TC Bertha

[Ivanhater]

The following post is NOT an official prognosis.

It looks like the TUTT in the central Atlantic may be de-amplifying slightly at H7-H8, and it also appears to be gradually lifting out, leaving a flatter ridge in its wake. Simultaneously, there is a broad longwave trough at the mid to upper levels across the eastern CONUS, displacing the upper level ridge to the central and eastern Atlantic. At the surface, a stationary front has weakened the western extent of the strong subtropical low level ridging. The big questions involve the strength of the rebuilding ridging, the movement of the TUTT, and the intensity of Bertha. The evolution of the TUTT suggests that upper level divergence/shear may decrease over the SW Atlantic near the NE Caribbean, which would be more conducive for slow intensification of Bertha down the road. On the other hand, the cyclone currently remains embedded within a stable environment, as evidenced by the stable boundary layer and open cell stratocumulus surrounding the TC. Although shear is minimal, the thermodynamic environment would argue for a weaker system and much slower deepening within the short term. A weaker Bertha would also be more vulnerable to shear. If Bertha is weaker than anticipated over the long term, a more westward track would be plausible, but the weaker intensity would also be detrimental when the TC encounters further shear from the next trough to enter the eastern CONUS. A deeper and more intense Bertha would avoid such dire prospects, but it would likely follow a more northerly path. The track also depends on the timing of Bertha's intensity trends. If Bertha remains weaker within the short term and primarily deepens as it bypasses the TUTT during the medium to long range, the chances for a CONUS landfall would be substantially greater, as opposed to a scenario where Bertha mainly deepens during the current short term. Currently, Bertha is clearly not intensifying significantly, and it is moving just north of due west at a brisk pace. Since models have clearly been deepening Bertha too quickly over the past few days and the thermodynamic environment is marginal for significant short term deepening, I'm inclined to support a more westward solution for Bertha within the short to medium term. This would raise the probabilities for a CONUS landfall, though they are still slim and uncertain.

If the situation evolves as I anticipate, Bertha's greatest threat to the United States will be concentrated along the Carolinas (especially North Carolina), as opposed to the Mid-Atlantic/Northeast to the north and Florida/Georgia to the south. Since the closest historical threats to the CONUS passed north of the NE Caribbean, I believe Bertha will pass just north of the Leeward Islands and that region, though some precipitation and breezy conditions are possible. On an unrelated note, the track of the first Cape Verde TC during a season can be a good indicator of the general "alley" for Cape Verde systems during the remainder of the season. In 1926, a July TC of Cape Verde origin moved NW through the Bahamas as a major (Cat 3) hurricane and eventually struck east-central FL near Merritt Island (Cat 2). Later in the season, a large, intense, long tracked Cape Verde TC dissected the SE coast of FL at Miami (Cat 4/125 kt/933 mb), becoming an extremely destructive system as it passed over the southern FL peninsula and made its second landfall near Perdido Key, AL (Cat 3). In 1996, Hurricane Bertha curved east of FL and struck NC (Cat 2); the other Cape Verde tropical cyclones of the season recurved east of the East Coast, with at least one (Edouard) passing close to the Carolinas, Mid-Atlantic, and Northeast. If Bertha curves north as expected, the other Cape Verde systems of the season will likely follow a similar pattern, with several systems recurving east of the East Coast and threatening Bermuda. A few (1-2) may scrape the East Coast and strike the Carolinas.

Current streamline analysis at H7-H8:

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8dlm1.html

H5-H8:

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8dlm2.html

Visible satellite data:

http://www.ssd.noaa.gov/goes/east/tatl/loop-vis.html

Just one correction on your post Miami..Perdido Key is in Florida, not Alabama..but great post

['CaneFreak]

The following post is NOT an official prognosis.

