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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Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 17th day of the month at 18:33Z
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: 07

Mandatory Data...

Observation Time: Sunday, 18:32Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 28.1N 78.3W
Location: 142 miles (229 km) to the E (90°) from Melbourne, FL, USA.
Turbulence: Light
Conditions Along Flight Route: In the clear
Pressure Altitude: 210 meters
Flight Level Wind: From 100° at 31 knots (From the E at ~ 35.6 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 22°C
Flight Level Dew Point: 18°C
Weather (within 30 nautical miles): Thunderstorm(s)
Mean Sea Level Pressure (MSLP): 1016 mb (extrapolated)

Optional Data...

Estimated Surface Wind: From 80° at 30 knots (From the E at ~ 34.5 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 31 knots (~ 35.7mph)
Member Since: Posts: Comments:
Quoting nymore:
Going from bad to worse for Eastern ND and western Minnesota tornado watch issued with mod. to high values. Tornadoes F2 and above moderate, severe wind high, 65 knts moderate, 2" plus hail high and these numbers have been rising all day



TORNADO WARNING BISMARCK ND - KBIS 111 PM CDT SUN JUL 17 2011
TORNADO WARNING EASTERN ND/GRAND FORKS ND - KFGF 111 PM CDT SUN JUL 17 2011
SVR T-STORM WARNING BISMARCK ND - KBIS 1244 PM CDT SUN JUL 17 2011
TORNADO WARNING EASTERN ND/GRAND FORKS ND - KFGF 1233 PM CDT SUN JUL 17 2011
TORNADO WARNING BISMARCK ND - KBIS 1213 PM CDT SUN JUL 17 2011
SVR T-STORM WARNING EASTERN ND/GRAND FORKS ND - KFGF 1145 AM CDT SUN JUL 17 2011
TORNADO WARNING BISMARCK ND - KBIS 1126 AM CDT SUN JUL 17 2011
TORNADO WARNING BISMARCK ND - KBIS 1057 AM CDT SUN JUL 17 2011
TORNADO WARNING BISMARCK ND - KBIS 1025 AM CDT SUN JUL 17 2011
SVR T-STORM WARNING BISMARCK ND - KBIS 1013 AM CDT SUN JUL 17 2011
Member Since: August 22, 2008 Posts: 12 Comments: 6010
450. JLPR2
Well now, we got TD winds

SFMR Peak (10s) Sfc. Wind: 31 knots (~ 35.6 mph)

But we need proof of the LLC existence before saying anything else.
Member Since: Posts: Comments:
449. Skyepony (Mod)
Quoting Patrap:
Flight,


..switch to Omni bravo on 212 for the pkg..


skye,check out the Humor in the STS-135 Execute pkg for today

Flight Day 10 (1.1 Mb PDF)



That was funny..


Not seeing any west winds there yet.
Member Since: Posts: Comments:
Quoting CybrTeddy:
Rick Knabb's latest post on this..
A low that developed in association with a frontal boundary is just off the east coast of central Florida and has been producing some concentrated thunderstorm activity since Saturday evening. Upper-level winds are not especially conducive for significant development, and forecast models do not suggest much development will occur, but the system has become more organized today, and a tropical depression could still form within the next day or two as the low generally meanders near east-central Florida.

I'm not sure what he's talking about with the upper-level winds being unfavorable, NHC says they're getting there.


He doesn't say they're unfavorable, just not "especially conducive". He even acknowledges that it has become better organized and could become a tropical depression. I'd say that's reasonable.
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This is not a TD right now, give it about 24-48 hours though and I think we will have one

40% right on the ball, pressures still too high even in an area of higher pressures.
Member Since: Posts: Comments:
18:31:30Z 28.050N 78.333W 981.3 mb
(~ 28.98 inHg) 299 meters
(~ 981 feet) 1015.6 mb
(~ 29.99 inHg) - From 95° at 27 knots
(From the E at ~ 31.0 mph) 21.5°C
(~ 70.7°F) 18.4°C
(~ 65.1°F) 28 knots
(~ 32.2 mph) 31 knots
(~ 35.6 mph) 1 mm/hr
(~ 0.04 in/hr) 29.9 knots (~ 34.4 mph)
110.7%
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Recon finding 25 knot winds...
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Going from bad to worse for Eastern ND and western Minnesota tornado watch issued with mod. to high values. Tornadoes F2 and above moderate, severe wind high, 65 knts moderate, 2" plus hail high and these numbers have been rising all day
Member Since: Posts: Comments:
MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT SUN JUL 17 2011

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA
AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W.

