Alert archive / Virginia / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 381, NWS Baltimore/Washington

August 19, 2011Fairfax County, Prince William County, Virginia

NWS Baltimore/Washington issued this severe thunderstorm warning at Aug 19, 2011, 12:10 AM EDT for Fairfax County, Prince William County, Virginia. It was in force for 31 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 19, 2011, 12:10 AM EDT (04:10 UTC)
Expired: Aug 19, 2011, 12:41 AM EDT
In force: 31 min
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon

Counties Fairfax County, VA, Prince William County, VA

The radar

The Sterling radar (KLWX), 25 km from the middle of the area, began a volume at 04:13 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 00:00Z, 4.2 hours before the alert went out and 196 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 27 J/kg
Mixed-layer CIN: -177 J/kg
Mixed-layer LCL: 1773 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 5 m²/s²
0-3 km storm-relative helicity: 34 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Baltimore/Washington wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 18, 8:52 PM EDT, 3 hours 18 minutes earlier.

Area forecast discussion, Aug 18, 8:52 PM EDT, 3 hours 18 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Hazardous weather outlook, Aug 18, 8:25 PM EDT, 3 hours 45 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
825 PM EDT THU AUG 18 2011

ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057-
191000-
CHESAPEAKE BAY NORTH OF POOLES ISLAND MD-
CHESAPEAKE BAY FROM POOLES ISLAND TO SANDY POINT MD-
CHESAPEAKE BAY FROM SANDY POINT TO NORTH BEACH MD-
CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD-
CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA-
TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD-
TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD-
TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA-
PATAPSCO RIVER INCLUDING BALTIMORE HARBOR-
CHESTER RIVER TO QUEENSTOWN MD-EASTERN BAY-
CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER-
PATUXENT RIVER TO BROOMES ISLAND MD-
TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH
ISLAND-DISTRICT OF COLUMBIA-NORTHERN BALTIMORE-HARFORD-
SOUTHERN BALTIMORE-PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-
CALVERT-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-
ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-
KING GEORGE-
825 PM EDT THU AUG 18 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE
CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN
CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF
COLUMBIA.

.DAY ONE...TONIGHT

SCATTERED STRONG THUNDERSTORMS WILL IMPACT ACROSS THE REGION THIS
EVENING. SOME OF THESE STORMS WILL PRODUCE LARGE HAIL...DAMAGING
WINDS AND FLASH FLOODING.

A SMALL CRAFT ADVISORY IS IN EFFECT FOR MARYLAND CHESAPEAKE BAY
AND THE LOWER TIDAL POTOMAC SOUTH OF COBB ISLAND UNTIL 2 AM.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

SHOWERS AND THUNDERSTORMS ARE LIKELY FRIDAY AFTERNOON AND EVENING.
ANY THUNDERSTORMS WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAIN
AND COULD LEAD TO LOCALIZED FLASH FLOODING. THUNDERSTORMS WILL
ALSO HAVE THE POTENTIAL TO PRODUCE DAMAGING WIND GUSTS AND LARGE
HAIL.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE REQUESTED TO RELAY HAZARDOUS WEATHER REPORTS TO THE
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON WEATHER FORECAST
OFFICE IN STERLING. ACTIVATION MAY BE NECESSARY FRIDAY
AFTERNOON AND EVENING.

MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504-
WVZ050>053-055-501>506-191000-
WASHINGTON-FREDERICK MD-CARROLL-MONTGOMERY-HOWARD-
EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-AUGUSTA-
ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-NELSON-
ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-LOUDOUN-ORANGE-CULPEPER-
NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND-
EASTERN HIGHLAND-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-HARDY-
WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL-
WESTERN PENDLETON-EASTERN PENDLETON-
825 PM EDT THU AUG 18 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN WEST VIRGINIA...
NORTHERN AND CENTRAL VIRGINIA...AND CENTRAL AND WESTERN MARYLAND
WITH THE EXCEPTION OF GARRETT COUNTY.

.DAY ONE...TONIGHT

SCATTERED STRONG THUNDERSTORMS WILL IMPACT ACROSS THE REGION THIS
EVENING. SOME OF THESE STORMS WILL PRODUCE LARGE HAIL...DAMAGING
WINDS AND FLASH FLOODING.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

SHOWERS AND THUNDERSTORMS ARE LIKELY FRIDAY AFTERNOON AND EVENING.
ANY THUNDERSTORMS WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAIN
AND COULD LEAD TO LOCALIZED FLASH FLOODING. THUNDERSTORMS WILL
ALSO HAVE THE POTENTIAL TO PRODUCE DAMAGING WIND GUSTS AND LARGE
HAIL.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE REQUESTED TO RELAY HAZARDOUS WEATHER REPORTS TO THE
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON WEATHER FORECAST
OFFICE IN STERLING. SPOTTER ACTIVATION MAY BE NECESSARY FRIDAY
AFTERNOON AND EVENING.

