TC Bertha

[wxman57]

Yep wxman57 the SHIPS only shows 8-10kts but I suppose with very very marginal SST's present the shear may be enough with the broad circulation to displace the convection a little, I also think this may have a ahrd time for a little while. It also shows that if its getting displaced center now, what will happen when it hits the real hardcore shear further NW?

On this track its going to get closer to the USA then many of us first thought, looking likely its going to just keep going WNW.

Or it may just dissipate, be torn apart in 4-5 days, or less.

[Ivanhater]

Yep wxman57 the SHIPS only shows 8-10kts but I suppose with very very marginal SST's present the shear may be enough with the broad circulation to displace the convection a little, I also think this may have a ahrd time for a little while. It also shows that if its getting displaced center now, what will happen when it hits the real hardcore shear further NW?

On this track its going to get closer to the USA then many of us first thought, looking likely its going to just keep going WNW.

Or it may just dissipate, be torn apart in 4-5 days, or less.

I don't see any models showing shear to be that strong in the future..may stay on the weaker side, but not enough to kill it off imo...

[gatorcane]

I'm not trying to alarm anybody AND I'M NOT SAYING THIS IS GOING DO WHAT ANDREW DID NOR WILL IT REACH THE INTENSITY...but systems can make left bends about the distant models are saying Bertha will be NE of the islands. In the above scenario, model guidance kept wanting to turn the system that formed Andrew out to sea but a Bermuda High managed to build in and shunt it westward.

[Extremeweatherguy]

Well, Bastardi still thinks this could be a threat Mid-Atlantic to Canada, but I don't think he has locked himself in, as he says it could still escape, depending on how strong it gets.

JB also sees a possible threat off Louisiana or Texas early next week from former 93L, but I don't see any model support for that.
Edit to add: I don't think it happens, but after calling Humberto from a week away, I don't automatically dismiss anything JB predicts.

Technically he said it could be an "east coast to Maritime problem" which would also include areas south of the mid-atlantic states such as the Bahamas, Florida, Georgia, South Carolina and North Carolina, but yeah, overall the idea is the same. He thinks this could be a potential threat to some landmass down the road.

As for the 93L call, I think that is a bit more questionable. The wave-axis could theoretically spark up into a system in the Gulf, but until there is model support, it is kind of hard to buy into that idea too much.

[cycloneye]

The low center is in the extreme SW part of the convection.

[KWT]

Well the shear is progged by the SHIPS to be at 33kts by 120hrs, the same sort of level that destroyed 93L. Now this is slightly different as it does have an estabblished circulation but if it does get hit by that sort of shear it would likely weaken somewhat at least.

Great image cycloneye, does anyone else find it strange to be talking about a Cape Verde tropical storm on the 4th of July!

[gatorcane]

Well the shear is progged by the SHIPS to be at 33kts by 120hrs, the same sort of level that destroyed 93L. Now this is slightly different as it does have an estabblished circulation but if it does get hit by that sort of shear it would likely weaken somewhat at least.

Great image cycloneye, does anyone else find it strange to be talking about a Cape Verde tropical storm on the 4th of July!

True we hope the shear will stick around though. There is a slight chance that it moves weak WNW to W and a ridge builds in off the EC...where conditions could become more favorable closer to the EC of the US. That is why the left bend in the models is starting to concern me some albeit not much really.

[Extremeweatherguy]

I'm not trying to alarm anybody AND I'M NOT SAYING THIS IS GOING DO WHAT ANDREW DID NOR WILL IT REACH THE INTENSITY...but systems can make left bends about the distant models are saying Bertha will be NE of the islands.

In the above scenario, model guidance kept wanting to turn the system that formed Andrew out to sea but a Bermuda High managed to build in and shunt it westward.

[img]image clipped[/img]

Not to mention that Andrew was also a pretty weak looking system until it suddenly started to explode east of the bahamas. One thing that we definitely have working in our favor this go around though is the fact that it is only July 4th and not late August. Conditions are probably not favorable enough to see a repeat of such a horrendous event (strength-wise).

[gatorcane]

I'm not trying to alarm anybody AND I'M NOT SAYING THIS IS GOING DO WHAT ANDREW DID NOR WILL IT REACH THE INTENSITY...but systems can make left bends about the distant models are saying Bertha will be NE of the islands.

In the above scenario, model guidance kept wanting to turn the system that formed Andrew out to sea but a Bermuda High managed to build in and shunt it westward.

[img]image clipped[/img]

Not to mention that Andrew was also a pretty weak looking system until it suddenly started to explode east of the bahamas. One thing that we definitely have working in our favor this go around though is the fact that it is only July 4th and not late August. Conditions are probably not favorable enough to see a repeat of such a horrendous event.

Indeed chances are extremely low, very very low in fact of a repeat scenario....

[dixiebreeze]

04/1200 UTC 14.8N 28.8W T3.0/3.0 BERTHA -- Atlantic Ocean

[KWT]

Hmm so that still supports keeping it at 45kts depsite not looking all that impressive right now dixiebreeze.

