Tropical Storm Bret forms near the northern Bahamas

By: Dr. Jeff Masters , 2:57 PM GMT on July 18, 2011

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Tropical Storm Bret formed last night over the Northwestern Bahama Islands, and is expected to bring heavy rains of 2 - 4 inches to the northernmost Bahama Islands today and Tuesday, as the storm drifts slowly to the north-northeast. Bret's formation date of July 17 is two weeks ahead of the usual formation date for the Atlantic's second storm of the season, which is August 1. The latest data from the Hurricane Hunters, taken between 4 - 5am EDT, showed a 100-mile wide area of tropical storm-force winds in excess of 39 mph affecting only the northernmost Bahama Islands--the Abacos. A personal weather station on Great Abaco Island recorded a wind gust of 48 mph at 12:23 am today. Satellite imagery shows that Bret has not improved in organization this morning, thanks to dry air to the northwest that has been blown into the storm's core by upper-level northwesterly winds. long-range radar out of Melbourne, Florida shows that Bret is currently dumping very little rain over the Bahamas, and one thin rain band from the storm is affecting the Florida East Coast with rainfall amounts less than a quarter inch. Wind shear is a moderate 10 - 15 knots, and sea surface temperatures are 28 - 29°C, which is 2°C above the 26.5°C threshold needed to support a tropical storm.


Figure 1. Morning satellite image of Tropical Storm Bret.

Forecast for Bret
None of the models develop Bret into a hurricane. though the GFDL model has it coming close. Given the current ragged appearance of the storm, plus the forecast by the SHIPS model that wind shear will rise to the high range, 20 - 25 knots, by Tuesday morning, it is unlikely Bret will become a hurricane. NHC is giving Bret a 22% chance of developing into a hurricane by Tuesday.

Steering currents are weak off the coast of Florida, and Bret can be expected to move slowly near 5 mph through Tuesday, before the storm gets caught in a trough of low pressure and lifted northeastwards out to sea. It currently appears that the only land areas that will be affected by Bret will be the northernmost Bahama Islands, today and Tuesday.

None of the reliable models predict tropical cyclone development over the remainder of the Atlantic through July 25.


Figure 2. Visible satellite image of Typhoon Ma-on from NASA's Aqua satellite taken July 18, 2011. Image credit: NASA.

Weakened Typhoon Ma-on headed towards Japan
Typhoon Ma-on has weakened to a large Category 1 storm as it heads towards Japan, and is expected to brush the east coast of the main island of Honshu on Tuesday. The typhoon weakened 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. Ma-on was expected to intensify once this process completed, but the eyewall replacement process significantly disrupted the storm, and it is unlikely Ma-on will be able to recover. This is good news for Japan, since Ma-on is a huge storm with tropical-storm force winds that extend 225 miles north of the center.

Jeff Masters

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It's spun up quickly and has the right environment, therefore it can spin down rapidly and dissipate at any time once the environment deterioates. If conditions aren't good down the road this thing COULD dissapear before Bermuda
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Wow, has anyone else noticed something? This is the second year in a row where the first storm of the season is a large monsoonal-type cyclone, while the second is small and compact.
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Was under a 30% chance of damaging winds earlier. SPC knocked that down quite a bit and local forecast discussion from Taunton MA is much more conservative since the morning. They were talking about supercells and an isolated tornado earlier, and this is what i'm looking at now. Maybe things will pop all of a sudden.



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Quoting Dakster:
PATRAP - I knew you wouldn't be able to resist the Hot Towers video for too long... All we need now is a pinhole eye alert...



Me tinks dat may be coming vary soon,
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.......Squeeze? Tempted?
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PATRAP - I knew you wouldn't be able to resist the Hot Towers video for too long... All we need now is a pinhole eye alert...
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Quoting Levi32:


You mean how it's being squeezed? The small size is in part due to the squeeze.
I don't *think* it is....
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This sure is an interesting system. Looking at the surrounding environment, Bret is not exactly in a very conducive environment. Divergence to the NW is poor and convergence and competing vorticity exists all along the front which is to its still a part of. This seems to be containing Bret and keeping him from growing too large. Interestingly enough, however, the tiny size (and low shear) is what is allowing it to continue to intensify fairly rapid, despite the conditions already mentioned.
Member Since: August 24, 2010 Posts: 19 Comments: 4358
Dora is organizing quickly.
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Quoting RitaEvac:
I think being spun off as a small vorticy with the frontal boundary has something to do with it being so small. Since being over warm water in the tropics it turned into a storm and able to sustain it's vort self.
Correct.
Quoting ProgressivePulse:



Is being sandwiched between to high pressure systems obstructing Bret's ability to expand and grow larger.

