Dolly nears hurricane strength

By: Dr. Jeff Masters , 1:12 PM GMT on July 22, 2008

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Tropical Storm Dolly is building an eyewall and is near hurricane strength, as it approaches a Wednesday landfall in Texas or northern Mexico. Visible satellite loops show that heavy thunderstorm activity continues to increase near the core of the storm, with good upper-level outflow to the west and north, but restricted on the south side, where an upper level low pressure system is interfering. Maximum surface winds measured by the SFMR instrument on the current Hurricane Hunter aircraft inside Dolly were 74 mph (65 kt), measured at 8:39 am EDT. These are bottom end Category 1 hurricane winds, so Dolly is very close to becoming a hurricane. However, the winds at the flight level of 10,000 feet have been considerably less than 74 mph, so don't expect NHC to upgrade Dolly based on this measurement. Water vapor satellite loops still show some dry air on the south side of Dolly, but the storm has insulated itself from this dry air by building an eyewall that was 50% complete as of 4 am EDT (Figure 1). Dolly's outer spiral bands are approaching the Texas/Mexico coast, and the center of the storm is now visible on Brownsville, Texas long-range radar


Figure 1. Microwave satellite image of Dolly at 4:08 am EDT Tue July 22, 2008. Note the partial formation of an eyewall on the north and east sides. The eyewall was about 50% complete at this time. Image credit: Navy Research Lab, Monterey.

The intensity forecast
Wind shear over Dolly is less than five knots, and is expected to remain below ten knots over the next two days. An upper level high pressure system is moving into place over the storm, which should enhance Dolly's upper-level outflow and allow more rapid intensification. Dolly is over waters of 29°C. The waters cool to about 28°C as Dolly approaches the coast and passes over a cool ocean eddy. The warm waters Dolly is currently over extend to a moderate depth, with a Tropical Cyclone Heat Potential of about 40-60 kJ/cm**2. This is below the value of 80 usually associated with rapid intensification, but still high enough to allow Dolly to put on a burst of rapid intensification prior to landfall. Our skill in making intensity forecasts is poor, but it currently appears that Dolly only has enough time to intensify into a Category 1 hurricane. A Category 2 hurricane still a possibility, but this would require Dolly staying over water a longer period of time than forecast. Even if Dolly does slow down and stay over water until Thursday, the very slow motion of the storm would cause it to upwell cold water from the ocean depths to the surface, putting a damper on intensification. I put the chances of Dolly reaching major hurricane status (Category 3 or higher) at 2%.

The track forecast
A trough of low pressure approaching the Midwest U.S. tonight will weaken the steering currents driving Dolly west-northwest, and probably impart more of a northwesterly motion to the storm tonight and Wednesday. The exact influence this feature will have on Dolly is uncertain, with four models predicting a landfall in northeastern Mexico--the UKMET, ECMWF, NOGAPS, and GFS--and two models predicting a Texas landfall--the GFDL (near Brownsville) and the HWRF (near Corpus Christi). Dolly could come ashore anywhere within the cone of uncertainty, and one should not assume the storm will track down the "skinny black line" NHC has drawn through their official forecast. The timing of Dolly's landfall, as predicted by the computer models, will be anywhere from 10 am - 10 pm Wednesday. However, the GFS and ECMWF hint that Dolly may stall out right by the coast Wednesday, and some slow and erratic motion is possible tomorrow before the storm finally comes ashore.

Links to follow:
Brownsville, TX long range radar
Texas marine forecasts and observations
Brownsville, TX weather
Corpus Christi, TX weather


Figure 2. Visible satellite image from 1130 GMT (7:30 am EDT) Tue July 22, 2008, showing the new tropical low pressure system that moved off the coast of Africa. Note the stratocumulus clouds to the west of the low, indicating cooler waters that will slow down development of the system. Image credit: Navy Research Lab, Monterey.

Elsewhere in the tropics
Tropical Storm Cristobal continues to head out to sea, and is not expected to hit land. Nova Scotia and Newfoundland may feel the fringes of the storm as it races to the east today and transitions into an extratropical storm.