GULF OF MEXICO...
WEAK PRES PATTERN ACROSS THE AREA WITH RATHER TRANQUIL
CONDITIONS ACROSS MUCH OF THE GULF. THE ONLY EXCEPTION BEING THE
SW GULF WHERE ELY WINDS 15-20 KT TONIGHT WILL DECREASE TO BELOW
20 KT MON. BUOYS AND LATEST SEA STATE ANALYSIS SHOW THAT SEAS
ARE IN 1-2 FT RANGE EXCEPT ACROSS THE SW ZONE WHERE BUOY 42055
IS REPORTING 4-6 FT. THE RIDGE WILL BE REINFORCED FROM STRONGER
HIGH PRES BUILDING SW FROM THE U.S. MID-ATLC COAST THROUGH MON
THEN DRIFT S TO ALONG 27N WED WITH MOSTLY LIGHT WINDS ACROSS THE
ENTIRE AREA. THE RIDGE SHIFTS TO THE E FRI AND SLY RETURN FLOW
WINDS INCREASE TO 15-20 KT OVER THE FAR NW GULF FRI.

SW N ATLC...
A 1014 MB LOW PRES IS E OF THE CENTRAL FLORIDA COAST CENTERED
NEAR 28N79W. THE LOW COULD POSSIBLY DEVELOP INTO A TROPICAL
CYCLONE WITHIN THE NEXT 48 HOURS. NUMEROUS SHOWERS AND TSTMS ARE
WITHIN 160 NM E AND SE OF THE LOW PRES. THE LOW PRES WILL REMAIN
NEARLY STATIONARY OVER THE NEXT 24-48 HOURS. A RIDGE WILL BUILD
WESTWARD ALONG 27N WED THROUGH FRI WITH LIGHT SW WINDS N OF THE
RIDGE AND 10-15 KT ELY WIND S OF THE RIDGE.
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Quoting CybrTeddy:


Remember, all the models have failed to develop it as far is as has because they have constantly and consistently not analysed a surface low in the initial conditions.
But still gives reason for caution, along with the rather high pressure we mentioned earlier.

ON recon obs., anybody checked RandyB's blog recently?

Also glad to see Drakoen in the blog... what's ur take on this?

Member Since: October 25, 2005 Posts: 19 Comments: 22734
In the absense of aircraft recon, the is the closest bouy out there 125 miles east of Cape Kennedy:

Station 41010
NDBC
Location: 28.906N 78.471W
Conditions as of:
Sun, 17 Jul 2011 17:50:00 UTC
Winds: E (80°) at 11.7 kt gusting to 15.5 ktSignificant Wave Height: 6.2 ft
Dominant Wave Period: 8 sec
Atmospheric Pressure: 30.04 in and steadyAir Temperature
: 79.7 F
Water Temperature: 83.3 F

Same approximate windspeeds as yesterday evening but the pressure is steady now as opposed to still rising yesterday but not dropping yet at this particular location.
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levi do you think there is a chance of this thing by florida going into the gulf of mexico, like some of the earlier models showed?
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Flight,


..switch to Omni bravo on 212 for the pkg..


skye,check out the Humor in the STS-135 Execute pkg for today

Flight Day 10 (1.1 Mb PDF)

Member Since: July 3, 2005 Posts: 428 Comments: 129902
Dry air intrusion from the north.
Member Since: Posts: Comments:
435. Skyepony (Mod)
Quoting Levi32:
Pressures are rising just north of the system at 1017mb now. That is one of the reasons to be skeptical of immediate development




It's not firing convection from the center now like it started to do earlier either.
Member Since: Posts: Comments:
Quoting CybrTeddy:
Rick Knabb's latest post on this..
A low that developed in association with a frontal boundary is just off the east coast of central Florida and has been producing some concentrated thunderstorm activity since Saturday evening. Upper-level winds are not especially conducive for significant development, and forecast models do not suggest much development will occur, but the system has become more organized today, and a tropical depression could still form within the next day or two as the low generally meanders near east-central Florida.

I'm not sure what he's talking about with the upper-level winds being unfavorable, NHC says they're getting there.




whats he smoking wind shear is at lest 5 too 10kt
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Light wispy clouds are indicative of a mid level circulation. Need to see some heavy convection.
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Levi, 98L itself seems to be embedded in a area of high surface pressures.. maybe that's why surface pressures are only 1014?
Member Since: July 8, 2005 Posts: 259 Comments: 24576
Quoting Levi32:


Yeah, all rain-flagged. WindSat does that a lot. The rainflagged barbs shouldn't be trusted, and even WindSat in general doesn't do so great with accurate wind speed as opposed to ASCAT.


Just noticed that.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Rick Knabb's latest post on this..
A low that developed in association with a frontal boundary is just off the east coast of central Florida and has been producing some concentrated thunderstorm activity since Saturday evening. Upper-level winds are not especially conducive for significant development, and forecast models do not suggest much development will occur, but the system has become more organized today, and a tropical depression could still form within the next day or two as the low generally meanders near east-central Florida.

