Thursday, June 30, 2005
Same Old Song
Steve Scolnik @ 3:45 PM
Thunderstorms yesterday evening brought brought significant rain to much of the area. Reader JT from northwestern Montgomery County reported 2.52" of rain, while closer to the Beltway, amounts were nearer 1". National Airport reported 1.03" and Dulles had 0.68". Andrews AFB was a bit under 0.5". There were some reports of trees down and power outages. The rain delayed the Nats 3-2 win over the Pirates by a little more than 2 hours.
Clouds mixed with sun were again keeping temperatures this afternoon to the mid and upper 80s, although a few of the usual suspects were reporting 90+, notably Leesburg (91) and Frederick (93). Radar at midafternoon showed scattered showers from near Pittsburgh southward through central West Virginia. These were ahead of a more organized line of storms which has been "bulldozing" through Ohio, in the words of the Weather Channel's Dr. Greg Forbes, knocking down trees and power lines. The line of storms, in turn, was well ahead of a cold front stretching southward through the Great Lakes from a rather impressive-looking low pressure area for this time of year (central pressure 989 mb) centered just north of Minnesota.
Outlook
Showers and thunderstorms are again a strong possibility this evening, with overnight lows in the low 70s. Tomorrow will remain humid with temperatures a bit warmer, highs near 90, and a 60% chance of thunderstorms by evening as a cold front approaches for the weekend.
Under the radar
An article "WSR-88D Radar, Tornado Warnings and Tornado Casualties" in the June issue of the American Meteorological Society's Weather and Forecasting journal analyzes the "impact of the installation of WSR-88D (Doppler) radars in the 1990s on the quality of tornado warnings and occurrence of tornado casualties." Using data on all of the nearly 15,000 tornadoes which occurred in the contiguous United States from 1986 to 1999, the study found a statistically significant improvement in tornado warnings after the installation of Doppler radar at National Weather Service Forecast Offices (WFOs). Using a statistical regression analysis of tornado injuries and fatalities, the authors found expected fatalities were lowered by 45% and expected injuries were lowered by 40% after Doppler installation. Based on the number of observed tornado casualties from 1997 to 1999, this represents an avoidance of 79 deaths and 1050 injuries per year.
Another interesting result of the research involved the effect of time of day. Based on the data, there are "66% fewer expected fatalities and 47% fewer expected injuries" for daytime storms vs. those occurring at night. There is also a significant, although smaller, effect for storms in the evening vs. those at night.
Clouds mixed with sun were again keeping temperatures this afternoon to the mid and upper 80s, although a few of the usual suspects were reporting 90+, notably Leesburg (91) and Frederick (93). Radar at midafternoon showed scattered showers from near Pittsburgh southward through central West Virginia. These were ahead of a more organized line of storms which has been "bulldozing" through Ohio, in the words of the Weather Channel's Dr. Greg Forbes, knocking down trees and power lines. The line of storms, in turn, was well ahead of a cold front stretching southward through the Great Lakes from a rather impressive-looking low pressure area for this time of year (central pressure 989 mb) centered just north of Minnesota.
Outlook
Showers and thunderstorms are again a strong possibility this evening, with overnight lows in the low 70s. Tomorrow will remain humid with temperatures a bit warmer, highs near 90, and a 60% chance of thunderstorms by evening as a cold front approaches for the weekend.
Under the radar
An article "WSR-88D Radar, Tornado Warnings and Tornado Casualties" in the June issue of the American Meteorological Society's Weather and Forecasting journal analyzes the "impact of the installation of WSR-88D (Doppler) radars in the 1990s on the quality of tornado warnings and occurrence of tornado casualties." Using data on all of the nearly 15,000 tornadoes which occurred in the contiguous United States from 1986 to 1999, the study found a statistically significant improvement in tornado warnings after the installation of Doppler radar at National Weather Service Forecast Offices (WFOs). Using a statistical regression analysis of tornado injuries and fatalities, the authors found expected fatalities were lowered by 45% and expected injuries were lowered by 40% after Doppler installation. Based on the number of observed tornado casualties from 1997 to 1999, this represents an avoidance of 79 deaths and 1050 injuries per year.
Another interesting result of the research involved the effect of time of day. Based on the data, there are "66% fewer expected fatalities and 47% fewer expected injuries" for daytime storms vs. those occurring at night. There is also a significant, although smaller, effect for storms in the evening vs. those at night.
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