[wxman57]

Hmm so that still supports keeping it at 45kts depsite not looking all that impressive right now dixiebreeze.

That was 4 1/2 hours ago when it had deep convection. Center is really exposed now and the convection has dropped off considerably.

[OuterBanker]

The fact that we are here at 52 pages about a Cape Verde tropical storm is absolutely amazing on July 4. Even if Bertha dissipates in the future this is a once in a lifetime experience. There are no comparables, Bertha of 96 was the closest and it was 15 degrees west and 3 degrees south when named. Can it really be used as a comparable? Early yesterday it was the majority voting for a fish story. Now it is up in the air. Will Bertha be a memory or a concern a week from now. JB's thought of west of 70 and north of 25 a week from now could become a reality.

I have two questions that I'm grappling with.

Is Bertha a fluke, or a sign of really bad CV season.

If Bertha does make it and threaten the US will it be presented as a history making storm, or will it be blamed on global warming.

And we are only in the first week of July.

[wxmann_91]

Bertha looks pretty sickly right now. I'd venture and say this thing doesn't make it past 72 hr.

[ekal]

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

My thoughts on this system:

While the intensity may have been increased based upon a QuikSCAT pass taken at around 8Z (9 hours ago), the cloud pattern of Bertha is noticeably less impressive today. The LLC is either close to being exposed or is exposed, and the circulation appears elongated north-south on visible satellite imagery. Convection is also less deep as compared to yesterday at this time. All of these observations have likely been caused by the stable air and lower SSTs in the vicinity of Bertha. Therefore, steady-state intensity, or weakening by 5-10 knots, looks to be on the order for the next 24-48 hours.

Between 48 and 84 hours, this system probably has its best opportunity to strengthen, provided that in two days, the system is healthy enough to do so. That is when SSTs are progged to increase from 25.8 degC to 27.3 degC along the forecast track, and shear is expected to remain around 12 knots (not ideal, but not prohibitive, either).

After 84 hours, SHIPS progs the shear to increase to over 30 knots, and that would almost certainly be a destructive blow, regardless of how intense the system becomes beforehand. Looking at the official forecast, I would expect weakening between 96 and 120 hours, possibly substantial. Of course, the shear forecast could change, but the shear northeast of the Lesser Antilles is associated with an upper-level jet that has become a semi-permanent feature over the past month (typical for June and July).

In terms of track, I think a WNW path to the vicinity of 20N, 55W is in order, due to a strong subtropical ridge to the north of the system for the duration of the forecast period. I don't expect the system to become deep enough to move more northwest, due to the marginal SSTs and, later, the forecast shear. Beyond 120 hours, however, Bertha nears the western edge of the subtropical ridge in the models, which would mean a gradual recurve regardless of intensity (provided it is not an open wave), but the position of the subtropical ridge in the models is, of course, subject to change.

Just my two cents.

[HURAKAN]

Loop: http://rammb.cira.colostate.edu/ramsdis ... is_floater

New convection developing but displaced from the center.

[Category 5]

I'm not ready to look at where it's going to turn yet. If that sheer holds up enough it won't matter.

[Extremeweatherguy]

I agree that Bertha doesn't look great this afternoon, but for a weak TS she really doesn't look all that bad either..

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

Based on the last few frames of the loop, it also appears that a new burst of convection is going up on the north side of the storm's circulation right now. Bertha is definitely trying her hardest to stay alive over the cooler waters she is now approaching.

['CaneFreak]

Wxman57:

I am curious to know how much longer this cyclone will be over these 25 to 26 degree C waters and once it emerges from these cooler waters if it will be able to survive the dry air that appears on the water vapor images that I am seeing. Thanks in advance for your input.

http://www.ssd.noaa.gov/goes/flt/t1/wv.jpg

[JonathanBelles]

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 04 2008

..SPECIAL FEATURE....

TROPICAL STORM BERTHA CENTERED NEAR 14.9N 29.7W AT 1500 UTC OR
ABOUT 335 NM W OF THE CAPE VERDE ISLANDS MOVING WNW AT 14 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED
WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT42 KNHC
FOR MORE DETAILS. BERTHA HAS MOVED W OF THE CAPE VERDE ISLANDS.
A BURST OF ISOLATED STRONG CONVECTION IS LOCATED N OF THE
CIRCULATION CENTER BETWEEN 29W-31W...WITH SCATTERED MODERATE
CONVECTION WITHIN 180 NM N AND 90 NM S OF THE CENTER. BERTHA
WILL BE PASSING OVER SLIGHTLY COOLER WATERS DURING THE NEXT 24
HOURS IN WHICH IT WILL MAINTAIN ITS INTENSITY WITH GRADUAL
STRENGTHENING FORECAST THEREAFTER AS ATMOSPHERIC CONDITIONS
APPEAR MORE FAVORABLE AND OCEANIC CONDITIONS REMAIN MARGINAL.