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 jeffs713:

Annular hurricanes are one of nature's oddities. Has anyone seen if they have run the program that "scores" storms on a scale to see if they are annular?
Its on the Ships text:

## ANNULAR HURRICANE INDEX (AHI) AL072010 EARL 08/31/10 06 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=4 NFAIL=3 ##
## AHI= 0 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##
## NOTE: 1 INSTEAD OF 2 GOES FILES USED

** PROBLTY OF AT LEAST 1 SCNDRY EYEWL FORMTN EVENT AL072010 EARL 08/31/2010 06 UTC **
TIME(HR) 0-12 12-24(0-24) 24-36(0-36) 36-48(0-48)
CLIMO(%) 31 31( 52) 30( 67) 31( 77) <-- PROB BASED ON INTENSITY ONLY
PROB(%) 24 76( 82) 71( 95) 62( 98) <-- FULL MODEL PROB (RAN NORMALLY)
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Quoting WhereIsTheStorm:


This seems to come up a lot. The computer models are guidance and are to be used with other tools. The NHC forecast is good out to 24 to 36 hours after that too many other factors creeping in. At that point they re-enter the data and come up with new computer models and readjust the cone to insure that it is accurate up to the next 24 to 36 hours. No one has ever stated that the 3 day cone is exactly the path that a storm is going to follow. They state that anywhere within the cone is where they expect the storm to be, so it can be outside the cone after 36 hours and still be accurate.

Now in this case, the cone/models have had to be adjusted every day due to this Hurricane not following the rules we have laid out and keeps not turning NW; but according to all the experts there will be a turn to the NW and then N at some point within the next 24 to 36 hours.

I hope this brings some understanding to this issue.

With all due respect if that turn doesnt happen before 36 hours it has a real chance of being a big problem for Fl. And that I dont like at all.
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480. 7544
hes getting close to the se bahamas now the nhc is waiting for more west wobbles to upgrade to hur watch foe the se bahamas imo
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If not for that 2-hour wobble west last night, Earl would be more in line with the NHC forecasts from yesterday morning.
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Quoting EastCarolina:


We had a TS come through the week before. If I can remember it was Dennis?

I was in Greenville and Floyd was catastrophic for the area


yes remember Dennis brushed us then did a loop and came back
Member Since: September 19, 2005 Posts: 2 Comments: 4154
Quoting TropicalNonsense:
none of the models currently initialize the oreintation of
the mid atlantic high correctly. This will hamper the forecast
even more i am guessing.

In which direction do you believe?
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Quoting hydrus:
Might end up looking a little like Isabel in 03. And near the same location I must say....


That ain't an eye, more like a moon crater.
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Quoting hydrus:
Might end up looking a little like Isabel in 03. And near the same location I must say....


Cool picture of Earlabel or is it IsaEarl
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Quoting hydrus:
Might end up looking a little like Isabel in 03. And near the same location I must say....

Annular hurricanes are one of nature's oddities. Has anyone seen if they have run the program that "scores" storms on a scale to see if they are annular?
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471. 2COOL
Quoting rareaire:
Floodman , Well said. I tire of people thinking its the adjuster whos out to get them. We in the industry know thats far from the truth. It is so important that folks clearly read that policy before they need to know whats in it...
I'd say it's far more apt to be the contractor's salesmen misleading them.
Member Since: May 26, 2006 Posts: 0 Comments: 22
none of the models currently initialize the oreintation of
the mid atlantic high correctly. This will hamper the forecast
even more i am guessing.

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Ok what's wrong with this thinking.

StormW points out, and it pretty clear he's right, that Earl is starting to suck in dry air. So here's the thought.

Dry Air = Weaker Earl = more westerly track ????
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Quoting will40:


ground was already saturated when Floyd came in so that made it worse


We had a TS come through the week before. If I can remember it was Dennis?

I was in Greenville and Floyd was catastrophic for the area
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467. Vero1
AF 300 is flying in Fiona at this time ~~seen on Google Earth RTMM classic
Member Since: July 21, 2008 Posts: 4 Comments: 2233
Quoting StormW:
Sucking in dry air...notice the outflow boundary over the extreme SE Bahamas:




The dry air won't help, but unless shear degrades the inner core (quite possible in a day or two), it won't really hurt. The western half of the hurricane is exposed to some westerly flow aloft, and you're seeing its effects on the cirrus outflow. So you might see some subsidence well away from the inner core as dry air fills in.
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The Atlantic A.C.E. (Accumulated Cyclone Energy) for 2010 has reached 43.2125. Couple of things notable about that:

1) This year's A.C.E. has more than quadrupled in just a bit over one week's time (it stood at 9.42 last Monday morning);

2) This year's A.C.E. has already exceeded that of 1997, the "weakest" year of the current "active" hurricane period;

3) In fact, this year's A.C.E. is already higher than that of 14 of the past 60 seasons;

4) With the help of Earl's forecasted numbers alone, this year's A.C.E. will surpass 2009's total sometime tomorrow.

