Tropical Storm Bertha forms--and sets a record

By: Dr. Jeff Masters , 3:18 PM GMT on July 03, 2008

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Tropical Storm Bertha is here. Overnight, a significant amount of heavy thunderstorm activity built up around the center, aided by Sea Surface Temperatures (SSTs) about 26°C (1°C above average for this date). This temperature is right at the threshold of where tropical storms can form. Also aiding the storm is 5-10 knots of wind shear. Bertha has good organization and a favorable environment for intensification, and should continue to slowly intensify today. There is not much African dust or dry air near the storm, and the main impediment to future intensification will be a region of colder SSTs the storm will track over on Friday and Saturday. These cooler SSTs have created some stable air to the northwest of Bertha. Evidence of this stable air in satellite imagery (Figure 1) can be seen in the form of a large area of stratocumulus clouds to the northwest of Bertha.


Figure 1. Visible satellite image of Bertha shortly before becoming a tropical storm. Note the large field of stratocumulus clouds to the storm's northwest, indicating stable air lying over cooler SSTs.

The forecast
Most of the computer models foresee 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 approaching trough of low pressure and recurve. A shallower, weaker storm might be able to avoid recurvature and continue west-northwest towards Bermuda.

The hurricane season of 2008 sets a new record
Today's formation of Bertha at 25° West longitude is the farthest east a tropical storm has ever formed in the Atlantic so early in the season. It is also the farthest east a tropical storm has formed in the month of July. Reliable records of Eastern Atlantic storms go back to 1967, the beginning of the geostationary satellite era.

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 last night has grow less organized this morning, due to an increase in wind shear to 15-20 knots. The disturbance is a rather small one, and thus vulnerable to wind shear. QuikSCAT satellite imagery from this morning shows no sign of a surface circulation. The SHIPS intensity model predicts wind shear will increase above 30 knots by Saturday morning over 93L, and it is unlikely this disturbance will develop into a tropical depression.

Both the GFS and NOGAPS models are forecasting the development of a tropical disturbance in the southern Gulf of Mexico's Bay of Campeche on Monday. The tropics are getting active!

I'll post an update Friday morning. Happy 4th of July weekend!
Jeff Masters

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1341. reedzone
1:44 PM GMT on July 04, 2008
Morning everyone and Happy Independance Day!
I'll be at the beach from 1 p.m. till about 10 p.m. so I'm gonna make a quick update on Bertha on my blog and track it for a while.
Member Since: July 1, 2008 Posts: 13 Comments: 7334
1340. BahaHurican
12:30 PM GMT on July 04, 2008
Happy 4th of July to all those out there who celebrate it.

We are having an Independence T-shirt Day here today since it is the last "casual Friday" before our own Independence Day on July 10. Everybody is supposed to wear a t-shirt commemorating our independence, or, failing that, a plain t-shirt in black, aquamarine or gold, which are our flag colours.

Ike, the ECMWF solution is not that "far out" if Bertha doesn't gain too much vertically. I personally think Bertha WILL make it to 60W before it recurves, partially because it seems to want to stay a bit further south than originally expected.
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1339. Patrap
12:28 PM GMT on July 04, 2008
New Blog for Dr. M.
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1338. Cavin Rawlins
12:26 PM GMT on July 04, 2008
Updated
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1337. Cavin Rawlins
12:26 PM GMT on July 04, 2008
1299. kmanislander 7:38 AM AST on July 04, 2008

The QuikSCAT pass was taken 3 hours before the 5am advisory. Bertha moved along way between the QuikSCAT pass and the 5am advisory.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1336. KEEPEROFTHEGATE (Mod)
12:24 PM GMT on July 04, 2008
i see (karen) lol bertha looks a little raggy this morning
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1332. melwerle
12:21 PM GMT on July 04, 2008
Morning JP, morning everyone...

Happy Fourth!
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1329. Patrap
12:19 PM GMT on July 04, 2008
Latest WV Image CV Islands Link
Member Since: July 3, 2005 Posts: 414 Comments: 125521
1327. IKE
12:16 PM GMT on July 04, 2008
1326. leftovers 7:14 AM CDT on July 04, 2008
Changing your chords Ike on Bertha?


LOL....I stand by my thoughts...doesn't make it to 60W...if I'm wrong, so be it....crow me....
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1325. Cavin Rawlins
12:13 PM GMT on July 04, 2008
Tropical Update
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1324. IKE
12:12 PM GMT on July 04, 2008
1323...not likely.......
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1323. TampaMishy
12:11 PM GMT on July 04, 2008
Thank you Ike....Do you think it'll hit Florida?
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1322. IKE
12:10 PM GMT on July 04, 2008
1321...yeah the ECMWF kind of waffles back and forth....
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1321. HurricaneSammy
12:09 PM GMT on July 04, 2008
but remember ike. .... Last season the ECMWF Forcasted a Miami major hurricane and nothing came....
1319. stormdude77
12:04 PM GMT on July 04, 2008
Morning y'all

Happy 4th of July to you guys in the the United States!
1318. IKE
12:03 PM GMT on July 04, 2008
00Z ECMWF has Big Bertha nearing the Bahamas before turning....

