Alert archive / Illinois / LaSalle County

Weather alerts in LaSalle County, Illinois, 2020

167 weather alerts in 2020, 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 2020. Tap one for its archive.

Alerts: 167
Warnings: 40
Watches: 34
Advisories: 52
Busiest month: May33 alerts
Busiest day: May 15, 20209 alerts

Over time

By month

Warning verification

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

1 of 2 tornado warnings covering LaSalle County in 2020 had a tornado report inside them; 0 of 2 tornado reports fell inside a warning.

LaSalle County, 2020

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	2	1	50%	2	0%
Severe thunderstorm warnings	13	9	31%	27	81%	31 min
Flash flood warnings	2	2	0%	0

Each office's whole area, 2020

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Chicago, IL: tornado warnings	25	5	80%	35	37%	13 min
NWS Chicago, IL: severe thunderstorm warnings	112	77	31%	443	83%	33 min
NWS Chicago, IL: flash flood warnings	19	11	42%	64	83%	114 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 9, 3:20 AM CST	Wind Advisory	LOT	15 hr
Jan 9, 11:15 AM CST	River Flood Watch	LOT	6 days
Jan 9, 11:23 AM CST	River Flood Watch	LOT	21 days
Jan 9, 11:23 AM CST	River Flood Watch	LOT	21 days
Jan 9, 1:36 PM CST	Winter Storm Watch	LOT	22 hr
Jan 10, 10:14 AM CST	River Flood Warning	LOT	3 days
Jan 10, 10:54 AM CST	River Flood Warning	LOT	6 days
Jan 10, 10:54 AM CST	River Flood Warning	LOT	12 days
Jan 10, 11:44 AM CST	Winter Weather Advisory	LOT	38 hr
Jan 10, 7:35 PM CST	River Flood Watch	LOT	70 hr
Jan 11, 8:51 AM CST	River Flood Warning	LOT	45 hr
Jan 11, 3:10 PM CST	Mesoscale Discussion	SPC	4 hr
Jan 11, 8:24 PM CST	River Flood Advisory	LOT	13 hr
Jan 12, 7:37 PM CST	Winter Weather Advisory	LOT	7 hr
Jan 14, 2:33 PM CST	Winter Weather Advisory	LOT	21 hr
Jan 16, 2:44 PM CST	Winter Weather Advisory	LOT	51 hr
Jan 18, 2:24 PM CST	Wind Chill Advisory	LOT	20 hr
Jan 20, 6:53 AM CST	River Flood Warning	LOT	7 days
Jan 24, 3:12 AM CST	Winter Weather Advisory	LOT	35 hr
Jan 24, 8:34 AM CST	Dense Fog Advisory	LOT	11 hr
Jan 24, 11:16 AM CST	River Flood Watch	LOT	47 hr
Jan 29, 6:01 PM CST	River Flood Advisory	LOT	15 hr
Feb 4, 7:52 AM CST	River Flood Advisory	LOT	13 hr
Feb 8, 1:38 PM CST	Winter Weather Advisory	LOT	26 hr
Feb 11, 2:38 PM CST	Winter Weather Advisory	LOT	52 hr
Feb 13, 2:07 PM CST	Wind Chill Advisory	LOT	20 hr
Feb 17, 8:24 PM CST	Dense Fog Advisory	LOT	6 hr
Feb 23, 2:11 PM CST	Winter Storm Watch	LOT	48 hr
Feb 25, 3:34 AM CST	Winter Weather Advisory	LOT	38 hr
Mar 5, 2:10 PM CST	Wind Advisory	LOT	22 hr
