Alert archive / Pennsylvania / Lancaster County

Weather alerts in Lancaster County, Pennsylvania, 2009

228 weather alerts in 2009, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.

Lancaster County and its neighbors

Each county as a circle sized by its count in 2009. Tap one for its archive.

Alerts
228
Warnings
53
Watches
26
Advisories
57
Busiest month
August57 alerts
Busiest day
June 9, 200913 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 4 tornado warnings covering Lancaster County in 2009 had a tornado report inside them; 1 of 1 tornado reports fell inside a warning, on average 19 minutes after it went out.

Lancaster County, 2009

WarningsWith a reportFalse alarm ratioReportsInside a warningMean lead time
Tornado warnings4175%1100%19 min
Severe thunderstorm warnings372046%2176%28 min
Flash flood warnings5260%1100%104 min

Each office's whole area, 2009

WarningsWith a reportFalse alarm ratioReportsInside a warningMean lead time
NWS State College, PA: tornado warnings13377%580%22 min
NWS State College, PA: severe thunderstorm warnings1668648%18280%26 min
NWS State College, PA: flash flood warnings382339%4393%64 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, Eastern Time. Each opens its own page with the text, the map, the radar and the sounding.

IssuedProductOfficeLasted
Jan 5, 3:10 AM ESTWinter Storm WatchCTP19 hr
Jan 5, 10:11 PM ESTWinter Weather AdvisoryCTP72 hr
Jan 6, 5:17 PM ESTMesoscale DiscussionSPC4 hr
Jan 7, 12:10 AM ESTMesoscale DiscussionSPC4 hr
Jan 8, 3:30 PM ESTWinter Storm WatchCTP23 hr
Jan 9, 2:32 PM ESTWinter Weather AdvisoryCTP37 hr
Jan 26, 3:30 AM ESTWinter Storm WatchCTP32 hr
Jan 27, 11:40 AM ESTWinter Storm WarningCTP31 hr
Jan 28, 12:31 AM ESTMesoscale DiscussionSPC5 hr
Jan 28, 7:53 AM ESTMesoscale DiscussionSPC5 hr
Feb 3, 8:40 PM ESTWinter Weather AdvisoryCTP28 hr
Feb 10, 3:31 PM ESTHigh Wind WatchCTP24 hr
Feb 11, 3:09 PM ESTHigh Wind WarningCTP28 hr
Feb 11, 3:09 PM ESTWind AdvisoryCTP32 hr
Feb 11, 8:00 PM ESTMesoscale DiscussionSPC60 min
Feb 11, 8:19 PM ESTSevere Thunderstorm WatchSPC3 hr
Feb 11, 10:14 PM ESTMesoscale DiscussionSPC61 min
Mar 1, 3:07 AM ESTWinter Storm WatchCTP12 hr
Mar 1, 11:31 AM ESTWinter Storm WarningCTP16 hr
Mar 1, 11:31 AM ESTWinter Weather AdvisoryCTP24 hr
Mar 8, 3:29 PM EDTWind AdvisoryCTP24 hr
Mar 10, 3:48 PM EDTWind AdvisoryCTP28 hr
Mar 23, 4:48 AM EDTRed Flag WarningCTP15 hr
Mar 27, 3:55 AM EDTDense Fog AdvisoryCTP6 hr
Mar 29, 1:49 PM EDTMesoscale DiscussionSPC116 min
Mar 29, 3:33 PM EDTSevere Thunderstorm WarningCTP42 min
Mar 29, 4:13 PM EDTSevere Thunderstorm WarningCTP62 min
