Ed Dunham
Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)
Reged:
Posts: 2565
Loc: Melbourne, FL
|
Bertha Near Bermuda, Watching Wave East of the Lesser Antilles
Sat Jul 12 2008 11:08 AM
|
|
|
4:00 PM 14-July-2008 Update
The government of Bermuda has issued a Hurricane Watch. Recent reconnaissance mission has detected wind just below hurricane strength in a rain ban arcing around the southwest semi-circle. That rain band is expected to pass over the island over the next several hours. It is possible that Bertha will reach minimal hurricane strength.
John (typhoon_tip)
2:54 PM 14-July-2008 Update
Satellite estimates for 94L are at (SSD / t#s) are 2.0 now, which is probably enough to start considering it a candidate for a depression, possibly late tonight or more likely tomorrow only if it holds like this for a while.
2:20 PM 14-July-2008 Update
Bertha is due east of Bermuda right now, and the outer eye type feature is onshore causing issues there.
The wave east of the lesser Antilles (94L) has improved slowly during the day and may form into a depression sometime tomorrow or so if it persists. It still lacks a good organized flow and convection and Satellite Estimes (Dvorak T-Numbers) still do not suggest a depression (look for T numbers 2 or higher)
9:30 AM 14-July-2008 Update
Bertha is near the island of Bermuda, causing Tropical Storm conditions on the island right now. Bermuda is under a Tropical Storm Warning currently.
East of the Lesser Antilles, the wave (94L) is looking not quite so good this morning. It has moved away from the Intra Tropical Convergence Zone, and is starting to see some circulation, but the convection is not there.
That said, if it persists (it may not) it will likely form into a depression either late today or more likely tomorrow.
The lesser Antilles will want to watch this one. Because of lack of good initialization in models (IE, the UKMet doesn't develop this at all), any real prediction of future track or intensity of this system is pure speculation.
7:30 PM 13-July-2008 Update
Tropical Storm watches remain up for Bermuda, as Bertha slowly moves along.
Nothing too much new to report, 94L (Wave east of the islands) is having more model runs come in, which suggests that the Leeward Islands (And all of the Lesser Antilles) need to watch it.
It is fairly active, but not overly so, for mid July, and this system is likely the next depression.
If it stays organized overnight (it may fall apart), it could develop by or on Tuesday into a depression.
The low off Charleston has fallen apart today, and is not being watched anymore.
8:30 AM 13-July-2008 Update
Bertha has weakened to a Tropical Storm, and the eye that has been visible the last few days has disappeared. It will likely meander for a bit.
Two new things are worth watching this morning, first the wave in the Central Atlantic (further south and west from where Bertha formed) is worth watching over the next several days to see if it forms, it is more likely this would track further westward if shear or dry air does not keep it from development.
The Windward islands in the Caribbean will want to watch this one, actually all the Lesser Antilles. Track wise a generally westward movement should occur. Again, it will be important to watch over the next several days.
East Atlantic (94L) Wave Chances of Development in the next 24 hours
Code:
(forget it) 0 1 2 3 4 5 6 7 8 9 10 (sure thing)
[------*-------------]
{{StormLinks|94L|94|3|2008|2|94L}}
---
Also southeast of Charleston, SC is a low pressure area that will have to be watched. Right now Shear would prevent any development, but if that lessens it is possible for something to form there.
Charleston Low Developmetn Chances in Next 24 hours
Code:
(forget it) 0 1 2 3 4 5 6 7 8 9 10 (sure thing)
[---*----------------]
More to come on both soon.
Original Update
Hurricane Bertha has been stationary, about 220 miles to the south southeast of Bermuda, for the past few hours. She has a nice circular presentation again as the shearing influence in the northwest quadrant has ceased. Sustained winds are now 85mph with gusts to 105mph and the central pressure, as reported by the hurricane hunters is 976MB. There is likely to be very little motion for the next day or two - Bertha is stuck in an area of negligible steering currents as the trough to her northwest is not expected to 'capture' the hurricane and move her off to the northeast in the open Atlantic. A stronger trough well to the northwest of Bertha, currently extending from the Great Lakes to Texas, is moving slowly eastward, but there is still some uncertainty as to whether that trough will be strong enough to move Bertha away from Bermuda early next week.
High pressure is likely to build to the north of Bertha as the first trough moves off to the northeast of the storm. Under the influence of that buildup in higher pressure to the north, Bertha's movement will be erratic - and slow for a few days, with a general northerly drift expected. Any additional jog to the west of north would bring the hurricane closer to Bermuda, and the Tropical Storm Watch for Bermuda has now been elevated to a Tropical Storm Warning.
Regarding intensity, Bertha is not likely to get any stronger - and in fact she has a much better chance of weakening. With the expectation for just a slow meander, I'm a bit surprised that the concept of 'upwelling' has not yet been mentioned in the intensity forecast. When a storm remains relatively stationary for an extended period of time, deeper - and colder - water is churned up in and around the eye of the storm and the system will slowly weaken as the SSTs cool down.
(Well, scratch that - Dr Avila just mentioned the likelyhood of upwelling in the latest NHC Discussion bulletin.)
In addition to Bertha, an active tropical wave near 10N 50W at 12/15Z is moving westward into an area of lighter wind shear.
ED
Update - Saturday 07/12 11:30AM ET
Tropical Storm Warning is now in effect for the island of Bermuda.
Bertha is a ragged looking tropical cyclone. Like much of yesterday, Bertha is composed of a massive eye and outer band of moderate convection, with a remnant inner eye and occasional attempts at eye-wall rattling around inside. Her movement has been virtually stationary over the last 6 hours. Dvorak numbers have eased by 5kts and her intensity is being officiated at 75kts. The stationary nature of Bertha may mean that SSTs are beginning to cool due to upwelling, and if so this would also begin to contribute to weakening.
The forecast essentially is unchanged. There seems to somewhat better agreement among the models that she will stagnate for another 2 days, but then slowly...ever so slowly begin to move north and eventually northeast or east.
John (typhoon_tip)
Event Related Links
{{StormCarib}}
{{BermudaNews}}
Use this link to monitor the current weather conditions at Hamilton, Bermuda:
Bermuda Weather
{{StormLinks|Bertha|02|2|2008|1|Bertha}}
{{StormLinks|94L|94|3|2008|2|94L}}
Edited by MikeC (Mon Jul 14 2008 07:05 PM)
|
|
Previous
Index
Next
Flat
Edit
Reply
Quote
