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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ok who agrees with the NHC track?
Member Since: July 22, 2010 Posts: 1 Comments: 3852
Quoting Drakoen:

That will put a pin in the baloon!
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It was very interesting to see the cyclogenesis on Melbourne radar.
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849. xcool
next
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848. 7544
wave bye bye to the new td

next
Member Since: May 6, 2007 Posts: 0 Comments: 6874

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I can't believe they got something so close to land so wrong. Granted, it isn't going to cause any serious problems to land immediately, but nevertheless...
Member Since: August 10, 2010 Posts: 2 Comments: 1971
...TROPICAL DEPRESSION FORMS JUST NORTH OF THE NORTHWEST BAHAMAS...
5:00 PM EDT Sun Jul 17
Location: 27.5°N 78.2°W
Max sustained: 35 mph
Moving: S at 2 mph
Min pressure: 1010 mb
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TD TWO on NHC site!

Predicted to peak at 60 mph.
Member Since: July 8, 2005 Posts: 259 Comments: 24576
Quoting txjac:
Dangit ...got to go grocery shopping ...just when things get exciting ...

See ya all when I get back ...anyone need anything since I'm going out?
a case of crow...
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438

URNT12 KNHC 172028

VORTEX DATA MESSAGE AL982011

A. 17/20:16:40Z

B. 27 deg 34 min N

078 deg 11 min W

C. NA

D. 24 kt

E. 310 deg 5 nm

F. 060 deg 25 kt

G. 320 deg 2 nm

H. EXTRAP 1010 mb

I. 23 C / 189 m

J. 24 C / 188 m

K. 21 C / NA

L. NA

M. NA

N. 1234 / 01

O. 0.02 / 1 nm

P. AF304 01BBA INVEST OB 14

MAX FL WIND 25 KT NW QUAD 20:16:00Z

SLP EXTRAP FROM BELOW 1500 FT

;
Member Since: July 15, 2006 Posts: 178 Comments: 56140
000
WTNT22 KNHC 172032
TCMAT2

TROPICAL DEPRESSION TWO FORECAST/ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL022011
2100 UTC SUN JUL 17 2011

CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

THE GOVERNMENT OF THE BAHAMAS HAS ISSUED A TROPICAL STORM WATCH FOR
GRAND BAHAMA ISLAND AND THE ABACO ISLANDS IN THE NORTHWEST BAHAMAS.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* GRAND BAHAMA ISLAND AND THE ABACO ISLANDS IN THE NORTHWEST BAHAMAS

TROPICAL DEPRESSION CENTER LOCATED NEAR 27.5N 78.2W AT 17/2100Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE SOUTH OR 180 DEGREES AT 2 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1010 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 27.5N 78.2W AT 17/2100Z
AT 17/1800Z CENTER WAS LOCATED NEAR 27.7N 78.2W

Member Since: September 23, 2005 Posts: 15 Comments: 11343
NHC have begun. Wikipedia posters, to your stations!
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Finally, the NHC declares TD 2!!!!!!! everyone
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Quoting KEEPEROFTHEGATE:
T.C.F.W.
02L/TD/B/CX
MARK
28.13N/78.11W


Looking very organised, losing convection but only to be expected in DMIN, overnight into the morning this thing will be looking very nice indeed.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
837. bwi
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 17th day of the month at 20:28Z
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: 14
A. Time of Center Fix: 17th day of the month at 20:16:40Z
B. Center Fix Coordinates: 27°34'N 78°11'W (27.5667N 78.1833W)
B. Center Fix Location: 130 miles (209 km) to the ENE (63°) from West Palm Beach, FL, USA.
C. Minimum Height at Standard Level: Not Available
D. Estimated (by SFMR or visually) Maximum Surface Wind: 24kts (~ 27.6mph)
E. Location of the Estimated Maximum Surface Wind: 5 nautical miles (6 statute miles) to the NW (310°) of center fix
F. Maximum Flight Level Wind Inbound: From 60° at 25kts (From the ENE at ~ 28.8mph)
G. Location of Maximum Flight Level Wind Inbound: 2 nautical miles (2 statute miles) to the NW (320°) of center fix
H. Minimum Sea Level Pressure: 1010mb (29.83 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 23°C (73°F) at a pressure alt. of 189m (620ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 24°C (75°F) at a pressure alt. of 188m (617ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 21°C (70°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind and Pressure
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 1,500 feet
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 25kts (~ 28.8mph) in the northwest quadrant at 20:16:00Z
Sea Level Pressure Extrapolation From: Below 1,500 feet

Member Since: Posts: Comments:
Quoting HurricaneSwirl:


It's 240 hours out. July 27. I'm pretty sure he has me on ignore too. I can never get him to answer my questions.
Quoting TxHurricanedude11:

about 10 days out...but its a sign activity should pick by the end of the month.
Thanks you guys for anwsering my question.
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00
URNT12 KNHC 172028
VORTEX DATA MESSAGE AL982011
A. 17/20:16:40Z
B. 27 deg 34 min N
078 deg 11 min W
C. NA
D. 24 kt
E. 310 deg 5 nm
F. 060 deg 25 kt
G. 320 deg 2 nm
H. EXTRAP 1010 mb
I. 23 C / 189 m
J. 24 C / 188 m
K. 21 C / NA
L. NA
M. NA
N. 1234 / 01
O. 0.02 / 1 nm
P. AF304 01BBA INVEST OB 14
MAX FL WIND 25 KT NW QUAD 20:16:00Z
SLP EXTRAP FROM BELOW 1500 FT
;
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Quoting HurricaneDean07:
does everyone know how wikapedia is becoming more accurate by getting rid of posts that are inaccurate?
i just posted the latest news about TD 2, and they freaking erased it. stupid wikapedia.

