Alert archive / Maryland / Flash Flood Warnings in 2009
Flash Flood Warning 7, NWS Baltimore/Washington
NWS Baltimore/Washington issued this flash flood warning at May 29, 2009, 12:40 AM EDT for Montgomery County, Maryland. It was in force for 69 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
- May 29, 2009, 12:40 AM EDT (04:40 UTC)
- Expired
- May 29, 2009, 1:49 AM EDT
- In force
- 69 min
- Issued by
- NWS Baltimore/Washington
- Area
- Storm-based polygon
- Flood severity
- None
County Montgomery County, MD
The radar
The Sterling radar (KLWX), 30 km from the middle of the area, began a volume at 04:41 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
Washington/Dulle, VA (KIAD), launched 00:00Z, 4.7 hours before the alert went out and 27 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.
- Mixed-layer CAPE
- 818 J/kg
- Mixed-layer CIN
- -9 J/kg
- Mixed-layer LCL
- 624 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km storm-relative helicity
- 72 m²/s²
- 0-3 km storm-relative helicity
- 112 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
What forecasters said that day
The local office's own words before this flash flood 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 flash flood warning went out at May 29, 12:15 AM EDT, 25 minutes earlier.
Area forecast discussion, May 29, 12:15 AM EDT, 25 minutes before
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</html>Hazardous weather outlook, May 29, 12:30 AM EDT, 10 minutes before
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Special weather statement, May 28, 7:12 PM EDT, 5 hours 28 minutes before
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 712 PM EDT THU MAY 28 2009 WVZ501-282345- WESTERN GRANT WV- 712 PM EDT THU MAY 28 2009 ...STRONG THUNDERSTORMS TO AFFECT WESTERN GRANT COUNTY... AT 712 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM 4 MILES SOUTHWEST OF BEECHWOOD...MOVING NORTHEAST AT 15 MPH. LOCATIONS THAT WILL LIKELY BE AFFECTED BY THIS STORM INCLUDE BAYARD. WIND GUSTS OF 40 TO 50 MPH AND SMALL HAIL CAN BE EXPECTED WITH THIS STORM. KRAMAR
Local storm report, May 28, 7:48 PM EDT, 4 hours 52 minutes before
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</html>Local storm report, May 28, 8:42 PM EDT, 3 hours 58 minutes before
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</html>Special weather statement, May 28, 11:05 PM EDT, 1 hour 35 minutes before
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</html>The office that day
Everything else NWS Baltimore/Washington issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 29, 12:14 AM EDT | Flash Flood Watch | LWX | Arlington, Fairfax, King George, Stafford, City of Alexandria, City of Fairfax and 1 more | 4 hr |
| May 29, 4:22 AM EDT | Flash Flood Watch | LWX | Arlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church | 15 hr |
| May 29, 1:06 PM EDT | Severe Thunderstorm Warning | LWX | Loudoun | 24 min |
| May 29, 2:21 PM EDT | Special Marine Warning | LWX | 114 min | |
| May 29, 2:40 PM EDT | Severe Thunderstorm Warning | LWX | Fairfax, Fauquier, Prince William, City of Manassas, City of Manassas Park | 24 min |
| May 29, 3:34 PM EDT | Severe Thunderstorm Warning | LWX | Greene, Madison, Orange | 41 min |
| May 29, 3:54 PM EDT | Special Marine Warning | LWX | 96 min | |
| May 29, 4:08 PM EDT | Special Marine Warning | LWX | 67 min | |
| May 29, 4:33 PM EDT | Special Marine Warning | LWX | 44 min | |
| May 29, 4:44 PM EDT | Special Marine Warning | LWX | 77 min | |
| May 29, 5:48 PM EDT | Special Marine Warning | LWX | 87 min | |
| May 29, 5:56 PM EDT | Special Marine Warning | LWX | 2 hr | |
| May 29, 2:24 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel, Baltimore, Howard, Montgomery, Prince George's, City of Baltimore | 51 min |
| May 29, 3:15 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel | 27 min |
| May 29, 5:39 PM EDT | Severe Thunderstorm Warning | LWX | Charles, Saint Mary's | 40 min |
| May 29, 5:52 PM EDT | Severe Thunderstorm Warning | LWX | Saint Mary's | 31 min |
Nearby
Flash Flood Warnings in Maryland, 2009Every flash flood warning in 2009
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.