In the hours before

Local storm report, Aug 18, 10:18 PM EDT, 1 hour 52 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Special weather statement, Aug 18, 10:45 PM EDT, 1 hour 25 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Local storm report, Aug 18, 11:15 PM EDT, 55 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Special weather statement, Aug 18, 11:16 PM EDT, 54 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Special weather statement, Aug 18, 11:25 PM EDT, 45 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Special weather statement, Aug 18, 11:58 PM EDT, 12 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

The office that day

Everything else NWS Baltimore/Washington issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 18, 8:00 PM EDT	Severe Thunderstorm Warning	LWX	Fairfax, Loudoun, City of Fairfax	45 min
Aug 18, 8:33 PM EDT	Special Weather Statement	LWX	Fauquier	27 min
Aug 18, 8:41 PM EDT	Severe Thunderstorm Warning	LWX	Shenandoah	49 min
Aug 18, 8:52 PM EDT	Special Weather Statement	LWX	Loudoun	23 min
Aug 18, 9:24 PM EDT	Special Weather Statement	LWX	Loudoun	36 min
Aug 18, 9:27 PM EDT	Special Weather Statement	LWX	Warren	33 min
Aug 18, 9:35 PM EDT	Special Weather Statement	LWX	Fauquier	25 min
Aug 18, 10:32 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Fauquier, Rappahannock	43 min
Aug 18, 10:45 PM EDT	Special Weather Statement	LWX	Loudoun	30 min
Aug 18, 10:56 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Fauquier, Rappahannock	49 min
Aug 18, 11:16 PM EDT	Special Weather Statement	LWX	Clarke, Loudoun	29 min
Aug 18, 11:25 PM EDT	Special Weather Statement	LWX	Prince William, City of Manassas	35 min
Aug 18, 11:28 PM EDT	Special Marine Warning	LWX		77 min
Aug 18, 11:46 PM EDT	Severe Thunderstorm Warning	LWX	Fairfax, Prince William, City of Manassas, City of Manassas Park	44 min
Aug 19, 1:30 PM EDT	Special Weather Statement	LWX	Rappahannock	30 min
Aug 19, 2:55 PM EDT	Special Marine Warning	LWX		50 min
Aug 19, 3:19 PM EDT	Special Marine Warning	LWX		64 min
Aug 19, 3:24 PM EDT	Special Marine Warning	LWX		96 min
Aug 19, 4:17 PM EDT	Special Marine Warning	LWX		88 min
Aug 19, 5:14 PM EDT	Special Weather Statement	LWX	City of Winchester	31 min
Aug 19, 5:22 PM EDT	Special Marine Warning	LWX		68 min
Aug 19, 5:23 PM EDT	Special Weather Statement	LWX	City of Winchester	37 min
Aug 19, 5:25 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Frederick	31 min
Aug 19, 5:29 PM EDT	Special Marine Warning	LWX		91 min
Aug 19, 6:05 PM EDT	Special Weather Statement	LWX	Loudoun	25 min
Aug 19, 6:09 PM EDT	Special Marine Warning	LWX		78 min
Aug 19, 6:16 PM EDT	Special Weather Statement	LWX	Prince William	14 min
Aug 19, 6:29 PM EDT	Special Weather Statement	LWX	Loudoun	31 min
Aug 19, 6:34 PM EDT	Special Weather Statement	LWX	Prince William	26 min
Aug 19, 6:39 PM EDT	Severe Thunderstorm Warning	LWX	Prince William, Stafford	47 min
Aug 19, 6:42 PM EDT	Special Marine Warning	LWX		93 min
Aug 19, 6:49 PM EDT	Special Marine Warning	LWX		97 min
Aug 19, 7:03 PM EDT	Special Weather Statement	LWX	Arlington, Fairfax, City of Fairfax, City of Falls Church	27 min
Aug 19, 7:06 PM EDT	Special Marine Warning	LWX		54 min
Aug 19, 7:13 PM EDT	Severe Thunderstorm Warning	LWX	Arlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church	35 min
Aug 19, 7:21 PM EDT	Special Weather Statement	LWX	City of Manassas Park	24 min
