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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552. 7544
7:22 PM GMT on July 17, 2011
Quoting jasonweatherman2011:
FISH STORM!!!!!


tada tada very typical lol
Member Since: May 6, 2007 Posts: 0 Comments: 6879
551. CaneHunter031472
7:22 PM GMT on July 17, 2011
Forgive my ignorance but I really think that this is already a TD if not a TS. What is the NHC waiting for?
Member Since: August 1, 2007 Posts: 0 Comments: 206
Quoting ackee:
when do u think 98L will be a TD

A 5PM
b 11pm
c 24 hours
D 48 HOURS
E 72 HOURS

b or c
Member Since: Posts: Comments:
Hurricane Hunters running their classic X pattern now. So far, so good this mission with several solid tropical depression force winds and even a tropical storm force wind reading. Also wind pattern so far so good for a closed circulation.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Quoting oceanbug:
In the suburbs north of Chicago we have a heat index of 92 and dew point of 69, along with an Ozone Action Day. It's not noon yet, so I expect the numbers will get worse. Don't want to catch up to Fargo, though.

I hope 98L (or whatever it becomes) stays away from the GOM! That would be really bad with those SST.

There's a blob off Apalachicola that bears watching.

You are lucky, the humidity in Fargo is unreal. I never imagined it could ever get so humid, I just about suffocated when I took out the garbage this morning!
Member Since: August 29, 2008 Posts: 0 Comments: 324
So Ma-on not handling that EWRC too well.... hope it keeps falling apart before it gets to Japan...

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546. 7544
looks like we may have some west winds maybe up to td sonner than 24hours imo
Member Since: May 6, 2007 Posts: 0 Comments: 6879
544. 7544
is the high pressure to the north suppose make 98l go west i dont see this it might just shoot ne right
Member Since: May 6, 2007 Posts: 0 Comments: 6879
542. xcool
TS coming soon
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Ackee, b(depending on how it looks after DMIN) or C(my safer Choice)
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting ackee:
when do u think 98L will be a TD

A 5PM
b 11pm
c 24 hours
D 48 HOURS
E 72 HOURS

c
Member Since: Posts: Comments:
Time: 18:48:00Z
Coordinates: 28.25N 77.5833W
Acft. Static Air Press: 998.9 mb (~ 29.50 inHg)
Acft. Geopotential Hgt: 149 meters (~ 489 feet)
Extrap. Sfc. Press: 1016.3 mb (~ 30.01 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 105° at 30 knots (From the ESE at ~ 34.5 mph)
Air Temp: 21.7°C (~ 71.1°F)
Dew Pt: 18.2°C (~ 64.8°F)
Peak (10s) Flt. Lvl. Wind: 32 knots (~ 36.8 mph)
SFMR Peak (10s) Sfc. Wind: 33 knots (~ 37.9 mph)
SFMR Rain Rate: 3 mm/hr (~ 0.12 in/hr)
Member Since: April 29, 2007 Posts: 0 Comments: 8161
I'll go with C. Only because the NHC seems to be conservative.
Member Since: March 10, 2006 Posts: 0 Comments: 11378
The most interesting thing to see will be how defined the circulation is. Recon plane north of the centre but just turned, moving back to the south.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting Patrap:


In the Tropics and esp the GOM, I never rule out a lingering Low with convection heading to warm ,tepid SST's.

The Atmosphere has a LOT of extra "Oomph" to offer as it trends towards chaos given a opportunity this time of year forward thru October and beyond.


True, the models don't always catch everything. Best to keep an eye out.
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Losing some convective bones heading into D-min side of things.


Member Since: July 3, 2005 Posts: 432 Comments: 131964
Quoting ackee:
when do u think 98L will be a TD

A 5PM
b 11pm
c 24 hours
D 48 HOURS
E 72 HOURS


B or C ackee.
Member Since: Posts: Comments:
The invest looks TD-ish this afternoon.

Looks like Ma-On is starting to weaken. It's CDO is falling apart.

