Category 4 Earl headed for a close brush with North Carolina

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

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 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.

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.

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 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 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

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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Quoting apocalyps:

Trough is weaker as expected and now the whole eastcoast(possible) and Florida(highest chance)are in the cone.Isnt that amazing?
Where is the cone that shows any part of Florida in it for Earl? I have yet to see it.
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331. Vero1
Quoting JVGazeley:
Looking tight for NC now...

How's the storm surge forecast look for NYC at the moment? Couple of feet?

Here is the Surf model for NJ/LI
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Quoting InTheCone:

What campus is that for?

Not sure but they do not seam to care about their students. I.E We got your money for the year now get the heck out in two hours when we say your on your own. Thats how that comes across to me.
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Man I can only think that a west shift will continue with the models. Delaware could be in for a powerful tropical storm conditions.
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chances for Earl to become a CAT 5 = 7%
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Quoting InTheCone:

What campus is that for?

Christopher Newport University
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From --

The forecast product most often used to convey the track forecast positions and the associated uncertainties is the aptly-named "cone of uncertainty."

Also known as the "error cone" and the "two-thirds probability cone," the cone of uncertainty was designed as a way to express the uncertainty visually. The uncertainty in the motion of storms is quantifiable: the uncertainty displayed in the cone is a statistical expression of the uncertainty in the forecast. The width of each section of the cone is scaled to represent two-thirds of the track forecast errors for each of the forecast periods from the past five hurricane seasons, hence "two-thirds probability cone." It means though that one-third of those past errors would lie beyond the boundaries of a present-day cone.

The cone of uncertainty comes in two varieties: the 3-day and the 5-day, belonging to the 3-day and 5-day track forecasts, respectively. It has two main purposes. The first is to communicate the spatial forecast coordinates (latitude and longitude) in a way that is user friendly to the average person. The second is to convey the scale of error that is currently taken to be inevitable given the current state of the science. Inherent in the cone's structure is the portrayal of uncertainty not only in a storm's future position but also in its (changing) forward speed.

All weather forecasts by necessity contain uncertainty. The more distant the forecast period (e.g., the 96h or 4-day forecast as compared to the 12h forecast), the larger the uncertainties generally are; this is why the cone is "cone-shaped." In portraying this uncertainty in a graphic and releasing it to the public, forecasters are implicitly advising people as to the present-day capabilities of the science. The cone itself contains information about where the science is in any given hurricane season, while the changes in the widths of its sections from one season to the next constitute a visual record of the rate at which it is progressing.

If the cone is an expression of where the science now stands, it is equally a portrait of how far it has to go. If it were possible to predict a storm's track exactly, the cone would disappear altogether; a single point on a map of some coastline indicating the exact spot of landfall would be all that might remain, with some precise hour and minute in the future time-stamped on it. The text advisory for this kind of forecast might contain but a single line, for instance: LANDFALL WILL OCCUR AT SOMECITY, GULF COAST TEXAS, FRI 2:03 P.M CDT. Such a forecast will never be possible, except in the realm of science fiction; the best that can be hoped for in a real-world future is an uncertainty cone that becomes progressively narrower with every passing hurricane season.
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@307, 308, glad someone got my point...the little shift could just be noise in the models, could be part of a trend...but we can't really tell that just by comparing those two runs.

the problem with a storm like earl is that it's coming so close, small shifts in the actual track will make a big difference...but the models won't be able to pick that up.
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Can someone help an old guy out who is going cross-eyed trying to figure out where the trough is that is supposed to arrive and save the day. Whip out a crayon. Maybe time for a tutorial.
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316. HadesGodWyvern (Mod)
India Meteorological Department
Tropical Cyclone Outlook
14:30 PM IST August 31 2010

An upper air cyclonic circulation may form over west central and adjoining northwest Bay of Bengal around 4 September which may subsequently develop into a low pressure area.

Broken low/medium clouds with embedded moderate to intense convection over Bay of Bengal between 9.0N to 15.0N east of 86.0E, northwest Bay of Bengal and Andaman Sea. Scattered low/medium clouds with embedded isolated weak to moderate convecton over rest of Bay of Bengal


Broken low/medium clouds with embedded moderate to intense convection over northeast Arabian Sea, east central and rest of east central Arabian Sea east of 70.0E. Broken low/medium clouds with embedded isolated weak to moderate convection over rest Arabian Sea north of 13.0N and southeast Arabian Sea
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Quoting StormW:

Very instructive Storm-thanks
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313. MahFL
A new burst of convection at the center.
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storm, its getting closer to the bahamas hour by hour when you think hurr. warnings...
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Looking tight for NC now...

