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Bertha approaches Bermuda, Invest 94L likely to develop

By: Dr. Jeff Masters, 11:00 AM GMT on July 14, 2008

One can tell that it is quickly becoming late July when the tropics start to heat up to the point when there are two systems to monitor in the Atlantic. Right now we are monitoring Tropical Storm Bertha close in on Bermuda at the same time as we watch Invest 94L approach the Lesser Antilles. Of the two systems, Invest 94L has the potential to create a much higher impact event.

Tropical Storm Bertha is holding on to strong tropical storm intensity as she wanders around the North Atlantic and slowly approaches Bermuda with maximum sustained winds of 65 mph and a central pressure of 990 mb. Bertha is finally making steady progress to the north-northwest at 8 mph which should brush her right up against Bermuda with 3-5 inches of rain, tropical storm force winds, and seas up to 18 feet. On Saturday I was flying from Hartford to Philadelphia and could see swells rolling off of Bertha reaching the East Coast of the U.S.


Bertha - Watches and Warnings

Storm's of Bertha's size and maturity rarely exhibit rapid intensity changes, especially as far north as Bermuda, unless they interact with some mid-latitude synoptic feature. Since Bertha is pretty well isolated in the middle of the Atlantic, significant changed in intensity are not expected over the coming couple of days. Bertha has managed to maintain decent convection for a mid-latitude tropical system and features one prominent band to the north of the circulation.

20080714.0845.goes12.x.ir1km.02LBERTHA.55kts-990mb-309N-634W.100pc.jpg
Bertha - Infrared satellite

Currently the main band of Bertha is still offshore of Bermuda, but is approaching the island. Some convection ahead of the storm is already bringing heavy rain and tropical storm force winds. To monitor Bertha's impact on Bermuda, check with the Bermuda Weather Service'sradar page and their weather web cam, as well as current surface observations.

westatlantic-radar-2008-07-14-0643.png
Bermuda radar

Motion first to the north and then to the east is expected over the next few days with some more wobbles to be expected on top of the general progression to the east. For the time being, I am disregarding the intensity forecast models as the general have little skill with tropical or hybrid systems in mid-latitudes. Instead 'persistence' seems like the best forecast for Bertha.

Click for full size model imagery:


Bertha - Track Forecast

Bertha - Wind Speed Forecast

Elsewhere in the Atlantic, halfway between Africa and the Lesser Antilles there is a strong tropical wave that looks likely to become a tropical depression in the next day or so. Convection has been persistent and is showing healthy curved outflow. Unfortunately we have yet to receive a good QuikScat pass of the system which is precluding me from making any bold statements about the circulation. While tropical waves do have associated cyclonic curvature in the flow, it seems unlikely at this point that a closed cyclonic circulation has yet developed. We'll wait for a more centralized core of convection and possibly verification from a QuikScat pass before we make that claim.

20080714.0815.goes12.x.ir1km.94LINVEST.25kts-1008mb-110N-405W.100pc.jpg
Invest 94L - Infrared satellite

Since yesterday is seems even more likely that Invest 94L will become Tropical Depression Three. It is far too early for public talk of a landfall at this time. You'll never see me issuing that kind of forecast until after a closed circulation is well-developed. Both the GFDL and the HWRF slowly develop the system as it tracks toward the west. The mostly likely situation is for us to see a strong tropical storm over the northeast Caribbean in about 5 days.

Click for full size model imagery:
94L_GFDL_5day.png
Invest 94L - GFDL 5-Day Forecast
94L_HWRF_5day.png
Invest 94L - HWRF 5-Day Forecast

However, the situation bears further watching. This system could eventually end up anywhere in the Caribbean, Gulf of Mexico, or western Atlantic, and at any strength. The model tracks are showing a huge spread which is expected. Weak systems, like invests, do not have a well developed circulation so differences in model initializations very often result in a wide range of track solutions, even among the members that agree on intensity.

Click for full size model imagery:


Invest 94L - Track Forecast

Invest 94L - Intensity Forecast


Writing from cheery old London this week, Bryan Woods.

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Up later than planned.
Good night all.
Looks like the mid-level center (11.9°N, 45.4°W) is lagging behind the low level center (12.2°N, 46.7°W).
go night jvj
good night jvj
JVJ, very true. I do believe things will get better in a few years. Well see what happens tomorrow. Training? Well I'm off to bed Goodnight all.
National Hurricane Center
Tropical Cyclone Outlook (Atlantic Basin)
06:00 AM UTC July 15 2008

The area of low pressure located about 1000 miles east of the Lesser Antilles continues to produce a broad area of weak and disorganized shower activity. Environmental conditions appear favorable for development and still has the potential to become a tropical depression within the next day or two as it tracks towards the west at 15 MPH.

