Alert archive / Illinois / LaSalle County

Weather alerts in LaSalle County, Illinois, 2009

184 weather alerts in 2009, 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 2009. Tap one for its archive.

Alerts: 184
Warnings: 63
Watches: 33
Advisories: 58
Busiest month: June33 alerts
Busiest day: June 19, 200910 alerts

Over time

By month

Warning verification

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

LaSalle County, 2009

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	0			0
Severe thunderstorm warnings	17	11	35%	11	73%	27 min
Flash flood warnings	3	1	67%	1	100%	189 min

Each office's whole area, 2009

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Chicago, IL: tornado warnings	12	3	75%	11	73%	11 min
NWS Chicago, IL: severe thunderstorm warnings	97	47	52%	183	68%	26 min
NWS Chicago, IL: flash flood warnings	25	10	60%	31	87%	80 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 3, 9:25 PM CST	Dense Fog Advisory	LOT	8 hr
Jan 8, 2:53 PM CST	Winter Weather Advisory	LOT	51 hr
Jan 9, 10:05 AM CST	Areal Flood Advisory	LOT	294 days
Jan 11, 10:49 AM CST	Areal Flood Advisory	LOT	292 days
Jan 12, 4:21 AM CST	Blizzard Watch	LOT	7 hr
Jan 12, 4:21 AM CST	Winter Weather Advisory	LOT	28 hr
Jan 12, 11:49 AM CST	Blizzard Warning	LOT	16 hr
Jan 12, 3:40 PM CST	Blizzard Watch	LOT	19 hr
Jan 13, 2:07 PM CST	Wind Chill Watch	LOT	13 hr
Jan 13, 3:02 PM CST	Winter Weather Advisory	LOT	33 hr
Jan 13, 11:38 PM CST	Mesoscale Discussion	SPC	4 hr
Jan 14, 3:23 AM CST	Wind Chill Warning	LOT	57 hr
Jan 14, 6:52 AM CST	Winter Storm Warning	LOT	17 hr
Jan 16, 3:08 PM CST	Wind Chill Advisory	LOT	9 hr
Jan 19, 9:21 AM CST	Areal Flood Advisory	LOT	143 days
Feb 9, 1:45 PM CST	River Flood Warning	LOT	24 hr
Feb 10, 4:00 AM CST	Flood Watch	LOT	41 hr
Feb 10, 5:19 PM CST	Areal Flood Advisory	LOT	121 days
Feb 11, 1:31 AM CST	Dense Fog Advisory	LOT	7 hr
Feb 11, 9:23 AM CST	River Flood Warning	LOT	36 hr
Feb 11, 10:52 AM CST	River Flood Advisory	LOT	47 hr
Feb 11, 11:43 AM CST	River Flood Warning	LOT	6 days
Feb 19, 1:38 PM CST	Winter Storm Watch	LOT	14 hr
Feb 20, 3:41 AM CST	Winter Storm Warning	LOT	34 hr
Feb 20, 3:41 AM CST	Winter Weather Advisory	LOT	41 hr
Feb 26, 3:50 AM CST	Dense Fog Advisory	LOT	11 hr
Feb 26, 10:41 AM CST	River Flood Watch	LOT	19 hr
Feb 26, 7:02 PM CST	Areal Flood Advisory	LOT	110 days
Feb 26, 8:33 PM CST	River Flood Watch	LOT	9 hr
Feb 27, 5:43 AM CST	River Flood Warning	LOT	38 hr
Feb 27, 5:43 AM CST	River Flood Warning	LOT	5 days
Mar 6, 3:28 PM CST	Flash Flood Watch	LOT	48 hr
Mar 7, 12:19 PM CST	River Flood Warning	LOT	9 days
Mar 7, 12:19 PM CST	River Flood Warning	LOT	43 days
Mar 8, 4:03 AM CDT	Areal Flood Warning	LOT	30 hr
Mar 8, 6:14 AM CDT	River Flood Warning	LOT	5 days
Mar 8, 7:11 AM CDT	Severe Thunderstorm Warning	LOT	64 min
