11pm EDT update
Florence has tracked slightly north of the 5pm forecast track and the 11pm track has been adjusted slightly to the right — northwards. Intensification has stopped for now apparently because of an eyewall replacement cycle. The NHC continues to say Florence has 140 mph winds. After the cycle is completed Florence may get stronger.
Military satellite microwave imagery this evening showed an apparent eyewall replacement cycle with a collapsing inner eye surrounded by a broader new eye.
5pm EDT update
Florence has strengthened to 140 mph sustained winds with a central pressure of 939 mb, now a solid category 4. Tonight Florence is heading into warmer waters with even more heat. The forecast track has been adjusted slightly to the north towards the Wilmington, NC metro area and beaches including Wrightsville beach and Figure 8 island. The center line of the track goes over where I am Friday morning.
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NOAA’s hurricane hunter plane has just found category 4 winds and pressures of 115 knot and 947 mb in rapidly intensifying Hurricane Florence. Flight level winds were even higher at 130 knots. That means that Florence’s sustained winds are now 130 miles per hour.
Hurricane Florence is on track for the Carolina coast, with the center of the cone of highest probability in the Cape Fear region. This highly populated region includes Wilmington, North Carolina and Myrtle Beach, South Carolina. I am situated an hour’s drive inland from Wilmington. I don’t have the time to blog because I have many preparations to do before Florence comes my way.
I was hoping that the strong trade winds that blew massive amounts of heat out of the tropical north Atlantic this summer would lessen this hurricane season, but the heat has been blown towards the east coast making the Carolina coast vulnerable to potentially the strongest hurricane in its history.
The water is so warm to depth that it could potentially, under worst case conditions, support a strong category 5 hurricane with a pressure of 900mb with sustained winds possibly as high as 200mph. After a brutally warm first ten days of September in the Carolinas the coastal waters inside the Gulf Stream are also very warm. There is no cool coastal zone this September.
Make no mistake, the increasing intensity of hurricanes we have seen since the turn of the millennium is because of the increasing area of the Atlantic ocean with extremely high heat content. Only areas of very high oceanic heat content can maintain category 4 and 5 hurricanes. Strong hurricanes mix cool water up from below except when the warm water layer is very thick.
Once inland, blocking high pressure to the north could cause Florence to slow or stall which could lead to massive flooding. However, it is impossible to forecast the details of such a scenario at this time. The amount of moisture that could be pulled in off the Atlantic is extraordinarily high.
I have to get back to my preparations and hope for the best. I guess this is the new normal now. We all hope that it won’t be us when hurricane season comes.
4pm EDT Update: We’ll see how the NHC interprets this sounding but it looks like Florence has spun up to at least 120 to 125 knots — about 140mph.
The NHC is likely to report 942 mb central pressure and 120 or 125 knot sustained winds, about 140mph sustained winds, for the 5pm EDT update. A 4pm dropsonde, a sounding device dropped from the airplane, found surface pressure in the eye was 942 mb. That’s a solid category 4 central pressure and wind speed.