A large low pressure system (97L) moved off the coast of Africa last night, and is generating some heavy thunderstorm activity over the ocean waters near the Cape Verde Islands. This morning's 2:53 am EDT QuikSCAT pass shows a closed circulation near 17N 19W, with winds in the 10-20 mph range. Sea Surface Temperatures (SSTs) are about 27°C, which is one degree above the 26°C threshold needed for tropical storm formation. SSTs will cool to 25-26°C on Wednesday as the low moves westward, which will slow any development. Wind shear is low enough for development, 5-10 knots, and is forecast to remain low enough for development over the next few days. Once the low reaches the mid-Atlantic late this week, SSTs will warm once again above 26°C, and we may get yet another July tropical depression. However, systems that come off the coast of Africa this far north rarely affect the Caribbean or U.S., and Bermuda is probably the only location that needs to be concerned.

Quiz question: Since hurricane began getting names in 1950, only one major hurricane that hit the U.S. did not get its name retired. Which one was it? A hint: the track was similar to Dolly's expected track. I'll have the answer in my update on Dolly this afternoon.

Jeff Masters

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1839. riograndpa
4:06 AM GMT on July 23, 2008
here in brownsville...nothing much to report right now,but bands are close and the wxman says it's slowed to 5mph and it'll be in the valley 24 hours at least! where's my swim fins????? (does that mean 5 hours of 80mph winds!!!!!
1838. riograndpa
4:05 AM GMT on July 23, 2008
here in brownsville...nothing much to report right now,but bands are close and the wxman says it's slowed to 5mph and it'll be in the valley 24 hours at least! where's my swim fins????? (does that mean 5 hours of 80mph winds!!!!!
1837. ClearH2OFla
9:49 PM GMT on July 22, 2008
Hey all reporting in from US 19 N and Bel Aire Road in my glass office building. The sun is shining but its raining like a beast. The palm trees are a blowing as well. Dolly hitting us with her tail feathers.
1836. melly
9:44 PM GMT on July 22, 2008
drj10526....The Weather Channel did NOT say that
1835. drj10526
9:42 PM GMT on July 22, 2008
the weather channel just said it was going to be bad beach weather the next couple of days in South padre....seems like an understatement....
Member Since: February 28, 2005 Posts: 3 Comments: 340
1834. melly
9:39 PM GMT on July 22, 2008
StormW Someone has dilusions of grandeur?¿
1833. txalwaysprepared
9:39 PM GMT on July 22, 2008
Quoting smmcdavid:
In League City... I've gotten zero rain here.


It sucks doesn't it. We need rain so badly!!!
Member Since: August 18, 2007 Posts: 0 Comments: 1642
1831. taistelutipu
9:36 PM GMT on July 22, 2008
New blog online with the answer to Dr. Master's question.
Member Since: August 20, 2007 Posts: 12 Comments: 640
1830. presslord
9:34 PM GMT on July 22, 2008
Alexking=stormyeyes=stormkat=stormtop
Member Since: August 13, 2007 Posts: 0 Comments: 10492
1829. Alexking
9:34 PM GMT on July 22, 2008
Between Victoria and Galveston is very likely.
But noone is of the hook as it keeps tracking north.It is following the coast
1828. polarcane
9:32 PM GMT on July 22, 2008
Quoting quakeman55:
Quoting jscs:

Quoting stormyeyes:
houston people better be taking
this serious.there is no way the high
will build back in with that low sw of
dolly.i am definitely worried with the
slowing down and the continued movement
towards the nnw.dolly is doing some rapid
strengthing right now.we really wont be able to
tell until the 5am advisory.dolly will be close to a cat 3 by that time.the high steering
dolly has weakened and now its a new
ball game.dolly can pick who she wants to
visit.if she stalls later tonight then
everyone from texas to fla will have to
keep in touch with the latest advisories.right now im worried about the houston area.


Quoting quakeman55:


Quoting txalwaysprepared:
Just spoke to a friend of mine who left for S. Padre Island yesterday (against my advice). She is there now.. not leaving. Only has a 1/4 tank of gas and is having trouble finding a station that still has gas. She's been to two stations and they were out. Also... she went to walmart and I believe target -- no candles or flashlights left.

I wish people prepared better.

Not to be mean but honestly, how ignorant and stubborn can people be sometimes? Well all I can say to her is good luck getting out of there...hopefully she'll learn a good lesson next time she decides to do that. Hope she can still escape...she needs to.


Tell her to make sure the blender and margarita mix are ready. Best way to ride out a Cat 1.

