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Bertha slowly intensifies, continues west-northwest

By: Dr. Jeff Masters , 12:22 PM GMT on July 04, 2008

Tropical Storm Bertha has slowly intensified overnight, with new heavy thunderstorm activity building up around the center. Sea Surface Temperatures (SSTs) are now slightly below the threshold of 26°C considered beneficial for tropical storms, and this is limiting Bertha's intensification. This morning's 4:01am EDT QuikSCAT pass revealed top winds of about 30 mph, but the satellite was not able to reliably detect Bertha's strongest winds, since QuikSCAT does poorly in heavy rain. Bertha's current intensity is based mostly on satellite imagery of the cloud patterns. The storm is under about 10 knots of wind shear. Bertha should continue to slowly intensify today.


Figure 1. Track chart of all Atlantic tropical storms that have formed east of 40°W longitude since 1851.

The forecast
Not much has changed in the forecast, with all of the computer models foreseeing a west-northwest track into the mid-Atlantic over the next five days, with a possible recurvature to the north by the end of the period. Whether this recurvature takes place depends on how strong Bertha gets. A larger, stronger storm will be more likely to "feel" the approach of the trough of low pressure expected to recurve Bertha, which a shallower, weaker storm might be able to avoid recurvature and continue west-northwest. Wind shear is expected to remain below 10 knots the next three days, then increase to 30-40 knots by day five, according to the GFS model, when Bertha hits a branch of the Subtropical jet stream. The GFDL model does not go along with this high shear forecast, and makes Bertha a Category 2 hurricane that begins recurving to the east of Bermuda. In contrast, the HWRF model keeps Bertha a weak tropical storm for the next six days. Suffice to say, there is a lot uncertainty in the long range intensity forecast for Bertha!

The hurricane season of 2008 sets a new record
Bertha's at 25° West longitude is the farthest east a tropical storm has ever formed in the Atlantic so early in the season. Reliable records of Eastern Atlantic storms go back to 1967, the beginning of the geostationary satellite era. It's remarkable that no other early July storm even comes close to matching how far east Bertha formed (Figure 1).

Is the formation of Bertha a harbinger of an active hurricane season?
Probably. According the the Hurricane FAQ, "as shown in (Goldenberg 2000), if one looks only at the June-July Atlantic tropical storms and hurricanes occurring south of 22°N and east of 77°W (the eastern portion of the Main Development Region [MDR] for Atlantic hurricanes), there is a strong association with activity for the remainder of the year. According to the data from 1944-1999, total overall Atlantic activity for years that had a tropical storm or hurricane form in this region during JJ have been at least average and often times above average. So it could be said that a JJ storm in this region is pretty much a "sufficient" condition for a year to produce at least average activity."

Elsewhere in the tropics
A tropical wave (93L) that passed through the Lesser Antilles Islands Wednesday night is now in the central Caribbean and is very disorganized, thanks to high wind shear. This wave is not expected to develop, and no computer models are predicting development anywhere else in the Atlantic over the next seven days.

I'll post an update Saturday morning. Happy 4th of July weekend!
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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388. FranAteMyRoof96
4:15 PM GMT on July 04, 2008
This may be a dumb question, but what is that hole in the clouds trailing behind ex-93L? Looks almost like a separate COC kicking up some convection:

Link
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387. moonlightcowboy
10:28 AM CDT on July 04, 2008


...cooler SST's now and ahead!
Member Since: December 31, 1969 Posts: Comments:
386. eye
4:16 PM GMT on July 04, 2008
Bertha wind field is so tiny, some places along the east coast could use a strong TS weak Cat 1....especially the northern coast of NC where there is that pesky fire that they are saying will only be put out (due to burning peet moss) if they get 2-3 inches of rain.
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385. Tazmanian
9:17 AM PDT on July 04, 2008
did any one see my post # 380???
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383. Drakoen
4:15 PM GMT on July 04, 2008
379. JFV 4:10 PM GMT on July 04, 2008
Oh my GOD, how noticeably is it pulling the ridge away in it's latest run Drak?




calm down lol. We will see what happens.
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382. Swells22
4:10 PM GMT on July 04, 2008
#378 Winds off TX are dead calm at KBRO / South Padre. Downbursts associated with up to 30 KT winds, the main threat aside from lightning. Sig wave swell in running high at 5 feet, so a very wet day offshore. But ... we needed the rain!
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381. Patrap
11:12 AM CDT on July 04, 2008
Bertha is well within the NHC Guidance envelope..

NHC on Bertha Link

First round of Boiled Shrimp is a soaking ,...
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380. Tazmanian
9:10 AM PDT on July 04, 2008
i may be jumping the gune a little but what evere that is this off the TX coast may be trying to get BETTER ORGANIZED may be not by march but its trying
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378. redrobin
11:07 AM CDT on July 04, 2008
Are the winds calm off the TX coast or in the qulf? That is a very large rain maker.
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377. stormlvr
3:46 PM GMT on July 04, 2008
That TPC 120 hour forecast point at 11AM is very important because it places Bertha on the very western fringes of the area where a turn could result in recurvature in the central Atlantic. Overshooting the weakness so to speak. Hopefully there will be enough pull to turn Bertha NW so that she will gain enough latitude and recurve off the east coast and spare us a July landfalling storm. Chances increase substantially for landfall if Bertha treks south of 25N and west of 65W but will have to see how the pattern unfolds along the coast at that point. IMO
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376. JRRP
4:06 PM GMT on Julio 04, 2008
Link
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375. Drakoen
4:07 PM GMT on July 04, 2008
The GFS 12z is pulling away the weakness in the ridge.
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373. Swells22
4:02 PM GMT on July 04, 2008
#355 that blob off S. Texas is something ... many sports fishermen went out for tournaments and we're a little worried about them ...
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372. WhereIsTheStorm
4:01 PM GMT on July 04, 2008
Thought the newer bloggers might like to have these links:

National Huricane Center
Link

This one is good for severe weather alerts from the National Weather Service
Link
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371. Drakoen
4:01 PM GMT on July 04, 2008
367. philliesrock 3:57 PM GMT on July 04, 2008
12z GFS notes:

-Keeps Bertha the same intensity, and south
-Develops another storm behind Bertha (!)