---
The NHC is a little more reasonable now then saying it can develop into a depression later today.
show an recent image on 94L


convection still west of the center..
WTF is this???????
It's got high winds, rain, and a potent circulation... but it appears to be spinning backwards?!?! Is this just a high between two tropical waves? Is quikscat messed up? Are we about to get a backwards-spinning storm?

I've been lurking here for years, and I've never seen anything like this.
what soon to be 95L sure looking good right now all so a new wave

you mean a southeast movement system?
Is that something unique?
It's the coming pole shift. The magnetic field has weak "holes" in it.
african coast is producing wave after wave.
Luckely shear in carribean is very high witch will keep the US safe from a big Hurricane hit.
But if shear in carribean falls coming week US may have big trouble.The pattern looks dangerous.Just hope shear remains high in carribean.
94L might be starting to get its act together. The low level center is now located under the eastern edge of the convective burst that developed over the previous 4-5 hours.

Diurnal effects are likely playing a role in this most recent convective outburst. However, if persistance is shown over the next 12 hours, advisories will likely be initiated.
2014 - This does not mean we are safe.

2015 - It looks like the people who doubted this system being a tropical storm by tonight were right, but I think it is getting its act together

My new intensity forecast (assuming the storm keeps moving west or wnw. )

12hrs - 35MPH
24hrs - 40MPH
36hrs - 40MPH
48hrs - 45MPH
60hrs - 40MPH
72hrs - 50MPH
84hrs - 55MPH
96hrs - 70MPH
108hrs - 85MPH
120hrs - 100MPH

my forecast was significantly adjusted to reflect the trend of slower-than-forecast development. Also, because it is approaching a higher sheer environment (though not as high as it is right now), I have also forecast possible weakening for day 3. Overall strength in this forecast is significantly lower. However, my general consensus is that rapid strengthening will ensue starting at around 96hrs. This is one element to the forecast I have not changed. Beyond 120hrs, it is likely this storm will become a major hurricane, assuming it does not interact with land.
by not as high sheer as it is today, i meant the higher sheer environment will be in a weakening stage by the time this system approaches it. It is also possible that the sheer may be weaker, in which case, my original forecast from 48hrs and beyond would become more realistic (storm strengthens to a hurricane in 3 days, major hurricane in 5 days)
So Chris do you have a projection for a path, just for speculation. Not worried about ****casting, just your take on its direction. I've been lurking and like to learn and have found the best way to learn is to look at all options and then check the reasoning after the fact. What ya thinkin?
Good Morning everyone who is here

To be completely honest I'm not interested or impressed with anything down in the tropics/ATL right now because everything is an IF right now. I mean "IF" 94L can build and maintain convection and "IF" it can get out of the dry air then we'll have something to watch and be concerned with. That blow up of convection that is back to the east of 94L well "IF" it breaks out of the ITCZ and can maintain on it's own and "IF" it can maintain/build convection for 12 hrs without being in the ITCZ then we'll have something to watch and be concern with. Right now everything is IF and dependent on something else happening. I'm not saying 94L isn't going to form into anything it could but if not by Thursday at the earliest Friday evening at the latest then I'd say next and lets start looking for the next feature or disturbance.
2020. KRL
Philippines Atmospherical, Geophysical, Astronomical Services and Administration

Tropical Cyclone Bulletin #7
============================
Tropical Storm "HELEN" has slightly intensified as it continues to move towards Extreme Northern Luzon.

Tropical Storm Helen (Kalmaegi) is positioned as of 4pm PST at 18.3ºN 123.4ºE or170 kms East of Aparri, Cagayan. The system has 10 minute sustained winds remains at 40 knots (75 km/h) with gusts up to 50 knots (90 km/h).

Signal Warning Number 2 (60-100 km/h)
=====================================
Luzon Region

1.Isabela
2.Cagayan
3.Calayan Group of Islands
4.Apayao
5.Batanes

Signal Warning Number 1 (30-60 km/h)
=====================================
Luzon Region

1.Ilocos Norte
2.Abra
3.Kalinga
4.Mt. Province
5.Ifugao
6.Nueva Vizcaya
7.Quirino
8.Aurora
2020. Thanks KRL for the models.

2019. So true, everything is so far out and so "iffy" but thats what makes it fun to watch isn't it?
Re #2019:

Usually it's "if's" concerning the tropics. It's not often sure bets.
2019.

Yes indeed, lots of if's out there today, but that's okay, it's sooo early in the season, there will be PLENTY more if's after these to watch. The fewer that develop the better!! The folks in the Carrib. certainly don't need them, and the US economy is not in any kind of shape to take on a big hit. So, let's just hope the if's don't make it to UH OH status!!
This should be an invest based on the QuikSCAT and satellite loops



First vis. shot of the day - 94l.