How's the storm surge forecast look for NYC at the moment? Couple of feet?
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Quoting DestinJeff:
Thank goodness for the cone, otherwise I might be left unprepared....

Jeff - The cone is drawn knowing that one third of storms will be outside of it.
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Its looking more like, Earl will Effect Virginia probably on Thursday in to Friday. btw, the track that the local mets show, look like Earl will be awful close to NC. They keep banking on Earl being more west of the coast. I'll believe it when I see it.jmo
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308. CJ5
Quoting rwdobson:

You're missing the point here. What I'm talking about is a fundamental limitation of the computer modeling that you have to consider when comparing one run to the next.

The models just aren't precise enough for this small shift to be meaningful.

I see your point. However, those that don't come in here often like us may interpret it another way. No harm, no foul
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Quoting rwdobson:

You're missing the point here. What I'm talking about is a fundamental limitation of the computer modeling that you have to consider when comparing one run to the next.

The models just aren't precise enough for this small shift to be meaningful.

They're not precise enough for this shift to be statistically significant, which is not the same as saying that it's meaningless. Consider, after all, a succession of 50 mile shifts in the same direction - their cumulative impact is indeed meaningful. So I wouldn't call this particular model run significant in its own right. But as an extension of a trend over the past 48 hours? That trend continues to be significant, and this is another data point - none of which mean much individually - to bolster the case that Earl is still shading slightly West.
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Quoting flstormhog:

Do you have to be a member to use the ignore feature?

On everyone's post there is a Quote and Ignore button you can hit ignore and it will put them on a list and then hit update and that's all you have to do.

And when someone quotes them if you wanna you can hit report and - and put them on ignore list to it's all up to what you wanna do. And that will take care of the messy troll business.
Cause right know we really need info on the storm and not being bothered with the trolls.
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There is plenty of good information on this blog, but you should always listen to the information from NHC and your local emergency professionals.

Anyone who could possibly be in an area where the cone is, and maybe just outside of should think of the following: what happens when you get a big storm?

Even if your home will be fine, will you have access roads out? Will high water cutoff the only road into your area? The impacts of a hurricane that just passes by can also cause issues, you don't need to have a direct hit from the eye.

Use your common sense and don't panic.

The NHC guidance says that the storm will be at its closest early on Friday morning. Don't wait until lunch on Thursday, what if the storm speeds up a little, your stuck.
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National Hurricane Survival Initiative
Before the Hurricane Begins
Develop a plan. Know your homes vulnerability to the threats above - surge, wind, and flooding. Check your supplies - water, batteries, food. For information on developing a Hurricane Supply kit, see our page on that topic. Know where you can evacuate to - friends, relatives, a hotel?

Know when to take action - Watch vs Warning
WATCH: Hurricane conditions are possible in the specified area of the WATCH, usually within 36 hours.
WARNING: Hurricane conditions are expected in the specified area of the WARNING, usually within 24 hours. Remember that there is no such thing as a "minor hurricane." Category 1 and 2 hurricanes still can do significant damage.

Prepare before a Watch or Warning is issued and be ready to evacuate when the Watch comes or earlier if so instructed.

An Approaching Storm
As a storm approaches, you should prepare your house and your yard. Some things to consider:

Turn down the temperature on your freezer and refrigerator as low as possible. This will buy you more time in the event of a power loss. 24 to 48 hours before will cool the food. Avoid opening them whenever possible. If you are evacuating.
Before you evacuate, call at least one person out of state to let them know your plans.
Ensure that your Hurricane Emergency Kit is fully stocked.
Charge electronic devices, for example, computers, cell phones, rechargeable batteries, razors, and the like.
Make extra ice, bag it - this will be useful to use and to keep the freezer cold.
If you have a generator, do NOT run it inside or near the house. But make sure you have fuel to run it.
Make sure your car has fuel.
Pick up yard debris - furniture, tools, decorative items, branches - anything loose that could become a missile. We have placed furniture in the pool upon occasion.
Secure boats, trailers, campers, RVs, and the like in the safest place you can find. Tie them down, anchor them, or however you can best secure them. But, take into account that there may be a storm surge.
Secure all doors and windows with locks, and shutters if available. Plywood, properly secured, can be effective. Don't forget your garage doors.
Move items that may be damaged by water to higher areas of your home if you can not take them with you if evacuating. Move them away from windows in case they are broken.
Huge items must even be secured in big storms. An engine block was found 40 or 50 feet up in a pine tree in the Homestead (actually Redlands) area after Andrew. Don't think that something is too big to be moved by the wind.
Re-check tie-downs.
Bring cars, bikes, scooters and anything like that into your garage if possible.
Bring in grills or other cooking items.
Bring in hoses, trash cans, hot tub covers, wind-chimes, plants.
Caulk and fill bathtubs - extra water comes in handy for toilets and more..
It may sound strange, but do your laundry, dishes, and take a shower. Why? Because if you lose power, having as much clean as possible will make a big difference.
Check if your pool pump should be on or off.
Close and fasten gates so they don't swing.
Close chimney flues.
Close/latch inside doors and cabinets.

