Bertha slowly intensifies, continues west-northwest

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

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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

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538. northtxhurricane
5:56 PM GMT on July 04, 2008
Time for everyone to put "Houstonian" on the ignore list..

Anyways...just out of the information I have...I'm going to say strong tropical storm or weak hurricane from anywhere in the Bermuda, Florida, and NCarolina triangle. Sound like a safe bet??
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537. NorthxCakalaky
5:55 PM GMT on July 04, 2008
Looks like our 2ed storm of the year will be a hurricane.
536. KEEPEROFTHEGATE (Mod)
5:31 PM GMT on July 04, 2008
bertha is building convection nicly
not playing by the rules
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535. Midweststorm
5:55 PM GMT on July 04, 2008
529

Go away troll.

Is it me or does bertha seem to be pulling moister and strength off that blob south of it?
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532. Levi32
9:53 AM AKDT on July 04, 2008
Guys keep in mind that this is only 1 or 2 model runs that have shifted so far. Lots of bouncing around is to be expected of the models, and Bertha is only barely in the range of the GOES-12 satellite, so we can't draw any conclusions about US landfall or the track yet. It's still a waiting game, and all of this still comes down to how strong Bertha is during the next 4 days.
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530. blueranch1
5:53 PM GMT on July 04, 2008
Been away all day. Is 93L gone?
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528. 305st0rm
5:51 PM GMT on July 04, 2008
i wonder how much further south it will shift
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525. oddspeed
5:50 PM GMT on July 04, 2008
still moving north

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524. 305st0rm
5:49 PM GMT on July 04, 2008
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523. FranAteMyRoof96
5:46 PM GMT on July 04, 2008
507.
Yes, but what we need for that is a large, slow-moving tropical storm, not a 'cane. I'm all for a ton of rain, just not the 80-90mph wind gusts that ate my roof.
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521. TampaSpin
1:48 PM EDT on July 04, 2008
The BamS is the southern track....we better be watching that track if Bertha does not organize stronger.
img src="Image and video hosting by TinyPic" alt="" />
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519. Drakoen
5:44 PM GMT on July 04, 2008
It looks like the NHC has to some big decision making to do. Go with the GFDL, HWRF, BAMM that strength the system to near or at hurricane strength and take it out to sea or go with the GFS, UKMET, NOGAPS, ECMWF, BAMS model keeps the system weaker on a more WNW track.
Member Since: October 28, 2006 Posts: 57 Comments: 31637
518. NorthxCakalaky
5:44 PM GMT on July 04, 2008
Tropical update on the The Weather Channel 50past the hour.
516. MrSea
5:42 PM GMT on July 04, 2008
514. Houstonian 5:42 PM GMT on July 04, 2008
ahh.......... soo now the bored bloggers are wish casting it to the eastern sea board..

blah blah blah

fish storm!!


naaa
lol
well i dont think this first weakness will recurve it. later in the week, if a new cold front comes off the east coast of the US, then it might turn IMO. this is all if the dry air that it is currently encountering doesnt eat it up completely! (i doubt that would happen, but it is losing a lot of convection on its west side) anyway im gonna watch the yankees and go to my family bbq so ill talk to you guys later. have a safe and enjoyable day
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515. HurricaneMaryJane
5:41 PM GMT on July 04, 2008
490. FLWeatherFreak91 5:27 PM GMT on July 04, 2008

477. diabeticstorm 1:19 PM EDT on July 04, 2008
there are too many kids on here pretending to know what they are saying, leave the predicting to the professionals.

I think you are very mistaken with that statement. My interest in the Weather started at the age of 12- and it was at that time when I learned much of the "professional" weather lingo necessary for discussing the wx. As my interest in atmo. science continued to deepen, I started learning the rules of forecasting and my knowledge of the subject soared. I posted on this blog all throughout Highschool, and starting in August I will be a full-time student at the Autonomous University of Santo Domingo studying nothing more but meteorology. When I return to the US I have an internship waiting for me at the Ruskin National Weather Service. Age does not determine knowledge. Thank you.


Wow, you just served her dirty style! Props my friend, and good luck when school starts! For now though, back to Bertha...

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513. moonlightcowboy
12:31 PM CDT on July 04, 2008
Thanks, Drak and just found you can do it on Google, too.

Photobucket

BAM (Beta and Advection) uses vertically-averaged winds and computes trajectories provided by the GFS model to provide track forecasts. There are three forms, BAMD (BAM Deep, 850-200 hPa), BAMM (BAM Medium, 850-400 hPa) and BAMS (BAM Shallow, 850-700 hPa) that use different altitudes of wind.

