Alert archive / Illinois / LaSalle County

Weather alerts in LaSalle County, Illinois, 2017

180 weather alerts in 2017, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.

LaSalle County and its neighbors

Each county as a circle sized by its count in 2017. Tap one for its archive.

Alerts: 180
Warnings: 54
Watches: 22
Advisories: 62
Busiest month: July35 alerts
Busiest day: March 1, 201711 alerts

Over time

By month

Warning verification

How often warnings here had a storm report inside them, and how much warning the reports had.

3 of 4 tornado warnings covering LaSalle County in 2017 had a tornado report inside them; 9 of 9 tornado reports fell inside a warning, on average 17 minutes after it went out.

LaSalle County, 2017

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	4	3	25%	9	100%	17 min
Severe thunderstorm warnings	24	13	46%	23	96%	22 min
Flash flood warnings	1	1	0%	1	100%	28 min

Each office's whole area, 2017

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Chicago, IL: tornado warnings	14	6	57%	17	76%	17 min
NWS Chicago, IL: severe thunderstorm warnings	158	76	52%	310	72%	21 min
NWS Chicago, IL: flash flood warnings	12	6	50%	27	81%	129 min

An office's figures cover every county it serves, including across state lines.

Verified by the Iowa Environmental Mesonet's Cow, which matches each storm-based warning with the local storm reports inside its polygon while it was in force, within 15 km of its edge: a tornado warning counts as verified on a tornado report, a severe thunderstorm warning on hail of 1 inch or more, a gust of 58 mph or more, or wind damage, a flash flood warning on a flash flood report. The false alarm ratio is the share of warnings with no such report; "inside a warning" is the probability of detection, the share of reports that fell inside one; lead time runs from the warning's issue to each report inside it, counting zero for a report that came first. A warning with no report is not proof nothing happened: reports come from spotters, the public and damage surveys, and are thin where few people live.

The alerts

Every alert, in the order issued. Times are local, Central Time. Each opens its own page with the text, the map, the radar and the sounding.

