Category 4 Earl headed for a close brush with North Carolina

By: Dr. Jeff Masters , 3:16 PM GMT on August 31, 2010

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Powerful Category 4 Hurricane Earl is pulling away from Puerto Rico and the northern Lesser Antilles Islands, and is eyeing its next potential landfall--North Carolina's Outer Banks. Earl brought heavy rain and high winds to Puerto Rico and much of the northern Lesser Antilles yesterday, though it appears that the islands were spared major damage. One exception may be Anegada in the British Virgin Islands, population 200. The eye of Earl passed just north of Anegada at noon yesterday, and Earl's south eyewall probably brought sustained winds of 100 mph to the island. Second hardest hit was probably Anguilla. Amateur weather observer Steve Donahue at anguilla-weather.com estimated gusts of 100 mph on Anguilla; his anemometer broke at 88 mph. Winds in St. Thomas in the U.S. Virgin Islands remained above tropical storm force (39 mph) for five hours yesterday afternoon, peaking at 52 mph, gusting to 62 mph, at 4:49 pm. Heavy rains hit Puerto Rico, where radar-estimated rainfall amounts of up to 5 - 7" occurred. Earl brought waves of sixteen feet to San Juan, and waves at buoy 41043 offshore of Puerto Rico reached 31 feet early this morning.


Figure 1. Morning satellite image of Earl, taken at 10:30am EDT 8/31/10. Image credit: NASA/GSFC.


Figure 2. Radar estimated rainfall for Earl from the San Juan, Puerto Rico radar. Isolated regions of 5 - 7 " of rain occurred in three locations on Puerto Rico. The rays fanning out to east from the radar location marked with a "+" are due to mountains blocking the view of the radar.

Intensity forecast for Earl
Wind shear as diagnosed by the latest SHIPS model forecast shows a moderate 10 - 20 knots of wind shear over Earl, due to upper level winds out of the southwest from a trough of low pressure to Earl's west. This moderate shear is predicted to continue through Friday, but should not appreciably affect Earl, since the hurricane is so large and strong. Ocean temperatures are a near-record 29.5 - 30°C, and very warm waters extend to great depth, resulting in a total ocean heat content favorable for intensification. Earl is undergoing an eyewall replacement cycle, which may diminish its winds by 10 -20 mph for a day or so. However, the storm will probably regain strength after completing this cycle, and it is likely Earl will be a major Category 3 or 4 hurricane at its closest approach to North Carolina Thursday night and Friday morning. By Friday night, when Earl will be making its closest approach to New England, wind shear will rise to a high 20 - 30 knots and ocean temperatures will plunge to 20°C, resulting in considerable weakening. Earl will still probably be a Category 2 hurricane on Friday night, when it could potentially make landfall in Massachusetts. Earl is more likely to be a Category 1 hurricane on Saturday morning, when it could potentially make landfall in Maine or Nova Scotia, Canada.


Figure 3. Swath of surface winds from Earl predicted by the 2am EDT Tuesday, August 31, 2010 runs of NOAA's GFDL model (left) and HWRF model (right). Hurricane force winds (yellow colors, above 64 knots) are predicted to stay off the coast. Tropical storm force winds (light green colors, above 34 knots) are predicted to affect coastal North Carolina, Massachusetts, and Eastern Maine. Winds between 58 mph - 73 mph (dark green colors) are predicted to small portions of the coast. Image credit: Morris Bender, NOAA/GFDL.