Quoting nymore:
Heat index in Fargo ND is 109 with an 81 degree dewpoint


I don't even dare go outside today. ICK!!!
Member Since: August 29, 2008 Posts: 0 Comments: 324
531. wpb
and west winds? may have to wait for the se pass of the flight
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Quoting HurricaneDean07:
Invest 98L:
Winds: 35 mph Pressure: 1015 MB
Coordinates: 77.6 W ; 27.8 N Movement: Stationary

Comments: Invest 98L is not moving much, and pressures are not falling. Though recon has found Tropical depression force winds, and a weak circulation is forming. Development won't occur for the next 6 to 12 Hours, unless further organization is evident. There is a High, 60%, Chance of formation in the next 48 Hours.


Pressure is dropping slowly.
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Quoting ackee:
when do u think 98L will be a TD

A 5PM
b 11pm
c 24 hours
D 48 HOURS
E 72 HOURS


C
Member Since: May 17, 2009 Posts: 2 Comments: 907
It appears have to issue new update to keep it up to date...

Invest 98L:
Winds: 35 mph Pressure: 1013 MB
Coordinates: 77.6 W ; 27.8 N Movement: Stationary

Comments: Invest 98L is not moving much, and pressures are not falling. Though recon has found Tropical depression force winds, and a weak circulation is forming. Development won't occur for the next 6 to 12 Hours, unless further organization is evident. There is a High, 60%, Chance of formation in the next 48 Hours.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
FlDewey,

Cool. I was there last weekend. Thought it looked familiar... I usually go out to the beach at 2nd and A1A in Melbourne Beach - just south of that.
Member Since: March 10, 2006 Posts: 0 Comments: 11378
526. ackee
when do u think 98L will be a TD

A 5PM
b 11pm
c 24 hours
D 48 HOURS
E 72 HOURS
Member Since: July 15, 2008 Posts: 0 Comments: 1382
Wow, last few hours has really gotten a nice presentation on radar. If this continues, will be a TD soon.
Member Since: Posts: Comments:
Quoting PakaSurvivor:
Pat.

Do you think something may form from the weather between my location and your?


In the Tropics and esp the GOM, I never rule out a lingering Low with convection heading to warm ,tepid SST's.

The Atmosphere has a LOT of extra "Oomph" to offer as it trends towards chaos given a opportunity this time of year forward thru October and beyond.
Member Since: July 3, 2005 Posts: 432 Comments: 131964
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 19:00:02 GMT
Member Since: July 15, 2006 Posts: 187 Comments: 58170
Quoting Dakster:
I would not think that NHC would do a STWO for a 70% chance...


They might if they think there's a reasonable chance they'll initiate advisories in the next 6-12 hours. They may not want to wait until 8 p.m. to tease the possibility of a tropical storm watch or warning in the immediate future.
Member Since: Posts: Comments:
Quoting clwstmchasr:


Your data must be more updated than what I am seeing on Google Earth.


AL, 98, 2011071718, , BEST, 0, 279N, 782W, 30, 1013, DB.
Member Since: Posts: Comments:
Invest 98L:
Winds: 35 mph Pressure: 1015 MB
Coordinates: 77.6 W ; 27.8 N Movement: Stationary

Comments: Invest 98L is not moving much, and pressures are not falling. Though recon has found Tropical depression force winds, and a weak circulation is forming. Development won't occur for the next 6 to 12 Hours, unless further organization is evident. There is a High, 60%, Chance of formation in the next 48 Hours.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting neutralenso:

Levi if you wanted to call it a td whats the highest pressure 98L would have to have??


There is no pressure requirement for a tropical depression. The pressure relative to the surrounding environment, though the absolute pressure is too, as it determines how easy it is to get air to rise. Here, with a ~1018mb environment around it, I'd like to see it get down below 1012mb, perhaps down to around 1010mb. However, that doesn't mean it can't become a tropical depression at a higher pressure than that.
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Quoting neutralenso:

Levi if you wanted to call it a td whats the highest pressure 98L would have to have??


It's rare to see a depression with anything higher than 1012MB.
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Quoting MysteryMeat:
I'm thinking red circle but no depression declaration if they do a STWO. Let's call it 70 percent with a "reconnaissance aircraft found the system has gotten better organized, but surface pressures are still high in the region" and an "interests along the Southeast coast from Florida to the Carolina should closely monitor this system, as tropical storm watches or warnings may be required"

Wonder why they require that a system be designated a TD before they can issue watches? Seems like a tropical storm watch wouldn't be out of line given the low's location and potential development.