""

2026.

That IS one healthy looking wave, has it parted ways from the ITCZ yet??

Looks like we will have another invest later today.
OSI SAF scatterometer 10N30W
So 95 is just around the corner. Seems like the train is firing up...
No it hasnt pulled away from the ITz yet . The wave at 45 sure has not done much either.
94L

morning
456 i believe the navy will put it up about 9am
94L 84O MILES DUE EAST BARBADOS
2035. crownwx
For the disturbance ESE of 94-L (Near 30W) to develop into anything significant, it will need to part from the ITCZ. I do not expect any development from it until it does so.
2036. IKE
2032....nice satellite of 94L.
IKE, do you ever sleep?
2038. IKE
Quoting Floodman:
IKE, do you ever sleep?


2nd attempt....

Go find the last post that I made on this blog.
2039. MahFL
The train left a few days ago lol, you missed it. :)
94L is under NE shear at the moment from a cut off low to it's north. the system should be out of this shear environment when it gets pass 50W, then it will have the chance at some form of organisation.
Short Range Forecast Discussion


A large portion of the florida peninsula is expected to be affected by an upper level low which is forecast to organize over the eastern gulf of mexico during the day today. A reflection of this upper level low will exist at the surface in the form of a surface low which should not move much over the next couple of days. Since the atmosphere will stay very moist south of the quasi-stationary front... Heavy rainfall is likely due to showers and thunderstorms which will begin to increase in coverage as tuesday night approaches.
2036. IKE

This one?
Good Morning to all........ 456 what are your views on the impact of 94L with the Northern Islands....I live in Guadeloupe and honour your thoughts.
2044. IKE
Quoting Floodman:
2036. IKE

This one?


LOL....I haven't posted on here since yesterday afternoon....the 8 pm EDST TWO.....
Good day everybody.
I live in saint martin and would like your opinion about 94L.
is it going trought the center of the lesser antilles or up north
thanks
2046. crownwx
My thoughts re: 94-L:

Satellite imagery is showing some flaring of convection, however, it seems this disturbance is having a tough time getting its act together. The reason for this may be a lack of low-level convergence. The other reason for this system not developing may be due to an upper level trough of low pressure dropping down right on top of this system causing shear over the system.

Overall, I am a lot less impressed with this system than I was yesterday at this time. Therefore, I would say development of this system will be slow to occur and development into a tropical depression may still happen over the next couple of days. The track model guidance shows a general west to west-northwest course over the next few days right into the Caribbean. The Lesser Antilles will be affected by this system on Thursday and at this point it looks like it may be a tropical depression or perhaps a weak tropical storm at best when it moves across the Lesser Antilles.
Wow, bit of a hole in the converstaion, huh?
2049.

LMAO - we'd all be dead!!!
someone said that once 94L gets pass 55W it should get it's act together so we'll see later today this evening whats 94L got up it's sleeve for us.
2052. crownwx
re: 2049:
Gee with that type of drinking game, I'll be passed out by 8:15 am Eastern....lol.


Off to the world of semi-productive behavior from which I hope to be modestly compensated!!

Good luck w/ the blobs - bbl!!
2054. JRRP
.
Morning everyone!

94L has been attepmting to redevelop convection over night and has managed to create a moist, cold cloudtop field just to the west of the circulation center. In fact, it looks to me as if the circulation center has been at least partially covered in new convection.

Still it's unlikely 94L will become a depression today in my opinion because the system obviously still lacks significant convection to the east, north, and south of the center.

The new convective blowup has punctured into stable air.

act together, act together , act together...
Quoting DestinJeff:
I just though of a new drinking game:

Everytime the words "94L is starting to get its act together" are posted, take a shot.


Outstanding...I want to party with you, dude!
2058. aquak9
And the teenagers could take a shot of Fresca!
2059. JRRP
poor 94L
Morning everybody!

Can somebody bring me up to speed on 94L if they dont mind? It's really early and I don't feel like reading the past 33 posts :)

thanks!

2060. HurricaneMaryJane 6:50 AM EST on July 15, 2008
Morning everybody!

Can somebody bring me up to speed on 94L if they dont mind? It's really early and I don't feel like reading the past 33 posts :)


Morning! 94L hasn't really changed much in organization over night except for a few bursts of convection to the west of the center. Fortunetly, it still has to get it's act together (Floodman, that's your que!).
2062. IKE
New blog sons and daughters.......
2063. belle77
Good to see you, Crownwx. I've lurked here a long time, but you pulled me out of the woodwork...got your site marked as a "favorite" and look forward to your input here. You've saved me lots of bucks on lots of divetrips!