Track forecast for Earl
The latest set of computer models runs from 2am EDT (6Z) this morning push Earl's projected track a little closer to the U.S. East Coast, and we now have two of our six reliable models predicting a U.S. landfall. The latest NOGAPS run shows Earl hitting the Outer Banks of North Carolina late Thursday night, then striking Southeast Massachusetts late Friday night, and Eastern Maine on Saturday morning. The HWRF model predicts a strike on Eastern Maine Saturday morning, but keeps Earl offshore from North Carolina and Massachusetts. None of the other computer models show Earl hitting the U.S., but several models bring Earl within 100 - 200 miles of North Carolina's Outer Banks and Southeast Massachusetts. It is likely that Earl will being a 12-hour period of heavy rain and tropical storm force winds of 39+ mph to North Carolina's Outer Banks, beginning on Thursday evening. NHC is giving Cape Hatteras a 12% chance of receiving hurricane force winds. By Friday evening, western Long Island, Rhode Island, and Southeast Massachusetts can expect a 6 - 8 hour period of heavy rain and tropical storm force winds of 39+ mph. NHC is giving Nantucket a 11% chance of receiving hurricane force winds. These odds are 4% for Boston, 6% for Providence, 5% for Eastport, Maine, and 11% for Yarmouth, Nova Scotia. The main determinant of whether Earl hits the U.S. or not is a strong trough of low pressure predicted to move off the U.S. East Coast Friday. This trough, if it develops as predicted, should be strong enough to recurve Earl out to sea. Keep in mind that the average error in position for a 3-day NHC forecast is 185 miles, which is about how far offshore Earl is predicted to be from Cape Hatteras three days from now. The average error in a 4-day forecast is 255 miles, which is about the distance Earl is expected to be from the coast of New England four days from now.

Regardless of Earl's exact track, the U.S. East Coast can expect a long period of high waves beginning on Thursday. Significant beach erosion and dangerous rip currents will be the rule, due to waves that will reach 10 - 15 feet in offshore waters. Waves from Hurricane Danielle killed two swimmers in the U.S. over the weekend and forced hundreds of water rescues along the U.S. East Coast. Earl's waves will be worse, and will likely cause millions of dollars in beach erosion damage.

Fiona
Tropical Storm Fiona is speeding west-northwest towards Hurricane Earl, but is unlikely to bring tropical storm force winds to the Lesser Antilles. Satellite loops show that heavy thunderstorm activity has increased in some of the outer bands this morning, but remains limited near the center. Wind shear is currently moderate, 10 - 15 knots, and the main impediment to development continues to be dry air associated with the Saharan Air Layer (SAL) surrounding the storm.

Forecast for Fiona
Fiona is moving quickly to the west-northwest, at about 24 mph. This means it is catching up to Earl, which is moving at 15 mph. By tonight, Fiona will be beneath Earl's upper-level outflow channel. Strong upper-level winds from Earl's upper-level outflow and a ridge of high pressure to the northwest of Fiona will bring high levels of wind shear, 20 - 30 knots, to Fiona tonight through Friday, and probably arrest the storm's development. The scenario now called for by all the models is for Fiona to be drawn into the low pressure wake of Earl and turn to the northwest. Fiona will pass to the northeast of the Lesser Antilles, and will probably not bring tropical storm force winds to the islands. Fiona should then continue to the northwest and then turn north, passing very close to Bermuda on Saturday morning. It is possible Earl could destroy Fiona through high wind shear before Saturday.


Figure 4. Morning satellite image of Fiona. High level cirrus clouds flowing out from the center of Earl as part of its upper level outflow can be seen starting to impinge upon the western side of Fiona's circulation.

Danielle is dead
Tropical Storm Danielle has succumbed to the cold North Atlantic waters, and is no longer a tropical storm.

98L
A new tropical wave (Invest 98L) moved off the coast of Africa yesterday, and is centered a few hundred miles south of the Cape Verdes Islands. Strong easterly winds from the African Monsoon are creating a moderate 10 - 20 knots of shear, and the disturbance is currently disorganized. A large area of dry air lies to the north and west of 98L, and this will interfere with development. The latest SHIPS model forecast predicts shear will remain moderate, 10 - 20 knots, for the next five days, and some slow development of 98L is possible as it moves westward at 15 mph. NHC is giving a 10% chance of this system developing into a tropical depression by Thursday, and none of the computer models develop it.


Figure 5. Morning satellite image of 98L.