Yep. We'll have to watch what's coming of the coast.
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370. breald
11:58 AM EDT on July 04, 2008
ok thanks
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369. Patrap
10:57 AM CDT on July 04, 2008
From the ESL site,

GOES WV Loop of Tropical Basin Link

GOES-12 Atmospheric Imagery Link
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368. Patrap
10:57 AM CDT on July 04, 2008
Some browser's wont allow DoD/navy Sites,sorry.
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367. philliesrock
11:47 AM EDT on July 04, 2008
12z GFS notes:

-Keeps Bertha the same intensity, and south
-Develops another storm behind Bertha (!)
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366. nrtiwlnvragn
11:56 AM EDT on July 04, 2008
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365. TampaSpin
11:53 AM EDT on July 04, 2008
Great loop here....at the top check LatLon and Trop Fcst Pts....
North Atlantic Visible loop
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364. breald
11:54 AM EDT on July 04, 2008
Hey Patrap I can't pull up any of your links.
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363. TampaSpin
11:45 AM EDT on July 04, 2008
Shear is improving it appears...its looking better.
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362. pearlandaggie
3:51 PM GMT on July 04, 2008
360. just looks like rain right now :)
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361. pearlandaggie
3:48 PM GMT on July 04, 2008
you're welcome, atmoag. i didn't know if anyone was going to look at the article since error propagation is such a dry subject. regardless, it really underscores how small errors in complex models can have a huge impact on the model output. your comment on initialization error is what sparked my memory....

"you-know-where", huh? LOL
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360. Tazmanian
8:49 AM PDT on July 04, 2008
i think what evere that is off the TX coast could be 94L be for the weekend is out it been seting there for days now
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359. Patrap
10:49 AM CDT on July 04, 2008
Fleet Numerical Meteorology and Oceanography Center
Current Tropical Storm Forecast Tracks
Updated: Fri Jul 4 06:30:00 GMT 2008

BERTHA_02L_2008070400
Link
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358. Drakoen
3:47 PM GMT on July 04, 2008
The latest runs are interesting. We'll have to see what happens.
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357. atmoaggie
3:42 PM GMT on July 04, 2008
based on the previous entries, here is a neat little article on error growth and propagation...

Error Growth Beyond The Hapless Butterfly


Thanks for the refresher pearlandag. We once did a full mock-up of Lorenz theory in one of my courses in college at you-know-where.

BTW, Lorenz passed away last year (or earlier this year, maybe)
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356. weatherboyfsu
3:47 PM GMT on July 04, 2008
Happy fourth to everyone!
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355. pearlandaggie
3:47 PM GMT on July 04, 2008
looks like a wet 4th for some of Texas...
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354. HurakanPR
11:37 AM AST on July 04, 2008
Very interesting Mr.Sea. 2002 Bertha ! Never heard about it,a weird "mini-storm, indeed.
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353. Patrap
10:47 AM CDT on July 04, 2008



EFS 1000/500 HPa Mean Thickness and SLP Displays ,Java Movie* Link
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352. KEEPEROFTHEGATE (Mod)
3:37 PM GMT on July 04, 2008
track mark
33.2w/15.4n
35.2w/15.8n
37.6w/16.5n
40.1w/16.9n
42.3w/17.1n
45.7w/17.8n
48.1w/18.2n
52.7w/18.6n
54.3w/18.8n
55.1w/19.3n
***stop****
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351. MrSea
3:43 PM GMT on July 04, 2008
ill be going now too, hope you all have a safe and happy independence day
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350. pearlandaggie
3:43 PM GMT on July 04, 2008
MrSea, have you seen this?

Link
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349. K8eCane
3:42 PM GMT on July 04, 2008
347.
hey taz
i thought you could read those maps lol
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348. MrSea
3:42 PM GMT on July 04, 2008
i guess everyone left to celebrate the day lol
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347. Tazmanian
8:38 AM PDT on July 04, 2008
how is wind shear by oh say 100hrs out what do mode runs say???
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346. JRRP
3:36 PM GMT on Julio 04, 2008
342
africa should monitore Bertha.. LOL
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345. MrSea
3:38 PM GMT on July 04, 2008
wow Bertha 2002 looks a lot like what could happen in the western gulf this week
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344. philliesrock
11:36 AM EDT on July 04, 2008
So I see that the NHC still wants a south track...
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343. MrSea
3:36 PM GMT on July 04, 2008
lol DocBen that's what i said
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342. DocBen
3:31 PM GMT on July 04, 2008
292. tropicfreak 3:06 PM GMT on July 04, 2008

How about that UKMET jog back to Africa!

:)
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340. MrSea
3:31 PM GMT on July 04, 2008
339. hurricane23 3:31 PM GMT on July 04, 2008
Will the trend continue?

0600 utc models...


12z early runs here

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339. hurricane23
11:30 AM EDT on July 04, 2008
.

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338. MrSea
3:29 PM GMT on July 04, 2008
336. popartpete 3:28 PM GMT on July 04, 2008
Look out Continental United States East Coast, this might be BERTHA 2!!!

Actually, there was probably a Bertha of some sort in 2002, so we could follow horror movie franchise naming philosophy, and call it "Bertha 3-D". Will we need special glasses??


Bertha 2002


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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