All this, and we're not even out of August yet. So...still want to call the season a bust? ;-)
Member Since: November 8, 2009 Posts: 4 Comments: 13510
The HH just found an extrap surface pressure of 935.9. That's likely to shift the next vortex message down slightly. So Earl is no longer weakening, and may even have strengthened slightly since midday. That may mean that it's starting to consolidate a new eyewall, which would be a worrisome prospect.
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463. MahFL
Earl moveing south of west now........
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Close brush with NC? Hhhmm, yup, but it'll "brush" rather significantly by the Bahamas, Turks % Caicos, first.

CRS, and folks, hope you all are all battened down and prepared!
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Quoting hydrus:
Might end up looking a little like Isabel in 03. And near the same location I must say....
way farther north than earl...
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Quoting Bayside:


Yeah, GRIP, but they are using a Global Hawk (UAV), DC-8, and WB-57 I think.


correct all upper level info gathering
Member Since: September 19, 2005 Posts: 2 Comments: 4154
do they need to put hurricane warnings up in the bahamas?
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Quoting StormsAreCool:
"But the models kept showing her turn to NW for five days...and finally got it right."


I guess if they keep saying the same thing over and over, it's bound to come true eventually.
Forecasting the movement of troughs relative to the movement of a Tropical Cyclone is probably the hardest
part of the overall forecast, Danielle's end result was nearly same as originally forecast, Earl's may not be..
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Quoting hydrus:
Might end up looking a little like Isabel in 03. And near the same location I must say....


Here's Issy....

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Quoting CloudGatherer:


Who's disputing that?

I simply wrote that when the model runs shift, even within their margin of error, that's worth noting, and aggregating with other predictive data. And I think that's hard to argue with.

There's no question in either the model runs or the forecasts that Earl will turn. When I wrote that it was "shading west" in the model run, I was talking about the timing of that turn. Every run for the past 48 hours has shown Earl moving slightly further to the West before he reaches his westernmost point and begins to recurve. That trend is significant, although the individual data points may not be.


I agree with your point; but this was also directed to the person that you had quoted; but this system only picked up your quote.

What I was disputing is that the everyone keeps saying the models are off. I was just stating that the models are good within a certain time period.

Your statement that it is worth noting that the models keep shifting is correct. I was not a disagreement.
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So the trough is looking tilted? Does that mean Earl will have a better chance of hugging the coast on its approach to the OBX coast? The GFS yesterday compared to today looks different. Still strong but tilted now? A few guys in here are worried about?

I live 1 block from the Atlantic Ocean here in Virginia Beach. Our local weather guys are saying " real bad" or not even a breeze. This is hopeless! STORM W !!!!!!
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What happens to the steering if dry air gets in an weakens it to a cat 2 or cat 3?
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Quoting will40:


NASA GRIP i think is what it is called


Yeah, GRIP, but they are using a Global Hawk (UAV), DC-8, and WB-57 I think.
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I have a hard time seeing how Fiona will miss the islands. She would have start moving NW like now.
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Quoting jason2010xxxx:
CAT 2 HURRICANE IF IT HIT CAPE CODE.


CODE RED! :-P
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449. JRRP
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Quoting snotly:
Larger eye is now forming for Earl.
Might end up looking a little like Isabel in 03. And near the same location I must say....
Member Since: September 27, 2007 Posts: 1 Comments: 21088
StormW what if anything do you make of the mslp lines on the NHC motion loops of Earl. They appear to becoming more west to east as opposed to north to south.
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445. hercj
Quoting Neapolitan:


"PREDICT is currently flying into Tropical Storm Fiona. The GV took off from Barbados and will recover there. There may be a follow-on mission planned for tomorrow, takeoff at 10UTC for a 5-6-h mission, recovering in St. Croix. Or there could be a simple ferry back to St. Croix. That decision will be made later today. A final mission is being considered for September 2, with a takeoff at 10UTC for an 8-h mission that will recover in St. Croix."