Mar 29, 4:21 PM EDTTornado WarningCTP39 min
Mar 29, 4:34 PM EDTSevere Thunderstorm WarningCTP71 min
Apr 3, 3:04 AM EDTHigh Wind WatchCTP9 hr
Apr 3, 9:31 AM EDTSpecial Weather StatementCTP74 min
Apr 3, 11:12 AM EDTSpecial Weather StatementCTP48 min
Apr 3, 11:47 AM EDTWind AdvisoryCTP28 hr
Apr 16, 3:06 PM EDTFrost AdvisoryCTP18 hr
Apr 21, 6:20 PM EDTSpecial Weather StatementCTP55 min
Apr 21, 7:06 PM EDTSevere Thunderstorm WarningCTP39 min
Apr 23, 2:57 AM EDTFrost AdvisoryCTP29 hr
Apr 28, 10:43 AM EDTRed Flag WarningCTP9 hr
May 5, 3:11 PM EDTFlood WatchCTP36 hr
May 7, 1:17 AM EDTAreal Flood AdvisoryCTP3 hr
May 15, 2:39 AM EDTDense Fog AdvisoryCTP5 hr
May 16, 1:00 PM EDTSevere Thunderstorm WatchSPC7 hr
May 16, 3:55 PM EDTMesoscale DiscussionSPC65 min
May 16, 6:29 PM EDTMesoscale DiscussionSPC2 hr
May 16, 8:30 PM EDTSevere Thunderstorm WarningCTP47 min
May 16, 9:04 PM EDTSpecial Weather StatementCTP71 min
May 16, 10:00 PM EDTAreal Flood AdvisoryCTP2 hr
May 18, 3:28 PM EDTFrost AdvisoryCTP17 hr
May 24, 7:11 PM EDTMesoscale DiscussionSPC64 min
May 29, 1:58 AM EDTAreal Flood AdvisoryCTP3 hr
May 29, 12:20 PM EDTMesoscale DiscussionSPC55 min
May 29, 1:26 PM EDTSevere Thunderstorm WatchSPC8 hr
May 29, 3:04 PM EDTSpecial Weather StatementCTP56 min
May 29, 3:13 PM EDTSevere Thunderstorm WarningCTP62 min
May 29, 4:30 PM EDTMesoscale DiscussionSPC60 min
Jun 2, 1:20 PM EDTSevere Thunderstorm WarningCTP55 min
Jun 2, 1:31 PM EDTMesoscale DiscussionSPC89 min
Jun 2, 2:17 PM EDTSpecial Weather StatementCTP58 min
Jun 3, 1:20 AM EDTSpecial Weather StatementCTP70 min
Jun 3, 10:38 PM EDTAreal Flood AdvisoryCTP3 hr
Jun 9, 5:09 AM EDTSevere Thunderstorm WarningCTP66 min
Jun 9, 6:01 AM EDTMesoscale DiscussionSPC59 min
Jun 9, 6:13 AM EDTSevere Thunderstorm WarningCTP27 min
Jun 9, 1:31 PM EDTSevere Thunderstorm WatchSPC6 hr
Jun 9, 1:54 PM EDTSevere Thunderstorm WarningCTP66 min
Jun 9, 2:07 PM EDTSevere Thunderstorm WarningCTP23 min
Jun 9, 2:27 PM EDTAreal Flood AdvisoryCTP3 hr
Jun 9, 2:35 PM EDTSevere Thunderstorm WarningCTP25 min
Jun 9, 2:50 PM EDTTornado WarningCTP25 min
Jun 9, 2:57 PM EDTSevere Thunderstorm WarningCTP63 min
Jun 9, 3:23 PM EDTSevere Thunderstorm WarningCTP37 min
Jun 9, 3:40 PM EDTMesoscale DiscussionSPC65 min
Jun 9, 4:11 PM EDTSevere Thunderstorm WarningCTP49 min
Jun 10, 3:01 PM EDTSpecial Weather StatementCTP59 min
Jun 10, 3:44 PM EDTAreal Flood AdvisoryCTP3 hr
Jun 10, 5:56 PM EDTSevere Thunderstorm WarningCTP34 min
Jun 10, 6:30 PM EDTSevere Thunderstorm WarningCTP30 min
Jun 10, 7:25 PM EDTSpecial Weather StatementCTP35 min
