A low pressure system over the Pacific Northwest pushed moisture and instability into the region bringing scattered showers to the area. Stronger upper level energy moving through North Central MT during the afternoon/evening brought the area increased potential for severe storms.
Every event with a place to put it. 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 TFX wrote it up.
A low pressure system over the Pacific Northwest pushed moisture and instability into the region bringing scattered showers to the area. Stronger upper level energy moving through North Central MT during the afternoon/evening brought the area increased potential for severe storms.
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 Aug 15, 11:08 AM MST, 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 1207 AM MDT Fri Aug 15 2014 AVIATION SECTION UPDATED .UPDATE... Two bands of light showers over north central MT are weakening. Have raised POPs slightly through 18Z to account for one of these bands over the Hill/Blaine county line. Drier air seen on WV is circulating into southwest MT and will keep most areas dry until late afternoon. Short term models suggest a subtle lobe of vorticity presently over NE Oregon will rotate through north central MT late this afternoon and early evening. Additionally, models indicate convergence along a weak surface boundary crossing the Continental divide around 00Z this evening. Expect a line of thunderstorms to form along this boundary and advance across north central Montana from around 00-06Z. Forecast soundings at CTB provide around 1200 J/kg CAPE prior to thunderstorm development, so heavy rain is possible with PW around 1.1 inches. Weak shear and a tall- skinny CAPE profile do not support any more than a minimal hail threat. Confidence in training or slow moving thunderstorms is not high enough to warrant a Flash Flood watch with FF guidance of 1.2 to 2 inches over the forecast area. However, rainfall rates will have to be monitored carefully this evening as precipitation develops and ponding or street flooding possible. Inhere ted forecast package already represents categorical POPS for our NW zones this evening, so have not made any changes. PAN && .AVIATION... UPDATED 1755Z. Upper-level low pressure system that was stationary over Washington/ Oregon now beginning to come east toward western Montana. Increasing moisture and instability ahead of the low is already generating scattered thunderstorms just west of the Continental Divide, with storm coverage expected to expand into central Montana this aftn. Given the current analysis, have moved up the VCTS/TSRA start times for KHLN/KCTB as conditions are destabilizing sooner than earlier forecast. Confidence for scattered storms west of KGTF is high, but more marginal for storm coverage from KGTF eastward due to several alternating bands of dry air and moisture. However, will keep mention of TSRA for remaining local terminals as several forecast parameters have been trending toward more TSRA development than past few days. Storm activity should gradually dissipate from west-to-east tonight. Expect VFR conditions away from storms, but MVFR and short-lived local IFR conditions possible close to any stronger convective cells. Waranauskas && .PREV DISCUSSION... /ISSUED 600 AM MDT Fri Aug 15 2014/ Today through Sunday...With the main upper level low pressure continuing to spin over the Pacific Northwest...scattered showers and thunderstorms will continue to move through the region over the next few days. The heaviest rain this morning will affect areas between Choteau and Cut Bank. Up to a 0.50 is possible from the heaviest showers. With more upper level energy moving through North Central MT late this afternoon/evening...another round of showers and thunderstorms will move through the area. The best area for storms later today is mainly north of a Boulder to White Sulphur Springs line. Isolated thunderstorms will be possible over the region on Saturday...as the upper level low slowly starts to pull to our East. By Sunday...the upper level should be far enough east that any showers/thunderstorms should be confined mainly to areas northeast of Great Falls early in the day...but the storms will spread back westward towards the Rockies by late in the day as the airmass becomes unstable. Generally temperatures will be