Alert archive / Virginia / Flash Flood Warnings in 1999

Flash Flood Warning 41, NWS Baltimore/Washington

September 29, 1999Albemarle County, Greene County, Virginia

NWS Baltimore/Washington issued this flash flood warning at Sep 29, 1999, 8:41 PM EDT for Albemarle County, Greene County, Virginia. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Sep 29, 1999, 8:41 PM EDT (00:41 UTC)
Expired
Sep 30, 1999, 12:40 AM EDT
In force
4 hr
Issued by
NWS Baltimore/Washington
Area
Whole counties

Counties Albemarle County, VA, Greene County, VA

The radar

The Sterling radar (KLWX), 127 km from the middle of the area, began a volume at 00:40 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

Roanoke, VA (KRNK), launched 00:00Z, 0.7 hours before the alert went out and 138 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-pSkew-T log-p diagram, Roanoke, VA at 00:00Z on 1999-09-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 191 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Roanoke, VA at 00:00Z on 1999-09-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 200 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
191 J/kg
Mixed-layer CIN
-20 J/kg
Mixed-layer LCL
720 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
200 m²/s²
0-3 km storm-relative helicity
241 m²/s²
Significant tornado parameter
0.2
Supercell composite
1.2

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 29, 8:41 PM EDTFlash Flood WarningLWXMadison, Page4 hr
Sep 29, 9:57 PM EDTFlash Flood WarningLWXClarke, Warren3 hr
Sep 29, 10:42 PM EDTFlash Flood WarningLWXRappahannock2 hr
Sep 29, 11:07 PM EDTSevere Thunderstorm WarningLWXFrederick, City of Winchester48 min
Sep 29, 11:14 PM EDTSevere Thunderstorm WarningLWXClarke, Warren31 min
Sep 29, 11:42 PM EDTSevere Thunderstorm WarningLWXLoudoun48 min
Sep 30, 12:22 AM EDTSevere Thunderstorm WarningLWXFairfax, City of Fairfax33 min
Sep 30, 12:22 AM EDTSevere Thunderstorm WarningLWXCity of Falls Church33 min
Sep 30, 12:41 AM EDTSevere Thunderstorm WarningLWXArlington, City of Alexandria44 min
Sep 29, 11:21 PM EDTSevere Thunderstorm WarningLWXWashington49 min
Sep 29, 11:55 PM EDTSevere Thunderstorm WarningLWXFrederick, Montgomery45 min
Sep 30, 12:41 AM EDTSevere Thunderstorm WarningLWXCarroll, Howard44 min
Sep 30, 12:55 AM EDTSevere Thunderstorm WarningLWXPrince George's45 min
Sep 29, 11:32 PM EDTSevere Thunderstorm WarningLWXJefferson43 min

Nearby

Flash Flood Warnings in Virginia, 1999Every flash flood warning in 1999

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.