Beryl slowly intensifying

Tropical Storm Beryl continues to slowly intensify. This afternoon's Hurricane Hunter aircraft reported a central pressure of 1002 mb at 4:22pm EDT, down 2 mb from the 11am advisory. The plane found winds as high as 57 knots at flight level (5,000 feet), which corresponds to about 50 mph at the surface--a 5 mph increase from the 11am advisory. The plane also made a visual observation of 60 mph winds at the surface. Satellite imagery continues to show a large blow-up of thunderstorms with very cold tops on the northwest side of Beryl. These cold tops mean the thunderstorms are reaching high levels of the atmosphere, and are therefore very intense.

If we examine the sea surface temperature plot for this morning (Figure 1), we see that Beryl is crossing the axis of the warmest waters of the Gulf Stream. These warm 27 - 28 C waters are probably responsible for the current burst of intensification. Beryl is moving north and should stay over these warmer waters until about midnight, so we can expect continued intensification for a few more hours. By early Thursday, Beryl is expected to encounter a region of high wind shear, and SSTs will start to cool. This should start to weaken the storm. The two most reliable intensity models used by NHC both forecast that Beryl will be a weak tropical storm with top winds of 40 - 50 mph at closest approach to New England.

Figure 1. 3D image of sea surface temperatures for July 19, 2006. Beryl is headed due north across the warmest waters of the Gulf Stream current today. Image credit: NOAA Environmental Modeling Center.

Beryl is expected to continue moving north today, then turn more to the northeast on Thursday as a trough of low pressure approaches from the west. Just how strong this trough is will determine how close Beryl passes to New England. Some of the forecast models are forecasting a strike on Long Island or Cape Cod Friday, but the official NHC forecast of a turn out to sea just south of New England sounds more reasonable, given that no July tropical storm --and only one July hurricane (1916)--has ever made landfall in New England.

Elsewhere in the tropics
An area of disturbed weather associated with an upper-level low pressure system has developed a few hundred miles north of Puerto Rico. Wind shear, dry air, and cold air temperatures will keep any development of this system to a minimum. A large cloud of African dust over the eastern Atlantic should keep things quiet there the rest of the week. There are no indications that Beryl's formation presages the beginning of a more active period in the Atlantic. Wind shear is expected to remain seasonably high for the rest of July, and none of the computer models are hinting at any development over the next week.

I'll be back with an update Thursday morning.

Jeff Masters