Link
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1316. TampaMishy
12:00 PM GMT on July 04, 2008
So where do you think Big Bertha is going to land?
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1315. kmanislander
11:52 AM GMT on July 04, 2008
You do that Storm

Coffee time for me

BBL
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1314. IKE
11:51 AM GMT on July 04, 2008
00Z UKMET...

Link
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1313. kmanislander
11:50 AM GMT on July 04, 2008
Here is the exposed circulation of ex 93L

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1310. IKE
11:48 AM GMT on July 04, 2008
00Z CMC....

Link
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1309. IKE
11:45 AM GMT on July 04, 2008
1307...your were right on with your forecast calling for increasing activity in the Atlantic in early/mid July......
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1308. kmanislander
11:44 AM GMT on July 04, 2008
Hi Storm

Happy 4th to you. Lots going on out there. Bertha near 13.8 according to QS. The next set of runs will be interesting
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1306. IKE
11:42 AM GMT on July 04, 2008
Good morning StormW...looks like your work is fixing to pick up........
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1305. kmanislander
11:42 AM GMT on July 04, 2008
Leftovers

So do I. My face still hurts from the storm that shall remain nameless !

93L will likely be put back up later today as the increase in convection and a 1011 to 1013 mb low would seem to warrant that.
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1302. kmanislander
11:39 AM GMT on July 04, 2008
Thanks HMJ

Hope it doesn't do anything crazy in my neighbourhood LOL
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1301. TheWeatherMan504
11:39 AM GMT on July 04, 2008
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1300. IKE
11:39 AM GMT on July 04, 2008
Long-term discussion from Tallahassee,Fl....

"Long term...(sunday night-Fri.)
The models appear to be in decent agreement through the extended
period. Sunday night through Monday...the upper trough that has been
across the region will begin to lift northeast as the upper ridge
builds back across the area. Monday night through Wednesday...the
European model (ecmwf) and GFS are showing an increase in deep layer moisture
across the eastern half of the County Warning Area as a tropical wave tracks north
around the subtropical ridge axis.
Thursday through Friday night...
the GFS/European model (ecmwf) show the upper ridge beginning to weaken once again
and shifting south as another short wave trough and cold front
approach the region from the northwest. Southwesterly flow and
increasing moisture ahead of this frontal boundary will provide
higher probabilities for shower/storm coverage across the area
during this period.".............


The tropical wave they mention...93L??????

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1299. kmanislander
11:38 AM GMT on July 04, 2008
I just noticed something else, about Bertha

The Hi Res quikscat pass this morning shows the center to actually be further South than 14.2N

13.8 or.9 would be more accurate. This will likely bring the next model runs further South again with the track
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1298. HurricaneMaryJane
11:36 AM GMT on July 04, 2008
Happy 4th of July everyone!

Kman, that was a great call on 93l...we're lucky to have you here!
1297. stoormfury
11:35 AM GMT on July 04, 2008
shear is expected to weaken and is all the breathing space 93L will want.' WATCH IT IN THE G/MEX'
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1296. Cavin Rawlins
11:31 AM GMT on July 04, 2008
The circulation of 93L can even be seen on the 6 km geostationary satellite of the central atlantic. Pretty impressive considering the amount of vertical wind shear. Should wind shear slacken anytime along the future trek, I dont think 93L will have much problem organizing, thats why it needs to be watch especially in the event it enters Gulf of Mexico. But I guess the Navy has other plans.
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1295. IKE
11:29 AM GMT on July 04, 2008
They need to put 93L back up.
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1294. IKE
11:28 AM GMT on July 04, 2008
1292. kmanislander 6:26 AM CDT on July 04, 2008
Hi Ike

Makes for interesting watching close to home !

There is a buoy at 75 West that will give us a good reading on this late today


Yeah....it does....the season is heating up in the Atlantic.
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1293. Cavin Rawlins
11:28 AM GMT on July 04, 2008
Bertha can now be seen on the CATL satellite page

http://www.ssd.noaa.gov/goes/east/catl.html

A floater should be available today.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
1292. kmanislander
11:26 AM GMT on July 04, 2008
Hi Ike

Makes for interesting watching close to home !

There is a buoy at 75 West that will give us a good reading on this late today
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1291. stoormfury
11:25 AM GMT on July 04, 2008
ok BahaHurican i will check it out. i was wating the 8.05 discussion
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About JeffMasters

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