ATL: TROPICAL DEPRESSION BONNIE - DISCUSSION

[Decomdoug]

Quote from the PB Post:

Tropical Depression, or Tropical Storm Bonnie, could threaten Florida by Thursday

by Eliot Kleinberg, Tuesday, July 20th, 2010, 2:48 pm

South Florida could be facing down a tropical depression, or Tropical Storm Bonnie, as early as Thursday night, forecasters said today.

http://blogs.palmbeachpost.com/eyeonthe ... -thursday/

[Weatherboy1]

Personally I'm supposed to fly out for a Chicago trip on Thursday afternoon. Hope I get out of here in time!

[chzzdekr81]

Looking good.

[Zadok]

Wow! It looks like things are starting to pick up.

[Aric Dunn]

Excerpt from Jeff Master's:
Surface observations show only light winds over Puerto Rico and the Dominican Republic, but the surface winds at Punta Cana on the eastern tip of the Dominican Republic have shifted to the west this afternoon, indicating that a surface circulation may be forming just north of that location.

I hate that, what does he consider "just north"?? Leaving me hanging again!!

lol just north means... something like this... the black circle is technically just north and yes its a big area but it clearly cant be too far north since that would be north of all the convection the same applies east and west... so essentially in and around the black circle and since there is no well defined circ there is no specific coordinates either... however using a little physics and analyzing both satellite and radar you can conclude the most likely area to watch over the next 24 hours which is circled in yellow. which then implies the general area of cyclo-genesis in about 24hrs which is boxed in red.

[hurricanefloyd5]

97L continues to grow more organized; headed for Bahamas and Florida

Posted by: JeffMasters, 7:07 PM GMT on July 20, 2010
A tropical wave (Invest 97L) between Puerto Rico and the Dominican Republic has continued to become more organized today, and is a threat to develop into a tropical depression as early as Wednesday morning. The disturbance has brought heavy rains of 8+ inches to Culebra and Vieques islands over the past day, and all of Puerto Rico and the Virgin Islands are under flash flood watches today. The storm could bring an additional 3 - 6 inches of rain to the islands over the next two days. The upper level low centered a few hundred miles north of the Dominican Republic is no longer bringing high levels of wind shear to 97L; wind shear has fallen to the moderate range, 10 - 15 knots, which should allow 97L to continue to develop today. Satellite images of 97L show a moderate area of steadily organizing thunderstorms, with curved bands developing to the north and east of the center. There are no signs of a surface circulation on satellite imagery or on the 10:38am EDT ASCAT pass. Surface observations show only light winds over Puerto Rico and the Dominican Republic, but the surface winds at Punta Cana on the eastern tip of the Dominican Republic have shifted to the west this afternoon, indicating that a surface circulation may be forming just north of that location. Long-range radar loops from San Juan do not show any evidence of a surface circulation. The Hurricane Hunter mission scheduled for today was canceled, but is scheduled to fly Wednesday afternoon.


Figure 1. Total precipitation from 97L as predicted by the 12Z (8 am EDT) July 20, 2010 run of the HWRF model. Image credit: Morris Bender, NOAA/GFDL.

Track Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west-northwest through Saturday. The rains from 97L's thunderstorms will bring the threat of isolated flooding to the Dominican Republic today and Wednesday, and to Haiti on Wednesday and Thursday. Heavy rains from 97L will begin moving into eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas on Wednesday, and South Florida can expect heavy rains to arrive as early as Thursday night. The latest suite of model runs from 8am EDT this morning (12Z) foresee a more northerly track for 97L into Central Florida. Several models develop 97L into a tropical storm, with both the GFDL and HWRF models predicting 97L will hit South or Central Florida as a tropical storm on Friday. Most of the models have 97L entering the Gulf of Mexico on Saturday, but the amount of time 97L has over the Gulf may be limited to a day or less if the storm ends up exiting into the Gulf near Tampa Bay. The NOGAPS model predicts a more southerly path across South Florida and into Louisiana.

Intensity Forecast for 97L
One factor potentially aiding development of 97L will be the Madden-Julian oscillation, which currently favors upward motion over the Gulf of Mexico and Caribbean. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. Also in favor of development are the warm ocean temperatures of 29°C. The SHIPS model predicts shear will stay in the moderate range, 10 - 20 knots, over the next five days. The primary detriment to development of 97L over the next three days will probably be the presence of dry, stable air in its path over the Bahamas, thanks to the upper-level low to the north of the Dominican Republic. If the center forms close to the coast of the Dominican Republic, the high mountains of Hispaniola may also be a problem for the storm. NHC is giving 97L a 60% chance of developing into a tropical depression by Thursday, which is a reasonable forecast. I think there is a 70% chance 97L will eventually become Tropical Storm Bonnie, sometime in the next five days. Sudden rapid development today or on Wednesday is unlikely, due to the dry air over the Bahamas. I put the odds of 97L making it to hurricane strength before reaching Florida at 30%, and I give a 20% chance it will be a hurricane in the Gulf of Mexico. The probability of 97L being a hurricane in the Gulf of Mexico will depend heavily upon how long the storm spends over land or interacting with land over the next four days, which is very uncertain.