Rick Knabb is gonna eat some crow.
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98L
Member Since: May 17, 2009 Posts: 2 Comments: 907
I would not think that NHC would do a STWO for a 70% chance...
Member Since: March 10, 2006 Posts: 0 Comments: 11378
Quoting neutralenso:
The only problem with 98L right now is that its getting some dry air in the NW quadrant but that should decrease in about 6 hours
I say your kinda right, posts #436 #456, I just don't see the circulation "walling off" the dry air with significant outflow within 12 to 18 hrs to start real intensification.
Member Since: Posts: Comments:
I'm thinking red circle but no depression declaration if they do a STWO. Let's call it 70 percent with a "reconnaissance aircraft found the system has gotten better organized, but surface pressures are still high in the region" and an "interests along the Southeast coast from Florida to the Carolina should closely monitor this system, as tropical storm watches or warnings may be required"

Wonder why they require that a system be designated a TD before they can issue watches? Seems like a tropical storm watch wouldn't be out of line given the low's location and potential development.
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We may see a Tropical Depression tonight.. Heck if they can classify that little naked swirl TD2 from last year, then they should be able to classify this the REAL TD2
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822

WHXX01 KWBC 171846

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS NATIONAL HURRICANE CENTER MIAMI FL

1846 UTC SUN JUL 17 2011



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL982011) 20110717 1800 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

110717 1800 110718 0600 110718 1800 110719 0600



LAT LON LAT LON LAT LON LAT LON

BAMS 27.9N 78.2W 27.8N 78.7W 27.9N 79.3W 28.1N 79.2W

BAMD 27.9N 78.2W 27.4N 78.4W 27.2N 78.6W 27.2N 78.9W

BAMM 27.9N 78.2W 27.6N 78.6W 27.6N 79.0W 27.6N 79.1W

LBAR 27.9N 78.2W 27.7N 78.5W 28.1N 79.2W 28.8N 79.9W

SHIP 30KTS 39KTS 46KTS 49KTS

DSHP 30KTS 39KTS 46KTS 49KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

110719 1800 110720 1800 110721 1800 110722 1800



LAT LON LAT LON LAT LON LAT LON

BAMS 28.4N 78.8W 29.3N 77.0W 30.5N 74.3W 31.7N 70.8W

BAMD 27.4N 79.2W 27.9N 80.0W 28.2N 81.3W 28.7N 83.9W

BAMM 27.9N 79.0W 28.7N 77.6W 29.2N 76.0W 30.1N 74.5W

LBAR 29.8N 80.3W 30.7N 80.7W 32.1N 79.7W 33.9N 78.6W

SHIP 50KTS 50KTS 44KTS 37KTS

DSHP 50KTS 50KTS 44KTS 37KTS



...INITIAL CONDITIONS...

LATCUR = 27.9N LONCUR = 78.2W DIRCUR = 155DEG SPDCUR = 3KT

LATM12 = 28.8N LONM12 = 78.5W DIRM12 = 151DEG SPDM12 = 6KT

LATM24 = 29.8N LONM24 = 79.1W

WNDCUR = 30KT RMAXWD = 50NM WNDM12 = 20KT

CENPRS = 1013MB OUTPRS = 1016MB OUTRAD = 150NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN
Member Since: July 15, 2006 Posts: 187 Comments: 58170
Dewey where was that taken??
Member Since: March 10, 2006 Posts: 0 Comments: 11378
Quoting CaneAddict:
98L continues to show signs of organization...I would not be surprised to see a depression after the recon is done. Thunderstorm activity is becoming more and more concentrated near the center and overall is looking impressive.


Welcome CaneAddict! Haven't seen you on in a while.
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Looks like 98L may come to visit.... lol not that we can't use the rain...
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Pat.

Do you think something may form from the weather between my location and your?
Member Since: September 20, 2010 Posts: 0 Comments: 235
502. xcool
98L MOVE TO SSE AT 10Mph jmo
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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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