It looks like the TUTT in the central Atlantic may be de-amplifying slightly at H7-H8, and it also appears to be gradually lifting out, leaving a flatter ridge in its wake. Simultaneously, there is a broad longwave trough at the mid to upper levels across the eastern CONUS, displacing the upper level ridge to the central and eastern Atlantic. At the surface, a stationary front has weakened the western extent of the strong subtropical low level ridging. The big questions involve the strength of the rebuilding ridging, the movement of the TUTT, and the intensity of Bertha. The evolution of the TUTT suggests that upper level divergence/shear may decrease over the SW Atlantic near the NE Caribbean, which would be more conducive for slow intensification of Bertha down the road. On the other hand, the cyclone currently remains embedded within a stable environment, as evidenced by the stable boundary layer and open cell stratocumulus surrounding the TC. Although shear is minimal, the thermodynamic environment would argue for a weaker system and much slower deepening within the short term. A weaker Bertha would also be more vulnerable to shear. If Bertha is weaker than anticipated over the long term, a more westward track would be plausible, but the weaker intensity would also be detrimental when the TC encounters further shear from the next trough to enter the eastern CONUS. A deeper and more intense Bertha would avoid such dire prospects, but it would likely follow a more northerly path. The track also depends on the timing of Bertha's intensity trends. If Bertha remains weaker within the short term and primarily deepens as it bypasses the TUTT during the medium to long range, the chances for a CONUS landfall would be substantially greater, as opposed to a scenario where Bertha mainly deepens during the current short term. Currently, Bertha is clearly not intensifying significantly, and it is moving just north of due west at a brisk pace. Since models have clearly been deepening Bertha too quickly over the past few days and the thermodynamic environment is marginal for significant short term deepening, I'm inclined to support a more westward solution for Bertha within the short to medium term. This would raise the probabilities for a CONUS landfall, though they are still slim and uncertain.

If the situation evolves as I anticipate, Bertha's greatest threat to the United States will be concentrated along the Carolinas (especially North Carolina), as opposed to the Mid-Atlantic/Northeast to the north and Florida/Georgia to the south. Since the closest historical threats to the CONUS passed north of the NE Caribbean, I believe Bertha will pass just north of the Leeward Islands and that region, though some precipitation and breezy conditions are possible. On an unrelated note, the track of the first Cape Verde TC during a season can be a good indicator of the general "alley" for Cape Verde systems during the remainder of the season. In 1926, a July TC of Cape Verde origin moved NW through the Bahamas as a major (Cat 3) hurricane and eventually struck east-central FL near Merritt Island (Cat 2). Later in the season, a large, intense, long tracked Cape Verde TC dissected the SE coast of FL at Miami (Cat 4/125 kt/933 mb), becoming an extremely destructive system as it passed over the southern FL peninsula and made its second landfall near Perdido Key, AL (Cat 3). In 1996, Hurricane Bertha curved east of FL and struck NC (Cat 2); the other Cape Verde tropical cyclones of the season recurved east of the East Coast, with at least one (Edouard) passing close to the Carolinas, Mid-Atlantic, and Northeast. If Bertha curves north as expected, the other Cape Verde systems of the season will likely follow a similar pattern, with several systems recurving east of the East Coast and threatening Bermuda. A few (1-2) may scrape the East Coast and strike the Carolinas.

Current streamline analysis at H7-H8:

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8dlm1.html

H5-H8:

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8dlm2.html

Visible satellite data:

http://www.ssd.noaa.gov/goes/east/tatl/loop-vis.html

Good post other than where you said stronger systems aren't affected by shear as much as weaker systems. I think you have that backwards. Someone please correct me if I am wrong.

[Tampa Bay Hurricane]

Thank you MiamiensisWX and Fact789 for your thorough analyses and perspectives regarding Bertha and the Cape Verde Season. Those forecasts were excellent
and skilled readings.

[MiamiensisWx]

The following post is NOT an official prognosis.