Issued	Product	Office	Lasted
Jan 2, 6:30 PM CST	Dense Fog Advisory	LOT	17 hr
Jan 10, 3:38 AM CST	Wind Advisory	LOT	17 hr
Jan 11, 10:02 AM CST	Freezing Rain Advisory	LOT	23 hr
Jan 11, 1:15 PM CST	Dense Fog Advisory	LOT	7 hr
Jan 12, 3:05 AM CST	Mesoscale Discussion	SPC	6 hr
Jan 15, 2:56 PM CST	Winter Weather Advisory	LOT	21 hr
Jan 16, 12:13 PM CST	Dense Fog Advisory	LOT	17 hr
Jan 16, 10:54 PM CST	River Flood Advisory	LOT	36 hr
Jan 17, 10:39 AM CST	River Flood Advisory	LOT	36 hr
Jan 17, 11:33 AM CST	River Flood Warning	LOT	10 days
Jan 17, 11:39 AM CST	River Flood Advisory	LOT	8 days
Jan 17, 8:40 PM CST	River Flood Warning	LOT	37 hr
Jan 20, 4:29 PM CST	Dense Fog Advisory	LOT	19 hr
Jan 21, 9:08 PM CST	Dense Fog Advisory	LOT	15 hr
Feb 6, 7:07 PM CST	Dense Fog Advisory	LOT	19 hr
Feb 20, 3:41 AM CST	Dense Fog Advisory	LOT	6 hr
Feb 21, 11:34 PM CST	Dense Fog Advisory	LOT	11 hr
Feb 28, 10:17 AM CST	River Flood Advisory	LOT	5 days
Feb 28, 10:17 AM CST	River Flood Advisory	LOT	5 days
Feb 28, 2:03 PM CST	Mesoscale Discussion	SPC	2 hr
Feb 28, 2:57 PM CST	Tornado Watch	SPC	7 hr
Feb 28, 4:14 PM CST	Severe Thunderstorm Warning	LOT	46 min
Feb 28, 4:27 PM CST	Tornado Warning	LOT	48 min
Feb 28, 4:51 PM CST	Tornado Warning Tornado observedConsiderable damage threat	LOT	39 min
Feb 28, 5:13 PM CST	Severe Thunderstorm Warning	LOT	47 min
Feb 28, 5:24 PM CST	Mesoscale Discussion	SPC	96 min
Feb 28, 5:36 PM CST	Tornado Warning	LOT	39 min
Feb 28, 6:13 PM CST	Tornado Warning	LOT	32 min
Feb 28, 6:24 PM CST	Severe Thunderstorm Warning	LOT	51 min
Feb 28, 6:26 PM CST	Areal Flood Advisory	LOT	3 hr
Feb 28, 7:41 PM CST	Severe Thunderstorm Warning	LOT	34 min
Feb 28, 8:04 PM CST	Severe Thunderstorm Warning	LOT	26 min
Feb 28, 8:06 PM CST	Mesoscale Discussion	SPC	84 min
Feb 28, 8:35 PM CST	Severe Thunderstorm Warning	LOT	40 min
Feb 28, 8:51 PM CST	Areal Flood Advisory	LOT	6 hr
Feb 28, 9:34 PM CST	Severe Thunderstorm Warning	LOT	56 min
Feb 28, 9:51 PM CST	Tornado Watch	SPC	6 hr
Mar 1, 12:21 AM CST	River Flood Warning	LOT	72 hr
Mar 6, 10:15 PM CST	Mesoscale Discussion	SPC	60 min
Mar 6, 10:35 PM CST	Severe Thunderstorm Watch	SPC	4 hr
Mar 7, 12:06 AM CST	Severe Thunderstorm Warning	LOT	54 min
Mar 7, 7:38 PM CST	Wind Advisory	LOT	22 hr
Mar 8, 9:35 AM CST	Red Flag Warning	LOT	7 hr
Mar 11, 3:43 PM CST	Winter Weather Advisory	LOT	44 hr
Mar 19, 11:50 PM CDT	Mesoscale Discussion	SPC	85 min
Mar 20, 5:01 AM CDT	Areal Flood Advisory	LOT	3 hr
Mar 29, 10:11 PM CDT	River Flood Watch	LOT	6 days
Mar 30, 9:57 AM CDT	River Flood Advisory	LOT	4 days
Mar 30, 11:29 AM CDT	River Flood Warning	LOT	64 hr
Mar 30, 11:29 AM CDT	River Flood Warning	LOT	20 days
Mar 30, 1:08 PM CDT	Areal Flood Advisory	LOT	6 hr
Mar 30, 3:46 PM CDT	River Flood Warning	LOT	47 hr
Mar 30, 4:00 PM CDT	River Flood Advisory	LOT	62 hr
Mar 30, 7:01 PM CDT	Areal Flood Advisory	LOT	5 hr
Apr 3, 10:04 AM CDT	River Flood Advisory	LOT	4 days
Apr 3, 11:08 AM CDT	River Flood Advisory	LOT	6 days
Apr 5, 10:08 AM CDT	River Flood Advisory	LOT	4 days
Apr 5, 11:48 AM CDT	River Flood Warning	LOT	5 days
Apr 5, 9:05 PM CDT	River Flood Warning	LOT	58 hr
Apr 10, 5:20 AM CDT	Special Weather Statement	LOT	40 min
Apr 10, 11:57 AM CDT	Mesoscale Discussion	SPC	3 hr
Apr 10, 12:26 PM CDT	Special Weather Statement	LOT	49 min
Apr 10, 1:48 PM CDT	Severe Thunderstorm Watch	SPC	8 hr
Apr 10, 3:25 PM CDT	Mesoscale Discussion	SPC	2 hr
Apr 14, 5:22 PM CDT	Special Weather Statement	LOT	53 min
Apr 16, 1:17 AM CDT	Special Weather Statement	LOT	43 min
Apr 28, 11:51 AM CDT	River Flood Watch	LOT	7 days
