Huge Western Caribbean low bringing heavy rains; Wisconsin levee failing

By: Dr. Jeff Masters , 12:26 PM GMT on September 27, 2010

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Today, for the first day since August 20, the National Hurricane Center will not be issuing any advisories for an Atlantic named storm. Thus ends a remarkably active 36-day period that saw the formation of ten named storms, six hurricanes, and five intense hurricanes--an entire hurricane season's worth of activity, compressed into just five weeks of the six-month season. This season is not done yet, as we still have three more weeks of peak hurricane season left to go, and the Western Caribbean is looking poised to generate a tropical storm sometime in the next ten days.


Figure 1. Morning satellite image of the Western Caribbean and Central America, showing the remains of Matthew over Mexico, and a large area of disturbed weather beginning to develop over the Western Caribbean.

A wet week ahead for the Western Caribbean, Florida, and the Western Bahamas
Pressures are falling over the Western Caribbean today as a large area of low pressure develops over the region. This low is bringing heavy rains across a huge area, from the Pacific shores of El Salvador, Guatemala, and Mexico, to eastern Cuba and Haiti. All of Central America, eastern Mexico, the western 2/3 of the Caribbean, plus the Bahamas and Florida can expect sporadic periods of very heavy tropical rains over the coming week, with peak amounts of 3 - 6 inches per day possible. In the Western Caribbean, a few hundred miles east of Mexico's Yucatan Peninsula, a region of concentrated thunderstorms has built this morning, and has the potential to develop into a tropical depression by Wednesday. A large trough of low pressure over the Eastern U.S. is producing steering currents that will pull this area of disturbed weather to the north-northeast across western Cuba on Tuesday and Wednesday. The disturbance should move over Florida on Wednesday and Thursday, and over North Carolina by Thursday and Friday. All of these regions can expect very heavy rains from the disturbance, and NHC is giving a 30% chance that the disturbance will develop into a tropical depression by Wednesday. The Hurricane Hunters are on call to investigate the disturbance this afternoon, if necessary.

Once the disturbance moves out of the Caribbean, the GFS and NOGAPS models predict that the Western Caribbean will "reload" and produce another tropical disturbance capable of developing into a tropical depression late this week or early next week. The steering currents are not expected to change over the coming ten days, and Florida and western Cuba can expect to see this second disturbance potentially bring a second round of heavy rain late this week and early next week.

Levee failing in Wisconsin due to rains from Hurricane Karl's moisture
In Portage, Wisconsin, about 25 miles north of Madison, a sub-standard 120-year-old levee is failing, thanks to flood waters 3.5 feet above flood stage on the Wisconsin River. The river was swollen last week by heavy rains of up to seven inches that fell in its watershed to the northwest. The rains were generated by a plume of very moist air associated with what was Hurricane Karl. This moisture was lifted over a warm front draped over Minnesota and Wisconsin on Wednesday and Thursday. These types of rain events are called Predecessor Rain Events (PREs), because they typically precede the actual arrival of the rain shield of a tropical storm.


Figure 2. Rainfall over Minnesota and Wisconsin for the seven-day period ending 8pm EDT Sunday 9/26/10. Heavy rains to the northwest of Portage, Wisconsin led to flooding along the Wisconsin River in Portage. Image credit: NOAA.

Canadian Military responds for Hurricane Igor relief
At least twenty communities in Newfoundland, Canada are still cut off from civilization after Tuesday's rampage by Hurricane Igor. The Canadian military has sent three warships and a number of helicopters into the disaster zone to deliver food, fuel, and medical supplies to those communities still cut off. Igor killed one person and caused over $100 million in damage to the island.


Figure 3. Miniature golf anyone? A house in St. John's Newfoundland now has a very three-dimensional front yard, thanks to Hurricane Igor's winds and rain. Image credit: Zach Goudie.

I'll have an update Tuesday morning.