Yeah but the problem is she'll be riding out a Cat 2 or higher...that's going to be trouble if she doesn't find a way out...
Not sure when the first part was written but this storm has headed farther west than Houston. A non factor for Houston!
Member Since: July 19, 2008 Posts: 1 Comments: 229
1827. rareaire
9:30 PM GMT on July 22, 2008
AP Texas News



July 22, 2008, 2:08PM
Governor issues Dolly disaster declaration


© 2008 The Associated Press

AUSTIN — Gov. Rick Perry has issued a disaster declaration for 14 South Texas counties in advance of Tropical Storm Dolly's arrival.

Perry said that because Dolly could make landfall along the Texas coast, "the state is taking all steps necessary to ensure the safety of our residents."

Dolly is expected to strengthen to hurricane level Tuesday and make landfall near Brownsville Wednesday.

The counties are: Aransas, Bexar, Brooks, Calhoun, Cameron, Hidalgo, Jim Wells, Kenedy, Kleberg, Nueces, Refugio, San Patricio, Victoria and Willacy.

The declaration allows the state to send emergency resources to the areas in the storm's path.

Member Since: August 19, 2007 Posts: 0 Comments: 1601
1826. unknownuser
9:29 PM GMT on July 22, 2008
From buoy 42002

5-day plot - Wave HeightWave Height (WVHT): 14.4 ft

Wind Speed (WSPD):29.1 kts
5-day plot - Wind Gust Wind Gust (GST) 33.0 kts
1825. condesa
9:29 PM GMT on July 22, 2008
1703, et al:
The Queen Isabella Memorial Bridge to S. Padre will close when winds hit 45 mph sustained, which I suspect won't be long. They are forecasting 90 mph winds by tomorrow morning.
Oh, and up to 20 inches of rain. And storm surge.
1824. SouthDadeFish
9:27 PM GMT on July 22, 2008
It looks like recon is staying out there for one more pass. Lets see what they find.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
1823. rareaire
9:27 PM GMT on July 22, 2008
DRAK YOU DID SAY MEXICO LOOK BACK AT IT
Member Since: August 19, 2007 Posts: 0 Comments: 1601
1822. smmcdavid
9:25 PM GMT on July 22, 2008
In League City... I've gotten zero rain here.
Member Since: September 20, 2005 Posts: 31 Comments: 2309
1821. bayoubrotha
9:25 PM GMT on July 22, 2008
Drakoen 9:23 PM GMT on July 22, 2008
Quoting bayoubrotha:
Quoting bayoubrotha:
Actually, the NHC has Dolly coming in at 26.0N, which is on the north side of Brownsville.


After it moves inland over extreme northern Texas.

Well, Drak, if Dolly can accomplish that feat, she is one for the record books.


I meant Mexico.


I know. I stand corrected. I was just kidding around.
Member Since: August 15, 2006 Posts: 0 Comments: 618
1820. bekroweather
9:25 PM GMT on July 22, 2008
Raining sporadically in downtown Houston...
1819. extreme236
9:24 PM GMT on July 22, 2008
I still think landfall near Brownsville.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1818. Patrap
9:23 PM GMT on July 22, 2008
GOM IR Loop Link
Member Since: July 3, 2005 Posts: 428 Comments: 129796
1817. dean2007
9:23 PM GMT on July 22, 2008
1815.
No problem
1816. Drakoen
9:23 PM GMT on July 22, 2008
Quoting bayoubrotha:
Quoting bayoubrotha:
Actually, the NHC has Dolly coming in at 26.0N, which is on the north side of Brownsville.


After it moves inland over extreme northern Texas.


Well, Drak, if Dolly can accomplish that feat, she is one for the record books.


I meant Mexico.
Member Since: October 28, 2006 Posts: 57 Comments: 30823
1815. Qccanelover
9:22 PM GMT on July 22, 2008
1808.

Thank a lot!
1814. TerraNova
9:21 PM GMT on July 22, 2008
Quoting Qccanelover:
What are the latest T-Numbers for Dolly?...A link would be appreciated a lot. THx!