BAMM shallow takes Bertha's track just north of Puerto Rico which would indicate the storm may have trouble strengthening. And, that may be the case out over the cooler SST's and limited moisture availability out to the west of the system. But, if she continues to move west or jog back to the south, I think we could see these models shift away from the mid-ATL.
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512. nrtiwlnvragn
1:38 PM EDT on July 04, 2008
ATTENTION...NATIONAL HURRICANE CENTER

NCEP COUPLED HWRF HURRICANE MODEL FORECAST MADE FOR

TROPICAL STORM BERTHA 02L

INITIAL TIME 12Z JUL 4

FORECAST POSITIONS (FROM STATS.SHORT FILE...)

HOUR LATITUDE LONGITUDE MIN PRESS (hPa) MAX SFC WIND (KTS)

HOUR: 0.0 LONG: -29.00 LAT: 14.70 MIN PRESS (hPa): 1000.00 MAX SURF WIND (KNOTS): 45.00
HOUR: 6.0 LONG: -30.50 LAT: 15.50 MIN PRESS (hPa): 994.00 MAX SURF WIND (KNOTS): 45.00
HOUR: 12.0 LONG: -32.10 LAT: 16.10 MIN PRESS (hPa): 998.00 MAX SURF WIND (KNOTS): 53.00
HOUR: 18.0 LONG: -33.90 LAT: 16.90 MIN PRESS (hPa): 998.00 MAX SURF WIND (KNOTS): 51.00
HOUR: 24.0 LONG: -35.60 LAT: 17.40 MIN PRESS (hPa): 1001.00 MAX SURF WIND (KNOTS): 47.00
HOUR: 30.0 LONG: -37.40 LAT: 18.00 MIN PRESS (hPa): 1001.00 MAX SURF WIND (KNOTS): 46.00
HOUR: 36.0 LONG: -39.20 LAT: 18.40 MIN PRESS (hPa): 1003.00 MAX SURF WIND (KNOTS): 47.00
HOUR: 42.0 LONG: -41.00 LAT: 18.60 MIN PRESS (hPa): 1001.00 MAX SURF WIND (KNOTS): 50.00
HOUR: 48.0 LONG: -42.60 LAT: 19.30 MIN PRESS (hPa): 1002.00 MAX SURF WIND (KNOTS): 51.00
HOUR: 54.0 LONG: -44.40 LAT: 19.70 MIN PRESS (hPa): 999.00 MAX SURF WIND (KNOTS): 51.00
HOUR: 60.0 LONG: -45.80 LAT: 20.10 MIN PRESS (hPa): 998.00 MAX SURF WIND (KNOTS): 50.00
HOUR: 66.0 LONG: -47.10 LAT: 20.50 MIN PRESS (hPa): 992.00 MAX SURF WIND (KNOTS): 61.00
HOUR: 72.0 LONG: -48.00 LAT: 21.10 MIN PRESS (hPa): 990.00 MAX SURF WIND (KNOTS): 58.00
HOUR: 78.0 LONG: -48.90 LAT: 21.90 MIN PRESS (hPa): 986.00 MAX SURF WIND (KNOTS): 63.00
HOUR: 84.0 LONG: -49.50 LAT: 22.60 MIN PRESS (hPa): 990.00 MAX SURF WIND (KNOTS): 56.00
HOUR: 90.0 LONG: -50.30 LAT: 23.40 MIN PRESS (hPa): 990.00 MAX SURF WIND (KNOTS): 59.00
HOUR: 96.0 LONG: -50.70 LAT: 24.60 MIN PRESS (hPa): 984.00 MAX SURF WIND (KNOTS): 59.00
HOUR: 102.0 LONG: -51.20 LAT: 25.40 MIN PRESS (hPa): 985.00 MAX SURF WIND (KNOTS): 57.00
HOUR: 108.0 LONG: -51.70 LAT: 26.30 MIN PRESS (hPa): 990.00 MAX SURF WIND (KNOTS): 51.00
HOUR: 114.0 LONG: -52.00 LAT: 26.70 MIN PRESS (hPa): 987.00 MAX SURF WIND (KNOTS): 54.00
HOUR: 120.0 LONG: -52.20 LAT: 27.50 MIN PRESS (hPa): 983.00 MAX SURF WIND (KNOTS): 54.00
HOUR: 126.0 LONG: -52.40 LAT: 28.10 MIN PRESS (hPa): 985.00 MAX SURF WIND (KNOTS): 55.00
FORECAST WAS RUN COUPLED FOR THE ENTIRE PERIOD...

DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT
REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD
NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC
OFFICIAL FORECAST.


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511. FLWeatherFreak91
1:36 PM EDT on July 04, 2008
I wonder where Baja is... he would very intrigued by all this right now
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510. MrSea
5:33 PM GMT on July 04, 2008
tampaspin i 100 percent agree. by next week i expect Bertha to be a Hurricane by the Bahamas (with a heat wave along the east coast by the way) and then later next week I think the hurricane will threaten the east coast. not wishcasting, not by any means confident either. just my current thoughts
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508. Drakoen
5:34 PM GMT on July 04, 2008
Model consensus:

Member Since: October 28, 2006 Posts: 57 Comments: 31637
507. NC0WX0Man
5:32 PM GMT on July 04, 2008
FranAte it would be awesome in the fact that it would put water in the Neuse (sp?) and al these other lakes around central NC. Raleigh and those areas are still under water restrictions and here in Fayetteville and southeastern NC we are not we've had plenty of rain so a slow moving tropical system with rain would help you out. ABC channel 11 news just said that the areas to the north of Harnett only have but so much drinking water left.
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506. Levi32
9:33 AM AKDT on July 04, 2008
Good morning guys! I just finished my morning update. It sounds like we are going to get a very interesting forecasting experience out of Bertha.
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505. K8eCane
5:33 PM GMT on July 04, 2008
347.
how dare you say eastern seaboard lol
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504. nash28
5:32 PM GMT on July 04, 2008
No one is gonna beat you up:-) It's a fairly plausable situation.
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503. nrtiwlnvragn
1:32 PM EDT on July 04, 2008
12Z GFDL

HOUR: .0 LONG: -29.12 LAT: 14.47 MIN PRESS (hPa): 1004.40 MAX SURF WIND (KNOTS): 51.70
HOUR: 6.0 LONG: -30.61 LAT: 15.43 MIN PRESS (hPa): 999.62 MAX SURF WIND (KNOTS): 48.66
HOUR: 12.0 LONG: -32.55 LAT: 15.82 MIN PRESS (hPa): 1002.28 MAX SURF WIND (KNOTS): 40.97
HOUR: 18.0 LONG: -34.43 LAT: 16.12 MIN PRESS (hPa): 1002.62 MAX SURF WIND (KNOTS): 40.12
HOUR: 24.0 LONG: -36.40 LAT: 16.48 MIN PRESS (hPa): 1003.69 MAX SURF WIND (KNOTS): 47.70
HOUR: 30.0 LONG: -38.20 LAT: 16.70 MIN PRESS (hPa): 1000.45 MAX SURF WIND (KNOTS): 41.28
HOUR: 36.0 LONG: -39.98 LAT: 16.93 MIN PRESS (hPa): 1005.18 MAX SURF WIND (KNOTS): 37.05
HOUR: 42.0 LONG: -42.10 LAT: 17.50 MIN PRESS (hPa): 1003.72 MAX SURF WIND (KNOTS): 48.87
HOUR: 48.0 LONG: -44.20 LAT: 17.96 MIN PRESS (hPa): 1003.36 MAX SURF WIND (KNOTS): 50.81
HOUR: 54.0 LONG: -46.27 LAT: 18.47 MIN PRESS (hPa): 1000.31 MAX SURF WIND (KNOTS): 51.94
HOUR: 60.0 LONG: -47.92 LAT: 18.89 MIN PRESS (hPa): 995.44 MAX SURF WIND (KNOTS): 58.25
HOUR: 66.0 LONG: -49.42 LAT: 19.25 MIN PRESS (hPa): 996.10 MAX SURF WIND (KNOTS): 54.63
HOUR: 72.0 LONG: -50.77 LAT: 19.92 MIN PRESS (hPa): 990.25 MAX SURF WIND (KNOTS): 66.61
HOUR: 78.0 LONG: -51.99 LAT: 20.31 MIN PRESS (hPa): 989.75 MAX SURF WIND (KNOTS): 65.70
HOUR: 84.0 LONG: -52.94 LAT: 20.92 MIN PRESS (hPa): 987.00 MAX SURF WIND (KNOTS): 71.68
HOUR: 90.0 LONG: -54.04 LAT: 21.54 MIN PRESS (hPa): 984.85 MAX SURF WIND (KNOTS): 72.10
HOUR: 96.0 LONG: -54.95 LAT: 22.32 MIN PRESS (hPa): 981.53 MAX SURF WIND (KNOTS): 76.87
HOUR:102.0 LONG: -55.99 LAT: 23.13 MIN PRESS (hPa): 981.13 MAX SURF WIND (KNOTS): 80.59
HOUR:108.0 LONG: -57.03 LAT: 23.77 MIN PRESS (hPa): 980.43 MAX SURF WIND (KNOTS): 75.30
HOUR:114.0 LONG: -58.13 LAT: 24.42 MIN PRESS (hPa): 978.53 MAX SURF WIND (KNOTS): 80.94
HOUR:120.0 LONG: -59.02 LAT: 25.04 MIN PRESS (hPa): 976.23 MAX SURF WIND (KNOTS): 83.02
HOUR:126.0 LONG: -60.01 LAT: 25.75 MIN PRESS (hPa): 975.64 MAX SURF WIND (KNOTS): 81.38

