFTING OF SNOW.
FOR THE REMAINDER OF THE FORECAST AREA...UNSTABLE NORTHWEST FLOW
ALOFT WITH MODELS INDICATING SOME EMBEDDED ENERGY. MOISTURE IS
VERY LIMITED AND IS MAINLY AT 700MB. HAVE LOWERED POPS OVER THE
EASTERN ZONES FOR TONIGHT AND CONTINUED TO MENTION JUST A FEW
SPRINKLES OR FLURRIES. RICHMOND
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
POTENTIAL FOR SNOW AND ARCTIC OUTBREAK STILL ON TRACK FOR THE
WEEKEND INTO NEXT WEEK. MAIN CHANGES TO FORECAST WERE TO BOOST POPS
SUN AND SUN NIGHT...AND TO LOWER TEMPERATURES NEXT WEEK.
ENERGY IN THE GULF OF AK THIS AFTERNOON...PER WATER VAPOR IMAGERY...
WILL DEVELOP INTO A CUTOFF UPPER LOW AND DIVE SE INTO NW MT ON SAT.
UPPER DIFLUENCE AND STRONG Q-VECTOR CONVERGENCE WILL PRECEDE THE
SYSTEM. THE SYSTEM WILL ELONGATE AS IT MOVES THROUGH THE FORECAST
AREA SAT NIGHT THROUGH SUN NIGHT. THE MODELS WERE IN GOOD AGREEMENT
WITH THE SYSTEM AND SHOWED A LARGE AMOUNT OF PACIFIC MOISTURE
ACCOMPANYING IT. FAIRLY STRONG FRONTOGENESIS WILL MOVE THROUGH THE
AREA LATE SAT INTO SAT EVENING. THE COMBINATION OF THE DYNAMICS AND
MOISTURE WILL BRING THE LIKELIHOOD OF SNOW TO THE AREA SAT AND SAT
NIGHT. AT THIS TIME IT APPEARS SEVERAL INCHES OF SNOW WILL OCCUR
ACROSS THE AREA EACH PERIOD. THE SNOW AMOUNTS WILL DEPEND UPON THE
TEMPERATURES AND STRENGTH OF THE LIFT. TEMPERATURES WILL BE NEAR
NORMAL ON SAT AHEAD OF THE SYSTEM AND HAVE RAISED THE HIGHS A BIT.
ARCTIC AIR WILL PLUNGE S INTO THE REGION SAT NIGHT THROUGH SUN NIGHT
BRINGING A DRASTIC TEMPERATURE CHANGE. LOWERED THE MINS A LITTLE FOR
SAT NIGHT AND EXPECT HIGHS ONLY IN THE SINGLE DIGITS FOR SUN. BASED
ON THE POSITION OF THE 700 MB LOW OVER THE EASTERN ZONES...HAVE
RAISED POPS TO HIGH CHANCE E OF KBIL ON SUN. WENT WITH CHANCE POPS SUN
NIGHT AND MIN TEMPERATURES BELOW ZERO.
THE MODELS DID NOT LINE UP AS WELL BEGINNING ON MON AND THE ECMWF
WAS COLDER AT 850 MB THAN THE GFS. DESPITE THE DIFFERENCES...THE
CHANCES FOR SNOW WILL BE SLIGHT FOR MON AND ARCTIC AIR WILL REMAIN
ENTRENCHED OVER THE AREA THROUGH MIDWEEK. THE NEXT CHANCE OF SNOW
WILL BE ON WED AT THE END OF THE PERIOD AS WARM ADVECTION ALOFT AND
PACIFIC MOISTURE MOVE INTO THE AREA. HAVE LOWERED THE TEMPERATURES
THROUGH MUCH OF THE WEEK DUE TO 850 MB TEMPERATURES FORECAST TO BE
IN THE TEENS TO 20S BELOW ZERO CELSIUS. GUIDANCE LOOKED TOO WARM
THROUGH MOST OF THE PERIOD. ARTHUR
&&
.AVIATION...
GUSTY WINDS WILL CONTINUE FROM JUDITH GAP SOUTH TO THE BEARTOOTH
FOOTHILLS THROUGH THURSDAY. WINDS OF 35 TO 50 KT WITH GUSTS TO 55
KT CAN BE EXPECTED IN THESE AREAS. OVER KLVM...WINDS WILL GUST TO
65 KT. LLWS WILL OCCUR OVER KBIL...KMLS AND KSHR THROUGH THURSDAY
AS WELL.
EXPECT AREAS OF MOUNTAIN OBSCURATION TONIGHT THROUGH THURSDAY DUE
TO SNOW SHOWERS. A FEW SNOW SHOWERS WILL BE POSSIBLE OVER KLVM ON
THURSDAY WITH MVFR CONDITIONS POSSIBLE. SOLUM
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 030/044 028/036 026/032 006/009 903/002 907/006 907/012
00/N 33/J 47/S 64/S 32/J 11/B 22/S
LVM 030/041 023/037 024/031 009/012 902/004 907/008 908/015
12/W 23/W 47/S 64/S 32/J 11/B 22/S
HDN 024/042 028/035 025/032 005/008 904/001 912/006 909/011
11/N 33/J 56/S 64/S 32/J 11/B 12/S
MLS 024/041 025/030 018/024 000/003 906/901 916/001 912/007
12/W 23/J 57/S 65/S 32/J 11/B 12/S
4BQ 024/042 026/033 020/027 005/008 904/001 911/004 913/011
11/N 32/J 56/S 65/S 32/J 11/B 12/S
BHK 022/035 021/027 011/018 903/000 909/904 913/000 915/007
12/W 22/J 56/S 65/S 32/J 11/B 12/S
SHR 023/044 027/035 024/032 005/008 905/000 912/006 910/014
11/E 23/J 46/S 64/S 22/J 11/B 12/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...HIGH WIND WARNING IN EFFECT UNTIL 6 PM MST THURSDAY FOR ZONES
28-41-63.