No, I don't think so.
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02L/H/B/C1
MARK
28.25N/76.98W
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Quoting Levi32:


You mean how it's being squeezed? The small size is in part due to the squeeze.


Yes that is what I was referring to... The squeeze
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According to recon., Bret has drifted east since the 2:00 pm position.
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04E/TS/D/CX
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Quoting Skyepony:


I agree unless they get another pass in & find higher.


Don't think they will get another pass since the advisory is being put together now, thats why I went with what I think would be a high end, 60 kt. Also since they got burned yesterday finding higher winds just after the advisory.
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Quoting RitaEvac:
I think being spun off as a small vorticy with the frontal boundary has something to do with it being so small. Since being over warm water in the tropics it turned into a storm and able to sustain it's vort self.



I think your right and I also think that if Bret were and averaged sized cyclone that it would have suffered a much different fate.
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Quoting earthlydragonfly:


Take a look at post 602



You mean how it's being squeezed? The small size is in part due to the squeeze.
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I think being spun off as a small vorticy with the frontal boundary has something to do with it being so small. Since being over warm water in the tropics it turned into a storm and able to sustain it's vort self.
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One thing that would make me really depressed is if a hurricane with very heavy rainfall heading toward TX dissipated in the Gulf while 200 miles away from TX.
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662. Skyepony (Mod)
Quoting nrtiwlnvragn:


Flight level at that time ~60 kt
SFMR at that time 40-47 kt

193800 2757N 07655W 8440 01498 0015 +191 +151 231059 061 046 001 03
193830 2756N 07654W 8425 01521 0028 +182 +153 231060 061 047 000 03
193900 2755N 07653W 8430 01522 0038 +180 +152 229061 062 047 000 03
193930 2754N 07651W 8425 01534 0047 +177 +150 229060 060 044 000 03
194000 2753N 07650W 8428 01540 0058 +173 +150 230059 060 042 001 00
194030 2752N 07649W 8430 01543 0061 +186 +123 232060 060 041 001 00
194100 2751N 07647W 8422 01559 0072 +178 +124 231056 058 040 000 03
194130 2749N 07646W 8429 01557 0079 +176 +121 232055 055 038 001 03


Could see them going with 60 kt at 5 PM.


I agree unless they get another pass in & find higher.
Member Since: August 10, 2005 Posts: 209 Comments: 39113
Quoting Levi32:


I'm not sure that I understand what you mean.



Is being sandwiched between to high pressure systems obstructing Bret's ability to expand and grow larger.

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BDA i was thinking the exact same thing
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Quoting RitaEvac:
Florida may never recover, since Bret formed throwing in dry air on the back side onto FL, might never return to the wet season, that would be a nightmare
Florida has been doing OK with rain recently, i feel with a very busy tropical season coming the Southeastern and Eastern U.S. will get plenty of rain, not so sure about the Texas area though? I think the drought over Texas would just dry up any tropical system
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Quoting Levi32:


I'm not sure that I understand what you mean.


Take a look at post 602

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Looks better with each passing frame. The thunderstorms around the core of the system grow taller and wider each frame. Bret is going to push hurricane status before it's over.

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Quoting Levi32:


No. It is a very tight system so winds may be upgraded at the 5pm advisory, but 998mb isn't going to give us a hurricane.
Thanks for that Levi.it will be interesting to see what will be the offical report from the NHC
Member Since: August 14, 2010 Posts: 10 Comments: 17658
655. BDAwx
Could the shallow nature of the convection have anything to do with the flight level winds being lower than surface winds?
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So here's my Unofficial Advisory:
Tropical Storm Bret:
Maximum Winds: 65 Mph
Minimum Pressure: 998 MB
Moving NNE at 2 Mph
Coordinates: 28.1 N ; 77 W
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Quoting Skyepony:
Dropsonde Location: Dropped in maximum wind band.