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) Invest 97
2) A look ahead at the coming two weeks

Today's show will be about 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.html. The show will be recorded and stored as a podcast.

Jeff Masters

[canes101]

[johngaltfla]

Buckle up boys and girls. We could have another wild storm hitting Florida and this one is in a weird position, much like Erin which was a nightmare to navigate when she hit.

[cycloneye]

hurricanefloyd5, thatr has been posted already. Lets not get repetitions of long discussions posted.

[KWT]

If I had to make a call I'd go for a strong TS into S.Florida right now, the models do seem to be in decent agreement about the broad solution, though the GFDL looks a bit too far north for my liking.

At least the center looks likely to stay north of the islands for now...

[HURAKAN]

Punta Cana, DR:

4 PM (20) Jul 20 80 (27) 75 (24) 29.88 (1012) WSW 6 showers in the vicinity
3 PM (19) Jul 20 78 (26) 75 (24) 29.88 (1012) WSW 6 showers in the vicinity
2 PM (18) Jul 20 78 (26) 73 (23) 29.88 (1012) WSW 6 showers in the vicinity
1 PM (17) Jul 20 80 (27) 75 (24) 29.88 (1012) SW 127 showers in the vicinity

4 hours of west winds. I'm thinking the 127 mph is wrong!!! lol

[Aric Dunn]

If I had to make a call I'd go for a strong TS into S.Florida right now, the models do seem to be in decent agreement about the broad solution, though the GFDL looks a bit too far north for my liking.

well the stronger the system the farther north it will likely go.... the models are the weakest take it farther south.. ukmet ,nogaps. models like the HWRF and GFDL are slightly stronger (moderate to strong TS)and farther north and the GFS which is basically in the middle of the models and has a weak TS. so it will be dependent its strength and where exactly the center takes shape..

[canes101]

Where can I get the coordinates of this system?

There are many different places to get them Hurriane.. Two quick ones for you..

1) you can go to Storm2ks invest 97L storm page via link here - http://www.storm2k.org/weather/hw3.php? ... ventnum=97 and on the top of the map you will see where it gives you the Position, (these are the coordinates your asking for), the winds, and the pressure

2) At Wunderground.. Go to there tropical page - http://www.wunderground.com/tropical/ and scroll down just a tad bit and you will see Invest 97L heading and right under that it will tell you the wind speed, the location (the coordinates your asking for), and movement...


Hope that helps you!

[canes04]

KWT,

I repectfully disagree, there is no way this will only be a TS. If there is no land interaction it could ramp up rather quickly.

[Rainband]

hurricanefloyd5, thatr has been posted already. Lets not get repetitions of long discussions posted.

Yes everyone Please don't duplicate or nonsense post. Things are going to be getting busy from the look of things. Help us keep the board running smoothly Thank You

[KWT]

KWT,

I repectfully disagree, there is no way this will only be a TS. If there is no land interaction it could ramp up rather quickly.

You may well be right on that, when you've got a upper high aloft and a system heading WNW in this region it tends to lead to strong systems...so I suppose a hurricane is certainly possible if it develops early and shear eases...

[MGC]

Convergance has improved today. Yesterday all the convection south of PR was moving westward, today convection is moving north towards the disturbance. 97L seems to be slowly organizing....Time to check my hurricane stuff...if Bonnie does become out of this a South Florida hit usually means a La-Miss hit or so it seems......MGC

[Bocadude85]

KWT,

I repectfully disagree, there is no way this will only be a TS. If there is no land interaction it could ramp up rather quickly.

Chances of this becoming a hurricane before Florida are relatively low. I wouldnt be surprised to see this go south of Florida to be honest.

[ocala]

If I had to make a call I'd go for a strong TS into S.Florida right now, the models do seem to be in decent agreement about the broad solution, though the GFDL looks a bit too far north for my liking.

well the stronger the system the farther north it will likely go.... the models are the weakest take it farther south.. ukmet ,nogaps. models like the HWRF and GFDL are slightly stronger (moderate to strong TS)and farther north and the GFS which is basically in the middle of the models and has a weak TS. so it will be dependent its strength and where exactly the center takes shape..

Do these models that take it north have a northerly bias for stronger storms? I'm just curious what you are basing this off of. Past model performance or just this storm?
Thanks

[Aric Dunn]

If I had to make a call I'd go for a strong TS into S.Florida right now, the models do seem to be in decent agreement about the broad solution, though the GFDL looks a bit too far north for my liking.

well the stronger the system the farther north it will likely go.... the models are the weakest take it farther south.. ukmet ,nogaps. models like the HWRF and GFDL are slightly stronger (moderate to strong TS)and farther north and the GFS which is basically in the middle of the models and has a weak TS. so it will be dependent its strength and where exactly the center takes shape..

Do these models that take it north have a northerly bias for stronger storms? I'm just curious what you are basing this off of. Past model performance or just this storm?
Thanks

well in general stronger systems will have a right bias... but i was talking about the latest model runs...