Apr 28, 12:09 PM CDT	River Flood Watch	LOT	6 days
Apr 28, 12:23 PM CDT	River Flood Watch	LOT	33 hr
Apr 28, 12:23 PM CDT	River Flood Watch	LOT	33 hr
Apr 28, 3:05 PM CDT	Flash Flood Watch	LOT	61 hr
Apr 29, 7:04 PM CDT	Areal Flood Advisory	LOT	3 hr
Apr 29, 8:50 PM CDT	Areal Flood Warning	LOT	6 hr
Apr 29, 9:02 PM CDT	River Flood Warning	LOT	5 days
Apr 29, 9:14 PM CDT	River Flood Warning	LOT	7 days
Apr 29, 9:14 PM CDT	River Flood Warning	LOT	20 days
Apr 30, 3:23 AM CDT	River Flood Warning	LOT	3 days
Apr 30, 10:04 PM CDT	River Flood Advisory	LOT	20 hr
May 6, 2:39 PM CDT	Frost Advisory	LOT	17 hr
May 9, 10:00 AM CDT	River Flood Advisory	LOT	36 hr
May 10, 12:00 PM CDT	River Flood Watch	LOT	3 days
May 10, 9:12 PM CDT	River Flood Advisory	LOT	34 hr
May 11, 7:32 AM CDT	River Flood Warning	LOT	53 hr
May 11, 10:49 AM CDT	River Flood Warning	LOT	53 hr
May 17, 3:30 AM CDT	Wind Advisory	LOT	19 hr
May 17, 3:44 PM CDT	Tornado Watch	SPC	9 hr
May 17, 9:59 PM CDT	Severe Thunderstorm Warning	LOT	61 min
May 17, 10:43 PM CDT	Severe Thunderstorm Warning	LOT	47 min
May 24, 4:05 AM CDT	River Flood Advisory	LOT	3 days
May 27, 7:29 PM CDT	River Flood Advisory	LOT	60 hr
Jun 13, 2:25 PM CDT	Mesoscale Discussion	SPC	3 hr
Jun 14, 12:06 PM CDT	Mesoscale Discussion	SPC	2 hr
Jun 14, 12:40 PM CDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 14, 4:07 PM CDT	Severe Thunderstorm Warning	LOT	38 min
Jun 14, 4:36 PM CDT	Severe Thunderstorm Warning	LOT	39 min
Jun 14, 4:39 PM CDT	Severe Thunderstorm Warning	LOT	36 min
Jun 15, 11:34 PM CDT	Severe Thunderstorm Warning	LOT	41 min
Jun 17, 1:35 AM CDT	Mesoscale Discussion	SPC	115 min
Jun 17, 2:44 PM CDT	Mesoscale Discussion	SPC	2 hr
Jun 17, 5:39 PM CDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 17, 8:06 PM CDT	Severe Thunderstorm Warning	LOT	39 min
Jun 17, 8:17 PM CDT	Mesoscale Discussion	SPC	58 min
Jun 17, 8:22 PM CDT	Special Weather Statement	LOT	23 min
Jun 18, 9:03 PM CDT	River Flood Advisory	LOT	70 hr
Jun 19, 11:43 AM CDT	River Flood Advisory	LOT	51 hr
Jun 19, 12:44 PM CDT	Mesoscale Discussion	SPC	3 hr
Jun 20, 2:05 PM CDT	Mesoscale Discussion	SPC	2 hr
Jun 23, 4:16 AM CDT	Special Weather Statement	LOT	29 min
Jun 23, 4:50 AM CDT	Special Weather Statement	LOT	25 min
Jul 5, 4:47 PM CDT	Special Weather Statement	LOT	58 min
Jul 10, 2:48 PM CDT	Mesoscale Discussion	SPC	117 min
Jul 10, 3:58 PM CDT	Severe Thunderstorm Watch	SPC	7 hr
Jul 10, 6:18 PM CDT	Mesoscale Discussion	SPC	87 min
Jul 10, 8:22 PM CDT	Special Weather Statement	LOT	38 min
Jul 10, 8:34 PM CDT	Severe Thunderstorm Warning	LOT	41 min
Jul 10, 8:56 PM CDT	Mesoscale Discussion	SPC	2 hr
Jul 11, 8:41 AM CDT	Severe Thunderstorm Warning	LOT	49 min
Jul 12, 3:41 AM CDT	Heat Advisory	LOT	12 hr
Jul 12, 2:32 PM CDT	Flash Flood Watch	LOT	12 hr
Jul 12, 11:32 PM CDT	Areal Flood Advisory	LOT	4 hr
Jul 13, 9:34 AM CDT	River Flood Advisory	LOT	36 hr
Jul 19, 5:45 PM CDT	Severe Thunderstorm Watch	SPC	6 hr
Jul 19, 8:30 PM CDT	Severe Thunderstorm Warning	LOT	30 min
Jul 19, 8:34 PM CDT	Severe Thunderstorm Warning	LOT	56 min
Jul 20, 6:47 AM CDT	Special Weather Statement	LOT	43 min
Jul 20, 7:27 AM CDT	Special Weather Statement	LOT	48 min
Jul 20, 2:15 PM CDT	Flash Flood Watch	LOT	42 hr
Jul 21, 12:32 AM CDT	Severe Thunderstorm Warning	LOT	43 min
Jul 21, 12:57 AM CDT	Severe Thunderstorm Warning	LOT	14 min
Jul 21, 1:11 AM CDT	Mesoscale Discussion	SPC	94 min
Jul 21, 8:39 AM CDT	River Flood Advisory	LOT	5 days
Jul 21, 4:52 PM CDT	Severe Thunderstorm Watch	SPC	9 hr
Jul 21, 4:53 PM CDT	River Flood Warning	LOT	5 days
