Portsmouth, VirginiaThe new record (7.07") broke the previous record of 6.05" set on August 15th, 1980. Both precip records resulted from severe thunderstorms which developed over the area and drifted, nearly stationary for several hours. The 1999 storm produced significantly more lightning.
July 1999 is now the wettest July in PWRS' 23 year record base for the Southeastern corner of Portsmouth, VA surpassing the old record of 11.80" in 1996.
Rainfall during the event was archived by our data logger as follows:
Between 2 and 3 PM - 0.83"
Between 3 and 4 PM - 3.66"
Between 4 and 5 PM - 2.23"
Between 5 and 10:00 PM - 0.35"
Two short periods of hail were noted during the storms, ranging from pea size to dime size hail.
An estimated 4 individual thunderstorms trained across SE Portsmouth during the afternoon and evening. Frequent, at times continuous, cloud-to-ground lightning created repeated power surges and losses. Shortly after 5PM the power to this site shut-down completely and was not restored until approximately 12:30 AM 7/25/99. Lightning diminished during the evening with more noticeable cloud-to-cloud patterns.
Winds noted at our two anemometers: at the 60' level, the RM Young Anemometer reported a wind gust to 52 MPH while the rooftop (30') Davis anemometer and the Maximum Gustmaster anemometer both recorded a 35 MPH gust.
A large oak tree was split down the middle, falling on a house garage some 125' to the north. Whether or not the downed tree resulted from lightning had not been determined at post time.
The temperature under sunny, hazy skies rose to the upper 90s by 2:10 PM as a trough in the upper levels moved into unstable, moist air over the region with convergent winds providing significant lift. However, the trough moved very slowly allowing the thunderstorms to become horrendous rainmakers.
Flooding of most local roadways was significant with a survey showing many stalled vehicles into late evening, some being abandoned during the height of the flash flooding.
A series of severe weather statements throughout the event followed the orginial posting of a severe thunderstorm watch issued by the Severe Storms Forecast Center. Radar indicated possible tornadoes near Camden County in Northeast NC.
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Summary of Weather Data for Portsmouth, VA [ 36 50 07N / 76 17 55W ] Saturday, July 24th, 1999, EDT |
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