TC Bertha

[CourierPR]

i except track to shift right.................

Based on what?

[lebron23]

i except track to shift right.................

Please list your evidence. Thanks!

some of major models are shifting north.

[lebron23]

http://my.sfwmd.gov/sfwmd/common/images ... orm_02.gif


if we see one more shift westward............the gulf coast has to watch

[curtadams]

In case people have forgotten, the NAM often grossly overestimates storms. It's like the Canadian that way. Other models forecasting an island brush forecast Bertha as no more than a remnant low there.

[NDG]

The following post is NOT an 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 including storm2k.org For Official Information please refer to the NHC and NWS products.

I am not ready to buy on Bertha staying strong and staying as a fish storm, more and more the Euro & UKMET track is starting to make sense to me, and here is why:
As Bertha continuous tracking between 30W & 40W responding to a weakness to her NW she will start gaining latitude, getting her into much cooler waters which should at least keep her as a weak or moderate TS, thus not responding to the mid level weakness as much. Pass 40W, where she could once again start gaining strength in warmer SST, the mid Atlantic troughiness will start lifting north as a huge trough develops just west of Europe pushing the eastern Atlantic center ridge westward, in the mean time most models keep a ridge strong over or in the vicinity of Bermuda, she misses the trough and she will get steered westward by the Bermuda ridge off the eastern US westward north of the Windward islands towards the Bahamas in a weaker form because of stronger shear.
Another thing is that this is early July, when usually the Atlantic ridge is much stronger than if it was to be in September.

I don't have much time this morning to post any new thoughts, but as I mentioned a couple of days ago, a strong Bermuda ridge (Centered over Bermuda) will become established as the central Atlantic trough starts lifting, and will stay in place through at least the next 5-7 days, do the math and surely this system could be a threat to the Bahamas and or Eastern US.

[Chacor]

639
WTNT22 KNHC 051449
TCMAT2
TROPICAL STORM BERTHA FORECAST/ADVISORY NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
1500 UTC SAT JUL 05 2008

TROPICAL STORM CENTER LOCATED NEAR 16.6N 37.3W AT 05/1500Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE WEST OR 280 DEGREES AT 18 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1000 MB
MAX SUSTAINED WINDS 45 KT WITH GUSTS TO 55 KT.
34 KT....... 75NE 30SE 0SW 75NW.
12 FT SEAS..300NE 150SE 75SW 240NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 16.6N 37.3W AT 05/1500Z
AT 05/1200Z CENTER WAS LOCATED NEAR 16.4N 36.4W

FORECAST VALID 06/0000Z 17.0N 40.1W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT... 75NE 30SE 0SW 75NW.

FORECAST VALID 06/1200Z 17.6N 43.9W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 30NE 0SE 0SW 30NW.
34 KT... 90NE 45SE 30SW 90NW.

FORECAST VALID 07/0000Z 18.4N 47.6W
MAX WIND 55 KT...GUSTS 65 KT.
50 KT... 30NE 0SE 0SW 30NW.
34 KT... 90NE 45SE 30SW 90NW.

FORECAST VALID 07/1200Z 19.1N 51.2W
MAX WIND 60 KT...GUSTS 75 KT.
50 KT... 50NE 30SE 0SW 50NW.
34 KT...100NE 60SE 30SW 100NW.

FORECAST VALID 08/1200Z 20.8N 57.5W
MAX WIND 65 KT...GUSTS 80 KT.
50 KT... 60NE 30SE 20SW 60NW.
34 KT...125NE 75SE 45SW 125NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 225 NM
ON DAY 4 AND 300 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 09/1200Z 23.0N 62.5W
MAX WIND 65 KT...GUSTS 80 KT.

OUTLOOK VALID 10/1200Z 25.0N 67.0W
MAX WIND 65 KT...GUSTS 80 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 16.6N 37.3W

NEXT ADVISORY AT 05/2100Z

$$
FORECASTER BROWN


Hurricane now forecast.

[AJC3]

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

Surprised no one caught this but the center is now actually EAST of the convection as a little RELATIVE easterly shear is now taking over because of the cyclone's rather fast motion (21mph). Relative shear can be explained in this manner. Imagine you are on your bike on a day with no wind at all (calm). You are pedaling 21 mph and you still have wind blowing in your face. Why? Wind blows by you due to your relative motion against the calm wind. If the wind was blowing 10 mph in your face, then the wind relative to you would only be 11 mph. If the wind was blowing from behind you at 10 mph, then the wind relative to you would be 31 mph.

Actually you have this bass-ackwards. If you have wind blowing directly into your face at 10 MPH and you are pedalling at 21 MPH, then it actually enhances the wind shear relative to you (31 MPH). If you are pedalling at that same speed and you have a tailwind of 10 MPH, then the wind shear would be only 11 MPH.

If you are pedalling at 21 MPH and you have a tailwind of 21 MPH, then you actually have NO relative shear, not 42 MPH of relative shear.