Mar 12, 8:42 AM CDT	Dense Fog Advisory	LOT	2 hr
Mar 18, 9:33 PM CDT	River Flood Watch	LOT	37 hr
Mar 19, 11:27 AM CDT	River Flood Advisory	LOT	23 hr
Mar 20, 10:55 AM CDT	River Flood Advisory	LOT	23 hr
Mar 25, 4:39 AM CDT	Dense Fog Advisory	LOT	6 hr
Mar 26, 8:33 PM CDT	River Flood Watch	LOT	52 hr
Mar 27, 10:12 AM CDT	River Flood Watch	LOT	24 hr
Mar 28, 9:50 AM CDT	River Flood Advisory	LOT	3 days
Mar 28, 2:43 PM CDT	Wind Advisory	LOT	29 hr
Mar 28, 2:45 PM CDT	Tornado Watch PDS	SPC	6 hr
Mar 28, 8:06 PM CDT	Mesoscale Discussion	SPC	54 min
Mar 28, 8:41 PM CDT	Tornado Watch	SPC	3 hr
Mar 28, 10:23 PM CDT	Mesoscale Discussion	SPC	97 min
Mar 29, 12:36 AM CDT	River Flood Warning	LOT	5 days
Mar 29, 8:25 AM CDT	River Flood Advisory	LOT	47 hr
Apr 6, 11:03 PM CDT	Mesoscale Discussion	SPC	2 hr
Apr 7, 5:07 PM CDT	Mesoscale Discussion	SPC	83 min
Apr 7, 7:22 PM CDT	Mesoscale Discussion	SPC	83 min
Apr 8, 3:08 PM CDT	Severe Thunderstorm Watch	SPC	6 hr
Apr 8, 4:02 PM CDT	Special Weather Statement	LOT	28 min
Apr 9, 3:18 AM CDT	Wind Advisory	LOT	16 hr
Apr 12, 3:57 AM CDT	Wind Advisory	LOT	36 hr
Apr 15, 5:22 AM CDT	Winter Weather Advisory	LOT	5 hr
Apr 16, 3:28 AM CDT	Winter Weather Advisory	LOT	32 hr
Apr 25, 3:09 AM CDT	Flood Watch	LOT	19 hr
Apr 26, 1:55 PM CDT	River Flood Warning	LOT	16 hr
Apr 28, 3:33 PM CDT	Mesoscale Discussion	SPC	87 min
Apr 28, 4:17 PM CDT	Severe Thunderstorm Warning	LOT	28 min
Apr 28, 4:45 PM CDT	Severe Thunderstorm Warning	LOT	45 min
Apr 28, 4:51 PM CDT	Mesoscale Discussion	SPC	114 min
Apr 29, 11:54 AM CDT	River Flood Watch	LOT	10 hr
Apr 29, 11:54 AM CDT	River Flood Watch	LOT	5 days
Apr 29, 11:54 AM CDT	River Flood Watch	LOT	21 days
Apr 29, 11:54 AM CDT	River Flood Watch	LOT	10 hr
Apr 29, 2:31 PM CDT	River Flood Warning	LOT	4 days
Apr 29, 2:31 PM CDT	River Flood Warning	LOT	21 days
Apr 29, 8:48 PM CDT	Areal Flood Advisory	LOT	7 hr
Apr 29, 9:23 PM CDT	River Flood Warning	LOT	52 hr
Apr 29, 9:52 PM CDT	River Flood Warning	LOT	56 hr
May 7, 3:33 AM CDT	Freeze Watch	LOT	24 hr
May 8, 3:56 AM CDT	Freeze Warning	LOT	27 hr
May 14, 10:01 AM CDT	River Flood Watch	LOT	3 days
May 14, 11:22 AM CDT	River Flood Watch	LOT	25 hr
May 14, 11:22 AM CDT	River Flood Watch	LOT	6 days
May 14, 12:06 PM CDT	Flash Flood Watch	LOT	17 hr
May 14, 2:44 PM CDT	River Flood Warning	LOT	7 days
May 14, 5:19 PM CDT	Mesoscale Discussion	SPC	116 min
May 14, 6:15 PM CDT	Severe Thunderstorm Watch	SPC	8 hr
May 14, 8:32 PM CDT	Areal Flood Advisory	LOT	4 hr
May 14, 8:47 PM CDT	River Flood Warning	LOT	22 days
May 14, 9:14 PM CDT	Flash Flood Warning	LOT	6 hr
May 14, 10:47 PM CDT	Areal Flood Advisory	LOT	4 hr