I'm sorry I reverted your section. I am very well aware that we have TD2, however, it is our rules to wait to update until the advisory is issued to not cause confusion to the people who don't know that the ATCF/BTK exists.
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Wow - 400 comments in two hours! going to take a while to catch up
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T.C.F.W.
02L/TD/B/CX
MARK
28.13N/78.11W
Member Since: July 15, 2006 Posts: 178 Comments: 56140
Not saying it will happen but NHC has "taken back" a renumber in ATCF before. Not official untill they issue an advisory.
Member Since: September 23, 2005 Posts: 15 Comments: 11343
Quoting washingtonian115:
I know your probally gonna ignore me.But what time frame is that?


It's 240 hours out. July 27. I'm pretty sure he has me on ignore too. I can never get him to answer my questions.
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what a shame NHC!
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Quoting CaneAddict:


Maybe some rain...Looks to me like it will meander around in its current area of a little bit and then take off NE or NNE towards the NC area.
I say it could get up 65mph.Shear should be lowering,and Sst are already high.Only problem is dry air.
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826. HCW
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3. REMARK: FLIGHT SCHEDULED FOR 18/1800Z WILL CONVERT TO AN
LOW-LEVEL INVEST MISSION IF THE FLIGHT SCHEDULED FOR
17/0600Z IS CANCELLED.


So I guess the mission is still on for 18/06Z, lol.
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824. bwi
If the lat-long grid is aligned correctly on the visible satellite, it looks like the 1010mb low is exactly where you'd expect -- right in the middle of the cloud swirl. And it's hard for me to see from the loop, but it certainly doesn't look like the cloud tops of the thunderstorms in the center are being sheared off. Maybe they're just not high enough, though. The water vapor loop makes it look like the dry air line dropping into central Florida will be disruptive, no?
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Well hello AL02,

Little doubt about notable west winds on circ's S side, as seen in Freeport Bahamas reports...

Somewhat similar with relative high ambient pressure regime, Hurricane Alicia in 1983 was declared a TD when the low fell to 1009 mb... and a TS at 1006 mb...
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Quoting weatherxtreme:
Question now is I guess how strong TD2 will get and where it will head eventually. I guess NE Florida will not see anything out of this now?


Maybe some rain...Looks to me like it will meander around in its current area of a little bit and then take off NE or NNE towards the NC area.
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Quoting CybrTeddy:


Correct, especially if the ECMWF has anything to say about it.
I know your probally gonna ignore me.But what time frame is that?
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Quoting HurricaneDean07:
does everyone know how wikapedia is becoming more accurate by getting rid of posts that are inaccurate?
i just posted the latest news about TD 2, and they freaking erased it. stupid wikapedia.


They were quite right too as well. The official hurricane source for the Public is the NHC, not the NRL Navy site we all use. Once proper advisories are commenced, then the TD 2 info would not be erased.
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Quoting HurricaneDean07:
does everyone know how wikapedia is becoming more accurate by getting rid of posts that are inaccurate?
i just posted the latest news about TD 2, and they freaking erased it. stupid wikapedia.
Do you mean Wikipedia?
Member Since: June 21, 2007 Posts: 10 Comments: 1657
1010.0 mb
(~ 29.83 inHg)
Member Since: July 8, 2005 Posts: 259 Comments: 24576
Question now is I guess how strong TD2 will get and where it will head eventually. I guess NE Florida will not see anything out of this now?
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Japan 1 US 1
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NHC IN TREMS Of DEVLOPMENT

Well least THEY have spell checka'
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Time: 19:55:30Z
Coordinates: 27.5667N 78.2167W
Acft. Static Air Press: 990.9 mb (~ 29.26 inHg)
Acft. Geopotential Hgt: 167 meters (~ 548 feet)
Extrap. Sfc. Press: 1010.1 mb (~ 29.83 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 256° at 3 knots (From the WSW at ~ 3.4 mph)
Air Temp: 23.3°C (~ 73.9°F)
Dew Pt: 21.7°C (~ 71.1°F)
Peak (10s) Flt. Lvl. Wind: 6 knots (~ 6.9 mph)
SFMR Peak (10s) Sfc. Wind: 16 knots (~ 18.4 mph)
SFMR Rain Rate: 4 mm/hr (~ 0.16 in/hr)
(*) Denotes suspect

I think this is probably the COC
Member Since: April 29, 2007 Posts: 0 Comments: 8134
Quoting CaneAddict:
Things in the atlantic should only continue to get more busy for the next few weeks.


Correct, especially if the ECMWF has anything to say about it.
Member Since: July 8, 2005 Posts: 259 Comments: 24576
Quoting clwstmchasr:


I'm eating crow big time on this one.


I thought it would take at least one more day.. I also thought it would take at least one more day for Arlene it was named later that day. Seems like the NHC is a lot less conservative this year.
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Were are shredding blog pages...
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I find TD 2 very similar to another system.

Tropical Storm Cristobal
July 19-23, 2008

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807. ackee
what have we learn from TD#2 models got it wrong and so did the NHC IN TREMS Of DEVLOPMENT lets see if they will get the track right
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does everyone know how wikapedia is becoming more accurate by getting rid of posts that are inaccurate?
i just posted the latest news about TD 2, and they freaking erased it. stupid wikapedia.
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100 weather related posts in 22 minutes!?!

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Things in the atlantic should only continue to get more busy for the next few weeks.
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98L Floater - RGB Color Infrared Loop
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The center is about 128 miles from the coast if you travel due west on the same longitude of the center.
Member Since: June 29, 2009 Posts: 13 Comments: 5315

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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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