I sure did...thanks for the correction....is that your analysis as well?

Well, what we had going on for a few days was he convective bursting being displaced north of the center (southerly shear). I think, based on the latest MI images I've been looking at, is that the displacement of the convection is still primarily to the north of the center, but not quite as far north, and perhaps a wee bit ahead of the center...so the direction of the shear vector could be changing just a bit (from south the SSE), while the magnitude may be decreasing some. All-in-all, I don't know if it's all that significant considering the less-than-favorable thermodynamic environment Bertha is embedded in.

I'd like to have a more recent MI pass to be sure about the shear though. We'll have a little better idea about this when we can compare the 15Z NHC center fix with a visible satellite image from roughly the same time (1515Z).

[lebron23]

16.6 north???

moving back west!

[cycloneye]

Breaking News=NHC forecasts for the first time a hurricane.

FORECAST VALID 08/1200Z 20.8N 57.5W
MAX WIND 65 KT...GUSTS 80 KT.
50 KT... 60NE 30SE 20SW 60NW.
34 KT...125NE 75SE 45SW 125NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 225 NM
ON DAY 4 AND 300 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 09/1200Z 23.0N 62.5W
MAX WIND 65 KT...GUSTS 80 KT.

OUTLOOK VALID 10/1200Z 25.0N 67.0W
MAX WIND 65 KT...GUSTS 80 KT.

[lebron23]

...Bertha moving quickly westward over the tropical Atlantic...

at 1100 am AST...1500z...the center of Tropical Storm Bertha was
located near latitude 16.6 north...longitude 37.3 west or about 885
miles...1420 km...west of the Cape Verde Islands and about 1705
miles...2740 km...east of the northern Leeward Islands.

Bertha is moving toward the west near 21 mph...33 km/hr...and this
general motion is expected to continue during the next couple of
days. Bertha will be about Half Way between the West Coast of
Africa and the Lesser Antilles by tonight or early Sunday.

Maximum sustained winds are near 50 mph...85 km/hr...with higher
gusts. Little change in strength is forecast today...but gradual
strengthening is possible on Sunday.

Tropical storm force winds extend outward up to 85 miles...140 km
from the center.

Estimated minimum central pressure is 1000 mb...29.53 inches.

Repeating the 1100 am AST position...16.6 N...37.3 W. Movement
toward...west near 21 mph. Maximum sustained winds...50 mph.
Minimum central pressure...1000 mb.

The next advisory will be issued by the National Hurricane Center at
500 PM AST.

$$
Forecaster Brown

['CaneFreak]

http://my.sfwmd.gov/sfwmd/common/images/weather/plots/storm_02.gif


if we see one more shift westward............the gulf coast has to watch

Ok, so lets review what has just transpired. Lebron 23 makes a post that says he expects a shift to the right of the official track by the NHC at 11 am based on the shift in track of some of the major models to the north (??????????). Then Lebron 23 says, "if we see one more shift westward............the gulf coast has to watch". I am confused!!!!!

[MiamiensisWx]

Cone has been shifted slightly right. West trend of cone has temporarily ended per NHC.

[lebron23]

http://my.sfwmd.gov/sfwmd/common/images/weather/plots/storm_02.gif


if we see one more shift westward............the gulf coast has to watch

Ok, so lets review what has just transpired. Lebron 23 makes a post that says he expects a shift to the right of the official track by the NHC at 11 am based on the shift in track of some of the major models to the north (??????????). Then Lebron 23 says, "if we see one more shift westward............the gulf coast has to watch". I am confused!!!!!

im saying i think it will shift right. BUT IF it does shift left gulf needs to watch

[MiamiensisWx]

000
WTNT42 KNHC 051452
TCDAT2
TROPICAL STORM BERTHA DISCUSSION NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
1100 AM EDT SAT JUL 05 2008

WHILE MOVING OVER COOLER WATERS DURING THE PAST 24 HOURS BERTHA
STRUGGLED A LITTLE BIT...HOWEVER NOW THAT IT IS HEADING FOR
SLIGHTLY WARMER WATERS BERTHA APPEARS TO BE A LITTLE BETTER
ORGANIZED. THE CYCLONE HAS MAINTAINED A CLUSTER OF DEEP CONVECTION
JUST NORTH AND WEST OF THE CENTER DURING THE PAST SEVERAL HOURS.
DVORAK INTENSITY ESTIMATES REMAIN BETWEEN 35-45 KT AND THE INITIAL
INTENSITY IS UNCHANGED. CONDITIONS SHOULD BECOME MORE CONDUCIVE
FOR STRENGTHENING AS SSTS ALONG THE PROJECTED PATH GRADUALLY
INCREASE AND THE SHEAR REMAINS LOW DURING THE NEXT 3 DAYS. THE NEW
NHC INTENSITY FORECAST IS UNCHANGED THROUGH 48 HOURS BUT NOW
PREDICTS BERTHA TO REACH HURRICANE STRENGTH IN 72 HOURS.
THEREAFTER...DUE TO UNCERTAINTIES IN THE AMOUNT OF PREDICTED
SHEAR...THE INTENSITY IS HELD A LITTLE BELOW THE LGEM...SHIPS...AND
GFDL MODELS WHICH SHOW ADDITIONAL INTENSIFICATION.