It looks like the TUTT in the central Atlantic may be de-amplifying slightly at H7-H8, and it also appears to be gradually lifting out, leaving a flatter ridge in its wake. Simultaneously, there is a broad longwave trough at the mid to upper levels across the eastern CONUS, displacing the upper level ridge to the central and eastern Atlantic. At the surface, a stationary front has weakened the western extent of the strong subtropical low level ridging. The big questions involve the strength of the rebuilding ridging, the movement of the TUTT, and the intensity of Bertha. The evolution of the TUTT suggests that upper level divergence/shear may decrease over the SW Atlantic near the NE Caribbean, which would be more conducive for slow intensification of Bertha down the road. On the other hand, the cyclone currently remains embedded within a stable environment, as evidenced by the stable boundary layer and open cell stratocumulus surrounding the TC. Although shear is minimal, the thermodynamic environment would argue for a weaker system and much slower deepening within the short term. A weaker Bertha would also be more vulnerable to shear. If Bertha is weaker than anticipated over the long term, a more westward track would be plausible, but the weaker intensity would also be detrimental when the TC encounters further shear from the next trough to enter the eastern CONUS. A deeper and more intense Bertha would avoid such dire prospects, but it would likely follow a more northerly path. The track also depends on the timing of Bertha's intensity trends. If Bertha remains weaker within the short term and primarily deepens as it bypasses the TUTT during the medium to long range, the chances for a CONUS landfall would be substantially greater, as opposed to a scenario where Bertha mainly deepens during the current short term. Currently, Bertha is clearly not intensifying significantly, and it is moving just north of due west at a brisk pace. Since models have clearly been deepening Bertha too quickly over the past few days and the thermodynamic environment is marginal for significant short term deepening, I'm inclined to support a more westward solution for Bertha within the short to medium term. This would raise the probabilities for a CONUS landfall, though they are still slim and uncertain.

If the situation evolves as I anticipate, Bertha's greatest threat to the United States will be concentrated along the Carolinas (especially North Carolina), as opposed to the Mid-Atlantic/Northeast to the north and Florida/Georgia to the south. Since the closest historical threats to the CONUS passed north of the NE Caribbean, I believe Bertha will pass just north of the Leeward Islands and that region, though some precipitation and breezy conditions are possible. On an unrelated note, the track of the first Cape Verde TC during a season can be a good indicator of the general "alley" for Cape Verde systems during the remainder of the season. In 1926, a July TC of Cape Verde origin moved NW through the Bahamas as a major (Cat 3) hurricane and eventually struck east-central FL near Merritt Island (Cat 2). Later in the season, a large, intense, long tracked Cape Verde TC dissected the SE coast of FL at Miami (Cat 4/125 kt/933 mb), becoming an extremely destructive system as it passed over the southern FL peninsula and made its second landfall near Perdido Key, AL (Cat 3). In 1996, Hurricane Bertha curved east of FL and struck NC (Cat 2); the other Cape Verde tropical cyclones of the season recurved east of the East Coast, with at least one (Edouard) passing close to the Carolinas, Mid-Atlantic, and Northeast. If Bertha curves north as expected, the other Cape Verde systems of the season will likely follow a similar pattern, with several systems recurving east of the East Coast and threatening Bermuda. A few (1-2) may scrape the East Coast and strike the Carolinas.

Current streamline analysis at H7-H8:

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8dlm1.html

H5-H8:

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8dlm2.html

Visible satellite data:

http://www.ssd.noaa.gov/goes/east/tatl/loop-vis.html

One of my main evidence for my argument is the fact that the TC has been repeatedly moving faster than originally expected.

In regards to 'CaneFreak's query, I was alluding to the fact that dissipation was more probable with a weaker Bertha vs. a deeper and stronger TC.

Thanks for the correction as well, Ivan - d'oh!

[Tampa Bay Hurricane]

MiamiensisWx that is the most impressive analysis I have read about tropical
weather!!! I am learning a lot!!!!

[cycloneye]

Hey Fact and Miami,those are great discussions that go in very deep details about all the factors involved in forecasting a cyclone.I see a bright future on both in the meteorology camp.

[OuterBanker]

TPC has been trending west since init. I see no recurve in latest. Personally I hope I see one.

http://www.nhc.noaa.gov/archive/2008/gr ... p_5W.shtml

[txwatcher91]

Great analysis MiamiensisWx! IMO I think it will either skirt NC, make landfall, or go out to sea. I am leaning towards skirt NC right now, but things can and will change.

[Tampa Bay Hurricane]

MiamiensisWx/Fact it is discussions like yours that make Storm2k such a great
place to get information.

[brunota2003]

Yeah...NC kinda sticks out there like a sore thumb. Perhaps we need to put NC's Barrier Islands on the endangered list?

[UpTheCreek]

That was awesome, I learned a LOT too.......thanks for that!

[Andrew92]

The following post is NOT official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.


