Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 8:16 PM GMT on September 24, 2008
A subtropical storm (one with characteristics of both a tropical and an extratropical storm) has developed off the coast of North Carolina today. This storm is being referred to as 94L by NHC. Visible satellite loops show that some heavy thunderstorm activity has developed near the center, which is characteristic of tropical storms. However, 94L's heaviest thunderstorm activity is well away from the center, in a long curved band that arcs from the center northeastwards for several hundred miles. This configuration is characteristic of a subtropical or extratropical storm. Thus, 94L qualifies as a hybrid subtropical storm. We typically get one or two subtropical storms per year in the Atlantic, and I've written up a subtropical storm tutorial that talks about the differences between the various types of storms. Subtropical storms get named by NHC if they are judged to be sufficiently tropical in nature. The exact criteria used to make this judgment are somewhat subjective, but 94L is currently judged to be more extratropical than tropical, so has not been named yet. NHC is currently giving 94L a high (>50% chance) of becoming a subtropical storm by Friday, and 94L would become Subtropical Storm Kyle if it were to get a name. Subtropical and tropical storms create similar winds, but tropical storms make more rain. Subtropical storms cannot strengthen to hurricane status--they must become fully tropical before that can happen. Thus, we need not fear rapid intensification of a subtropical storm. Transition to a tropical storm typically takes one to three days.
Figure 1. Current satellite image of 94L. Image credit: NOAA.
The storm is affecting a wide area of ocean from South Carolina to Virginia. The Diamond Shoals buoy near Cape Hatteras reported 14 foot waves and sustained winds of 40 mph at 2:50 pm EDT. The highest waves, though, have been up near the Virginia/North Carolina border, where the Virginia Beach buoy measured 17 foot seas at 7:50 am EDT. Winds should increase to 40-50 mph along the coast of North Carolina tonight through Thursday as the storm approaches shore. This unnamed storm will affect North Carolina like a tropical storm would. Expect tide levels of 3-6 feet above normal along the coast, and rain amounts of 2-3 inches. Cape Hatteras, NC radar shows a modest but expanding area of rain off the coast. Wind shear is currently 20-30 knots over the low, and is expected to remain at that level for the next two days. Water temperatures are about 27°C under the storm, and will cool to 26°C as 94L approaches the coast. No significant strengthening is likely before landfall. Landfall will occur between Thursday afternoon and Friday morning, on the North Carolina coast between the Outer Banks and the South Carolina border. The exact landfall point is unimportant, since 94L's highest winds extend over a broad area. Most of coastal North Carolina will be impacted by this storm's highest winds. The Hurricane Hunters just arrived at the storm, so we'll have a good idea of 94L's winds by 7 pm EDT.
Dominican Republic disturbance 93L
Tropical disturbance 93L is re-organizing over the waters just north of the Dominican Republic. Visible satellite loops show heavy thunderstorm activity is increasing, but the the system has no well-defined center yet. Several surface swirls are competing to become the center of circulation 93L will consolidate around. NHC is giving 93L a moderate (20-50% chance) of developing into a tropical depression by Friday, but I believe it is high (>50%). Pressures at Punta Cana on the eastern tip of the Dominican Republic remain the lowest they've been for the week--1006 mb. I expect 93L will spread rains of 2-4 inches to northern Haiti, the northern Dominican Republic, western Puerto Rico, and the Turks and Caicos Islands today through Thursday.
Wind shear remains near 15-20 knots, which is marginal for development. The current wind shear forecast from the SHIPS model keeps the shear at 15-25 knots for the remainder of the week. The computer models take 93L northwards to a landfall in New England or Nova Scotia on Saturday or Sunday, and I doubt the storm would hit as anything stronger than a 50 mph tropical storm. The storm is too disorganized at present, and there is too much shear in the forecast to allow 93L to become a hurricane.
Links to follow
Cape Hatteras, NC weather
The Hurricane Ike, "Presslord will wear a dress challenge" begins
A huge thanks go to everyone who has contributed to the portlight.org charity! We raised enough dough to send another truck with relief supplies to Winnie and Bridge City, Texas, where traditional relief efforts have fallen short. Wunderground member Presslord (AKA Paul Timmons, Jr.), who is coordinating this effort, has announced that if we raise an additional $10,000 mark, he will pose in a dress for our wunderphoto gallery. I know I personally will be contributing to help decorate our wunderphoto gallery (but more so to help out the people of Winnie and Bridge City!)
The latest from Presslord:
Attention all Hands!!!!!!!!!!!!
As of this point we have raised just over $22,000.00 for our Ike relief efforts...and we are spending it as fast as it comes in...will break it down in a few days.
Patrap is on the scene and Icepilot is on the way with a load....stormjunkie and FLDART are gonna do some needs assessment today and head back to regroup for the next round.
I flew my wife home from Houston last night...her flight landed at 10:40P...we were up until past 5A this morning...she had much to say...lots of tears...some of joy...some of frustration...but suffice it to say: the "Forgotten People" we set out to help directly are far better shape because of what y'all made possible.
Figure 2. doorless Winnie-Stowell Firehouse. FEMA informed them it would be six months before they would get new doors. Image credit: Storm Junkie.
Your contributions do make a difference, and you can read more about the effort at at stormjunkie's blog.
I'll have an update Thursday.
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