(Link)

Final T# = 3.9
Adj T# = 4.1
Raw T# = 4.2
Member Since: July 30, 2007 Posts: 76 Comments: 4063
1813. BeenThereinMiami
9:21 PM GMT on July 22, 2008
Quoting bigdoge3:
ok i dong get it! it seems like it moving more north all day but the coordinates been saying west? plus inthe last frame it looks liek alittle eat take can someone help me out and explain it


That is because hurricanes don't track in a perfectly straight line when you are watching the track on radar scales. Think of it like putting a piece of fabric under a high power microscope. You will see every weave, hill and bump in the fabric, but when you look at it normally it looks smooth. To really see which direction it is heading overall, you kind of have to back up and take a more Gulf of Mexico-sized perspective, otherwise you'll drive yourself nuts looking at every apparent wiggle and wobble.

So in a nut shell the more you magnify the hurricane image (like watching the radar loop), the more likely you will see what are really very small changes in the overall track.
1812. bayoubrotha
9:21 PM GMT on July 22, 2008
Quoting bayoubrotha:
Actually, the NHC has Dolly coming in at 26.0N, which is on the north side of Brownsville.


After it moves inland over extreme northern Texas.


Well, Drak, if Dolly can accomplish that feat, she is one for the record books.
Member Since: August 15, 2006 Posts: 0 Comments: 618
1810. Stoopid1
9:21 PM GMT on July 22, 2008
I'm sticking to my first thought, a lower end cat 1 in Brownsville. I know, it could be stronger, but I think when she hits the cool eddy it will taper her off. Bottom line though, everyone from North Mexcio to Corpus Cristi should be ready.
Member Since: August 6, 2007 Posts: 24 Comments: 2755
1809. jscs
9:21 PM GMT on July 22, 2008
Welcome Hurricane Dolly!
Member Since: February 14, 2007 Posts: 0 Comments: 141
1808. dean2007
9:21 PM GMT on July 22, 2008
Quoting Qccanelover:
What are the latest T-Numbers for Dolly?...A link would be appreciated a lot. THx!

Link
Here's a link the numbers indicate hurricane Dolly, right on with the NHC 5pm EDT update.
1807. AggiemetinKaty
9:20 PM GMT on July 22, 2008
anyone think the trough in west texas, seen on water vapor imagery, keeps Dolly moving north for a while. I have noticed that the models have consistently overintensified the high over east texas this year. Maybe another reason this storm moves a little farther north.
1806. unknownuser
9:19 PM GMT on July 22, 2008
Well Dolly has grown up and is now officially a hurricane
Link
She also appears to be starting to form a pretty decent eye from what I see.
I predict landfall just north of Brownsville with 95-105 mph winds:)
1805. Drakoen
9:19 PM GMT on July 22, 2008
Quoting bayoubrotha:
Actually, the NHC has Dolly coming in at 26.0N, which is on the north side of Brownsville.


After it moves inland over extreme northern Mexico.
Member Since: October 28, 2006 Posts: 57 Comments: 30823
1804. Qccanelover
9:19 PM GMT on July 22, 2008
What are the latest T-Numbers for Dolly?...A link would be appreciated a lot. THx!
1803. Cavin Rawlins
9:19 PM GMT on July 22, 2008
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1802. TerraNova
9:18 PM GMT on July 22, 2008
Here's the latest wind field analysis for Dolly, showing that the most intense portion of the storm (as far as winds go) is located east of the center. The portion of the storm to the east of the eye isn't entirely in range of KBRO yet. Winds have probably strengthened since 1630z (obviously, since Dolly is now a hurricane), but the strongest portion of the storm still appeares to be east of the center according to satellite imagery.

Member Since: July 30, 2007 Posts: 76 Comments: 4063
1801. Cavin Rawlins
9:18 PM GMT on July 22, 2008
Quoting trunkmonkey:
For 456, is the score 1-major 1-small,
2-tropical storms for 2008??


yea
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1800. hosweather
9:18 PM GMT on July 22, 2008
The 12Z GFS does not have the ridge building in significantly from the west until 48 hours out. It also has Dolly stalling at the coast right at the tex-mex border from about 30 hrs to 54 hours. If Dolly intensifies faster than expected and does her stalling a bit off the coast, she could pile up a lot water along the south Texas coast. Very small differences in track and intensity could have very large differences in effect. No one on the south Coast of Texas should take Dolly lightly. She could even drift more northerly as the ridge builds in.
1799. PanhandleChuck
9:17 PM GMT on July 22, 2008
I'm sure the rest of you have blocked alexking, but i'm finding his ignorance quite amusing. LOL
Member Since: May 13, 2008 Posts: 0 Comments: 1414
1798. hurricane23
9:17 PM GMT on July 22, 2008
15 canes in the middle of no were is fine with me. 2005 clearly was a different situation as there were mutiple tc landfalls.
Member Since: May 14, 2006 Posts: 8 Comments: 13841
1797. CaneAddict
9:17 PM GMT on July 22, 2008
1790. extreme236 9:16 PM GMT on July 22, 2008

