Four Inch Rain
by
Mark Bradford, ATSC/RTS Chief Meteorologist
July 23 2008
Wettest
Day since 2005 Brings Drought Relief, Downs Trees
Wednesday, July 23, 2008 was the rainiest day at Kwajalein since Halloween 2005. La Nina conditions had caused dry weather here this year and we were 5.69" below normal rainfall as of Tuesday morning. A large area of showers began to develop near Kwajalein Tuesday night and heavy showers began at 9:10 Tuesday evening. Between then and 1248 Wednesday afternoon, when showers finally ended, we accumulated 4.64" of rain.
During the overnight hours Wednesday, the central Marshall Islands received widespread heavy showers with embedded thunderstorms. Four wind burst events accompanied the showers here, the first occurred between 1030 and 1040 PM Tuesday with a peak wind gust of 34 knots, it was followed by short events at 0715, 0900, and a long burst between 1000 and 1100 Wednesday morning. The last wind burst had wind gusts up to 45 knots at 1046 AM. The strong winds felled a few coconut trees, knocked down palm fronds, broke limbs on various small trees, and blew over garbage cans and dumpsters. The rains caused localized flooding with lagoon road covered near the helicopter hangar. By Thursday morning the catchment areas of the Kwajalein runway were still holding water.
The break in the drought has been presaged by an unusual number of thunderstorms this month. Since the 4th of July we have had 5 thunderstorm days and had lightning on several additional days. We average only 10 thunderstorm days per year with most of them occurring in September, October, and November.
October 30/31, 2005 was the last date that we had more than four inches of rain in a 24 hour period. In that case a very intense thunderstorm dropped 3.25" of rain in 90 minutes and the total 24 hour storm was 4.05".
As strong as Wednesday's storm was, it didn't approach record levels. The maximum single day rainfall for July at Kwajalein is 5.68" recorded in 1983, and the most rainfall ever recorded here in a single day was 17.15" in December 1972. While Kwajalein has experienced much stronger winds during tropical cyclones, sustained winds over 30 knots with gusts to 45 knots are impressive for a wet season shower system.