seasonable over the next few days...with afternoon highs generally in the lower to mid 80s across the region. Brusda Sunday night through Friday...Models take an upper trough over central Montana Sunday evening to eastern Montana Monday and into the Dakotas Monday night. Still expect isolated to scattered showers to affect the plains and adjoining mountains Sunday evening before ending around midnight. Monday should be a mostly dry day as a weak upper ridge develops over Idaho and western Montana. Then as has been advertised an upper trough will be developing over the northwest U.S. Models differ on the details of this development and on weather disturbances embedded within the trough that will be affecting the forecast area. In particular by Friday the GFS has an upper trough over the Pacific Northwest. A disturbance ahead of the upper trough develops into a closed low as it moves north through western Montana Friday night. Associated with this the GFS has precipitation amounts of a half-inch or more over the western mountains. The ECMWF on the other hand has a more broad upper trough. Due to model differences have gone with a general trend of increasing the chances of precipitation from Tuesday into Thursday. High temperatures from the upper 80s to low 90s Tuesday are expected to cool to the low 60s to low 70s Friday. Blank && .PRELIMINARY POINT TEMPS/POPS... GTF 84 58 82 58 / 50 60 20 20 CTB 79 54 78 54 / 70 80 20 20 HLN 85 55 84 55 / 40 40 20 10 BZN 85 51 84 51 / 30 30 10 10 WEY 74 43 75 42 / 20 20 10 10 DLN 80 50 82 50 / 20 20 10 10 HVR 86 60 85 60 / 50 60 30 30 LWT 82 57 81 57 / 40 60 30 20 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && weather.gov/greatfalls www.twitter.com/NWSGreatFalls www.facebook.com/NWSGreatFalls
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
1203 PM MDT FRI AUG 15 2014
MTZ008-015-151830-
BEAVERHEAD MT-MADISON MT-
1203 PM MDT FRI AUG 15 2014
...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN MADISON AND NORTHERN
BEAVERHEAD COUNTIES UNTIL 1230 PM MDT...
AT NOON MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 21 MILES SOUTHWEST OF DIVIDE...OR 28 MILES
NORTHWEST OF DILLON...MOVING EAST AT 40 MPH.
HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN.
LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...WISE RIVER...GLEN AND
DEWEY.
IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.
LAT...LON 4589 11314 4589 11310 4582 11300 4577 11279
4567 11269 4564 11268 4569 11257 4577 11249
4575 11247 4575 11233 4561 11220 4535 11306
4561 11329
TIME...MOT...LOC 1802Z 249DEG 35KT 4553 11299
PANSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREAT FALLS MT 1225 PM MDT FRI AUG 15 2014 MTZ014-052-053-151915- BROADWATER MT-CENTRAL AND SOUTHERN LEWIS AND CLARK MT-JEFFERSON MT- 1225 PM MDT FRI AUG 15 2014 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN LEWIS AND CLARK... NORTHERN JEFFERSON AND EXTREME NORTHWESTERN BROADWATER COUNTIES UNTIL 115 PM MDT... AT 1218 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 8 MILES WEST OF HELENA...MOVING NORTHEAST AT 30 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. * LOCATIONS IMPACTED INCLUDE... HELENA... EAST HELENA AND MONTANA CITY... IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. LAT...LON 4690 11172 4659 11166 4646 11219 4665 11231 TIME...MOT...LOC 1825Z 246DEG 26KT 4658 11211 WARANAUSKAS
The Great Falls radar (KTFX), 117 km away, was scanning. The volume nearest the first event began at 18:36 UTC.
5 hail, 1 heavy rain, 1 thunderstorm wind. Local standard time, as filed.
Large hail, measuring 1.75 inches (golf ball sized), was reported along with heavy rain.
Large hail, measuring 1.25 inches (half dollar sized), was reported along with heavy rain.
Hail, measuring 0.75 inches (penny sized), was reported to have damaged sheds and awnings.
Hail, measuring 0.75 inches (penny sized), was reported along with heavy rain.
Hail, measuring 0.75 inches (penny sized), was reported along with heavy rain.
Heavy rain, measuring 0.70 inches in 20 minutes, was reported.
High wind gusts, measuring 50KT (58 MPH), were reported in Big Sandy, MT.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2014Every state in 2014This day in weather historyWarnings in Montana, August 2014
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: 536489, 536491, 536493, 536494, 536495, 536496, 536498.