Jul 21, 6:28 PM CDT	Mesoscale Discussion	SPC	92 min
Jul 21, 8:01 PM CDT	Severe Thunderstorm Warning	LOT	44 min
Jul 21, 8:07 PM CDT	Areal Flood Warning	LOT	3 hr
Jul 21, 8:35 PM CDT	Mesoscale Discussion	SPC	115 min
Jul 21, 9:36 PM CDT	River Flood Advisory	LOT	63 hr
Jul 21, 11:11 PM CDT	Areal Flood Advisory	LOT	3 hr
Jul 21, 11:23 PM CDT	Mesoscale Discussion	SPC	67 min
Jul 22, 10:33 AM CDT	River Flood Warning	LOT	66 hr
Jul 22, 10:33 AM CDT	River Flood Warning	LOT	5 days
Jul 23, 1:03 PM CDT	Mesoscale Discussion	SPC	2 hr
Jul 26, 4:55 PM CDT	Mesoscale Discussion	SPC	65 min
Aug 3, 5:18 PM CDT	Mesoscale Discussion	SPC	2 hr
Aug 10, 2:47 PM CDT	Severe Thunderstorm Watch	SPC	6 hr
Aug 10, 5:31 PM CDT	Mesoscale Discussion	SPC	89 min
Aug 10, 7:36 PM CDT	Severe Thunderstorm Warning	LOT	39 min
Aug 28, 2:10 PM CDT	Special Weather Statement	LOT	65 min
Aug 28, 2:53 PM CDT	Areal Flood Advisory	LOT	3 hr
Aug 28, 3:51 PM CDT	Special Weather Statement	LOT	24 min
Aug 28, 4:42 PM CDT	Areal Flood Advisory	LOT	3 hr
Aug 29, 2:02 AM CDT	Dense Fog Advisory	LOT	7 hr
Aug 30, 4:30 AM CDT	Dense Fog Advisory	LOT	5 hr
Sep 14, 1:14 AM CDT	Dense Fog Advisory	LOT	9 hr
Oct 14, 2:55 AM CDT	Flash Flood Watch	LOT	25 hr
Oct 14, 7:55 AM CDT	Areal Flood Advisory	LOT	3 hr
Oct 14, 11:46 AM CDT	River Flood Advisory	LOT	55 hr
Oct 14, 5:09 PM CDT	Tornado Watch	SPC	8 hr
Oct 14, 6:01 PM CDT	Mesoscale Discussion	SPC	89 min
Oct 14, 6:45 PM CDT	Special Weather Statement	LOT	45 min
Oct 14, 7:24 PM CDT	Areal Flood Advisory	LOT	12 hr
Oct 14, 7:33 PM CDT	Severe Thunderstorm Warning	LOT	57 min
Oct 14, 9:04 PM CDT	Mesoscale Discussion	SPC	86 min
Oct 14, 10:02 PM CDT	Flash Flood Warning	LOT	8 hr
Oct 14, 10:47 PM CDT	River Flood Warning	LOT	67 hr
Oct 14, 10:57 PM CDT	River Flood Warning	LOT	47 hr
Oct 14, 10:57 PM CDT	River Flood Warning	LOT	4 days
Oct 15, 5:45 AM CDT	Areal Flood Warning	LOT	6 hr
Oct 25, 3:00 AM CDT	Frost Advisory	LOT	29 hr
Oct 27, 3:29 PM CDT	Freeze Warning	LOT	42 hr
Nov 4, 11:33 PM CDT	Dense Fog Advisory	LOT	10 hr
Nov 19, 9:53 AM CST	River Flood Advisory	LOT	36 hr
Nov 19, 2:49 PM CST	River Flood Advisory	LOT	4 days
Dec 4, 3:10 AM CST	Wind Advisory	LOT	39 hr
Dec 23, 3:21 AM CST	Winter Weather Advisory	LOT	39 hr
Dec 26, 12:54 PM CST	Wind Chill Advisory	LOT	22 hr
Dec 28, 8:33 PM CST	Winter Weather Advisory	LOT	24 hr
Dec 29, 1:05 PM CST	Wind Chill Advisory	LOT	24 hr
Dec 30, 6:27 PM CST	Wind Chill Advisory	LOT	14 hr

By product

Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.

Product	Alerts
Severe storms
Severe Thunderstorm Warning	24
Tornado Warning	4
Severe Thunderstorm Watch	8
Tornado Watch	4
Mesoscale Discussion	28
Special Weather Statement	14
Flooding
Areal Flood Warning	3
Flash Flood Warning	1
River Flood Warning	20
Flash Flood Watch	4
River Flood Watch	6
Areal Flood Advisory	12
River Flood Advisory	23
Winter
Freezing Rain Advisory	1
Winter Weather Advisory	4
Heat
Heat Advisory	1
Cold
Freeze Warning	1
Frost Advisory	2
Wind Chill Advisory	3
Wind and dust
Wind Advisory	4
Fire
Red Flag Warning	1
Fog and smoke
Dense Fog Advisory	12

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2016 2018

Sources

National Weather Service watches, warnings, advisories and statements from the Iowa Environmental Mesonet's VTEC archive, which reconstructs tornado, severe thunderstorm, flash flood and marine warnings back to 1986 from the NWS text archive. Storm Prediction Center watches and mesoscale discussions from SPC's archive through the Mesonet. County centers from the US Census Bureau. Warning verification from the Mesonet's Cow. Rebuilt daily.