A strong thunderstorm in Archuleta County produced a number of cloud-to-ground lightning strikes, with at least one that resulted in property damage.
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 GJT wrote it up.
A strong thunderstorm in Archuleta County produced a number of cloud-to-ground lightning strikes, with at least one that resulted in property damage.
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 Grand Junction, CO wrote its last area forecast discussion before the first event at Sep 30, 10:56 AM MST, 44 minutes earlier.
Area Forecast Discussion National Weather Service GRAND JUNCTION CO 1156 AM MDT Sat Sep 30 2017 .SHORT TERM...(Today through Sunday) Issued at 426 AM MDT Sat Sep 30 2017 A -25C core @ 500mb closed low will drop into the Pacific NW over the next 36 hours, with excellent dynamics and a strong upper level jet accompanying it. An active weather day expected today as a couple of weather features track west to east through the region. A well-defined shortwave disturbance on satellite this morning will reach eastern Utah late this morning and western Colorado by noon with strong upper level jet support on its heels. Showers and thunderstorms along this shortwave may pack some punch, with the strongest storms expected over the southwestern Colorado valleys this afternoon with forecast CAPE values over 1000J/kg and 40+kts of bulk shear to support organized storms. Considering this energy and moisture availability, very heavy rain will be possible with stronger storms. Decided against a flash flood watch, anticipating the threat will be isolated. Initial storm motion is expected to be southwest to northeast...then becoming west to east with an additional line of thunderstorms developing mainly from the Uncompahgre Plateau and north this evening. Forecast models are hinting that these thunderstorms will continue overnight into Sunday as they trek eastward across Colorado. The cold core closed low will drop further south as a 100+ kt upper level polar jet reaches eastern UT and western CO Sunday morning. Showers and thunderstorms may continue across NE Utah and NW Colorado Sunday morning, but will further develop Sunday afternoon as the cold front associated with this system stalls somewhere near the I-70 corridor. The trickiest part of this forecast is figuring out where exactly the front will stall on Sunday and into Monday. .LONG TERM...(Sunday night through Friday) Issued at 426 AM MDT Sat Sep 30 2017 Cooler air really begins to drop into Utah and Colorado on Sunday night with 700 mb temps reaching somewhere between -3 and -5C by early Monday morning. Anticipating measurable snow above about 8,000 ft in the Flattops, Elkhead, Park, Gore Ranges and even into the Roan Cliffs Sunday night into Monday morning. Initial estimates predicted are in the 4-8" range above 9,000 ft in these areas, with quickly lowering amounts below 9,000 ft down to 8000 ft. The high country (above 10,000ft) could see significant amounts of snow wherever the front stalls, but want to see continued indication that cold enough air will get to region for significant snow before issuing any headlines. Rain and snow are progged to remain along or north of I-70. For the synoptic pattern, global models are in good agreement through Monday afternoon, but consistency in the location and depth of the trough diverge beyond Tuesday. The GFS cuts off an area of low pressure over the northern Great Basin, with stronger southwesterly flow over the western slope on Tuesday. The ECMWF does not cut off the upper level low until Wednesday, keeping the western slope drier. Both solutions indicate southwesterly flow of some extent over the Four Corners, with the jet slowly lifting north by Friday. This northward shift of the jet should allow some milder weather to work back into the region, with temperatures trending upward to near seasonal averages by Wednesday through Friday. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1156 AM MDT Sat Sep 30 2017 An upper level disturbance will bring numerous thunderstorms to west-central and northwest Colorado this afternoon and evening. This activity will result in brief MVFR visibility in heavy rain to TAF sites along the I-70 corridor and CIGS below ILS breakpoints at KRIL, KEGE and KASE. Showers will be more scattered over the south, but could bring additional rain to KTEX, KDRO and KGUC with conditions similar to those described previously. Guidance suggests showers will hold off over KVEL until this evening, but this activity is unlikely to cause flight conditions to fall below VFR levels there. Showers will decrease this evening and overnight and chances for additional showers at TAF sites are low. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...JAM LONG TERM...JAM/MAC AVIATION...NL
Hazardous Weather Outlook National Weather Service GRAND JUNCTION CO 450 AM MDT Sat Sep 30 2017 COZ001>014-017>023-UTZ022>025-027>029-011100- Lower Yampa River Basin-Central Yampa River Basin- Roan and Tavaputs Plateaus-Elkhead and Park Mountains- Upper Yampa River Basin-Grand Valley-Debeque to Silt Corridor- Central Colorado River Basin-Grand and Battlement Mesas- Gore and Elk Mountains/Central Mountain Valleys- Central Gunnison and Uncompahgre River Basin- West Elk and Sawatch Mountains-Flat Tops- Upper Gunnison River Valley-Uncompahgre Plateau and Dallas Divide- Northwest San Juan Mountains-Southwest San Juan Mountains- Paradox Valley/Lower Dolores River- Four Corners/Upper Dolores River-Animas River Basin- San Juan River Basin-Southeast Utah-Eastern Uinta Mountains- Eastern Uinta Basin-Tavaputs Plateau-Arches/Grand Flat- La Sal and Abajo Mountains-Canyonlands/Natural Bridges- 450 AM MDT Sat Sep 30 2017 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight A storm system will bring gusty winds, rain, and thunderstorms to the region today, with the strongest storms anticipated across southwestern Colorado. Moderate to heavy rain will be possible with stronger storms. .DAYS TWO THROUGH SEVEN...Sunday through Friday A cold front drops into Northeast Utah and Northwest Colorado Sunday night into Monday morning. Moderate snow accumulations are possible above 9000 ft mainly north of I-70. Light snow accumulations may impact Vail Pass early Monday morning. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed, but spotters are encouraged to report significant weather to the National Weather Service.
