98L may develop into a tropical depression near Florida; Ma-on a threat to Japan

By: Dr. Jeff Masters , 3:09 PM GMT on July 17, 2011

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A tropical disturbance (Invest 98L) has formed off the east coast of Florida, along the tail end of a cold front that pushed off the coast late last week. This disturbance has the potential to develop into a tropical depression that will bring heavy rains to the northern Bahamas and east coast of Florida today through Tuesday. Satellite imagery shows that the disturbance has become more organized this morning, with an expanding area of intense thunderstorms, the beginnings of a surface circulation, and upper-level outflow on the east and north sides of the storm. Some rotation of 98L is also evident on long-range radar out of Melbourne, Florida, but the rain showers are poorly organized and there is little evidence of low-level spiral banding. Wind shear is a moderate 10 - 20 knots, and sea surface temperatures are 27 - 28°C, which is plenty warm enough to support a tropical storm. There is dry, continental air over North Florida, and upper level winds out of the northwest are driving this dry air into the center of 98L, retarding development.


Figure 1. Morning satellite image of Invest 98L.

Forecast for 98L
The models are shy about developing 98L; only the HWRF model shows a tropical depression developing. The SHIPS model predicts that wind shear will be in the low to moderate range, 5 - 15 knots, over the next five days. NHC is giving 98L a 30% chance of developing into a tropical depression by Wednesday. Given the recent satellite and radar presentation of the storm, I'd put those odds higher, at 50%. A hurricane hunter aircraft is scheduled to investigate 98L this afternoon.

Steering currents are weak off the coast of Florida, and 98L can be expected to move slowly at less than 5 mph over the next two days. The HWRF and GFDL models predict 98L will execute a clockwise loop, heading towards the coast of Florida on Monday, then looping northeastwards towards South Carolina later in the week. The track of 98L will depend strongly on how intense the storm gets; a weak system is likely to stay farther to the south, while a stronger system will "feel" upper level winds with a west-to-east component, and tend to move to the northeast, parallel to the coast.

None of the reliable models predict tropical cyclone development over the remainder of the Atlantic through July 23.

U.S. heat wave to last at least another week
An unusually intense, widespread, and long-lasting heat wave over the majority of the U.S. continues to set numerous daily record highs. The latest long-range forecasts from the GFS and ECMWF models predict that the ridge of high pressure responsible for the heat wave will remain entrenched over the center or eastern portion of the country during the coming week, so the heat wave should continue for all but the Pacific Northwest through July 23. The GFS model does show that the ridge will break down some during the period 10 - 16 days from now, but such long range forecasts have low skill, and the heat wave could easily continue through the remainder of July. I'll present a more detailed look at the heat wave later this week.


Figure 2. Microwave satellite image of Typhoon Ma-on at 08:26 UTC July 17, 2011, over the West Pacific Ocean. The typhoon was undergoing an eyewall replacement cycle, with the inner eyewall collapsing and a new, larger eyewall forming from an outer spiral band. Image credit: Navy Research Lab, Monterey.

Typhoon Ma-on headed towards Japan
Powerful Category 3 Typhoon Ma-on is headed northwestward towards Japan, and is expected to brush the east coast of the main island of Honshu on Tuesday. The typhoon has weakened some over the past day, thanks to an eyewall replacement cycle where the inner eyewall collapsed, and a new, larger eyewall formed from an outer spiral band. Once this process completes, Ma-on is expected to intensify into a Category 4 storm. With water temperatures along the path of the typhoon ranging from 29 - 30°C, and wind shear expected to remain in the low to moderate range of 5 - 15 knots, Ma-on has the potential to hit Japan as a major Category 3 storm. The typhoon is unusually large, with winds of tropical storm force (39+ mph) extending out almost 350 miles to the north of the storm. A large portion of the south coast of Japan will receive tropical storm-force winds and large battering waves from Ma-on. Although the typhoon is currently a minimal Category 3 storm, its large size means that Ma-on has a tremendous amount of total kinetic energy, characteristic of a Category 5 storm. This means that Ma-on has the potential to bring a large and highly destructive storm to the coast on the right front side of where the eye makes landfall. If the eye remains just offshore, as some models are predicting, this storm surge will largely miss Japan, though.

