ATL: TROPICAL DEPRESSION BONNIE - DISCUSSION

[Wx_Warrior]

Going out on a limb & sticking my neck out - I don't think we are deadling with a Katrina type storm here on July 21.

[Vortmax1]

This is why it would have been nice to have a flight this afternoon.

[Aric Dunn]

well we wont be seeing much strengthening being that the shear is rather high ..

[x-y-no]

Going out on a limb & sticking my neck out - I don't think we are deadling with a Katrina type storm here on July 21.

I wasn't suggesting we are. Just pointing out how incredibly bad something can look and still develop rather impressively.

(although I'd note we did have two majors in July that year too ...)

[Tropics Guy]

Once 97L gets near the T & C islands (SE bahamas) , then it should have better southerly inflow into the system, not being disrupted by the DR landmass, though the ULL shear will still keep it in check from developing rapidly...........

TG

[Ivanhater]

[gatorcane]

More convection developing on the Northeastern side of the "LLC"....

As for what x-y-no posted, the point is that systems can develop rapidly in this area if conditions are good. Katrina went from looking like that to a CAT1 into S. Florida. Conditions don't appear to be as good this time around though.

[Comanche]

not sure if this was posted earlier this morning but here it is again. Hopefully this will bring a little reality to the "could see rapid intensification" crowd.

Posted by: JeffMasters, 12:53 PM GMT on July 21, 2010

A tropical wave (Invest 97L) near the north coast of Hispaniola has been disrupted by interaction with the island, plus the effects of moderate wind shear of 10 - 20 knots. The storm is no longer a threat to develop into a tropical depression today, and the Hurricane Hunter flight that was scheduled for today has been postponed until Thursday. The disturbance has brought heavy rains of 8+ inches to Culebra, Vieques, the Virgin Islands, and some of the northern Lesser Antilles Islands. Wunderblogger Weather456 reported that the power was knocked out on the island of St. Kitts for about 24 hours, due to the intense lightning associated with 97L. All of Puerto Rico and the Virgin Islands are under flash flood watches today.

Satellite images of 97L show a relatively meager number of heavy thunderstorms that are not well-organized. The curved bands to the north and east of the center have disappeared, and there is no evidence of low-level spiral banding or of a surface circulation. Surface observations over the northern Dominican Republic show only light winds, with no westerly winds indicating that a surface circulation is forming. Long-range radar loops from San Juan show a much reduced amount of thunderstorm activity.


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 to Haiti on today and Thursday. Heavy rains from 97L will affect eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas Thursday, and South and Central Florida can expect heavy rains to arrive Thursday night or Friday morning. The latest suite of model runs from 2am EDT this morning (6Z) foresee 97L making landfall on the Florida coast somewhere between Miami and Cape Canaveral on Friday, then continuing into the Gulf of Mexico on Saturday. Only the Canadian model foresees a threat to Texas, and the other models predict a second landfall between eastern Louisiana and the Florida Panhandle.

Intensity Forecast for 97L
The primary detriment to development of 97L today will be its close proximity to the landmass of Hispaniola. Once the storm pulls away from the island tonight, 97L has a better chance of development. Also hindering development over the next two days will 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. The SHIPS model predicts shear will stay in the moderate range, 10 - 20 knots, over the next three days, which should allow for some steady development of 97L on Thursday and Friday before it reaches Florida. NHC is giving 97L a 60% chance of developing into a tropical depression by Friday, 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 before 97L reaches Florida is unlikely, due to the storm's current state of disorganization and the dry air over the Bahamas. It's very unlikely that 97L has time to organize into a hurricane before hitting Florida. I put the odds of 97L making it to hurricane strength before reaching Florida at 5%, 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 water in the Gulf, which is very uncertain. The environment in the Gulf of Mexico should be favorable for intensification, if passage over Florida does not disrupt the storm too much.

I'll have a new post Thursday morning, or earlier if there's a major change to 97L.

[StormClouds63]

Going out on a limb & sticking my neck out - I don't think we are dealing with a Katrina type storm here on July 21.

I still get a chuckle out of your avatar ... glad you brought back everyone's old pal

I agree ... no Katrina with this one ... more like Chris from 2006.