Splash Location: 27.94N 76.86W
Splash Time: 19:40Z

Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1004mb (29.65 inHg) Sea Level (Surface) 25.0°C (77.0°F) 23.7°C (74.7°F) 210° (from the SSW) 55 knots (63 mph)
1000mb 37m (121 ft) 24.6°C (76.3°F) 23.6°C (74.5°F) 210° (from the SSW) 55 knots (63 mph)
925mb 719m (2,359 ft) 21.0°C (69.8°F) 20.2°C (68.4°F) 230° (from the SW) 58 knots (67 mph)
850mb 1,452m (4,764 ft) 19.0°C (66.2°F) 16.6°C (61.9°F) 230° (from the SW) 61 knots (70 mph)


Flight level at that time ~60 kt
SFMR at that time 40-47 kt

193800 2757N 07655W 8440 01498 0015 +191 +151 231059 061 046 001 03
193830 2756N 07654W 8425 01521 0028 +182 +153 231060 061 047 000 03
193900 2755N 07653W 8430 01522 0038 +180 +152 229061 062 047 000 03
193930 2754N 07651W 8425 01534 0047 +177 +150 229060 060 044 000 03
194000 2753N 07650W 8428 01540 0058 +173 +150 230059 060 042 001 00
194030 2752N 07649W 8430 01543 0061 +186 +123 232060 060 041 001 00
194100 2751N 07647W 8422 01559 0072 +178 +124 231056 058 040 000 03
194130 2749N 07646W 8429 01557 0079 +176 +121 232055 055 038 001 03


Could see them going with 60 kt at 5 PM.
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Product: Air Force Temp Drop (Dropsonde) Message (UZNT13 KNHC)
Transmitted: 18th day of the month at 20:00Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 307)
Storm Number: 02
Storm Name: Bret (flight in the North Atlantic basin)
Mission Number: 3
Observation Number: 06

Part A...

Date: Near the closest hour of 20Z on the 18th day of the month
Highest Mandatory Level For Which Wind Was Reported: 850mb
Coordinates: 27.9N 76.9W
Location: 198 miles (318 km) to the N (8°) from Nassau, Bahamas.
Marsden Square: 080 (About)

Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1004mb (29.65 inHg) Sea Level (Surface) 25.0°C (77.0°F) 23.7°C (74.7°F) 210° (from the SSW) 55 knots (63 mph)
1000mb 37m (121 ft) 24.6°C (76.3°F) 23.6°C (74.5°F) 210° (from the SSW) 55 knots (63 mph)
925mb 719m (2,359 ft) 21.0°C (69.8°F) 20.2°C (68.4°F) 230° (from the SW) 58 knots (67 mph)
850mb 1,452m (4,764 ft) 19.0°C (66.2°F) 16.6°C (61.9°F) 230° (from the SW) 61 knots (70 mph)

Information About Radiosonde:
- Launch Time: 19:38Z
- About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction.

Remarks Section...

Dropsonde Location: Dropped in maximum wind band.

Splash Location: 27.94N 76.86W
Splash Time: 19:40Z

Release Location: 27.92N 76.88W
Release Time: 19:38:53Z

Splash Location: 27.94N 76.86W
Splash Time: 19:40:40Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):
- Wind Direction: 220° (from the SW)
- Wind Speed: 58 knots (67 mph)

Deep Layer Mean Wind (average wind over the depth of the sounding):
- Wind Direction: 225° (from the SW)
- Wind Speed: 58 knots (67 mph)
- Depth of Sounding: From 843mb to 1003mb

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: 215° (from the SW)
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Courtesy: NASA/Goddard Space Flight Center Scientific Visualization Studio

'Towers in the Tempest' is a narrated animation that explains recent scientific insights into how hurricanes intensify. This intensification can be caused by a phenomenon called a 'hot tower'. For the first time, research meteorologists have run complex simulations using a very fine temporal resolution of 3 minutes. Combining this simulation data with satellite observations enables detailed study of 'hot towers'. The science of 'hot towers' is described using: observed hurricane data from a satellite, descriptive illustrations, and volumetric visualizations of simulation data. The first section of the animation shows actual data from Hurricane Bonnie observed by NASA's Tropical Rainfall Measuring Mission (TRMM) spacecraft. Three dimensional precipitation radar data reveal a strong 'hot tower' in Hurricane Bonnie's internal structure. The second section uses illustrations to show the dynamics of a hurricane and the formation of 'hot towers'. 'Hot towers' are formed as air spirals inward towards the eye and is forced rapidly upwards, accelerating the movement of energy into high altitude clouds. The third section shows these processes using volumetric cloud, wind, and vorticity data from a supercomputer simulation of Hurricane Bonnie. Vertical wind speed data highlights a 'hot tower'. Arrows representing the wind field move rapidly up into the 'hot tower, boosting the energy and intensifying the hurricane. Combining satellite observations with super-computer simulations provides a powerful tool for studying Earth's complex systems.

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Quoting earthlydragonfly:
Hey Levi,

Could the size of Bret have something to do with its position between two high pressure systems?