Mar 8, 9:13 AM CDT	Wind Advisory	LOT	12 hr
Mar 8, 11:18 AM CDT	River Flood Warning	LOT	4 days
Mar 9, 3:39 AM CDT	Flash Flood Watch	LOT	24 hr
Mar 10, 2:03 AM CDT	Areal Flood Warning	LOT	36 hr
Mar 10, 3:37 AM CDT	Wind Advisory	LOT	27 hr
Mar 24, 4:08 AM CDT	Wind Advisory	LOT	16 hr
Mar 24, 10:28 PM CDT	Mesoscale Discussion	SPC	92 min
Mar 24, 10:48 PM CDT	Severe Thunderstorm Warning	LOT	42 min
Mar 27, 12:58 PM CDT	Winter Storm Watch	LOT	19 hr
Mar 28, 3:40 AM CDT	Winter Storm Warning	LOT	24 hr
Mar 29, 3:11 AM CDT	Winter Weather Advisory	LOT	8 hr
Mar 29, 3:42 AM CDT	Mesoscale Discussion	SPC	4 hr
Apr 5, 10:50 AM CDT	Mesoscale Discussion	SPC	115 min
Apr 7, 10:18 AM CDT	River Flood Warning	LOT	12 hr
Apr 19, 10:06 AM CDT	River Flood Watch	LOT	11 hr
Apr 19, 8:59 PM CDT	River Flood Warning	LOT	23 days
Apr 24, 2:16 AM CDT	Dense Fog Advisory	LOT	6 hr
Apr 25, 5:32 PM CDT	Mesoscale Discussion	SPC	73 min
Apr 26, 2:01 PM CDT	Areal Flood Advisory	LOT	57 days
Apr 27, 10:55 AM CDT	River Flood Advisory	LOT	11 hr
Apr 27, 9:38 PM CDT	River Flood Warning	LOT	47 hr
Apr 28, 12:44 AM CDT	Areal Flood Advisory	LOT	55 days
Apr 29, 3:10 PM CDT	Flash Flood Watch	LOT	20 hr
Apr 30, 5:28 AM CDT	River Flood Warning	LOT	47 hr
Apr 30, 7:01 AM CDT	Areal Flood Advisory	LOT	53 days
Apr 30, 7:25 PM CDT	River Flood Warning	LOT	23 hr
May 6, 2:46 PM CDT	Areal Flood Advisory	LOT	49 days
May 7, 3:48 PM CDT	Severe Thunderstorm Warning	LOT	42 min
May 7, 4:06 PM CDT	Severe Thunderstorm Warning	LOT	37 min
May 8, 8:35 PM CDT	Mesoscale Discussion	SPC	85 min
May 13, 5:39 AM CDT	River Flood Warning	LOT	18 days
May 13, 9:16 AM CDT	River Flood Warning	LOT	12 hr
May 13, 11:13 AM CDT	River Flood Warning	LOT	5 days
May 13, 4:08 PM CDT	River Flood Watch	LOT	5 hr
May 13, 5:47 PM CDT	Mesoscale Discussion	SPC	88 min
May 13, 5:54 PM CDT	Severe Thunderstorm Warning	LOT	34 min
May 13, 6:02 PM CDT	Tornado Watch	SPC	5 hr
May 13, 6:26 PM CDT	Severe Thunderstorm Warning	LOT	28 min
May 13, 8:35 PM CDT	Mesoscale Discussion	SPC	85 min
May 13, 9:09 PM CDT	River Flood Warning	LOT	4 days
May 13, 10:17 PM CDT	Mesoscale Discussion	SPC	58 min
May 14, 3:34 PM CDT	Flash Flood Watch	LOT	30 hr
May 15, 11:05 AM CDT	River Flood Warning	LOT	22 hr
May 15, 12:38 PM CDT	Wind Advisory	LOT	2 hr
May 15, 2:48 PM CDT	Areal Flood Advisory	LOT	57 days
May 15, 5:46 PM CDT	Flash Flood Warning	LOT	6 hr
May 15, 11:16 PM CDT	Areal Flood Warning	LOT	12 hr
May 16, 11:27 AM CDT	Areal Flood Warning	LOT	24 hr
May 25, 7:52 PM CDT	River Flood Advisory	LOT	25 days
Jun 1, 1:31 PM CDT	Mesoscale Discussion	SPC	59 min
Jun 1, 2:37 PM CDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 1, 6:13 PM CDT	Severe Thunderstorm Warning	LOT	62 min
Jun 1, 6:34 PM CDT	Mesoscale Discussion	SPC	86 min
Jun 8, 1:44 AM CDT	Flash Flood Warning	LOT	8 hr