Jun 10, 9:40 PM EDTAreal Flood AdvisoryCTP3 hr
Jun 10, 9:55 PM EDTFlash Flood WarningCTP4 hr
Jun 11, 4:04 AM EDTFlash Flood WatchCTP23 hr
Jun 11, 10:01 PM EDTMesoscale DiscussionSPC59 min
Jun 13, 8:09 PM EDTMesoscale DiscussionSPC66 min
Jun 14, 12:02 AM EDTSpecial Weather StatementCTP58 min
Jun 18, 11:40 AM EDTMesoscale DiscussionSPC95 min
Jun 20, 7:15 AM EDTAreal Flood AdvisoryCTP3 hr
Jun 20, 7:50 AM EDTSpecial Weather StatementCTP70 min
Jun 20, 3:31 PM EDTSpecial Weather StatementCTP44 min
Jun 20, 3:59 PM EDTSevere Thunderstorm WarningCTP45 min
Jun 26, 2:19 PM EDTMesoscale DiscussionSPC56 min
Jun 26, 2:42 PM EDTSevere Thunderstorm WatchSPC7 hr
Jun 26, 4:15 PM EDTSevere Thunderstorm WarningCTP60 min
Jun 26, 7:33 PM EDTMesoscale DiscussionSPC57 min
Jun 26, 9:11 PM EDTMesoscale DiscussionSPC64 min
Jun 30, 12:27 PM EDTSevere Thunderstorm WarningCTP78 min
Jun 30, 12:39 PM EDTSevere Thunderstorm WarningCTP81 min
Jun 30, 1:14 PM EDTSevere Thunderstorm WarningCTP76 min
Jun 30, 1:41 PM EDTSpecial Weather StatementCTP79 min
Jun 30, 1:54 PM EDTSevere Thunderstorm WarningCTP66 min
Jul 1, 12:03 PM EDTMesoscale DiscussionSPC87 min
Jul 2, 7:40 PM EDTSpecial Weather StatementCTP35 min
Jul 2, 8:18 PM EDTSpecial Weather StatementCTP27 min
Jul 11, 8:07 PM EDTSpecial Weather StatementCTP38 min
Jul 11, 9:06 PM EDTSevere Thunderstorm WarningCTP54 min
Jul 11, 10:11 PM EDTSpecial Weather StatementCTP79 min
Jul 11, 11:45 PM EDTAreal Flood AdvisoryCTP3 hr
Jul 11, 11:48 PM EDTSpecial Weather StatementCTP27 min
Jul 16, 4:04 PM EDTMesoscale DiscussionSPC86 min
Jul 23, 10:09 AM EDTAreal Flood AdvisoryCTP3 hr
Jul 23, 7:25 PM EDTSevere Thunderstorm WarningCTP65 min
Jul 23, 7:35 PM EDTAreal Flood AdvisoryCTP3 hr
Jul 24, 3:34 PM EDTMesoscale DiscussionSPC86 min
Jul 24, 4:16 PM EDTSevere Thunderstorm WarningCTP59 min
Jul 24, 5:15 PM EDTSpecial Weather StatementCTP45 min
Jul 25, 6:36 AM EDTDense Fog AdvisoryCTP3 hr
Jul 25, 3:50 PM EDTSevere Thunderstorm WatchSPC5 hr
Jul 26, 2:13 AM EDTSpecial Weather StatementCTP17 min
Jul 26, 3:40 AM EDTFlash Flood WatchCTP16 hr
Jul 26, 1:40 PM EDTMesoscale DiscussionSPC2 hr
Jul 26, 3:14 PM EDTMesoscale DiscussionSPC2 hr
Jul 26, 3:51 PM EDTSevere Thunderstorm WatchSPC7 hr
Jul 26, 5:35 PM EDTSpecial Weather StatementCTP25 min
Jul 26, 6:11 PM EDTSpecial Weather StatementCTP19 min
Jul 26, 6:16 PM EDTSpecial Weather StatementCTP29 min
Jul 26, 6:37 PM EDTMesoscale DiscussionSPC113 min
Jul 26, 6:41 PM EDTSpecial Weather StatementCTP34 min
Jul 26, 7:30 PM EDTSpecial Weather StatementCTP45 min
Jul 27, 7:34 PM EDTSpecial Weather StatementCTP26 min