Exactly! Ya nailed it right on the head.
Member Since: October 5, 2007 Posts: 3 Comments: 2151
1796. gsueagle07
9:17 PM GMT on July 22, 2008
Is that true about the wind field.....hurricane force winds ONLY extend 15 miles.....my god that has to be one of the smallest hurricane force wind fields I have ever heard of...
1795. bayoubrotha
9:17 PM GMT on July 22, 2008
Actually, the NHC has Dolly coming in at 26.0N, which is on the north side of Brownsville.
Member Since: August 15, 2006 Posts: 0 Comments: 618
1794. extreme236
9:16 PM GMT on July 22, 2008
Dolly's CDO has become much more circular.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1793. quakeman55
9:16 PM GMT on July 22, 2008
Quoting jscs:
Quoting stormyeyes:
houston people better be taking
this serious.there is no way the high
will build back in with that low sw of
dolly.i am definitely worried with the
slowing down and the continued movement
towards the nnw.dolly is doing some rapid
strengthing right now.we really wont be able to
tell until the 5am advisory.dolly will be close to a cat 3 by that time.the high steering
dolly has weakened and now its a new
ball game.dolly can pick who she wants to
visit.if she stalls later tonight then
everyone from texas to fla will have to
keep in touch with the latest advisories.right now im worried about the houston area.

Quoting quakeman55:

Quoting txalwaysprepared:
Just spoke to a friend of mine who left for S. Padre Island yesterday (against my advice). She is there now.. not leaving. Only has a 1/4 tank of gas and is having trouble finding a station that still has gas. She's been to two stations and they were out. Also... she went to walmart and I believe target -- no candles or flashlights left.

I wish people prepared better.

Not to be mean but honestly, how ignorant and stubborn can people be sometimes? Well all I can say to her is good luck getting out of there...hopefully she'll learn a good lesson next time she decides to do that. Hope she can still escape...she needs to.


Tell her to make sure the blender and margarita mix are ready. Best way to ride out a Cat 1.

Yeah but the problem is she'll be riding out a Cat 2 or higher...that's going to be trouble if she doesn't find a way out...
Member Since: March 31, 2002 Posts: 1 Comments: 1276
1792. trunkmonkey
9:16 PM GMT on July 22, 2008
For 456, is the score 1-major 1-small,
2-tropical storms for 2008??
Member Since: August 18, 2007 Posts: 0 Comments: 596
1791. CaneAddict
9:16 PM GMT on July 22, 2008
1760. Weather456 9:08 PM GMT on July 22, 2008
Quoting CybrTeddy:
This is madness! 2 two Hurricanes in July!?


Last time that happened was July 2005. Interesting stuff.


Let's hope it's not a 2005....lol.
Member Since: October 5, 2007 Posts: 3 Comments: 2151
1790. extreme236
9:16 PM GMT on July 22, 2008
Quoting Drakoen:
Quoting extreme236:
Quoting Drakoen:
The NHC think Dolly will make landfall just south of the Texas/Mexican border.


Looks more like right on the line of the border from the track.


Look at the line again.


It still looks on the line...the discussion said on the line as well...oh well no point in paying attention to the exact line anyway right? lol
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1789. dean2007
9:16 PM GMT on July 22, 2008
Quoting quakeman55:
Quoting CybrTeddy:
This is madness! 2 two Hurricanes in July!?

Don't forget that happened in 2005 with Dean and Emily...but then again 2005 itself was complete and total madness...

It was Dennis and Emily, Dean was in 2007 and Felix were the only Cat 5's in 2007. I don't remember if there were any Cat 5's in 2006, that was a poor season, I'm sure many of us would take that kind of a season again, but this season seems like it can take on the 2008 season, maybe not quite 28 named storms, but maybe 17 to 20.

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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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