I'm not sure that I understand what you mean.
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Quoting MississippiWx:


Just going off of the Vortex message...
lol I know man, not trying to knock what you were saying.

I was just trying to guess what the NHC would do with the data. I really doubt they will give it 70mph.
Member Since: August 24, 2010 Posts: 19 Comments: 4358
Quoting TomTaylor:
probably 60, maybe 65, on the next NHC update. I really doubt they will bump it from 50 to 70.


Yeah, I'm thinking they might go with 60 from the ATCF estimate or 65 in light of the new recon data. They will probably ignore the 69 mph reading even though it was used in the vortex message.
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Quoting HurricaneDean07:
Latest RGB Shows eye cleared out.
Click Here To See Eye

Latest WV shows its not an eye at all, more of a dry slot.

http://www.ssd.noaa.gov/goes/flt/t1/flash-wv.html
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Hey Levi,

Could the size of Bret have something to do with its position between two high pressure systems?
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Storm Relative 1km Geostationary Visible Imagery



Time of Latest Image: 201107181945
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Quoting TomTaylor:
probably 60, maybe 65, on the next NHC update. I really doubt they will bump it from 50 to 70.


Just going off of the Vortex message...
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Quoting washingtonian115:
So according to the recon Bret is intensifying and almost a hurricane correct?.Don't leave me in the dark now...


No. It is a very tight system so winds may be upgraded at the 5pm advisory, but 998mb isn't going to give us a hurricane.
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Quoting MississippiWx:


Unofficially a 70mph TS.
Thanks.Bret has sure been an small but interesting system to track.
Member Since: August 14, 2010 Posts: 10 Comments: 17658
Quoting Levi32:
What's funny is the "eyewall" came literally out of nowhere. One hour, there was no convection in the area, and the next hour, there was an eyewall. The area of sinking air that we are calling the "eye" appeared nearly instantaneously, probably due to the fact that the system is already very dry and shallow to begin with.

I wouldn't expect the feature to last very long.
Besides shallow, the smallest ones can do all sorts of things amazingly fast...Bret's really quite small for this latitude.
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Dropsonde Location: Dropped in maximum wind band.

Splash Location: 27.94N 76.86W
Splash Time: 19:40Z

Release Location: 27.92N 76.88W View map)
Release Time: 19:38:53Z

Significant Wind Levels...

963mb 225° (from the SW) 64 knots (74 mph)
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Quoting MississippiWx:


Unofficially a 70mph TS.
probably 60, maybe 65, on the next NHC update. I really doubt they will bump it from 50 to 70.
Member Since: August 24, 2010 Posts: 19 Comments: 4358
Quoting Houdude:
Seems like the disturbed weather just south of La. is getting some organization. Semblance of rotation, high level outflow and some streamers moving up from the south.


Hard to develop when it's over land. :-D It will only be a rain maker as it slowly drifts west and dissipates.
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02L/H/B/C1
MARK
28.25N/76.98W
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Quoting Skyepony:
Dropsonde Location: Dropped in maximum wind band.

Splash Location: 27.94N 76.86W
Splash Time: 19:40Z

Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1004mb (29.65 inHg) Sea Level (Surface) 25.0C (77.0F) 23.7C (74.7F) 210 (from the SSW) 55 knots (63 mph)
1000mb 37m (121 ft) 24.6C (76.3F) 23.6C (74.5F) 210 (from the SSW) 55 knots (63 mph)
925mb 719m (2,359 ft) 21.0C (69.8F) 20.2C (68.4F) 230 (from the SW) 58 knots (67 mph)
850mb 1,452m (4,764 ft) 19.0C (66.2F) 16.6C (61.9F) 230 (from the SW) 61 knots (70 mph)


That data at least looks like it stacks up a bit better.
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Quoting washingtonian115:
So according to the recon Bret is intensifying and almost a hurricane correct?.Don't leave me in the dark now...


Unofficially a 70mph TS.
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Quoting RitaEvac:
Florida may never recover, since Bret formed throwing in dry air on the back side onto FL, might never return to the wet season, that would be a nightmare


Never??? That would be horrible, Florida would look like Death Valley...
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Quoting Cotillion:
Uh, maximum flight level is 53kts, but surface is 60kts?

That's peculiar.
Peculiar, yes. Impossible, no.
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Quoting ProgressivePulse:
L. Eye Character: Not Available
M. Eye Shape: Not Available


Oh well XD
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So according to the recon Bret is intensifying and almost a hurricane correct?.Don't leave me in the dark now...
Member Since: August 14, 2010 Posts: 10 Comments: 17658

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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.