TC Bertha

[KWT]

Yep indeed there is so much uncertainty with this system, a really interesting early season storm though I have to admit!
I was expecting this sort of thing in Mid-August, not early July!

to be fair to Accuweather that track is nearly the same as the NHC, northern Caribbean islands are almost in the cone of uncertainty, not quite but close enough.

[Chacor]

Yep indeed there is so much uncertainty with this system, a really interesting early season storm though I have to admit!
I was expecting this sort of thing in Mid-August, not early July!

to be fair to Accuweather that track is nearly the same as the NHC, northern Caribbean islands are almost in the cone of uncertainty, not quite but close enough.

The NHC does not do seven-day forecasts. Five-day forecasts are still very difficult to get spot-on, let alone seven days out. Accuweather is only going to cause panic with its "forecast" of an NC/SC hit in a week, when the TPC/NHC hasn't even mentioned landfall.

[KWT]

yeah true but a lot of the generally public will just extrap the NHC forecast anyway and besides I don't think too many people are going to be paying too much attention to Bertha right now anyway given how far east it is, I think people will start becoming more aware of it IF the NHC does start to show at least a risk of landfall.

[gotoman38]

I'm generally not a fan of accuwx or their products. I have a problem that their cone appears smaller in the near term for instance.

But extending the dates is not necessarily a bad thing.... and highlighting the fact that nearly the entire east coast of north america is in the uncertainty cone now doesn't seem unreasonable at all to me.

[gotoman38]

every new track is comes closer to the usa.

reposted for this page

[gotoman38]

That's an unofficial slackuweather forecast. They should not be doing seven-day forecasts when even the NHC's three- to five-day forecast has a large cone of uncertainty. They're just going to cause panic. Don't take everything at face value and follow the NHC's guidance, that's the best.

Compare the NHC track:

NHC cone is closer to the islands.

[KWT]

First Vis.images coming on now:

http://www.ssd.noaa.gov/goes/flt/t1/vis-l.jpg

Hmmm circulation still underneath the cconvection, tohugh it is on the Southern side of it it does look like its tucked in a little bit since about 9hrs ago where part of it was exposed. Not amazing looking right now but its holding its own in some pretty cool waters for tropical development.

Also looking at the SST's its only about 12hrs away from getting back into the warmer waters again.

[Normandy]

Interesting turn of events, and it shows that early model runs really cannot be trusted, especially when they overdo the intensity of a system (They should not have been considered because Bertha in no way was becoming a deep TS days after it emerged off Africa). These types of systems are ones you always must watch, weaker ones that keep sliding under the radar until they get to better conditions (ala Andrew, the series of events that caused Katrina's genesis). It worries me that it will get this close to the US now.

Also, I wouldn't really bet on it dissipating. I think folks are forgetting that this system isn't some disorganized Tropical Depression. Looking at visibles one can see it has a fairly healthy circulation and has always had one since emerging off Africa. I think if it would have dissipated it would have done so already. I like the NHC's track, but i doubt it'll ever get to 60 kts (especially since they forecast shear later). I like a consistent 40-50 kt intensity throughout their forecast period.

[Gustywind]

000
FXCA62 TJSJ 050735
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
335 AM AST SAT JUL 5 2008


OF PARTICULAR INTEREST...TROPICAL STORM BERTHA CONTINUES TO CHURN
OUT IN THE TROPICAL ATLANTIC OCEAN...POSING ONLY A THREAT TO
SHIPPING LANES AT THIS TIME. THE SYSTEM SHOULD MAINTAIN A WESTWARD
TRACK FOR THE NEXT DAY AS IT PROPAGATES AROUND THE PERIPHERY OF
THE ATLANTIC SURFACE HIGH. GUIDANCE SUGGESTS AN EVENTUAL WEST-
NORTHWESTERLY TRACK WITH TIME...WHICH NOW PLACES THE FEATURE
MUCH CLOSER TO THE LOCAL ISLANDS BY WEDNESDAY OF NEXT WEEK. WILL
DEFER TO FUTURE FORECAST PACKAGES BEFORE INCREASING THE
PRECIPITATION ON WEDNESDAY UNTIL THE TRACK OF BERTHA IS MORE
CERTAIN.

.MARINE...
AS TROPICAL STORM BERTHA ADVANCES WITH A WESTWARD COMPONENT TOWARD
THE NORTHEAST CARIBBEAN BY THE MIDDLE OF NEXT WEEK...A DYNAMIC
FETCH SETUP COULD OCCUR AND GENERATE NORTHEASTERLY SWELLS ACROSS
THE LOCAL WATERS. ADDITIONALLY...A NEW AFRICAN EASTERLY WAVE IS
SEEN EXITING THE AFRICAN COAST WHICH COULD ADD TO A POSSIBLE SWELL
EVENT BY THE END OF THE NEXT WORK WEEK. IT IS IMPERATIVE TO
NOTE...HOWEVER THAT THIS IS A HIGHLY UNCERTAIN SOLUTION AT THIS
TIME DUE TO POSSIBLE TRACK ERRORS IN THE CURRENT FORECAST.
MARINERS ARE URGED TO STAY ABREAST OF THE LATEST UPDATES FROM THE
NATIONAL WEATHER SERVICE FOR THE MOST UP-TO-DATE INFORMATION.

[KWT]

Indeed Normandy, I was thinking that if this could slip past 60W underneath 24N then the chances of a east coast threat really do start to rise and that seems increasingly possible, indeed even the NHC offical forecast is pretty close to the mark with that.

[dixiebreeze]

05/0545 UTC 16.3N 34.3W T3.0/3.0 BERTHA

Hanging in there this morning

[KWT]

Hmmm still at 3.0 therefore still justifies 45kts the next advisory so hasn't weakened according to that even though it does look a little on the messy side this morning.

[Blown Away]

If the latest convective burst is over the LLC then Bertha is on the NHC track. If that burst is on the N side of the LLC then Bertha is tracking S of the NHC track. Bertha appears to be going almost due W, IMO.

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

[Vortex]

6z nam

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

[KWT]

Looks like that convective burst is right over the LLC of Bertha which may mean shear isn't quite as high as it was yesterday when the convection was well displaced at times. It seems to have lost a little bit of its shape mind you but its not a bad looking system still.

[cycloneye]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 05 JUL 2008 Time : 111500 UTC
Lat : 16:38:20 N Lon : 35:58:29 W


CI# /Pressure/ Vmax
3.3 / 998.7mb/ 51.0kt


Final T# Adj T# Raw T#
(3hr avg)
3.3 3.4 3.4

Latitude bias adjustment to MSLP : +2.3mb

Center Temp : -24.8C Cloud Region Temp : -41.7C

Scene Type : SHEAR (0.04^ TO DG)

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

[Blown Away]

Am I correct in seeing the LLC at 16.2N/36W?

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

[KWT]

Well its estimated to be just a tiny bit south of 16.4N and pretty much 36W so yeah your not far wrong, pretty evident that the LLC is tucked in under the convection and the fact its flared up over the LLC rather to the north may be suggesting shear is starting to lessen just as it starts to get closer to the warmer waters.

[O Town]

[KWT]

Great loop you can see the system is right on the track of the NHC forecast which is good, can also see the way that strong convective burst has developed over the last few hours, it seems like every 9-12hrs a big burst of convection develops!