Northeast flooding continues; Hong Hong breathing easier

Major flooding continues across New Hampshire, southwest Maine, and northeast Massachussetts today, where an additional 1-3 inches of rain has fallen in the past day and another inch is expected today. The culprit "cut off low"--a large low pressure system that got separated from the jet stream--is drifting slowly northeastward, and is expected to leave the area tonight, bringing an end to the heavy rains and the worst of the flooding. However, an active jet stream pattern over the next seven days will continue to bring occasional rain to the area, and area rivers--which are generally five to eight feet above flood stage--will be slow to fall. By next Tuesday, the GFS model is indicating that a more summer-like weather pattern may emerge, with the jet stream retreating northwards and warmer, dryer air moving in.


Figure 1. Rainfall amounts for New England estimated by radar, ending at 10am EDT Monday May 16.

Typhoon Chanchu
The season's first typhoon has continued to weaken, and was a Category 3 storm with 125 mph sustained winds at 8am EDT this morning. Chanchu (which means "pearl" in Chinese), is expected to continue to weaken over the next day due to dry air, cooler ocean temperatures in its path, and interaction with land. The typhoon is expected to spare Hong Kong a direct hit, and come ashore over the Guangdong province on China's eastern coast on Wednesday as a Category 2 storm. This is a far cry from last Friday's intensity forecast, which projected that Chanchu would strike as a Category 5 supertyphoon! Chanchu is yet another example of our poor ability to make accurate long-range hurricane intensity forecasts.

Chanchu delivered a serious blow to the Philippines over the weekend, killing at least 37 and leaving thousands homeless.


Figure 2. Typhoon Chanchu at 5:30 am EDT Tuesday, with 125 mph sustained winds.

My next blog will be Wednesday, when I'll talk more about air pollution, plus the Northeast flooding and Typhoon Chanchu.

Jeff Masters