what is predict and please link me to wherever that came from. thank you by the way.
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Quoting crashingwaves:



I've been telling people on here to keep watching Earl. I was saying that Earls track could change avoiding a curve out to sea. I remember H. Floyd missing a trough that woulld take him out to sea. Instead he tracked up the EC seaboard with lots of flooding rain. I have seen the track & the models change so much, it would make your head spin. I also don't agree that Earl will just brush the NC coast. jmo, to much inconsistencys in the track & models. Even our local mets today keep saying their not quite sure if Earl will be more east and stay out to sea or more west and slam NC. At this point, I believe its going to be a mess, for anyone from NC upward. I also think Florida should also keep an eye out just in case. It doesn't hurt to be prepared, should the track change. Look at Katrina, she took a bee line straight for LA/Miss. What a disaster that was. I live in Yorktown, Va. and I'm ready for whatever weather conditions we should get.

1 this is good to hear. you are ahead of the game. Good Luck!!!

It is always better to be prepared reguardless. I agree that this is
a possibly dangerous situation. The forecast is error prone
because of so many systems interacting. It becomes a timing issue.
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Here's a very nice, very high altitude image of Hurricane Frank taken by a NASA jet this past Saturday.

Click for larger image:
Member Since: November 8, 2009 Posts: 4 Comments: 13510
Quoting JRRP:
CMC
GASTOOOON!!!!
Link


....and Fiona heading for Bermuda
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441. MahFL
GRIP not grim....lol
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440. 7544
Quoting markot:
storm, has earl turned more west last few hours, its not far from the south east bahamas now.....


if thats true will the get as much as pr did ?and will the dom get some watches soon if he doesnt make that turn today
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439. Vero1
Quoting will40:


NASA GRIP i think is what it is called


GRIP website: Has all info from schedule to flight following.

http://grip.nsstc.nasa.gov/current_weather.html
Member Since: July 21, 2008 Posts: 4 Comments: 2233
Quoting crashingwaves:



I've been telling people on here to keep watching Earl. I was saying that Earls track could change avoiding a curve out to sea. I remember H. Floyd missing a trough that would take him out to sea. Instead he tracked up the EC seaboard with lots of flooding rain. I have seen the track & the models change so much, it would make your head spin. I also don't agree that Earl will just brush the NC coast. jmo, to much inconsistencys in the track & models. Even our local mets today keep saying their not quite sure if Earl will be more east and stay out to sea or more west and slam NC. At this point, I believe its going to be a mess, for anyone from NC upward. I also think Florida should also keep an eye out just in case. It doesn't hurt to be prepared, should the track change. Look at Katrina, she took a bee line straight for LA/Miss. What a disaster that was. I live in Yorktown, Va. and I'm ready for whatever weather conditions we should get.

Just north of ya, Gloucester here. We'll see folks prepping throughout tonight and tomorrow, well into the end of the week. Hopefully, they don't cause too much chaos.
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437. MahFL
The GV is going to Fiona and later 4 Sep the Global Hawk will fly for 24 hours over Earl. Part of the GRIM project, I think.
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436. hercj
Quoting jeffs713:

Hrm.... IIRC, there is another NOAA research project (can't remember the acronym), but it has to do with watching storm genesis, and they are using a G-V, I think.

An previously unheard of research project comes up out of the blue with a 55 million dollor aircraft that NOAA would love to have and just appears on the scene when we have our first major cyclone event of the year. Does anyone but me think this is just a tad strange?
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storm, has earl turned more west last few hours, its not far from the south east bahamas now.....
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Quoting Sting13:
Storm, i thank you for all the info you put out, you are very dedicated to helping people on wunderground. 1 quick question that is confusing me a bit. Once it makes its approach towards NS, NHC says its a TS(after it passes over), CHC says its a post tropical storm, and accuweather says it could be a category 1 hurricane. I'm rather confused.

No one can predict precisely how fast the storm will deteriorate as it approaches northeastern Canada - it will depend on the track it takes, the extent to which it interacts with land masses to the south, and the shear it encounters en route. Besides, which side of the line it falls on is relatively unimportant - a strong tropical storm, a weak hurricane, an extratropical cyclone - at this point in time, the preparations for all three are fairly similar.
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at this point any trends left in the models are increasingly significant.

i would expect more to come too. When the Hurricane watches
start going up along the east coast people are gonna have a cow.
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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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