Jeff Masters

Wisconsin River Flooding in Wisconsin Rapids September 2010 (LadyWriter)
Jackson Street Bridge late Saturday afternoon at cresting.
Wisconsin River Flooding in Wisconsin Rapids September 2010
Wisconsin River Flooding in Wisconsin Rapids September 2010 (LadyWriter)
Taken from First Avenue while looking eastward toward Grand Avenue Bridge/Elks Club when the flooding was at its worst
Wisconsin River Flooding in Wisconsin Rapids September 2010

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164. IKE
Quoting weathermanwannabe:
98. IKE 9:33 AM EDT on September 27, 2010

Morning Ike.....Notice how this happens, with Tallahassee NWS, every year?.......They often forecast a "double whammy" round of t-storms with an approaching front, forcast incliment weather for the entire morning or afternoon, then, what actually happens is that "one" front comes through and the weather clears out nicely.......On that note, how are you looking over there West of me in Defuniak?


Mostly cloudy now and 67.5.

Should be clearing here shortly.
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Quoting tacoman:
the recon data thats a joke there wont be any because recon will be cancelled..
If that's true, that will also answer his question.
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People should check their WU mail/
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Well, I note that many mid and south Florida entities are dropping the rain projections for the next week back down to 40 to 50 percent. I kind of agree with that. I think most of the Caribbean mess will not lift that far north. It's just not setting up right for that. JMO
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Quoting Kristina40:


Yep, hubby was sure he was going to need a rain slicker today for work after listening to the weather. I was watching the line of storms move in with the front behind him and told him he wouldn't need it for more than an hour or so for the drive in this morning. It's still very humid here but that should clear out today.


Should be nice tommorow afternoon if the wind dies down and Fall fishing should start picking up as more fronts come through........Gonna take the afternoon off tommorow and try some fishing for Reds.......:)
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Quoting butterflymcb:
Can I get StormW's new blog link? Or name? Without getting anyone in trouble?

butterflymcb~~Boy since that front come thru it is nice and cool this morning in Alabama.

you have mail.
sheri
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Quoting HurricaneGeek:


From what I understand, this is the deal:
The RECON plane is set for 2 pm Eastern Time (18z). Most likely, they are waiting for data from this mission before designating an invest. This way, they'll be able to put the most accurate information into the models.
There are not se guidelines to follow when designating in invest, like there are with a TD/TS/Hurricanes. I gather that it's upto the forecaster's disgression.
Asssuming things stay as they are, I assume at the 2 pm TWO, the chances will be risen to 40 or 50%, although that might be too generous because looking at the 850mb vorticity map, like Chicklit's post #75, you see nothing has really consolidated. Howeverm convection has grown stronger over the past few hours. Here is a visible loop.


As I mentioned early this morning the best view of what is developing is via the shortwave. A low level broad circulation is becoming more pronounced with time at 19.0N and 86W. Go here Link and speed up loop and zoom in.
Member Since: August 22, 2010 Posts: 0 Comments: 652
Quoting Waltanater:
1992 was an El Nino year, not La Nina.


Got them mixed up.......Thanks.
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I would say that Mexico has been hit considerably this year.

Although, some like to neglect that, obviously. Alex and Karl have caused close to $6bn damage between them. That's equivalent to a fair few Hurricane Deans or Hurricane Emilys in damage.

Around 75 people have lost their lives.

Yes, it isn't quite a 2005 for them after what Wilma and Stan did in particular.

However, don't be myopic and discount it, either.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
question... Dr. Masters posted that NHC would not be issuing any advisories on a system today... couldnt this system form today if recon goes in and finds it closed already?
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Quoting Cotillion:


50 is orange. 60 is red.

30% is the usual requirement for invest status, though it does vary - depends if they feel it is worthwhile or not. There's no specific timing, either, like there often is with renumbers.


Oops
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting afj3:
Hello everyone. Quick question: Why hasn't the NHC given this Caribbean low an invest number yet? Or has it? Also, when does the NHC decide to give a system an invest number?
I think they are waiting for the recon data.
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It looks like the front is going to push farther south and east than earlier expected. Check out the water vapor loop. Maybe only extreme SE FL will see any significant rain.
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140. afj3
Quoting HurricaneGeek:


From what I understand, this is the deal:
The RECON plane is set for 2 pm Eastern Time (18z). Most likely, they are waiting for data from this mission before designating an invest. This way, they'll be able to put the most accurate information into the models.
There are not se guidelines to follow when designating in invest, like there are with a TD/TS/Hurricanes. I gather that it's upto the forecaster's disgression.
Asssuming things stay as they are, I assume at the 2 pm TWO, the chances will be risen to 40 or 50%, although that might be too generous because looking at the 850mb vorticity map, like Chicklit's post #75, you see nothing has really consolidated. Howeverm convection has grown stronger over the past few hours. Here is a visible loop.