Aug 19, 7:43 PM EDT	Flash Flood Warning	LWX	Arlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church	87 min
Aug 19, 7:45 PM EDT	Special Weather Statement	LWX	Prince William, City of Manassas, City of Manassas Park	30 min
Aug 19, 7:54 PM EDT	Special Weather Statement	LWX	Arlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church, City of Manassas and 1 more	36 min
Aug 19, 7:58 PM EDT	Special Marine Warning	LWX		92 min
Aug 18, 8:23 PM EDT	Special Weather Statement	LWX	Washington	37 min
Aug 18, 8:30 PM EDT	Severe Thunderstorm Warning	LWX	Washington	30 min
Aug 18, 9:29 PM EDT	Special Weather Statement	LWX	Washington	46 min
Aug 18, 9:39 PM EDT	Severe Thunderstorm Warning	LWX	Washington	51 min
Aug 18, 10:11 PM EDT	Severe Thunderstorm Warning	LWX	Frederick, Washington	49 min
Aug 18, 10:36 PM EDT	Severe Thunderstorm Warning	LWX	Frederick, Washington	39 min
Aug 18, 11:53 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Harford	52 min
Aug 18, 11:58 PM EDT	Special Weather Statement	LWX	Baltimore, Howard, Montgomery, City of Baltimore	32 min
Aug 19, 11:54 AM EDT	Flash Flood Watch	LWX	Anne Arundel, Baltimore, Carroll, Prince George's, City of Baltimore	8 hr
Aug 19, 2:02 PM EDT	Special Weather Statement	LWX	Allegany	28 min
Aug 19, 2:32 PM EDT	Special Weather Statement	LWX	Allegany	13 min
Aug 19, 2:46 PM EDT	Special Weather Statement	LWX	Frederick	14 min
Aug 19, 2:57 PM EDT	Special Weather Statement	LWX	Calvert	33 min
Aug 19, 3:21 PM EDT	Special Weather Statement	LWX	Calvert	24 min
Aug 19, 3:25 PM EDT	Special Weather Statement	LWX	Allegany	35 min
Aug 19, 3:54 PM EDT	Severe Thunderstorm Warning	LWX	Washington	32 min
Aug 19, 4:16 PM EDT	Special Weather Statement	LWX	Calvert	29 min
Aug 19, 4:45 PM EDT	Special Weather Statement	LWX	Calvert	30 min
Aug 19, 4:51 PM EDT	Special Weather Statement	LWX	Carroll	39 min
Aug 19, 4:53 PM EDT	Severe Thunderstorm Warning	LWX	Washington	39 min
Aug 19, 5:15 PM EDT	Flash Flood Warning	LWX	Allegany	3 hr
Aug 19, 5:15 PM EDT	Special Weather Statement	LWX	Baltimore	30 min
Aug 19, 5:17 PM EDT	Special Weather Statement	LWX	Baltimore	28 min
Aug 19, 5:19 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Harford	41 min
Aug 19, 5:21 PM EDT	Special Weather Statement	LWX	Saint Mary's	24 min
Aug 19, 5:31 PM EDT	Special Weather Statement	LWX	Calvert	29 min
Aug 19, 5:40 PM EDT	Special Weather Statement	LWX	City of Baltimore	35 min
Aug 19, 5:43 PM EDT	Special Weather Statement	LWX	Baltimore	47 min
Aug 19, 5:45 PM EDT	River Flood Warning	LWX	Allegany	3 hr
Aug 19, 5:51 PM EDT	Special Weather Statement	LWX	Harford	24 min
Aug 19, 5:54 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Harford, City of Baltimore	51 min
Aug 19, 6:00 PM EDT	Flash Flood Warning	LWX	Baltimore	118 min
Aug 19, 6:03 PM EDT	Special Weather Statement	LWX	Prince George's	27 min
Aug 19, 6:14 PM EDT	Special Weather Statement	LWX	Harford	31 min
Aug 19, 6:26 PM EDT	Special Weather Statement	LWX	Anne Arundel	34 min
Aug 19, 6:30 PM EDT	Special Weather Statement	LWX	Prince George's	30 min
Aug 19, 6:36 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, City of Baltimore	54 min
Aug 19, 6:40 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Prince George's	50 min
Aug 19, 6:44 PM EDT	Special Weather Statement	LWX	Harford	31 min
Aug 19, 6:54 PM EDT	Special Weather Statement	LWX	Anne Arundel	36 min

Nearby

Severe Thunderstorm Warnings in Virginia, 2011 Every severe thunderstorm warning in 2011

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.