Subtropical Storm Beryl Takes Aim at the SE US

Subtropical Storm Beryl:

Subtropical Stom Beryl formed late last night from the system that was formerly being called Invest 94L. It is very rare to have two named systems before the official start of the Atlantic Hurricane Season on June 1st. In fact, it has only happened two times since 1851 when we began keeping track of tropical cyclones: 1887 and 1908 .

Aircraft reconnaissance is currently enroute to investigate the storm and give a more accurate reading of Beryl’s intensity. As of 2pm EDT the NHC listed Beryl at:

...BERYL STALLS OFF THE COAST OF THE SOUTHEASTERN UNITED STATES... SUMMARY OF 200 PM EDT...1800 UTC...INFORMATION ---------------------------------------------- LOCATION...31.6N 76.3W ABOUT 230 MI...375 KM ESE OF CHARLESTON SOUTH CAROLINA ABOUT 330 MI...535 KM ENE OF JACKSONVILLE FLORIDA MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...SW OR 230 DEGREES AT 6 MPH...9 KM/H MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES

Beryl is still a subtropical cyclone since it is generating its energy from both baroclinic and tropical processes. Visible satellite imagery shows that Beryl is starting to slowly generate more convection and if this process can continue Beryl will probably become a fully tropical cyclone before landfall.

Visible Satellite Imagery of STS Beryl

Track Forecast for Beryl:

Beryl has recently stalled about 230 miles ESE of Charleston, South Carolina. Beryl is being blocked by a ridge of high pressure to the NW of the cyclone:

Steering Currents for STS Beryl

Beryl is expected to resume a SW motion later today as he is steering around the periphery of the ridge. This motion should become more westerly tomorrow as a trough of low pressure moves in from the NW United States and erodes the ridge. The trough is also visible on the steering current chart above.

Here is the latest forecast cone from the National Hurricane Center:

Official Forecast Track for STS Beryl

As you can see, the aforementioned trough will act to kick Beryl out to the NE after landfall is made. However, there is a lot of uncertainty in terms of how far inland Beryl will penetrate before the trough recurves the cyclone. The more time over land, the weaker the cyclone will be as it possibly makes a second landfall on the Outer Banks of North Carolina. Computer models are tightly clustered around an initial landfall location near the FL/GA border. The models diverge rather significantly after that with the possibilities of Beryl either remaining over land is it moves over the Mid-Atlantic States, re-emerging and brushing the Outer Banks, or re-emerging and staying offshore. If Beryl does move out over water again and comes close to the Outer Banks, it will probably be a very weak cyclone with little potential for significant wind damage.

Intensity Forecast For Beryl:

Beryl’s intensification process is being limited by an upper tropospheric low pressure system located directly over the cyclone. This is very common in subtropical cyclones. This upper-level low (ULL) is pumping dry air into the cyclone, which is easily seen on water vapor imagery:

Water Vapor Imagery of STS Beryl

Healthy tropical cyclones have an upper-level anticyclone directly above the circulation, which acts to pump the outflow of the thunderstorms away from the circulation and draws up new energy at the surface. As convection develops, the computer models are forecasting the ULL to weaken and Beryl should become fully tropical on Sunday. Aiding this process will be the warm waters of the Gulfstream Beryl is traversing. If Beryl can move south of the FL/GA border, this warm water extends all the way to the coastline. On the other hand, if Beryl remains north of the border, the coastal shelf waters cool off to levels relatively unfavorable for intensification.

Even if Beryl transitions to a fully tropical cyclone, it is unlikely that the storm reaches hurricane strength. At the 11am EDT advisory, the NHC was only giving Beryl an 8% chance of becoming a hurricane. As a result, significant wind damage is not expected at this time, but the probability of Beryl strengthening more than forecast (45 knots) will be increased if Beryl can become a tropical cyclone quicker than expected. Computer models are not too enthusiastic with strengthening the cyclone:

Computer Model Intensity Forecast for STS Beryl

I think Beryl will most likely come ashore just north of Jacksonville, FL as a 50 knot tropical storm. If this occurs Beryl will probably bring more good than harm to a geographical region suffering severe drought:

The NHC is forecasting rainfall totals of 3-6 inches, which should put a nice dent into the drought levels in the SE US.

A tropical storm is still something that should not be taken lightly, especially if it is an upper-end tropical storm. Those living under the warned areas should closely monitor the progress of the storm for further updates.

I will have an update again when conditions warrant.

-Mike

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