Thanks!
Member Since: June 10, 2008 Posts: 0 Comments: 349
Quoting weathermanwannabe:
98. IKE 9:33 AM EDT on September 27, 2010

Morning Ike.....Notice how this happens, with Tallahassee NWS, every year?.......They often forecast a "double whammy" round of t-storms with an approaching front, forcast incliment weather for the entire morning or afternoon, then, what actually happens is that "one" front comes through and the weather clears out nicely.......On that note, how are you looking over there West of me in Defuniak?


Yep, hubby was sure he was going to need a rain slicker today for work after listening to the weather. I was watching the line of storms move in with the front behind him and told him he wouldn't need it for more than an hour or so for the drive in this morning. It's still very humid here but that should clear out today.
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Quoting weathermanwannabe:
The current status of CONUS and the Gulf goes to show you that numbers mean very little; it's all about track and general steering patterns. First A storm in 1992 was Andrew (in a La Nina Year) and here we are in late September, in a very active year, with the US abnd Caribbean relatively unscathed.......I would have never imagined that this was going to happen given all the gloom and doom at the beginning of the season from experts and amateurs alike. Season not over but so far so good; incredible considering the numbers.
1992 was an El Nino year, not La Nina.
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Quoting StormChaser81:


50% is red circle


50 is orange. 60 is red.

30% is the usual requirement for invest status, though it does vary - depends if they feel it is worthwhile or not. There's no specific timing, either, like there often is with renumbers.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting StormChaser81:


50% is red circle
Red is greater than 50%
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Quoting StormChaser81:


50% is red circle


red is higher than 50.
orange is 30-50
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Quoting cat5hurricane:

It's at least got some relatively low shear in it's favor...


That's for sure... currently under to 5KTS to 10KTS shear.

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Quoting HurricaneGeek:
An invest will most likely be named at 2pm and maybe a 50% orange circle.


50% is red circle
Member Since: August 11, 2008 Posts: 0 Comments: 2315
An invest will most likely be named at 2pm and maybe a 50% orange circle.
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Quoting WxLogic:
12Z 850MB VORT:



500MB VORT:



Based on the updated VORT images... there has been an increase in Low/Mid level circulation in the area below:



Low level convergence as per CIMSS



Upper Level Divergence:



Based on CIMSS Convergence/Divergence updates, it appears a low level circulation is getting better established.

If further organization keeps happening by 15Z we could see this region be updated with a 50% to 60% and an INVEST named.


seems like maybe its forming a few degrees east of what the models thought
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98. IKE 9:33 AM EDT on September 27, 2010

Morning Ike.....Notice how this happens, with Tallahassee NWS, every year?.......They often forecast a "double whammy" round of t-storms with an approaching front, forcast incliment weather for the entire morning or afternoon, then, what actually happens is that "one" front comes through and the weather clears out nicely.......On that note, how are you looking over there West of me in Defuniak?
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Quoting afj3:
Hello everyone. Quick question: Why hasn't the NHC given this Caribbean low an invest number yet? Or has it? Also, when does the NHC decide to give a system an invest number?


From what I understand, this is the deal:
The RECON plane is set for 2 pm Eastern Time (18z). Most likely, they are waiting for data from this mission before designating an invest. This way, they'll be able to put the most accurate information into the models.
There are not se guidelines to follow when designating in invest, like there are with a TD/TS/Hurricanes. I gather that it's upto the forecaster's disgression.
Asssuming things stay as they are, I assume at the 2 pm TWO, the chances will be risen to 40 or 50%, although that might be too generous because looking at the 850mb vorticity map, like Chicklit's post #75, you see nothing has really consolidated. Howeverm convection has grown stronger over the past few hours. Here is a visible loop.
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120. IKE
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12Z 850MB VORT:



500MB VORT:



Based on the updated VORT images... there has been an increase in Low/Mid level circulation in the area below:



Low level convergence as per CIMSS



Upper Level Divergence:



Based on CIMSS Convergence/Divergence updates, it appears a low level circulation is getting better established.

If further organization keeps happening by 15Z we could see this region be updated with a 50% to 60% and an INVEST named.
Member Since: Posts: Comments:

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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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