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502. Tazmanian
10:31 AM PDT on July 04, 2008
ok STL
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501. TampaSpin
1:28 PM EDT on July 04, 2008
493. JFV 1:28 PM EDT on July 04, 2008
A significant track chnage at 5pm Drak?


I don't think it would be significant but, it will be further South. What is significant is the islands and PR is coming into play down the road including the Bahamas and the Eastern Sea board in my opinion......there you have it. Im sure some will beat me up for this post....lol
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500. 305st0rm
5:31 PM GMT on July 04, 2008
Good Afternoon, all!!
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499. Drakoen
5:30 PM GMT on July 04, 2008
493. JFV 5:28 PM GMT on July 04, 2008
A significant track chnage at 5pm Drak?


We'll see what happens.
Member Since: October 28, 2006 Posts: 57 Comments: 31637
498. Drakoen
5:29 PM GMT on July 04, 2008
496. moonlightcowboy 5:29 PM GMT on July 04, 2008
Drak, is there a site to single out and run just the BAMM models?


skeetobiteweather.com
Member Since: October 28, 2006 Posts: 57 Comments: 31637
497. FLWeatherFreak91
1:28 PM EDT on July 04, 2008
492. nash28 1:28 PM EDT on July 04, 2008 Hide this comment.
FLWeather- NWS Ruskin huh??? Very cool. I'd love to do it..


i'm fairly positive that's where my life is taking me... I've been talking a lot to the MIC there and i think he is fairly impressed with my obsession with the subject... He asked me if i would be available for work in his office after I finish school.
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496. moonlightcowboy
12:27 PM CDT on July 04, 2008
Drak, is there a site to single out and run just the BAMM models?
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495. stoormfury
5:25 PM GMT on July 04, 2008
i woulg not be surprise that the almost naked Bertha after a few hours and feeling the effect of the rebuilding of the ridge start a slow wsw track
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494. MrSea
5:27 PM GMT on July 04, 2008
well said FLWeatherFreak91
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492. nash28
5:27 PM GMT on July 04, 2008
FLWeather- NWS Ruskin huh??? Very cool. I'd love to do it..
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490. FLWeatherFreak91
1:22 PM EDT on July 04, 2008
477. diabeticstorm 1:19 PM EDT on July 04, 2008 Hide this comment.
there are too many kids on here pretending to know what they are saying, leave the predicting to the professionals.


I think you are very mistaken with that statement. My interest in the Weather started at the age of 12- and it was at that time when I learned much of the "professional" weather lingo necessary for discussing the wx. As my interest in atmo. science continued to deepen, I started learning the rules of forecasting and my knowledge of the subject soared. I posted on this blog all throughout Highschool, and starting in August I will be a full-time student at the Autonomous University of Santo Domingo studying nothing more but meteorology. When I return to the US I have an internship waiting for me at the Ruskin National Weather Service. Age does not determine knowledge. Thank you.
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489. Drakoen
5:25 PM GMT on July 04, 2008
486. stoormfury 5:24 PM GMT on July 04, 2008
Drak what is really going with the track of Berthia? the dynamics in the tropics are really changing quickly. does that mean that the northern lesser antilles should watch this system closely?


Yes they should. Even folks in the eastern Bahamas should as well as Bermuda.
Member Since: October 28, 2006 Posts: 57 Comments: 31637
488. nash28
5:25 PM GMT on July 04, 2008
Stoorm- Yes. Everyone needs to watch this closely.
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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