Beryl intensifying

Tropical Storm Beryl spent the night looking pretty ragged, but is starting to put on a burst of intensification. This morning's Hurricane Hunter aircraft just left the storm, and reported a central pressure of 1004 mb at 8am EDT, down 1 mb from the previous advisory. The plane found winds as high as 52 knots (60 mph) at 5,000 foot altitude, which corresponds to about 50 mph at the surface--a 5 mph increase from the 5am advisory. Satellite imagery shows a large blow-up of thunderstorms with very cold tops on the southwest 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 has just started 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 tonight, so we can expect continued intensification today. Once Beryl gets north of the Virginia/Maryland border, SSTs cool rapidly, and intensification should cease. Wind shear is currently 5 - 10 knots, which is low enough to allow intensification. Beryl will probably not spend enough time over these warm waters to make it to hurricane status, but New England may have a strong tropical storm with 60 mph winds on its doorstep Friday. Note, however, that the two primary intensity forecast models used by NHC--the GFDL and SHIPS--predict that Beryl will only be a weak tropical storm with 45 mph winds on Friday when it approaches 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
The rest of the tropical Atlantic is quiet today. A large cloud of African dust has just pushed off the coast of Africa, which should keep things quiet over the eastern Atlantic 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.

There will not be a Hurricane Hunter aircraft in Beryl until 2pm EDT. I'll be back with an update around 4pm today when the aircraft has had time to sample the storm.

Jeff Masters