BERTHA HAS BEEN MOVING A LITTLE MORE WESTWARD DURING THE PAST 6-12
HOURS AND THE INITIAL MOTION ESTIMATE IS 280/18. A WEAKNESS IN THE
RIDGE BETWEEN 50W-60W IS FORECAST TO LIFT NORTHWARD AND THE
SUBTROPICAL RIDGE WILL REMAIN THE PREDOMINANT STEERING MECHANISM
FOR THE NEXT SEVERAL DAYS. THIS SHOULD KEEP BERTHA ON A GENERAL
WEST TO WEST-NORTHWEST HEADING AT A RATHER BRISK PACE. THERE
REMAINS A LARGE AMOUNT OF MODEL SPREADS AT DAYS 4 AND 5.
HOWEVER...MOST OF THE MODEL TRACKS HAVE SHIFTED A LITTLE
NORTHWARD...EXCEPT FOR THE UKMET WHICH KEEPS A WEAKER TROPICAL
CYCLONE MOVING WESTWARD. THE MODEL CONSENSUS SHIFTED VERY CLOSE TO
THE NHC TRACK...SO LITTLE CHANGE WAS NEEDED FROM THE PREVIOUS
OFFICIAL FORECAST.

FORECAST POSITIONS AND MAX WINDS

INITIAL 05/1500Z 16.6N 37.3W 45 KT
12HR VT 06/0000Z 17.0N 40.1W 45 KT
24HR VT 06/1200Z 17.6N 43.9W 50 KT
36HR VT 07/0000Z 18.4N 47.6W 55 KT
48HR VT 07/1200Z 19.1N 51.2W 60 KT
72HR VT 08/1200Z 20.8N 57.5W 65 KT
96HR VT 09/1200Z 23.0N 62.5W 65 KT
120HR VT 10/1200Z 25.0N 67.0W 65 KT

$$
FORECASTER BROWN

[HURAKAN]

Since 5 AM, 0.1°N and 2.0°W.

[cheezyWXguy]

Cone has been shifted slightly right. West trend of cone has temporarily ended per NHC.

That's because its now expected to be stronger

['CaneFreak]

http://my.sfwmd.gov/sfwmd/common/images/weather/plots/storm_02.gif


if we see one more shift westward............the gulf coast has to watch

Ok, so lets review what has just transpired. Lebron 23 makes a post that says he expects a shift to the right of the official track by the NHC at 11 am based on the shift in track of some of the major models to the north (??????????). Then Lebron 23 says, "if we see one more shift westward............the gulf coast has to watch". I am confused!!!!!

im saying i think it will shift right. BUT IF it does shift left gulf needs to watch

This synoptics are not there for this to go into the GOM...if anything it might graze FL and head up the east coast but it will more than likely not go into the GOM.

[brunota2003]

Oh goody. Hey any other Eastern NC'ers, getting that Deja vu feeling yet? Berta '96 was "supposed" to go out to sea, only to hit NC as a Hurricane...hrm

[cycloneye]

The Tropical Storm Wind probability is now touching the Northern Leewards,the BVI,US.VI and Eastern Puerto Rico.

[ronjon]

I think ronjon meant that most recurve, but said there are exceptions such as Bertha 1996, and seemed to agree
with jamies statement that this can break climatology.

Climatology is simply past history. There isn't a mystical force that prevents something we have not seen from occurring. There are also several arguments that our climatological record is flawed, so some "unprecedented" events may not be so rare.

Wow, I was off an hour or so and missed the reaction to my comment regarding climatology. Anyway, my point, and thanks TBH for clarifying, is that when you look at the entire statistical index of storms forming in the far east Atlantic Ocean, the vast majority recurve out into the open sea. My point is made just by examining recent history. The period from 1995-2001 was one of the most active 7 year periods on record. However, of the 27 major
hurricanes formed during this period, only three made landfalls on the U.S. coast. Now this changed in 2004 and 2005 but you get my point. Further, what is the average number of landfalling storms per year - maybe two out of 11 total storms per year. There's alot of open ocean out there to recurve. Does that mean I ignore synoptics? - of course not. That's what has all of us glued to the storm. Does Bertha have chance to impact the eastern US? I say yes based on some of the global model runs. And if it does, it will be quite remarkable for a storm that formed this far east just south of the Cape Verde Islands. Might mean a strong Atlantic ridge this year which will not bode well for us or our caribbean neighbors. Ah, I got caribbean spelled correctly this time.