Jul 27, 8:53 PM EDTSpecial Weather StatementCTP37 min
Jul 27, 9:25 PM EDTSpecial Weather StatementCTP35 min
Jul 27, 10:36 PM EDTSpecial Weather StatementCTP24 min
Jul 27, 11:29 PM EDTSpecial Weather StatementCTP31 min
Jul 28, 3:08 PM EDTSpecial Weather StatementCTP67 min
Jul 28, 3:33 PM EDTSpecial Weather StatementCTP72 min
Jul 29, 4:24 PM EDTSpecial Weather StatementCTP51 min
Jul 29, 5:05 PM EDTMesoscale DiscussionSPC55 min
Jul 31, 10:20 AM EDTMesoscale DiscussionSPC85 min
Jul 31, 12:06 PM EDTMesoscale DiscussionSPC84 min
Aug 1, 4:05 AM EDTDense Fog AdvisoryCTP5 hr
Aug 1, 2:48 PM EDTSpecial Weather StatementCTP37 min
Aug 1, 3:40 PM EDTAreal Flood AdvisoryCTP3 hr
Aug 1, 4:01 PM EDTFlash Flood WarningCTP3 hr
Aug 1, 6:15 PM EDTAreal Flood AdvisoryCTP79 min
Aug 2, 12:36 AM EDTAreal Flood AdvisoryCTP3 hr
Aug 2, 4:14 AM EDTSpecial Weather StatementCTP61 min
Aug 2, 5:08 AM EDTFlash Flood WatchCTP10 hr
Aug 2, 5:08 AM EDTSpecial Weather StatementCTP52 min
Aug 2, 5:27 AM EDTAreal Flood AdvisoryCTP3 hr
Aug 2, 8:18 AM EDTSpecial Weather StatementCTP27 min
Aug 2, 8:19 AM EDTAreal Flood AdvisoryCTP3 hr
Aug 2, 8:29 AM EDTSevere Thunderstorm WarningCTP61 min
Aug 2, 9:36 AM EDTFlash Flood WarningCTP3 hr
Aug 2, 9:53 AM EDTSpecial Weather StatementCTP37 min
Aug 9, 2:45 PM EDTMesoscale DiscussionSPC60 min
Aug 9, 3:09 PM EDTHeat AdvisoryCTP28 hr
Aug 9, 3:18 PM EDTSevere Thunderstorm WatchSPC5 hr
Aug 9, 5:19 PM EDTSevere Thunderstorm WarningCTP56 min
Aug 9, 5:59 PM EDTSevere Thunderstorm WarningCTP46 min
Aug 9, 7:11 PM EDTMesoscale DiscussionSPC2 hr
Aug 10, 5:09 PM EDTSevere Thunderstorm WatchSPC5 hr
Aug 10, 8:15 PM EDTMesoscale DiscussionSPC2 hr
Aug 11, 11:07 PM EDTSpecial Weather StatementCTP38 min
Aug 12, 12:37 AM EDTSpecial Weather StatementCTP23 min
Aug 12, 7:47 PM EDTAreal Flood AdvisoryCTP3 hr
Aug 12, 11:50 PM EDTFlash Flood WarningCTP3 hr
Aug 13, 1:40 AM EDTAreal Flood AdvisoryCTP3 hr
Aug 13, 4:33 AM EDTFlash Flood WatchCTP15 hr
Aug 14, 4:04 AM EDTDense Fog AdvisoryCTP6 hr
Aug 15, 6:30 AM EDTDense Fog AdvisoryCTP4 hr
Aug 18, 2:44 PM EDTSpecial Weather StatementCTP31 min
Aug 18, 6:02 PM EDTSevere Thunderstorm WarningCTP88 min
Aug 19, 6:05 PM EDTMesoscale DiscussionSPC55 min
Aug 19, 6:31 PM EDTSevere Thunderstorm WarningCTP59 min
Aug 19, 7:43 PM EDTSpecial Weather StatementCTP32 min
Aug 19, 8:13 PM EDTAreal Flood AdvisoryCTP3 hr
Aug 20, 3:20 PM EDTSpecial Weather StatementCTP25 min
Aug 20, 3:52 PM EDTSevere Thunderstorm WarningCTP53 min
Aug 20, 4:22 PM EDTSpecial Weather StatementCTP53 min
Aug 20, 4:29 PM EDTTornado WarningCTP31 min
Aug 20, 4:57 PM EDTTornado WarningCTP63 min