If this system gets named Bonnie, it won't compare to your 1986 version over in the Golden Triangle.

[RL3AO]

I see the same thing Ivan. Its starting to develop.

[hookemfins]

The cloud swirl appears to be a different heights. The N clouds are a higher altitude and S look to at lower level. There may be a weak MLC bit no LLC.

[cycloneye]

Down to 50%

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT WED JUL 21 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

UNFAVORABLE UPPER-LEVEL WINDS AND THE EFFECTS OF THE HIGH TERRAIN OF
HISPANIOLA HAVE DISRUPTED THE STRUCTURE OF THE TROPICAL WAVE THIS
MORNING. THE AXIS OF THE WAVE IS APPROACHING THE SOUTHEASTERN
BAHAMAS WITH MOST OF THE CLOUDINESS...SHOWERS AND GUSTY WINDS
EXTENDING EASTWARD FOR SEVERAL HUNDRED MILES. THIS ACTIVITY WILL
LIKELY SPREAD OVER THE BAHAMAS DURING THE NEXT DAY OT TWO AS THE
WAVE MOVES GENERALLY WESTWARD AT 10 TO 15 MPH. ALTHOUGH THE WAVE IS
CURRENTLY DISORGANIZED AND DEVELOPMENT IS NOT ANTICIPATED
TODAY...UPPER-LEVEL WINDS COULD BECOME A LITTLE MORE FAVORABLE ON
THURSDAY. THERE IS A MEDIUM CHANCE...50 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER AVILA

[tolakram]

Watching this MADIS station

http://www.wunderground.com/weatherstat ... ?ID=MD0758

Overview: http://www.wunderground.com/wundermap/? ... 090&zoom=9

[Weatherboy1]

I think it's actually notable that we apparently have a tight LLC or low center that has developed. The shear is definitely a problem, don't get me wrong. But we now have a mechanism for a developing system as soon as the shear lets up. Before we just had a wave and unorganized convection.

[Wx_Warrior]

x-y-no....

You are correct! Forgot about that!

Just don't think it's the right setup now for a major. Could be totally wrong.

[jlauderdal]

Down to 50%

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT WED JUL 21 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

UNFAVORABLE UPPER-LEVEL WINDS AND THE EFFECTS OF THE HIGH TERRAIN OF
HISPANIOLA HAVE DISRUPTED THE STRUCTURE OF THE TROPICAL WAVE THIS
MORNING. THE AXIS OF THE WAVE IS APPROACHING THE SOUTHEASTERN
BAHAMAS WITH MOST OF THE CLOUDINESS...SHOWERS AND GUSTY WINDS
EXTENDING EASTWARD FOR SEVERAL HUNDRED MILES. THIS ACTIVITY WILL
LIKELY SPREAD OVER THE BAHAMAS DURING THE NEXT DAY OT TWO AS THE
WAVE MOVES GENERALLY WESTWARD AT 10 TO 15 MPH. ALTHOUGH THE WAVE IS
CURRENTLY DISORGANIZED AND DEVELOPMENT IS NOT ANTICIPATED
TODAY...UPPER-LEVEL WINDS COULD BECOME A LITTLE MORE FAVORABLE ON
THURSDAY. THERE IS A MEDIUM CHANCE...50 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER AVILA

http://www.nhc.noaa.gov/gtwo/two_atl.gif

stacy stewart will pump that up to about 70 on his next shift

[Steve]

For the Joe B fans, he put out a free video today (see link below). He's not worried about anything beyond South Florida but thinks the leftover moisture (south of Hispanola) and the next wave coming through could spell trouble for the Gulf next week (168ish hours).

http://www.accuweather.com/video/731462 ... e-gulf.asp

Also, thank you to the moderators for putting in the "Foes" feature in User CP.

[Vortmax1]

Thank you Forecaster Avila!

[Florida1118]

Im saying in 50hrs. we have Bonnie. it may look like crap but its starting to pull itself back now. What do think the intensity will be? Im saying 45mph.

[KWT]

There certainly is turning down there though I'm not sure its that close to being a closed low as the ULL may wel be making an optical illusion.

Its sheared no doubt but I'd have personally held at 60%. I still think there is a much better chance of it developing then not but clearly not going to get a good set-up anytime soon.