If you have time, help your neighbors. Debris in their yards can easily impact your home and yard.

During a storm.

Stay inside, away from windows
Be alert for tornadoes
Stay away from flood waters and storm surge. It can be deceptively strong.
Be aware of the eye. It may be calm, but winds can and will pick up quickly and could catch you outside.
Un-plug electronic devices that are not in use to avoid surge damage.

After a Storm

Know power safety - avoid downed lines
Know food safety - what is good and for how long.
Chain saw safety is critical
Generator safety is important too
Water treatment - whether water needs to be boiled or not.
Listen to local officials
Use flashlights instead of candles
Inspect your home for damage.
Stay off roads as much as possible
You may need to super-chlorinate your pool

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The EMCWF has shifted slightly west again, making Earl a coast hugger!!
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Can't wait until Fiona catches up to Earl. Should be an interesting interaction to watch.
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FEMA assistance info.

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The new and much larger eye is starting to become visible on RGB link
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Quoting DestinJeff:
Thank goodness for the cone, otherwise I might be left unprepared....

The Cone is just another brick in the wall.
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Quoting will40:

all you have to do is quote the comment number and it will show the name

Oh well...not that big of a deal. People can deal with one quote.

Moving on..
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Quoting StormW:

Yes ma'am! models did the same with Danielle...but you won't get a lot of folks to admit it.

I suppose we could have argued the intricacies of Danielle's forecast and model performance if she had wound up doing more than skirting past Bermuda. I don't recall NHC being too far off on that one, but to be honest I haven't checked. It is painfully obvious, however, that Earl's forecast has heretofore been blown. Big time.
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Quoting CJ5:

..and the NHC compute thier track based off what? I assume models are part of it, don't you. While 50 miles doesn't seem like much, we have seen those 50 miles continue to add up he over the past few days. If the models add only 50 miles in the next few runs we will be into SC.

You're missing the point here. What I'm talking about is a fundamental limitation of the computer modeling that you have to consider when comparing one run to the next.

The models just aren't precise enough for this small shift to be meaningful.
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Looks like 30 degrees North, 75 degrees West will be a key point. If Earl can get turned Northward before that point and to its south and west, then I'd say that would be good for the U.S. assuming Earl behaves and turns on out North and East.
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Quoting catastropheadjuster:

Floodman~~ Good Morning, What you wrote I couldn't of said it any better. I always try to take care of the insured. They have went thru a lot when we have to come out and we are there to take care of there needs, not to take away from them in the hour of need. I always try to be fair. There are some out there that try to take advantage of a catastrophe.

Most of us work that way...we try to get things reported as quickly as possible and as accurately as possible...the issue with this kind of work is that the 80-20 rule applies; you find that 80% of your time is taken up by 20% of your insureds. One more proviso: the ones that are yelling the loudest are typically the ones with the least amount of damage
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Folks from NC to New England, remain calm, cool, collective, focused.

I agree, as soon as watches are warnings are posted, please, please, take the appropriate actions, even if that includes evacuating your area.

MANY people are praying for a favorable outcome. I hope this scenario does not become an ugly one. Everybody knows this is the price we pay for living by the Atlantic Ocean on the Eastern Seaboard.
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Quoting muddertracker:
Keeper..are your posts being eaten by the blog or are you attempting a mind-reading experiment?
what with the models thay are three different ones nam ukmet and gfs which is done running

o and by the way JFV is back can you guess who he is THE CLUE WOULD BE THE MONTH OF SEPTEMBER
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you can say that again.


sounds like someone playing with bubble wrap in here LOL
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

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