A rare triple threat in the Western Pacific
Over in the Western Pacific, we have an unusual triple feature--three named storms all within 700 miles of each other. A 3-way interaction between these storms is occurring, making for a very tough forecast situation. The storm of most concern is Typhoon Kompasu, which hit Okinawa today as a Category 2 typhoon. Kompasu is expected to recurve northeastward and hit North Korea on Thursday as a Category 2 typhoon. It is unusual for a powerful typhoon to thread the tight Yellow Sea and hit North Korea, and I don't know how prepared they are for strong typhoons. Kompasu is expected to hit the most populous region of North Korea, but the country is pretty mountainous, and a significant storm surge disaster is probably unlikely. In the South China Sea, Tropical Storm Lionrock and Tropical Storm Namtheun are moving through the straights between Taiwan and China towards each other. Neither are predicted to develop into typhoons, but heavy rains are occurring in Guangdong and Fujian Provinces, further exacerbating the flood conditions China has suffered this summer.


Figure 6. An unusual triple feature over the Western Pacific--three simultaneous named storms all within 700 miles of each other. Image credit: NOAA/SSD.

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question to broadcast@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line.

Today's show will be about 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

I may have a short update this afternoon, once the latest models runs are available.
Jeff Masters

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It is likely a watch will go up soon. Evacuations from the northern outer banks can happen quickly compared to the southern end of the banks.
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Think Earl sucked up some dry air off Haiti/DR, there were arc clouds earlier and the left side of the storm collapsed a good bit, it's recovering now, but the core appears to have been stable.
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Their's a shift in the cone to the west?.I hope not,because remember folks even if E
arl does hit along the east coast as a cat 2 storm,the storm surge could still be high,due in part that some places are vonurable.
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F5 F5 F5 F5 F5 F5 F5 F5 F5 F5 F5 F5 F5 F5 F5
Member Since: September 6, 2007 Posts: 0 Comments: 6505
Quoting moonlightcowboy:



Another map (one or the other not updated) is showing 1027mb.


Not good....way too many variables out there!
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Earl is N of the forecast points.
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Quoting markot:


they said big shift to the west


cool
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Quoting angiest:


There is a clear jog to the right, but then it looks to resume the same heading. Need more satellite frame.

Or really need radar.


yeah, radar would be nice...and it looks like the sat loop lost the last frame.
Member Since: June 12, 2002 Posts: 0 Comments: 1589
1323. 900MB
Quoting TerraNova:
12-15 ft feet for Long Island




Yikes!
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1322. hydrus
Quoting TropicalNonsense:
if the high flatten's out instead of moving out of the way
the Southeast may take a direct hit from a cat3-4.

And here ya go.. Image wont post.
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1321. markot
Quoting TampaTom:


Holy shift, Batman!
the weatherchannel said
Member Since: September 2, 2009 Posts: 0 Comments: 226
Quoting sammywammybamy:
They Need to Disconnect the Caller.


:-)
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1319. angiest
Quoting rwdobson:


Look at the visible sat instead. Earl is clearly going more north during the last few frames, and not due west, or even close to due west.


There is a clear jog to the right, but then it looks to resume the same heading. Need more satellite frame.

Or really need radar.
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oh these callers so badly want to hear about a new york doomsday
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Quoting moonlightcowboy:
Howly cow!!.And wait who said Earl would hit Florida.That's very foolish on their part....
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Thanks everyone for your comments! I just read the Dare Co. news release and it doesn't sound like they're going to evacuate. I wonder if they go under a Hurricane watch if that'll change their mind...
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Quoting VAbeachhurricanes:


1023mb high, still strong



Another map (one or the other not updated) is showing 1027mb.
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@1285, the weakness is already there in the map you are showing. Note how the high center over the US is weaker than the high center near Bermuda...Earl will be steered by the high to its east, causing it to go north.
Member Since: June 12, 2002 Posts: 0 Comments: 1589
1309. Thaale
Quoting MississippiWx:
I think the models are missing something with 98L. It has good structure and could develop more quickly than Fiona did. The 850mb vorticity isn't that strong but it has increased over the past 3 hours. Mid level vorticity is adequate and if it can make it down to the surface, I see no reason why 98L wouldn't develop. Shear is forecast to increase in a few days, but that's a little iffy to me because I really see nothing that would shear it too much. I think this is one of those systems that models just miss out on sometimes.