Jun 8, 11:54 AM CDT	Mesoscale Discussion	SPC	96 min
Jun 8, 1:23 PM CDT	Severe Thunderstorm Watch	SPC	6 hr
Jun 8, 3:53 PM CDT	Mesoscale Discussion	SPC	67 min
Jun 11, 5:00 AM CDT	Flash Flood Warning	LOT	10 hr
Jun 18, 9:42 AM CDT	Mesoscale Discussion	SPC	93 min
Jun 18, 10:11 AM CDT	Severe Thunderstorm Watch	SPC	6 hr
Jun 18, 1:17 PM CDT	Mesoscale Discussion	SPC	88 min
Jun 18, 11:07 PM CDT	Mesoscale Discussion	SPC	53 min
Jun 18, 11:30 PM CDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 19, 7:14 AM CDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 19, 1:08 PM CDT	Flash Flood Watch	LOT	8 hr
Jun 19, 1:54 PM CDT	Mesoscale Discussion	SPC	96 min
Jun 19, 2:24 PM CDT	Severe Thunderstorm Watch	SPC	8 hr
Jun 19, 5:37 PM CDT	Mesoscale Discussion	SPC	53 min
Jun 19, 5:49 PM CDT	Severe Thunderstorm Warning	LOT	41 min
Jun 19, 6:23 PM CDT	Severe Thunderstorm Warning	LOT	52 min
Jun 19, 6:38 PM CDT	Severe Thunderstorm Warning	LOT	67 min
Jun 19, 9:25 PM CDT	River Flood Warning	LOT	14 hr
Jun 22, 11:13 AM CDT	River Flood Warning	LOT	24 hr
Jun 22, 3:15 PM CDT	Heat Advisory	LOT	52 hr
Jun 23, 11:27 AM CDT	River Flood Advisory	LOT	72 hr
Jun 25, 10:18 AM CDT	Heat Advisory	LOT	9 hr
Jun 25, 12:48 PM CDT	Severe Thunderstorm Watch	SPC	6 hr
Jun 25, 3:57 PM CDT	Severe Thunderstorm Watch	SPC	5 hr
Jun 27, 2:41 PM CDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 27, 6:22 PM CDT	Mesoscale Discussion	SPC	113 min
Jun 27, 6:32 PM CDT	Severe Thunderstorm Warning	LOT	58 min
Jun 27, 7:12 PM CDT	Severe Thunderstorm Warning	LOT	32 min
Jul 5, 3:58 AM CDT	Dense Fog Advisory	LOT	5 hr
Jul 24, 3:52 PM CDT	Mesoscale Discussion	SPC	83 min
Jul 24, 5:02 PM CDT	Tornado Watch	SPC	6 hr
Jul 24, 7:20 PM CDT	Mesoscale Discussion	SPC	85 min
Jul 24, 9:22 PM CDT	Mesoscale Discussion	SPC	53 min
Jul 24, 9:58 PM CDT	Severe Thunderstorm Warning	LOT	47 min
Jul 24, 10:43 PM CDT	Severe Thunderstorm Warning	LOT	62 min
Jul 24, 11:28 PM CDT	Areal Flood Advisory	LOT	6 hr
Jul 27, 11:40 PM CDT	Special Weather Statement	LOT	95 min
Aug 4, 4:29 AM CDT	Dense Fog Advisory	LOT	4 hr
Aug 4, 9:14 AM CDT	Severe Thunderstorm Warning	LOT	76 min
Aug 8, 4:07 AM CDT	Heat Advisory	LOT	38 hr
Aug 9, 8:30 PM CDT	Mesoscale Discussion	SPC	90 min
Aug 9, 9:34 PM CDT	Areal Flood Advisory	LOT	61 min
Aug 9, 10:55 PM CDT	Mesoscale Discussion	SPC	95 min
Aug 19, 11:51 AM CDT	Mesoscale Discussion	SPC	114 min
Aug 19, 12:49 PM CDT	Tornado Watch	SPC	6 hr
Aug 19, 3:19 PM CDT	Mesoscale Discussion	SPC	86 min
Aug 19, 4:01 PM CDT	Severe Thunderstorm Warning	LOT	55 min
Aug 19, 4:37 PM CDT	Severe Thunderstorm Warning	LOT	53 min
Aug 19, 5:40 PM CDT	Areal Flood Advisory	LOT	5 hr
Aug 26, 1:59 PM CDT	Flash Flood Watch	LOT	37 hr
Aug 27, 8:46 PM CDT	Areal Flood Advisory	LOT	6 hr
Sep 9, 9:19 PM CDT	Dense Fog Advisory	LOT	12 hr
