Louisa Storm Survey, National Weather Service

National Weather Service (NWS) officials from Wakefield conducted a storm survey for a severe weather event that took place in Louisa county, VA on Monday, July 16, 2007. Personnel from the NWS concluded that damage found across the county was due to, and consistent with straightline winds, commonly known as microbursts. A microburst is a convective downdraft generally effecting an area less than 2 miles wide, with peak winds lasting up to, or less than 5 minutes. The microburst caused numerous downed trees and powerlines across Louisa county, as well as numerous areas of minor structural damage, especially in and around the town of Louisa. In addition to the wind damage, numerous reports of large hail were reported across the county, with nickel to quarter sized hail reports common between 2:30pm and 3:30 pm on Monday afternoon. Below is a map of the damaged area. The red arrow in the image is the direction of the microburst that pushed through the county Monday afternoon.

(Pictures above show widespread trees down across the county due to microburst. Click the thumbnails for a larger picture.)

Below is the detailed Local Storm Report from the 16th:

000
NWUS51 KAKQ 181540
LSRAKQ

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE WAKEFIELD VA
1140 AM EDT WED JUL 18 2007


..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0240 PM     TSTM WND DMG     2 NNE EXIT 136 ALONG I  38.01N 78.19W
07/16/2007                   LOUISA             VA   PUBLIC

            ROOF BLOWN OFF OF BARN...ABOUT 4 MILES SOUTH OF BOSWELLS
            TAVERN IN WESTERN LOUISA COUNTY.


0245 PM     HAIL             2 NW LOUISA             38.04N 78.03W
07/16/2007  E0.88 INCH       LOUISA             VA   FIRE DEPT/RESCUE

            ALSO NUMEROUS TREES REPORTED DOWN...WITH POWER OUTAGES IN
            MUCH OF THE TOWN OF LOUISA.


0245 PM     TSTM WND GST     3 NW LOUISA             38.04N 78.04W
07/16/2007  E80.00 MPH       LOUISA             VA   NWS STORM SURVEY

            BASED ON FINDINGS OF NWS SURVEY...DOWNED AND DEFOLIATED
            TREES...AND MINOR STRUCURAL DAMAGE WERE DUE TO AND
            CONSISTENT WITH STRAIGHT-LINE WIND DAMAGE...OR
            MICROBURSTS. THE DEGREE OF DAMAGE FOUND INDICATES THAT
            WIND GUSTS WITHIN THE SEVERE THUNDERSTORM GUSTED BETWEEN
            70 AND 90 MPH. NUMEROUS AREAS IN THIS LOCATION WERE ALSO
            FOUND TO HAVE MINOR HAIL DAMAGE...WITH UP TO QUARTER SIZE
            HAIL REPORTED IN THIS AREA.


0250 PM     TSTM WND DMG     5 SSW MINERAL           37.94N 77.94W
07/16/2007                   LOUISA             VA   NWS STORM SURVEY

            NUMEROUS LARGE TREES UPROOTED.


0310 PM     HAIL             LOUISA                  38.02N 78.00W
07/16/2007  E1.00 INCH       LOUISA             VA   PUBLIC

            QUARTER-SIZED HAIL


0315 PM     HAIL             LOUISA                  38.02N 78.00W
07/16/2007  E0.88 INCH       LOUISA             VA   TRAINED SPOTTER

            WIND GUST TO 50 MPH AND NUMEROUS TREES REPORTED DOWN
            ACROSS LOUISA.


0321 PM     HAIL             FERNCLIFF               37.93N 78.11W
07/16/2007  E0.75 INCH       LOUISA             VA   TRAINED SPOTTER


0330 PM     TSTM WND DMG     1 W LOUISA              38.02N 78.02W
07/16/2007                   LOUISA             VA   TRAINED SPOTTER

            NUMEROUS TREES DOWN NEAR ROUTE 33


0345 PM     TSTM WND DMG     2 SW FERNCLIFF          37.91N 78.14W
07/16/2007                   FLUVANNA           VA   PUBLIC

            DOWNED TREE JUST EAST OF HIGHWAY 15 IN NORTHERN FLUVANNA
            COUNTY. RESIDENT REPORTS THAT DOWNED TREE WAS
            SUBSEQUENTLY STRUCK BY LIGHTNING IN FRONT OF HIS HOME
            MINUTES LATER.


0407 PM     TSTM WND DMG     1 N OILVILLE            37.72N 77.79W
07/16/2007                   GOOCHLAND          VA   TRAINED SPOTTER

            TREES DOWN NEAR EXIT 167 ALONG I-64.


0415 PM     HAIL             5 S MONTPELIER          37.74N 77.68W
07/16/2007  E1.00 INCH       HANOVER            VA   TRAINED SPOTTER

            QUARTER-SIZED HAIL AND WIND GUSTS TO 45 MPH.


0520 PM     HAIL             JAMESTOWN               37.22N 76.76W
07/16/2007  E0.50 INCH       JAMES CITY         VA   PUBLIC


0545 PM     TSTM WND DMG     FARNHAM                 37.89N 76.63W
07/16/2007                   RICHMOND           VA   EMERGENCY MNGR

            TREES AND POWERLINES DOWN


0550 PM     TSTM WND DMG     FARNHAM                 37.89N 76.63W
07/16/2007                   RICHMOND           VA   EMERGENCY MNGR

            ROOF BLOWN OFF BOAT HOUSE. LARGE TREE DOWN


0550 PM     TSTM WND DMG     5 NE BELLE ISLE STATE P 37.83N 76.53W
07/16/2007                   LANCASTER          VA   COUNTY OFFICIAL

            TREES DOWNED ONTO POWERLINES ALONG HIGHWAY 3.


&&

$$