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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When is the HH mission scheduled for?
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Quoting SLU:
40% is rather conservative given the system's organisation.

Also the developing low midway between 98L and Bermuda might need a yellow circle very soon.



Was wondering about that.
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THis is a good example Models Do Not tell all!!
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Night all, Can someone keep an eye on 98L for me, I don't want it doing anything sneaky while I'm asleep. Kind of a mild night here, good for sleeping. Night all.
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298. SLU
40% is rather conservative given the system's organisation.

Also the developing low midway between 98L and Bermuda might need a yellow circle very soon.

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Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 17th day of the month at 17:31Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Mission Purpose: Investigate second suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 04

Mandatory Data...

Observation Time: Sunday, 17:25Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 28.1N 83.3W
Location: 52 miles (83 km) to the W (280°) from Tampa, FL, USA.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 7,630 meters
Flight Level Wind: From 360° at 11 knots (From the N at ~ 12.6 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: -20°C
Flight Level Dew Point: -21°C
Weather (within 30 nautical miles): Overcast / Undercast
400 mb Surface Altitude: 7,610 geopotential meters
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If you look at the IR and WV imagery you can see why its 40%...
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Quoting hurricane23:


Still don't think the ridge over the interior united states will be sufficient enough to take this through florida and into the gomex. It should stall/meander then take off towards the NE.


U.S. Gulf Coast Shield wins again! Na Na Na Na hey hey hey goodbye! lol
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294. 7544
so its not moving kinda stuck there hmmmmm
Member Since: May 6, 2007 Posts: 0 Comments: 6874
LSU Earth Scan Low Cloud Product.
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HAVE CHANGED LITTLE IN ORGANIZATION OVER THE PAST SEVERAL HOURS... sounds like a snub to me. Stewart, so shouldn't be surprised.
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40%, from Pasch/Stewart who are naturally conservative.
Member Since: July 8, 2005 Posts: 259 Comments: 24578
LOL


40%
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How is this going to move west? Imo I doubt it...
Member Since: June 21, 2007 Posts: 10 Comments: 1657
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Is anyone seeing the recon on Googlearth into 98L ? I am only seeing the 2 non tasked missions going on in the Northern GOM South of Fl and South of TX / LA














































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Quoting hurricanehunter27:
Anybody have a rapid scan for L98


Link
Member Since: September 23, 2005 Posts: 15 Comments: 11343
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.

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Quoting Stormchaser2007:
FWIW, there are three planes out right now.



Still don't think the ridge over the interior united states will be sufficient enough to take this through florida and into the gomex. It should stall/meander then take off towards the NE.
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Quoting MrstormX:


Convection will come and go, especially on a storm of this size. The Circulation is way more important.


I agree, merely an observation. DMAX overnight will see this fire up, imo.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
At 17:12:30Z (first observation), the observation was 121 miles (194 km) to the W (275°) from Tampa, FL, USA.
At 17:22:00Z (last observation), the observation was 66 miles (106 km) to the W (279°) from Tampa, FL, USA.

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Quoting NICycloneChaser:
Convection is diminishing, not enough to be a TD yet. Definitely organising though.


Convection will come and go, especially on a storm of this size. The Circulation is way more important.
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Convection is diminishing, not enough to be a TD yet. Definitely organising though.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting scott39:
It looks like 98L is still attached to the front some.


The front has all but seperated:

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Look like we should have a TS by Tomorrow.
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It looks like 98L is still attached to the front some.
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looks stationary remember to expect the unexpected 2011
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5-10 knots

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Quoting hurricanehunter27:
Anybody have a rapid scan for L98


Link
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now theres banding one hr to go
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POSS T.C.F.A.
INV98/XX/L
MARK
27.87N/77.97W
Member Since: July 15, 2006 Posts: 178 Comments: 56141
266. 7544
morning all so the now the models do not show 98l going west anymore could this change after recon gets the data all in all its looking good right now they may clasify it as its very close to land soon
Member Since: May 6, 2007 Posts: 0 Comments: 6874
Quoting Stormchaser2007:

Looks to me that the LLC and the MLC are slightly displaced, the LLC being to the west of the MLC.
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Whatever this means.

Information About Radiosonde:
- Launch Time: 16:46Z
- About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction.

Remarks Section...

Splash Location: 28.31N 86.7W
Splash Time: 16:54Z

Release Location: 28.31N 86.7W View map)
Release Time: 16:46:38Z

Splash Location: 28.31N 86.7W (
Splash Time: 16:54:46Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):
- Wind Direction: 75° (from the ENE)
- Wind Speed: 3 knots (3 mph)

Deep Layer Mean Wind (average wind over the depth of the sounding):
- Wind Direction: 0° (from the N)
- Wind Speed: 0 knots (0 mph)
- Depth of Sounding: From 376mb to 1017mb

Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding:
- Lowest 150m: 158 gpm - 8 gpm (518 geo. feet - 26 geo. feet)
- Wind Direction: 70° (from the ENE)
- Wind Speed: 3 knots (3 mph)
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Quoting Thundercloud01221991:


do you know this or are you guessing because to me it looks more like 60-70%
I don't think he "knows" but this is his thoughts on it.
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Anybody have a rapid scan for L98
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As of the last dropsonde at 16:46Z, the plane's...

Location: 143 miles (231 km) to the SSW (206°) from Panama City, FL, USA
Member Since: April 29, 2007 Posts: 0 Comments: 8134
FWIW, there are three planes out right now.

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98L is ingesting dry air for now. TD on Monday.
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Quoting FSUstormnut:
seems like it is starting to wrap dry air on the west side... i say 50-60%,, but it have a way to go before TD.


a ways to go? It's pretty close.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
seems like it is starting to wrap dry air on the west side... i say 50-60%,, but it have a way to go before TD.
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Latest Ascat showing western side of circulation.
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Fleet Weather Center Norfolk Tropical Feed
No Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico
By Maritime.CDO@navy.mil (FWC-N CDO) from Fleet Weather Center Norfolk Virginia. Published on Sun, Jul 17, 2011.

As of Sun, 17 Jul 2011 17:00:01 GMT
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Quoting Stormchaser2007:
AL, 98, 2011071712, 03, SHIP, 0, 282N, 788W, 20, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 12, 289N, 793W, 23, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 24, 283N, 800W, 27, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 36, 277N, 810W, 31, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 48, 273N, 819W, 36, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 60, 270N, 827W, 39, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 72, 271N, 830W, 43, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 84, 272N, 832W, 46, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 96, 272N, 832W, 47, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 108, 270N, 833W, 49, 0, , 0, , 0, 0, 0, 0,
AL, 98, 2011071712, 03, SHIP, 120, 268N, 835W, 50, 0, , 0, , 0, 0, 0, 0,
making that move to the SSW.
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wonder how close recon is getting?
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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.

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