17 September 2014

Edouard becomes first major hurricane since 2012

On Tuesday morning at 11am EDT, Edouard was upgraded to a Category 3 hurricane (115mph).  A major hurricane is defined to be any Category 3-4-5 hurricane, and the last one was Sandy when it made landfall on eastern Cuba on October 25, 2012.

However, Edouard only held that intensity for 6 hours.  The last two major hurricanes (Sandy 2012 and Michael 2012) also each held that intensity for just 6 hours.  In one day, Hurricane Rina in October of 2011 racked up as much time as a major hurricane as all other storms combined did in the subsequent 1,064 days!

Visible satellite image over Edouard from 8:45am EDT. (NASA)
As of today at 5am EDT, Edouard's intensity is back down to 90mph.  It is centered about 600 miles northeast of Bermuda and heading northeast at 20mph.
It will continue to weaken over decreasing water temperatures and increasing wind shear as it accelerates to the northeast toward the Azores.


Edouard's activity brings the seasonal ACE (Accumulated Cyclone Energy) up to about 52% of average for this date.  So although 4 out of the 5 storms became hurricanes so far, the overall numbers and intensities are falling well short of average.

Only 1 of the 4 hurricanes made landfall anywhere (Arthur), but NONE of them have existed in the tropics!!  All four hurricanes formed north of 24N, a sign that the weak El Nino is suppressing activity in the tropical Atlantic, as expected.  The figure below shows the typical influence of El Nino on hurricane activity in the East Pacific and in the Atlantic... 2014 couldn't fit this any more perfectly!

Typical influence of El NiƱo on Pacific and Atlantic seasonal hurricane activity. (NOAA)
Elsewhere across the basin, there's an easterly wave about to exit the African coast today, and models generally develop it over the next few days, but not very aggressively.


15 September 2014

Edouard becomes strongest Atlantic hurricane in nearly 700 days

Since my last post on Friday morning, Edouard was upgraded to a Category 1 hurricane on Sunday afternoon, then again to a Category 2 hurricane early Monday morning.  Eduoard is the fifth named storm and the forth hurricane... the last time 4 out of the first 5 storms became hurricanes was 1996 (which coincidentally used the same name list as 2014)!

The intensity is currently estimated at 105mph, making it slightly stronger than Arthur back in July of this year, stronger than any storm in all of 2013, and tied with Sandy on the morning of October 29, 2012: 686 days ago.

As of 5am EDT today, Edouard is located about 700 miles east-southeast of Bermuda in the middle of the Atlantic.  The forecast track is shown below - recurving by 60W and staying very far away from any land.


Additional strengthening is likely, and within a day or two, Edouard could become a Category 3 (major) hurricane.  It would be the first major hurricane in the Atlantic since Sandy BRIEFLY reached that status when making landfall on eastern Cuba on October 25, 2012.

Visible satellite image of Hurricane Edouard from 8:15am EDT.  (NOAA)
The disturbance that was passing over southern Florida on Friday entered the Gulf and dissipated.  Aside from Edouard, there are no other areas of interest today.


12 September 2014

Edouard forms, and possible Gulf storm next week?

At 11pm EDT on Thursday (03Z on Friday), TD6 was upgraded to Tropical Storm Edouard.  This is latest date for the fifth named storm since Ernesto formed on September 22, 1994.  But, climatologically, it's actually right on schedule... the average date for the fifth named storm is September 11!  And if it becomes a hurricane soon (which it should), it would be well ahead of the average date for the forth hurricane, September 28.  (these dates utilize the full 1851-2013 period of record... they change if a different period is chosen)


As of 5am EDT on Friday, Eduoard's intensity was estimated at 40mph and it is moving west-northwest at 15mph.  It is battling moderately strong wind shear and dry air, but over the next 3-5 days the shear should relax and Edouard is forecast to intensify to a minimal hurricane out in the open central Atlantic.

Visible satellite image from 8:30am EDT over the tiny and sheared Tropical Storm Edouard. (NASA)
The track forecast with cone of uncertainty can be found here; the recuravature around 55W is supported by all models.

Next... the disturbance that was over the northwest Bahamas yesterday is now inland over the southern Florida peninsula.  However, dry air and shear (sound familiar?) have taken their toll on the small embryo circulation.  But what happens when it enters the Gulf of Mexico?

Visible satellite image from 8:45am EDT.  (NOAA)
First, a look at the past 24 hours of rainfall over Florida (8am-8am).  Parts of Palm Beach County got nearly 5", and 1-3" fell across portions of Broward and Miami-Dade Counties.  The remainder of southern Florida will likely be similar as the weak system drifts slowly west today.

Estimated rainfall totals from 8am Thu through 8am Fri. (NOAA)
The disturbance will enter the Gulf of Mexico by early Saturday morning, then  models (the colored lines on this map show track forecasts from 9 skillful models: the first 4 are global and last 5 are regional) diverge on how quickly it curves back to the north.  As of now, conditions in the Gulf this weekend and next week appear to be only slightly conducive for development.  SSTs are very warm, there is less dry air, but the wind shear should remain strong.  Through the next 5 days, models generally forecast this to become a tropical storm, but none bring it up to a hurricane.  It certainly can't be dismissed though... if the longer-range shear outlook is wrong, the intensity forecast could be very wrong.  The next name on the list is Fay.