Bertha may pose a long-range threat to the U.S.
Tropical Storm Bertha has maintained it's strength overnight, but is having trouble with Sea Surface Temperatures (SSTs) of 25°C--one degree below the threshold of 26°C considered beneficial for tropical storms. This morning's QuikSCAT pass missed Bertha, but last night's pass confirmed winds of at least 40mph. Satellite estimates of Bertha's strength have consistently put the storm's strength at 50 mph over the past day. The storm is under about 10-15 knots of wind shear.
Figure 1. Latest satellite image of Bertha.
The forecast
The models are now more confident that Bertha will not take a turn to the north east of Bermuda, with two models--the UKMET and NOGAPS--calling for the storm to pass very near the northern Lesser Antilles Islands by Tuesday night and Wednesday morning. These islands should anticipate the possibility of tropical storm conditions as early as Tuesday night, even though the current official track keeps Bertha well north of the islands. Bertha may be large enough to bring tropical storm force winds 100-200 miles from the center by Tuesday. A threat to the East Coast of the U.S. is now possible, with such an event most likely to occur about 7-10 days from now. It is also possible that high wind shear will tear apart Bertha (as predicted by the ECMWF model), or that the storm will recurve to the north just east of North Carolina, missing the U.S. The long range track of Bertha is highly uncertain, and it is too early to speculate how likely each of these scenarios is.
By Sunday morning, Bertha will be over SSTs of 26°C, which will warm to 27°C by Monday and 28°C Tuesday. this should allow Bertha to intensify to near Category 1 hurricane strength. However, by Tuesday, wind shear is expected to increase to 20 knots and remain high for several days, as Bertha encounters a branch of the subtropical jet stream. The higher shear should weaken the storm.
Elsewhere in the tropics
There are no threat areas to discuss in the tropical Atlantic, and none of the models are forecasting tropical storm formation in the next seven days.
I'll post an update by Sunday afternoon.
Jeff Masters
Reader Comments
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2.7 /1005.0mb/ 39.0kt
Its gotta be wrong, look where it has the storm center
Conversation this morning reminds me of my house - every one disagrees just to disagree.
I see the UKMET shifted east, but Bertha has shifted south as the steering has suggested it would do for a couple of days now. Expect the models to follow.
This thing has not played out yet. Anything can still happen including a CONUS landfall.
Global 12 FT Wave Probability Link
Have a good morning posting...
2561. TampaSpin 1:55 PM GMT on July 06, 2008
One thing of great importance in my opinion. I think it is very important for Bertha to cross the 20N line at or before 55W or she might just stay south.
really...? 20N /55W, those coordinates look suspicously familiar. i am with you though, by default and about 20 posts that reference same.
Sorry for double posting i have had that in my blog the last 2 days.....i should have read backwards.
Having read all the information that I can find about the models and their accuracy, I don't think that anything past 3-4 days has improved.
That said, all the reliance on the 7-10 track is unrealistic. More important is the discussions of the conditions that could either aid the models or change them.
For now, anyone who is lurking needs to know there is a storm out there, where it will go is far from certain, and that it is certainly not time to panic for anyone.
I do get a little concerned about those who post with all the "omg". You are going to scare people who lurk that don't have a lot of knowledge.
Bertha has been improving nicely on the infrared, though. If she can do that out in the central Atlantic with all that dry air ahead of her, I bet she'd do quite well in Carribean or Bahaman water...
But, if it makes it to 20n at or around 50w, that looks to be only brief as the track will likely move back to the west and maybe jog again to the swest. However, at 60w all of the steering levels show a continual movement to the nwest. And, it can still make it out to sea there, but it's going to be a more difficult turn imo. Also, it does put the northern islands in a close threat area, too. And, I still wouldn't rule out a CONUS landfall.
Link
2583. moonlightcowboy 9:09 AM CDT on July 06, 2008 Hide this comment.
2574. Yeah, Sammy, I expect they will; but, that'll likely be temporary. Just looking at the new steering suggests a nwest movement now before turning back to the west once again.
But, if it makes it to 20n at or around 50w, that looks to be only brief as the track will likely move back to the west and maybe jog again to the swest. However, at 60w all of the steering levels show a continual movement to the nwest. And, it can still make it out to sea there, but it's going to be a more difficult turn imo. Also, it does put the northern islands in a close threat area, too. And, I still wouldn't rule out a CONUS landfall.
Look what's ahead if it continues WNW>>>
Weaker? West?
Current path
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