Jeff Masters

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Quoting CybrTeddy:
40%, from Pasch/Stewart who are naturally conservative.
Especially Pasch. Stacey might give it a bit more of a go. But truly, model support still not really there, is it? Without that I think they want to see a little more persistance with this. Keep in mind we r heading towards Dmin over next 6+ hours, so 98L will have the opportunity to prove that it's made of something more than a hiss of hot water and a couple thunderstorms...
Member Since: October 25, 2005 Posts: 19 Comments: 21392
Thanks pcolaDan for the description of the flight trac. Ma-on is huge and dangerous and now just sorry for those in its p 'Super-Typhoon' path
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Quoting NICycloneChaser:
Could someone tell me how you track the recon planes on google earth?


Click the Live Recon Data in Google Earth to download the KMZ file then load that into Google Earth
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Surface Observations showing some westerly winds south of the system, although generally light.
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SFMR has been turned on.

000
URNT15 KNHC 171812
AF304 01BBA INVEST HDOB 15 20110717
180230 2803N 07956W 8589 01480 0191 174 -103 008008 009 /// /// 03
180300 2803N 07954W 8822 01248 0194 181 -079 029007 008 /// /// 03
180330 2803N 07952W 9056 01026 0195 196 -022 048009 011 /// /// 03
180400 2803N 07952W 9056 01026 0191 205 027 038012 014 /// /// 03
180430 2802N 07949W 9523 00586 0190 211 051 037014 015 /// /// 03
180500 2802N 07947W 9668 00450 0185 219 069 042016 016 /// /// 03
180530 2802N 07945W 9791 00339 0180 229 085 043016 016 /// /// 03
180600 2802N 07944W 9817 00315 0177 230 099 043016 016 /// /// 03
180630 2802N 07942W 9810 00320 0177 230 111 039015 016 /// /// 03
180700 2802N 07940W 9813 00319 0177 230 121 040015 016 /// /// 03
180730 2802N 07939W 9809 00321 0177 229 130 037014 015 /// /// 03
180800 2802N 07937W 9809 00321 0176 230 138 036014 015 /// /// 03
180830 2802N 07935W 9813 00317 0176 230 144 041015 016 /// /// 03
180900 2802N 07934W 9812 00319 0176 230 149 040016 016 /// /// 03
180930 2802N 07932W 9813 00316 0174 230 154 041015 016 /// /// 03
181000 2802N 07930W 9813 00316 0175 228 157 038015 016 /// /// 03
181030 2802N 07929W 9814 00315 0174 229 160 039015 016 /// /// 03
181100 2802N 07927W 9811 00317 0173 230 163 040016 017 023 000 00
181130 2802N 07925W 9813 00315 0172 229 166 041016 017 023 000 00
181200 2802N 07924W 9811 00315 0172 230 167 040015 015 021 001 03
$$
;
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Quoting CybrTeddy:
As the day goes on convection will continue to wane to mostly blues and yellows, when this happens it is to be expected, followed by a blowup with classification tomorrow PM imo.


I completely agree.
Member Since: August 10, 2010 Posts: 2 Comments: 1971

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394. 7544
will recon find a llc ?
Member Since: May 6, 2007 Posts: 0 Comments: 6686
As the day goes on convection will continue to wane to mostly blues and yellows, when this happens it is to be expected, followed by a blowup with classification tomorrow PM imo.
Member Since: July 8, 2005 Posts: 259 Comments: 23560
Could someone tell me how you track the recon planes on google earth?
Member Since: August 10, 2010 Posts: 2 Comments: 1971
98L sitting almost stationary.... so glad my recon on google earth isnt lagging today.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Almost seems to me that 40% is a little low Just IMO. being really conservative but bet that will change before long!
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389. Skyepony (Mod)
Fresh Windsat..looks open on the SE side.
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Quoting Levi32:


Most of the spin you see is mid-level. There is some circulation at the surface, but it is not that strong at all.


I agree
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98L
Floater - Visible Loop
Member Since: July 3, 2005 Posts: 420 Comments: 127512
Satellite presentation is impressive but IR isn't as impressive as satellite. Don't think we'll see a TD today but tomorrow. But I did say the same thing about Arlene and look how that turned out :x
Member Since: July 7, 2008 Posts: 2 Comments: 3237

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT SUN JUL 17 2011

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

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A BROAD AREA OF LOW
PRESSURE LOCATED ABOUT 125 MILES EAST OF MELBOURNE FLORIDA
HAVE CHANGED LITTLE IN ORGANIZATION OVER THE PAST SEVERAL HOURS.
UPPER-LEVEL WINDS HAVE BECOME A LITTLE MORE CONDUCIVE FOR
DEVELOPMENT TODAY...AND THIS SYSTEM HAS A MEDIUM CHANCE...40
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES LITTLE. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT
IS ENROUTE TO INVESTIGATE THE AREA LATER TODAY.