WIND ADVISORY IN EFFECT UNTIL 5 PM MST THURSDAY FOR ZONES
65-66.
WY...NONE.
&&
WEATHER.GOV/BILLINGSHAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BILLINGS MT 851 PM MST WED JAN 5 2011 MTZ028>042-056>058-063>068-WYZ098-099-070400- SOUTHERN WHEATLAND-MUSSELSHELL-TREASURE-NORTHERN ROSEBUD-CUSTER- FALLON-NORTHERN STILLWATER-YELLOWSTONE-POWDER RIVER-CARTER- SOUTHERN BIG HORN-EASTERN CARBON-NORTHERN PARK- NORTHERN SWEET GRASS-GOLDEN VALLEY-RED LODGE FOOTHILLS- NORTHERN BIG HORN-SOUTHERN ROSEBUD-JUDITH GAP-PARADISE VALLEY- LIVINGSTON AREA-BEARTOOTH FOOTHILLS-ABSAROKA/BEARTOOTH MOUNTAINS- CRAZY MOUNTAINS-NORTHEAST BIG HORN MOUNTAINS-SHERIDAN FOOTHILLS- 851 PM MST WED JAN 5 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL MONTANA...SOUTH CENTRAL MONTANA...SOUTHEAST MONTANA AND NORTH CENTRAL WYOMING. .DAY ONE...TONIGHT STRONG SOUTHWEST TO WEST WINDS WILL CONTINUE ALONG THE EASTERN SLOPES OF THE MOUNTAINS FROM LIVINGSTON AND NYE TO BIG TIMBER AND HARLOWTON. ANYONE PLANNING TO TRAVEL IN THESE AREAS CAN EXPECT DANGEROUS CROSS WINDS...ESPECIALLY ALONG PORTIONS OF I-90 FROM LIVINGSTON TO BIG TIMBER...AND ALONG HIGHWAY 191 FROM BIG TIMBER TO JUDITH GAP. TEMPERATURES WILL FALL INTO THE UPPER 20S OVERNIGHT AND WILL CAUSE ROADWAYS TO BECOME VERY ICY. THE COMBINATION OF STRONG WINDS AND ICY ROADWAYS WILL CREATE HAZARDOUS TRAVELING CONDITIONS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH WEDNESDAY STRONG SOUTHWEST TO WEST WINDS WILL CONTINUE ALONG THE EASTERN SLOPES OF THE MOUNTAINS THURSDAY. LOCATIONS WHICH WILL BE AFFECTED BY STRONG WINDS INCLUDE NYE...LIVINGSTON...BIG TIMBER AND HARLOWTON. THE STRONGEST WINDS ARE EXPECTED NEAR LIVINGSTON AND NYE THURSDAY MORNING...WHEN GUSTS MAY REACH 70 MPH. THOUGH NOT AS STRONG AS WINDS FURTHER WEST...GUSTY WINDS WILL SPREAD WELL OUT INTO THE PLAINS ON THURSDAY WITH GUSTS OF 35 TO 45 MPH COMMON. TRAVELERS ALONG INTERSTATE 90 FROM BIG TIMBER TO LIVINGSTON AND ALONG HIGHWAY 191 FROM BIG TIMBER TO JUDITH GAP SHOULD BE PREPARED FOR DANGEROUS CROSS WINDS. A STRONG PACIFIC STORM SYSTEM WILL MOVE INTO THE NORTHERN ROCKIES THIS WEEKEND...BRINGING THE POTENTIAL FOR SIGNIFICANT SNOW ACCUMULATIONS. THOUGH DETAILS ARE UNCERTAIN AT THIS TIME... SIGNIFICANT SNOWFALL AMOUNTS ARE POSSIBLE ACROSS THE REGION FROM FRIDAY NIGHT INTO SUNDAY. A SURGE OF ARCTIC AIR WILL ACCOMPANY THIS STORM SYSTEM...AND IS EXPECTED TO BRING MUCH BELOW NORMAL TEMPERATURES BEGINNING SUNDAY AND LASTING THROUGH ALL OF NEXT WEEK. STAY TUNED TO THE LATEST FORECAST AS THE WEATHER PATTERN EVOLVES LATER THIS WEEK. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The national radar mosaic for the moment the first event began.
4 high wind. Local standard time, as filed.
Wind gusts of 60 mph were also reported.
Wind gusts of 60 mph were also reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2011Every state in 2011This day in weather historyWarnings in Montana, January 2011
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 274225, 274223, 274226, 274230.