What do you think about the SAL maybe suppressing development, Mississippi? There's a goodly amount of dry air and dust out there still spreading south and west, which 98L will have to deal with as it progresses W to WNW. Whether or not 98L will develop anyway, maybe this is part of the reason the models are showing slow to no development?

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Link

Just looking at this it appears to be east of what they are predicting...
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12-15 feet for Long Island


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the east coast should be ok just some big waves and maybe a breeze
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Quoting moonlightcowboy:


1023mb high, still strong
Member Since: September 6, 2007 Posts: 0 Comments: 6505
1303. CJ5
1276. TerraNova 8:22 PM GMT on August 31, 2010
Quoting CJ5:


That shows a clear W direction at the end.


MIMIC-TPW isn't a very good indicator of motion since the image has to be manually adjusted to keep the storm centered. It's proving to be hard determining Earl's motion without radar.



Thanks, I had a hint that might be the case but wasn't so sure. Thanks for telling me.
Member Since: July 4, 2007 Posts: 0 Comments: 1755
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Rainbow:


NGP Model Output:
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting markot:
they said big shift to the west



Who said?
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Quoting CJ5:


Look back at the images I was referencing. They show no wobble in the last few seconds. Now, it could be that particular graphic is not good with direction but you would have to be blind not to see it.


Look at the visible sat instead. Earl is clearly going more north during the last few frames, and not due west, or even close to due west.
Member Since: June 12, 2002 Posts: 0 Comments: 1589
1296. markot
they said big shift to the west
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1295. snotly
Start spreading the news, I'm leaving today...
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1293. KEEPEROFTHEGATE (Mod)
models nam ukmet gfs

Member Since: July 15, 2006 Posts: 171 Comments: 53841
Question For Dr. Masters-

Do you think that the loop current stoping will affect the hurricane season? - Alex
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1290. hydrus
Quoting KanKunKid:


Yeah! ALL DOOM

That guy can stop Earl can't he?
Kid. Admin will probably get you for the graphic..lol That was slick...:)
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"Let me ask you this question. Do you honestly think that the NHC, even if it were to see Earl riding the coast from SC to Maine as a Cat 2-4, would release that information prematurely? You have to think in terms of economic, political and emotional impact. This is labor day weekend coming up. Our economy is in the crapper and the NHC, local authorities and local Mets certainly don't want to induce panic. "

Why would anyone want to induce panic other than trolls on here or the ignorant media looking to hype a situation?


You are missing my point entirely. My point being that the NHC is conservative by nature and is not going to present a dangerous situation to the public until it is a certainty. Not hype it, the opposite...wait until there is no other option.
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1288. CJ5
Quoting PSLFLCaneVet:
Not seeing it. Weebles wobble and so on.


Look back at the images I was referencing. They show no wobble in the last few seconds. Now, it could be that particular graphic is not good with direction but you would have to be blind not to see it.
Member Since: July 4, 2007 Posts: 0 Comments: 1755
if the high flatten's out instead of moving out of the way
the Southeast may take a direct hit from a cat3-4.

Member Since: July 3, 2007 Posts: 0 Comments: 524
This marine forecast from NOAA doesn't exactly jive with the official NHC track. The question is, do you agree with this scenario?

I see a high pressure system firmly entrenched over the East or at the very minimum, the Southeast, with not much chance of moving very fast. Just look at your water vapor imagery from the MidWest, there's very little erosion taking place now, that would move this high pressure system enough to create large weakness north of Earl.



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everyone else is being conservative because they don't want to create hype or panic besides TWC
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1283. markot
Quoting tropicfreak:


Thats not good. Who said it, was it a regular or a hurricane expert like knabb or norcross?
regular
Member Since: September 2, 2009 Posts: 0 Comments: 226

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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