Aug 21, 10:01 AM EDTMesoscale DiscussionSPC119 min
Aug 21, 11:28 AM EDTSevere Thunderstorm WatchSPC7 hr
Aug 21, 12:06 PM EDTSevere Thunderstorm WarningCTP54 min
Aug 21, 12:21 PM EDTAreal Flood AdvisoryCTP114 min
Aug 21, 12:41 PM EDTSevere Thunderstorm WarningCTP49 min
Aug 21, 1:27 PM EDTSevere Thunderstorm WarningCTP63 min
Aug 21, 1:40 PM EDTSevere Thunderstorm WarningCTP35 min
Aug 21, 2:17 PM EDTFlash Flood WarningCTP2 hr
Aug 21, 2:23 PM EDTSevere Thunderstorm WarningCTP21 min
Aug 21, 9:29 PM EDTSpecial Weather StatementCTP46 min
Aug 21, 9:59 PM EDTAreal Flood AdvisoryCTP3 hr
Aug 22, 1:37 PM EDTFlash Flood WatchCTP12 hr
Aug 22, 8:52 PM EDTAreal Flood AdvisoryCTP3 hr
Aug 28, 7:40 PM EDTAreal Flood AdvisoryCTP3 hr
Aug 28, 8:17 PM EDTFlash Flood WatchCTP7 hr
Sep 11, 8:09 AM EDTAreal Flood AdvisoryCTP4 hr
Sep 11, 12:05 PM EDTAreal Flood AdvisoryCTP4 hr
Sep 23, 8:49 PM EDTSpecial Weather StatementCTP26 min
Sep 23, 9:12 PM EDTSpecial Weather StatementCTP78 min
Oct 6, 2:59 PM EDTWind AdvisoryCTP29 hr
Oct 9, 10:36 PM EDTSpecial Weather StatementCTP39 min
Oct 13, 3:28 AM EDTFrost AdvisoryCTP30 hr
Oct 18, 3:58 AM EDTSpecial Weather StatementCTP2 hr
Oct 18, 11:16 AM EDTFreeze WatchCTP3 hr
Oct 18, 2:26 PM EDTFreeze WarningCTP19 hr
Oct 19, 2:30 PM EDTFrost AdvisoryCTP18 hr
Oct 24, 2:55 PM EDTAreal Flood AdvisoryCTP3 hr
Oct 24, 3:28 PM EDTAreal Flood AdvisoryCTP3 hr
Oct 24, 3:43 PM EDTSpecial Weather StatementCTP47 min
Oct 24, 5:03 PM EDTSpecial Weather StatementCTP27 min
Nov 26, 3:07 AM ESTDense Fog AdvisoryCTP6 hr
Dec 3, 3:58 AM ESTSpecial Weather StatementCTP47 min
Dec 3, 4:47 AM ESTSpecial Weather StatementCTP28 min
Dec 5, 4:27 AM ESTWinter Weather AdvisoryCTP14 hr
Dec 5, 5:17 PM ESTSpecial Weather StatementCTP58 min
Dec 9, 3:29 AM ESTFlood WatchCTP9 hr
Dec 9, 3:38 AM ESTWind AdvisoryCTP26 hr
Dec 12, 3:17 PM ESTFreezing Rain AdvisoryCTP25 hr
Dec 17, 10:08 PM ESTWinter Storm WatchCTP17 hr
Dec 18, 2:38 PM ESTWinter Storm WarningCTP32 hr
Dec 19, 12:34 AM ESTMesoscale DiscussionSPC5 hr
Dec 19, 6:57 AM ESTMesoscale DiscussionSPC6 hr
Dec 19, 12:27 PM ESTMesoscale DiscussionSPC6 hr
Dec 24, 2:05 PM ESTWinter Weather AdvisoryCTP29 hr
Dec 26, 8:56 AM ESTAreal Flood AdvisoryCTP6 hr
Dec 28, 2:33 PM ESTWind AdvisoryCTP28 hr
Dec 30, 2:45 PM ESTWinter Weather AdvisoryCTP19 hr
Dec 31, 6:40 PM ESTWinter Weather AdvisoryCTP6 hr

By product

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

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force nowTornadoes on recordForecastThe radar archive20082010

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.