May 14, 10:57 PM CDT	Severe Thunderstorm Warning	LOT	48 min
May 14, 11:40 PM CDT	Severe Thunderstorm Warning	LOT	50 min
May 15, 1:20 AM CDT	Areal Flood Warning	LOT	9 hr
May 15, 1:35 AM CDT	Areal Flood Advisory	LOT	115 min
May 15, 11:58 AM CDT	River Flood Warning	LOT	9 days
May 16, 2:47 PM CDT	Flash Flood Watch	LOT	32 hr
May 16, 7:52 PM CDT	River Flood Warning	LOT	5 days
May 17, 1:44 PM CDT	Mesoscale Discussion	SPC	2 hr
May 17, 2:04 PM CDT	Areal Flood Advisory	LOT	6 hr
May 17, 3:29 PM CDT	Areal Flood Advisory	LOT	94 min
May 17, 4:32 PM CDT	Flash Flood Warning	LOT	6 hr
May 17, 10:10 PM CDT	Areal Flood Warning	LOT	30 hr
May 18, 11:59 AM CDT	Mesoscale Discussion	SPC	91 min
May 23, 11:29 AM CDT	Mesoscale Discussion	SPC	2 hr
May 23, 12:33 PM CDT	Tornado Watch	SPC	8 hr
May 23, 2:08 PM CDT	Severe Thunderstorm Warning	LOT	67 min
May 23, 2:51 PM CDT	Mesoscale Discussion	SPC	84 min
May 24, 12:43 AM CDT	River Flood Advisory	LOT	3 days
May 24, 8:43 AM CDT	River Flood Warning	LOT	25 hr
May 28, 5:17 PM CDT	Special Weather Statement	LOT	28 min
Jun 3, 8:30 AM CDT	Special Weather Statement	LOT	60 min
Jun 5, 12:26 PM CDT	Mesoscale Discussion	SPC	94 min
Jun 9, 2:33 AM CDT	Wind Advisory	LOT	21 hr
Jun 9, 6:20 PM CDT	Mesoscale Discussion	SPC	115 min
Jun 22, 12:48 PM CDT	Mesoscale Discussion	SPC	2 hr
Jun 22, 1:36 PM CDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 22, 4:53 PM CDT	Special Weather Statement	LOT	52 min
Jun 22, 6:15 PM CDT	Special Weather Statement	LOT	45 min
Jun 22, 6:53 PM CDT	Areal Flood Advisory	LOT	3 hr
Jun 26, 1:38 PM CDT	Severe Thunderstorm Watch	SPC	8 hr
Jun 26, 3:39 PM CDT	Mesoscale Discussion	SPC	2 hr
Jun 26, 7:53 PM CDT	Special Weather Statement	LOT	22 min
Jun 26, 8:22 PM CDT	Severe Thunderstorm Warning	LOT	53 min
Jun 26, 8:53 PM CDT	Severe Thunderstorm Warning	LOT	40 min
Jun 26, 10:37 PM CDT	Areal Flood Advisory	LOT	3 hr
Jun 27, 3:50 PM CDT	Special Weather Statement	LOT	25 min
Jun 27, 4:16 PM CDT	Special Weather Statement	LOT	29 min
Jul 9, 2:51 PM CDT	Mesoscale Discussion	SPC	114 min
Jul 9, 5:39 PM CDT	Mesoscale Discussion	SPC	96 min
Jul 11, 3:58 PM CDT	Severe Thunderstorm Watch	SPC	8 hr
Jul 11, 7:17 PM CDT	Mesoscale Discussion	SPC	58 min
Jul 11, 8:25 PM CDT	Severe Thunderstorm Warning	LOT	80 min
Jul 12, 4:42 AM CDT	Special Weather Statement	LOT	48 min
Jul 15, 5:35 PM CDT	Mesoscale Discussion	SPC	85 min
Jul 17, 3:36 AM CDT	Heat Advisory	LOT	40 hr
Jul 19, 5:28 AM CDT	Special Weather Statement	LOT	62 min
Jul 19, 7:31 AM CDT	Special Weather Statement	LOT	59 min
Jul 19, 8:44 AM CDT	Areal Flood Advisory	LOT	6 hr