what??? have changed little???? it looks sto me like a developing TD on satellite.
Member Since: April 23, 2011 Posts: 104 Comments: 14870
Quoting yonzabam:


I'm no expert, either. Strictly amateur, but I've been watching the loops on the NHC site for years, and if Brett-to-be hasn't got 40 mph winds already in some quadrants, I'd be surprised. Seems to me to be spinning pretty fast. No idea if there's a closed circulation, though.


Most of the spin you see is mid-level. There is some circulation at the surface, but it is not that strong at all.
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98L looks like a small TS
Member Since: May 21, 2006 Posts: 5091 Comments: 114696
Quoting jasonweatherman2011:
AT 2PM going up to 40%!!
Good call on this one, Jase.
Member Since: October 25, 2005 Posts: 19 Comments: 21392
Quoting MrstormX:
The 40% is stupid to me, but im no expert.


I think they were being conservative because they had a flight en-route to investigate. They are already planning on writing a special statement to increase. I would have thought it should have gone RED
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379. Skyepony (Mod)
Quoting scott39:
?

98L...& I may have spoke too soon..fresh ASCAT..
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Quoting dealsbeachdia:
My son is flying to Beijing Tuesday. How will Ma-on affect flights?Looks like a huge storm


Been looking, best I can see, routes to Beijing from San Francisco and LA fly a more northerly route above Korea. Ma-on is supposed to go well south of there.

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Recon approaching 98L, less than 10 minutes away.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
40 percent was being on the safe side until recon could get more data, you know how the NHC is!
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Member Since: July 3, 2005 Posts: 420 Comments: 127512
Quoting MrstormX:
The 40% is stupid to me, but im no expert.


I'm no expert, either. Strictly amateur, but I've been watching the loops on the NHC site for years, and if Brett-to-be hasn't got 40 mph winds already in some quadrants, I'd be surprised. Seems to me to be spinning pretty fast. No idea if there's a closed circulation, though.
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Get your F5 ready for that recon data.
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The winds have been picking up here in JAX since this morning almost like we are getting small bands intermittently.
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At recon's current latitude it has a dead on shot into the center of 98L
Member Since: October 3, 2010 Posts: 40 Comments: 4129
At 17:52:30Z (first observation), the observation was 5 miles (7 km) to the SW (223°) from Melbourne, FL, USA.
At 18:02:00Z (last observation), the observation was 41 miles (66 km) to the E (96°) from Melbourne, FL, USA
Member Since: August 24, 2010 Posts: 0 Comments: 676
Quoting TxHurricanedude11:
Once the aircraft finds a much better organized system expect an special TWO to be issued.


Anytime now
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WoW 98L looking good this afternoon. I figured they would give it a nice color with the crayons soon enough! Now need to watch the other blob to the NE of that one LOL! Blobs all over now to look at.
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365. 7544
looks like a llc has formed ?
Member Since: May 6, 2007 Posts: 0 Comments: 6686
Member Since: July 3, 2005 Posts: 420 Comments: 127512
The 40% is stupid to me, but im no expert.
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Quoting Walshy:
Tornado Warning


Hate to hear that. Seems like those are never ending this year. Hope everyone stays safe.
Member Since: August 24, 2010 Posts: 0 Comments: 676
360. txjac
Is that were you are at walshy?
Member Since: April 24, 2010 Posts: 1 Comments: 2454
358. Bonz
Quoting MrstormX:


I know, which is why I hate TWC. If you are looking for gardening tips, then it is fine.


They don't even do gardening tips for my area (S. Florida).

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Tornado Warning
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Quoting Skyepony:
I'm 1/2 expecting a depression here.
?
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354. Skyepony (Mod)
I'm 1/2 expecting a depression here.
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353. SLU
Quoting AtHomeInTX:


Thanks. Looks like things are heating up out there finally. Hopefully we'll have advantageous steering this year.


Yep!
Member Since: July 13, 2006 Posts: 12 Comments: 4834
Hurricane Hunters crossing over Central Florida and about to head out over the Atlantic Ocean towards the disturbance. I'm expecting that recon will find a better organized system than the NHC is currently suggesting.
Member Since: April 14, 2007 Posts: 8 Comments: 5163

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.