A New Month Begins with Joaquin Strengthening to Category Three While Forecast Uncertainty Remains

Since the last post to the GWC and Hurricaneville blog last night on Hurricane Joaquin in the Western Atlantic.  Things have become more serious.  As I had indicated last night, Joaquin appeared to be rapidly deepening.  If you recall, Hurricane Hunter aircraft detected a much stronger storm with 105 mile per hour winds, and a minimum central pressure of 954 millibars, or 28.17 inches of Hg.  Over a three hour span, the pressure dropped some 13 millibars.

Well, after the last report was posted to the blog, Joaquin further intensified.  As of the 5:00 AM Advisory on Thursday morning from the National Hurricane Center, Joaquin’s winds have increased to 120 miles per hour, and the minimum central pressure in its eye has dropped another 6 millibars to 948 millibars, or 27.99 inches of Hg.  So, in the last 12 hours (from 5:00 PM on Wednesday to 5:00 AM on Thursday), Joaquin’s pressure has dropped some 21 millibars, or about 0.63 inches of Hg (Mercury).  Another concern is the uncertainty of the forecast.

When I woke up this morning, I checked my Facebook feed, and found a post by The Weather Channel’s Bryan Norcross, which was posted late last night.  It basically points out that the situation with Joaquin is becoming more dire:  A strengthening storm with no real consensus on where it will go.  Yesterday, the models had a fairly wide range of solutions with the GFS and several other models pointing to a U.S. landfall from North Carolina’s Outer Banks to the Tidewater region of Virginia while the European, or ECMWF model, had the storm heading to the east toward Bermuda, and eventually out to sea.  There are many players coming into this game right now, and that is what is creating the forecasting challenge.

The bottom line here is that although the National Hurricane Center has a cone of uncertainty pointing in general direction of the Mid-Atlantic and the Northeast, there is still a great deal of uncertainty in the forecast that the cone should be wider.  In other words, all residents along the East Coast from Florida to Maine should pay close attention to this storm, and be prepared to act quickly if and when Joaquin makes a definitive move.  Another concern with Joaquin is that if the storm does decide to head toward the Eastern Seaboard, it could pick up in forward speed like many East Coast Hurricanes in the past do.  Two strong examples of that scenario off the top of my head would be the Long Island Express of 1938 and Hurricane Gloria, which struck Long Island and New England almost 30 years ago to the day (September 27, 1985).

When you have a strong hurricane moving up the East Coast in a mostly south to north trajectory, the forward motion adds to or subtracts from the speed of the sustained winds rotating around the storm’s center.  For example, if you have a hurricane with say 120 mph winds like Joaquin, and it is moving up the coast at a rate of 45 to 50 mph, locations on the eastern side, particularly in the dreaded northeast quadrant of the storm, where you have the highest winds and surge, sustained winds could easily be 165 to 170 mph.  Meanwhile, to the west, winds will slacken to only about 70 to 75 mph.  Those were the types of situations that happened with the Long Island Express of 1938, where the storm was moving up to 70 miles per hour up the East Coast.  To put a real fix on that type of motion, the Long Island Express was near Cape Hatteras at about 7:00 AM on September 21, 1938, and by 2:00 PM, it was crossing Long Island.

Now, while I have gone into a good deal of detail about this scenario, it may not happen at all.  Instead, we could see a scenario similar to Hurricane Floyd, or Hurricane Irene, where the storm slowly creeps up the coast.  A slow moving storm would be great news in terms of the wind and surge, but it would be a big problem in terms of rain.  With hurricanes and tropical storms, rainfall is proportional to how fast the storm is moving.  With both Floyd and Irene, the storms were slow movers, and as a result, there was a good deal of rain.  On the other hand, Sandy was a bit more of a fast mover, and as a result, there was less rain.  Getting back to the storm, here are the most recent particulars on Joaquin as of 5:00 AM on Thursday.  The storm is located some 65 miles to the Southeast of San Salvador in the Bahamas, or 20 miles to the North of Samana Cays in the Bahamas.

Maximum sustained winds with Joaquin are up to 120 miles per hour with gusts in upwards of 150 miles per hour.  Minimum central pressure is now down to 948 millibars, or 28.17 inches of Hg.  The storm is moving to the West-Southwest at a slow pace of 7 miles per hour.  A Hurricane Warning is in effect for the Central Bahamas and the Northwestern Bahamas including:  the Abacos, Berry Islands, Eleuthera, Grand Bahama Island, and New Providence.  A Hurricane Watch is in effect for Bimini and Andros Island in the Bahamas. A Tropical Storm Warning is in effect for Southeastern Bahamas excluding the Turks and Caicos Islands, and Andros Island.  To repeat, there is still a great deal of uncertainty in the forecast with Joaquin.  Not only in the projected path of the storm, but also with the intensity.  It is imperative that residents along the East Coast of the United States pay very close attention to this storm.