Special Weather Statement National Weather Service Grand Junction CO 718 AM MDT SAT SEP 30 2017 COZ019-021-301400- Southwest San Juan Mountains CO-Four Corners/Upper Dolores River CO- 718 AM MDT SAT SEP 30 2017 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL MONTEZUMA COUNTY UNTIL 800 AM MDT... At 718 AM MDT, Doppler radar was tracking a strong thunderstorm 9 miles southeast of Cortez, or 32 miles north of Shiprock, moving northeast at 35 mph. Half inch hail and winds in excess of 40 mph will be possible with this storm. Locations impacted include... Cortez, Mancos and Mesa Verde National Park. This includes the following highways... U.S. Highway 160 in Colorado between mile markers 41 and 60. Colorado 145 between mile markers 13 and 22. LAT...LON 3711 10847 3721 10865 3759 10838 3744 10811 TIME...MOT...LOC 1318Z 215DEG 31KT 3724 10850 NL
Special Weather Statement
National Weather Service Grand Junction CO
757 AM MDT SAT SEP 30 2017
COZ018>021-301430-
Southwest San Juan Mountains CO-
Paradox Valley/Lower Dolores River CO-
Northwestern San Juan Mountains CO-
Four Corners/Upper Dolores River CO-
757 AM MDT SAT SEP 30 2017
...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN DOLORES AND NORTH
CENTRAL MONTEZUMA COUNTIES UNTIL 830 AM MDT...
At 753 AM MDT, Doppler radar was tracking a strong thunderstorm near
Dolores, or 32 miles northwest of Durango, moving northeast at 40
mph.
Nickel size hail and winds in excess of 40 mph will be possible with
this storm.
Locations impacted include...
Dolores, Dunton and Stoner.
This includes Colorado 145 between mile markers 12 and 36, and
between mile markers 49 and 54.
LAT...LON 3741 10833 3749 10852 3790 10835 3788 10825
3783 10820 3780 10794
TIME...MOT...LOC 1353Z 208DEG 34KT 3752 10840
ADLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1155 AM MDT SAT SEP 30 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1150 AM HAIL PALISADE 39.11N 108.36W
09/30/2017 E0.25 INCH MESA CO PUBLIC
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1156 AM MDT SAT SEP 30 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1145 AM HAIL 2 SE FRUITA 39.14N 108.70W
09/30/2017 E0.25 INCH MESA CO NWS EMPLOYEE
BRIEF HEAVY RAIN, GUSTY WINDS.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1209 PM MDT SAT SEP 30 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1200 PM HAIL 1 S FRUITVALE 39.08N 108.48W
09/30/2017 E0.25 INCH MESA CO PUBLIC
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1233 PM MDT SAT SEP 30 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1149 AM TSTM WND GST 10 SSW DOUGLAS PASS 39.46N 108.88W
09/30/2017 M58 MPH GARFIELD CO MESONET
MESONET STATION DMMC2, DEMAREE - 16 N MACK.
&&The Albuquerque radar (KABX), 229 km away, was scanning. The volume nearest the first event began at 18:40 UTC.
1 lightning. Local standard time, as filed.
Lightning struck the Oak Brush communications site and damaged law enforcement communications equipment.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2017Every state in 2017This day in weather historyWarnings in Colorado, September 2017
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: 717142.