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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Quoting Levi32:


Thanks :)

I really hope I can do stuff in my blog eventually but for now I can only pop in randomly from time to time to check on things.


lol I will take what I can get!! somethings better then nothing :)
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hurricane watches warnings will be needed for the bahamas......
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filling in eye.. sure is getting hard to see it.
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Quoting ho77yw00d:


Hi Levi so glad to see you on and are able to still have time for WU!!! Hope all is well and you will continue to pop in here your opinion in very valuable ;)

Danielle~


Thanks :)

I really hope I can do stuff in my blog eventually but for now I can only pop in randomly from time to time to check on things.
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Thanks Dr M.

We're focused on the Atlantic but the events in the WPAC certainly is fascinating too.
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Hey Storm!! how are you today sir?
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Quoting RecordSeason:
Levi:


yes, there is dry air, but it is still very far away from the CDO.

heck, I've seen cat 5 storms that have dry air practically adjacent to the CDO...so that's still plenty room to maintain or even strengthen.

It's when you see bands of dry air actually getting engulfed by a storm, then you know it's a goner. Right now, I see no real evidence of that happening just yet.


There's been dry air in the core since last night, and dry air is affecting Earl or you wouldn't be seeing these:

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Quoting Levi32:


Actually, that is higher than the extrapolated pressure during the last vortex which officially reported 939mb central pressure. With this storm, extrapolations have consistently been several millibars too low. Thus, Earl is likely holding intensity or slightly weakening since the last vortex.


Hi Levi so glad to see you on and are able to still have time for WU!!! Hope all is well and you will continue to pop in here your opinion in very valuable ;)

Danielle~
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It's a beautiful day to prepare for the storm..
North Carolina to Maine, and Nova Scotia
Start preparations now,
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Thanks Dr.; I was looking at all that warm water between Earl and the Carolina Outer Banks; they may sustain a major category hit (vacation homes) if the track shifts anymore to the West between now and Thursday.....Cantore will probably arrive at the Outer Banks on Wednesday.
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I wonder if dry air may be getting to Earl. Some of the western side cold cloud tops as seen on infrared seem to be pretty thin on visible, and also there are many outflow boundaries on the west side as well, a sign that there may be some dry air over there.

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10:


Yeah, saw that earlier.

Some models calling for cat 4 approaching long island and cape cod...

If that happens...just wow...
Member Since: June 13, 2010 Posts: 0 Comments: 2336
Quoting StormW:
HURRICANE EARL/TS FIONA/INVEST 98L SYNOPSIS AUG. 31, 2010 ISSUED 11:00 A.M. EDT


Thank you, Storm!
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Quoting Levi32:


Actually, that is higher than the extrapolated pressure during the last vortex which officially reported 939mb central pressure. With this storm, extrapolations have consistently been several millibars too low. Thus, Earl is likely holding intensity or slightly weakening since the last vortex.


well as I said they are not quite to the lowest pressures yet either
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Levi:


yes, there is dry air, but it is still very far away from the CDO.

heck, I've seen cat 5 storms that have dry air practically adjacent to the CDO...so that's still plenty room to maintain or even strengthen.

It's when you see bands of dry air actually getting engulfed by a storm, then you know it's a goner. Right now, I see no real evidence of that happening just yet.
Member Since: June 13, 2010 Posts: 0 Comments: 2336
Outerbanks: You need to go and take care of things. Anything loose becomes a hazard. The earlier you leave, the quicker you return.
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Quoting OracleDeAtlantis:
I like that word "brush" Dr. Masters. We all hope it's a brush?


A Cat4 "brush", sort of makes you wonder doesn't it :)
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Quoting Thundercloud01221991:
Earl is strengthening... 935 reported from recon and just entered the eye... we could see this back down to 933-931 here soon


Actually, that is higher than the extrapolated pressure during the last vortex which officially reported 939mb central pressure. With this storm, extrapolations have consistently been several millibars too low. Thus, Earl is likely holding intensity or slightly weakening since the last vortex.
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Interesting that HWRF tracks so much closer to shore, but also shows Earl as a much smaller and weaker storm. If HWRF is right about the track, but GFDL is closer to the mark on intensity (and I should note that the current NHC forecast is much closer to GFDL's intensity through 72 hours) then this storm won't have to make landfall to do some very bad things.
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75 W is the key. If it crosses by .2, Cape Cod gets a direct hit. If it crosses by .4, Montauk is a direct hit. If it gets to 76W, bad news for Northeast.
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"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."


Again, no mention of dry air? I'm getting puzzled this morning. The NHC said nothing about dry air either in the 11am discussion. Earl is running right into it...probably won't be able to be any stronger than Cat 3 after 24 hours from now, or sooner. It is even possible he won't even be a major as he passes North Carolina.

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Photobucket
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I like that word "brush" Dr. Masters. We all hope it's a brush?
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and a close brush it will be

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Earl is strengthening... 935 reported from recon and just entered the eye... we could see this back down to 933-931 here soon
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Updated



AOI

AOI

AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
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Just for the sake of nice, round numbers, call the first frame 20N 66.5W

Second frame, 21N 67.5W
7 hrs, 316°

06:15 UTC

Photobucket

13:15 UTC

Photobucket
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Glad to see that Fiona will probably fizzle out and the wave behind is not likely to be a threat as of now...The only thing to presently deal with is Earl.
Anticipate horrific beach erosion along the eastern seaboard. Hopefully, people will have sense enough to stay out of the water!!!!
But there are always a few crazies and often a few wind up dead, unfortunately, due to people wanting to get into wicked surf.
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2 saying a hit now huh?
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I guess we should go to prev blog and let the others know a new thread was opened?
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Japan Meteorological Agency
Tropical Disturbance Summary
TROPICAL DEPRESSION XX
21:00 PM JST August 31 2010
==================================

At 12:00 PM UTC, Tropical Depression (1012 hPa) located at 10.0N 167.0E has 10 minute sustained winds of 25 knots with gusts of 40 knots. The depression is reported as moving west at 15 knots.
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Yeah! New blog thread. Thank you Dr Masters.

So much going on out there for us to watch.
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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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