Jul 19, 10:03 AM CDT	Severe Thunderstorm Warning	LOT	57 min
Jul 19, 10:12 AM CDT	Mesoscale Discussion	SPC	93 min
Jul 19, 10:22 AM CDT	Severe Thunderstorm Warning	LOT	53 min
Jul 26, 9:34 PM CDT	Areal Flood Advisory	LOT	116 min
Aug 10, 10:42 AM CDT	Mesoscale Discussion	SPC	93 min
Aug 10, 11:26 AM CDT	Severe Thunderstorm Watch PDS	SPC	7 hr
Aug 10, 1:36 PM CDT	Mesoscale Discussion	SPC	114 min
Aug 10, 2:03 PM CDT	Severe Thunderstorm Warning	LOT	87 min
Aug 10, 3:11 PM CDT	Tornado Warning	LOT	34 min
Aug 10, 3:36 PM CDT	Mesoscale Discussion	SPC	84 min
Aug 10, 4:23 PM CDT	High Wind Warning	LOT	90 min
Aug 15, 4:40 PM CDT	Mesoscale Discussion	SPC	95 min
Sep 6, 2:53 AM CDT	Severe Thunderstorm Watch	SPC	6 hr
Sep 6, 9:32 PM CDT	Mesoscale Discussion	SPC	118 min
Oct 4, 3:46 AM CDT	Frost Advisory	LOT	28 hr
Oct 14, 3:33 AM CDT	Wind Advisory	LOT	15 hr
Oct 14, 3:44 AM CDT	Red Flag Warning	LOT	15 hr
Oct 14, 7:41 PM CDT	Freeze Watch	LOT	7 hr
Oct 15, 2:35 AM CDT	Freeze Warning	LOT	30 hr
Oct 16, 2:40 PM CDT	Wind Advisory	LOT	28 hr
Oct 16, 2:52 PM CDT	Fire Weather Watch	LOT	12 hr
Oct 16, 2:52 PM CDT	Red Flag Warning	LOT	29 hr
Oct 22, 3:30 AM CDT	Dense Fog Advisory	LOT	9 hr
Oct 22, 6:29 AM CDT	Areal Flood Advisory	LOT	3 hr
Oct 31, 10:44 AM CDT	Wind Advisory	LOT	30 hr
Nov 10, 2:58 AM CST	Wind Advisory	LOT	24 hr
Nov 10, 1:28 PM CST	Mesoscale Discussion	SPC	92 min
Nov 10, 1:48 PM CST	Mesoscale Discussion	SPC	87 min
Nov 10, 2:05 PM CST	Tornado Watch	SPC	6 hr
Nov 10, 3:48 PM CST	Severe Thunderstorm Warning	LOT	57 min
Nov 10, 4:18 PM CST	Tornado Warning	LOT	27 min
Nov 10, 4:34 PM CST	Severe Thunderstorm Warning	LOT	71 min
Nov 14, 3:04 AM CST	Wind Advisory	LOT	41 hr
Nov 18, 2:15 PM CST	Wind Advisory	LOT	26 hr
Dec 23, 2:32 AM CST	Wind Advisory	LOT	25 hr
Dec 28, 3:04 PM CST	Winter Weather Advisory	LOT	39 hr
Dec 29, 3:52 PM CST	Mesoscale Discussion	SPC	4 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	13
Tornado Warning	2
Severe Thunderstorm Watch	7
Tornado Watch	4
Mesoscale Discussion	30
Special Weather Statement	11
Flooding
Areal Flood Warning	2
Flash Flood Warning	2
River Flood Warning	16
Flash Flood Watch	2
Flood Watch	1
River Flood Watch	15
Areal Flood Advisory	11
River Flood Advisory	8
Winter
Winter Storm Watch	2
Winter Weather Advisory	11
Heat
Heat Advisory	1
Cold
Freeze Warning	2
Freeze Watch	2
Frost Advisory	1
Wind Chill Advisory	2
Wind and dust
High Wind Warning	1
Wind Advisory	13
Fire
Red Flag Warning	2
Fire Weather Watch	1
Fog and smoke
Dense Fog Advisory	5

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2019 2021

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.