Sep 10, 8:44 PM CDT	Dense Fog Advisory	LOT	11 hr
Sep 12, 4:08 AM CDT	Dense Fog Advisory	LOT	5 hr
Sep 12, 9:43 PM CDT	Dense Fog Advisory	LOT	11 hr
Sep 26, 4:41 AM CDT	Dense Fog Advisory	LOT	5 hr
Sep 27, 5:55 AM CDT	Dense Fog Advisory	LOT	4 hr
Sep 27, 5:32 PM CDT	Mesoscale Discussion	SPC	88 min
Sep 27, 8:22 PM CDT	Tornado Watch	SPC	3 hr
Oct 6, 9:09 PM CDT	Wind Advisory	LOT	5 hr
Oct 9, 4:37 AM CDT	Frost Advisory	LOT	24 hr
Oct 9, 4:00 PM CDT	Freeze Warning	LOT	41 hr
Oct 29, 11:22 AM CDT	River Flood Warning	LOT	10 days
Oct 29, 3:13 PM CDT	Flood Watch	LOT	24 hr
Oct 29, 9:32 PM CDT	River Flood Warning	LOT	3 days
Oct 30, 8:54 PM CDT	River Flood Warning	LOT	24 hr
Oct 30, 10:00 PM CDT	River Flood Advisory	LOT	48 min
Oct 30, 10:14 PM CDT	River Flood Advisory	LOT	7 hr
Oct 31, 4:51 AM CDT	River Flood Warning	LOT	54 hr
Nov 20, 9:38 PM CST	Dense Fog Advisory	LOT	10 hr
Nov 23, 7:07 AM CST	Dense Fog Advisory	LOT	3 hr
Nov 23, 9:40 PM CST	Dense Fog Advisory	LOT	11 hr
Dec 6, 3:42 PM CST	Winter Storm Watch	LOT	30 hr
Dec 7, 9:35 PM CST	Winter Weather Advisory	LOT	50 hr
Dec 8, 11:22 AM CST	Mesoscale Discussion	SPC	5 hr
Dec 9, 3:20 PM CST	Wind Chill Advisory	LOT	20 hr
Dec 12, 1:18 PM CST	Areal Flood Warning	LOT	22 hr
Dec 12, 7:35 PM CST	Freezing Rain Advisory	LOT	14 hr
Dec 14, 3:57 AM CST	Dense Fog Advisory	LOT	9 hr
Dec 17, 2:47 PM CST	Areal Flood Warning	LOT	24 hr
Dec 22, 11:31 AM CST	Winter Storm Watch	LOT	17 hr
Dec 22, 3:35 PM CST	Winter Weather Advisory	LOT	29 hr
Dec 23, 3:45 AM CST	Flood Watch	LOT	55 hr
Dec 23, 6:44 AM CST	Mesoscale Discussion	SPC	4 hr
Dec 24, 10:05 AM CST	River Flood Warning	LOT	3 days
Dec 24, 12:37 PM CST	River Flood Warning	LOT	24 hr
Dec 24, 12:37 PM CST	River Flood Warning	LOT	8 days
Dec 24, 11:25 PM CST	Areal Flood Warning	LOT	12 hr
Dec 25, 2:29 PM CST	River Flood Advisory	LOT	10 hr
Dec 25, 5:28 PM CST	River Flood Warning	LOT	25 hr
Dec 25, 9:30 PM CST	River Flood Warning	LOT	39 hr
Dec 26, 9:33 AM CST	Winter Weather Advisory	LOT	11 hr
Dec 27, 12:33 PM CST	River Flood Advisory	LOT	7 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	17
Severe Thunderstorm Watch	9
Tornado Watch	4
Mesoscale Discussion	29
Special Weather Statement	1
Flooding
Areal Flood Warning	7
Flash Flood Warning	3
River Flood Warning	30
Flash Flood Watch	6
Flood Watch	3
River Flood Watch	4
Areal Flood Advisory	14
River Flood Advisory	8
Winter
Blizzard Warning	1
Winter Storm Warning	3
Blizzard Watch	2
Winter Storm Watch	4
Freezing Rain Advisory	1
Winter Weather Advisory	8
Heat
Heat Advisory	3
Cold
Freeze Warning	1
Wind Chill Warning	1
Wind Chill Watch	1
Frost Advisory	1
Wind Chill Advisory	2
Wind and dust
Wind Advisory	5
Fog and smoke
Dense Fog Advisory	16

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2008 2010

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.