I'm not sure what he's talking about with the upper-level winds being unfavorable, NHC says they're getting there.
Member Since: July 8, 2005 Posts: 259 Comments: 24576
Quoting cchsweatherman:


Yet another sign of a building ridge north of Invest 98L.



wish means its going too the gulf
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting Levi32:
Pressures are rising just north of the system at 1017mb now. That is one of the reasons to be skeptical of immediate development



Yet another sign of a building ridge north of Invest 98L.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Quoting islander101010:
nhc official has just red carded the beast east of cape kennedy


huh?
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Member Since: June 9, 2007 Posts: 4 Comments: 15950
Quoting Tazmanian:
i sure we have seen TD and TS at this MB be for


We have, but have they had Frontal Lows attached/close by/near them
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424. Skyepony (Mod)
The ASCAT was near 2 hrs old, Windsat over 6 hrs. Nice to have recon going in.
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Quoting cchsweatherman:


Not so sure about that. WINDSAT showed numerous gale force winds this morning surrounding the east side of the system.


Yeah, all rain-flagged. WindSat does that a lot. The rainflagged barbs shouldn't be trusted, and even WindSat in general doesn't do so great with accurate wind speed as opposed to ASCAT.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Pressures are rising just north of the system at 1017mb now. That is one of the reasons to be skeptical of immediate development

Member Since: November 24, 2005 Posts: 635 Comments: 26700
nhc official has just red or is that orange carded the beast east of cape kennedy
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i sure we have seen TD and TS at this MB be for
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting neutralenso:
Until pressures drop the percentage will only go up a little or stay the same. eventually 98l will move northward towards the carolinas


Still don't think N
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Afternoon everyone. COC is really tightening down in those last couple of sat frames. Impressive improvement since last night.
Member Since: December 18, 2006 Posts: 7 Comments: 2687
Quoting Levi32:


There's a difference between a well-defined circulation and a strong circulation. It's well-defined in the sense that observations suggest it may be closed, or nearly so, but it is very weak. The winds out there are not that strong.


Not so sure about that. WINDSAT showed numerous gale force winds this morning surrounding the east side of the system.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Quoting HarryMc:


Click the Live Recon Data in Google Earth to download the KMZ file then load that into Google Earth


Got it. Thanks.
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Quoting washingaway:


I agree


Me too. Looking at the recon feed and the
ASCAT - it looks like 98L's circulation isn't properly developed yet, it seems like the South East quadrant hasn't got its act together, however that may be because of the frontal low that's right next to it.

Photobucket
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Time: 18:11:00Z
Coordinates: 28.0333N 79.45W
Acft. Static Air Press: 981.1 mb (~ 28.97 inHg)
Acft. Geopotential Hgt: 317 meters (~ 1,040 feet)
Extrap. Sfc. Press: 1017.3 mb (~ 30.04 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 40° at 16 knots (From the NE at ~ 18.4 mph)
Air Temp: 23.0°C (~ 73.4°F)
Dew Pt: 16.3°C (~ 61.3°F)
Peak (10s) Flt. Lvl. Wind: 17 knots (~ 19.5 mph)
SFMR Peak (10s) Sfc. Wind: 23 knots (~ 26.4 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)
(*) Denotes suspect data
Member Since: April 29, 2007 Posts: 0 Comments: 8134
Quoting Levi32:


There's a difference between a well-defined circulation and a strong circulation. It's well-defined in the sense that observations suggest it may be closed, but it is very weak. The winds out there are not that strong.


agreed, I think this will get there, but its not there yet
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Quoting Hurricanes101:
pressures still very high out there, and they are dropping very little

probably the reason for the 40%
Was just about to say that. Reports of pressures running 1016mb-1017mb. Not much action in terms of low pressure, but a closed surface circulation is trying to form at the surface.
Member Since: October 28, 2006 Posts: 57 Comments: 30832
Quoting cchsweatherman:


Not sure what you're seeing. All surface observations in the area show a pretty well defined circulation at the surface.


There's a difference between a well-defined circulation and a strong circulation. It's well-defined in the sense that observations suggest it may be closed, or nearly so, but it is very weak. The winds out there are not that strong.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Real data any minute
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see the clouds shooting west out of the cir. area?
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pressures still very high out there, and they are dropping very little

probably the reason for the 40%
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Quoting BahaHurican:
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...


Remember, all the models have failed to develop it as far is as has because they have constantly and consistently not analysed a surface low in the initial conditions.
Member Since: July 8, 2005 Posts: 259 Comments: 24576
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.


Not sure what you're seeing. All surface observations in the area show a pretty well defined circulation at the surface. In addition, RGB satellite imagery shows low level clouds definitely wrapping around the system.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Quoting HarryMc:


Click the Live Recon Data in Google Earth to download the KMZ file then load that into Google Earth


OOPS.. Hit post too soon... link is
http://tropicalatlantic.com/recon/
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POSS T.C.F.A.
INV98/XX/L
MARK
27.87N/77.97W
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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: 22734

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