Despite being kind of inactive for a while over here, I do have some thoughts on Bertha. If what I'm seeing from the models proves correct, I think it will stay near the cutting edge of the warm waters to where it can sustain itself. It currently is holding together nicely though which concerns me in terms of it getting stronger. I expect Bertha to still only strengthen slowly at the cusp of warm waters, but intensify it will - becoming at least a strong tropical storm by Tuesday, and maybe even a C1 hurricane. I'm unsure as to how the shear will impact the storm, but I think it will be down to a 60-65 mph tropical storm after passing through the shearing environment, if it stays far enough to the north. From there on, it's too early to tell for me how much shear will continue to impact it or if it will at all.

It almost goes without saying that the Caribbean is out of the woods unless somehow the ridge of high pressure intensifies dramatically. But the East Coast and Bermuda need to watch this just in case. I think Bermuda is more likely to receive a visit from Bertha right now, but one storm comes to my mind when thinking about this one. That storm is Edouard from 1996. Early on, he was forecast to quickly go out to sea, but all he did was keep progressing westward enough to become a dangerous threat to land. The big difference is Edouard was a C4; Bertha will fortunately be much weaker. I'm not willing to even guess where Bertha would most affect the East Coast if it does, but I do think she has a good chance of pulling an Eddie before most likely going out to sea.

But one more thing before I conclude: If Bertha does manage to strike the East Coast, this storm could also be comparable to storms like Esther in 1961 or Isabel in 2003. These storms started out moving what appeared at first to be comfortably north, but still kept making it westward to where they became significant threats to land. Isabel's materialized, and Esther's almost did until it weakened dramatically from its large loop off the coast. Of course these storms where much stronger, but the point is Bertha could still pull a track like one of these two, or just be an Edouard (which I think is more likely).

-Andrew92

[Andrew92]

Oh, and my post came before I had a chance to read Miamiensys's post. Take it really for what it's worth compared to his! Meaning his is likely better.

-Andrew92

[Weatherboy1]

When trying to figure out if an Atlantic TC may impact the U.S., I find it helpful to read the model discussions and look at the forecast maps available at the HPC's web site. For instance, you can get maps going out to 7 days at the following link:

http://www.hpc.ncep.noaa.gov/medr/medr.shtml

Current thinking appears to be that a shallow front/trough will approach the east coast about six days but not dig too far south. That starts to turn Bertha to the NW and N, but then leaves her behind. That, in turn, could open up the possibility of the storm being shoved back west, in my opinion. The question would be "At what latitude?" Off North Carolina? Further up the Mid-Atlantic coast? At this time, I'm not too worried in South FL because I think this will be a threat farther north (if at all). But considering we're still talking about a week out, any forecast is extremely speculative.

[hurricanefloyd5]

Bertha looks to be firing more conviction now. maybe it will be abit stronger by the 5pm adv. tonight.

http://www.ssd.noaa.gov/goes/flt/t1/loop-rgb.html

[cycloneye]

Anthony,did you see the 12z EURO tracking near your neck of the woods? What do you think about that?

[MiamiensisWx]

The northward shift evident in several global models is likely influenced by a combination of factors.

1) They are picking up on the overall progression and evolution of the pattern, which favors weaker ridging in the W Atlantic from the lower levels to the upper levels
2) They are (again) overestimating the intensity and intensification of Bertha within the short to medium term; intensification of Bertha will likely occur, but the most significant gradual deepening will not occur until the medium to longer range
3) They are not taking the long term movement (faster/just N of due west) of Bertha into account

In regards to the last statement, the current movement of the LLC suggests it will pass very slightly south of the next TPC forecast position. The system looks very unimpressive in terms of organization.

http://www.ssd.noaa.gov/goes/east/tatl/loop-vis.html

[hurricanefloyd5]

Cycloneye IF and WHEN bertha gets over the gulf stream do you think it I mean bertha will stregthen abit quicker???

[wzrgirl1]

I have a question....if she were to make landfall in the CONUS....what timeframe are we looking at? 7 days? 10 days? I know it depends on whether or not she slows down, etc. But, at this point, an estimation would suffice. Thanks.

[Weatherboy1]

wzrgirl1 -- We're probably talking about 7 days out if Bertha were to make a beeline for FL (unlikely, in my opinion). Farther up the coast and you're probably in the 8-9 days out timeframe. I personally think that about 48 hours from now, we'll have a much better idea what area of the U.S. (if any) is likely to be impacted.