Dr. Jeff Masters' WunderBlog

Huge Western Caribbean low bringing heavy rains; Wisconsin levee failing

Posted by: Dr. Jeff Masters, 12:26 GMT le 27 septembre 2010

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 (LadyWriter)

Taken from First Avenue while looking eastward toward Grand Avenue Bridge/Elks Club when the flooding was at its worst

Categories: Flood Hurricane

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2851. kimoskee 13:59 GMT le 28 septembre 2010
Met Service of Jamaica NEWS RELEASE September 27, 2010 –5:00 p.m. * FLASH FLOOD WATCH UPGRADED TO FLASH FLOOD WARNING FOR ALL PARISHES* The Meteorological Service has upgraded the Flash Flood Watch to a Flash Flood Warning for low-lying and flood prone areas of all parishes until 5:00 p.m. tomorrow. A FLASH FLOOD WARNING means flooding has been reported or will occur shortly.Motorist and pedestrians should not attempt to cross flooded roadways or other low-lying areas as strong currents are likely. Residents in low-lying areas should be on the alert for rising waters and be ready to move quickly to higher ground. A broad area of Low Pressure continues to produce widespread showers and thunderstorms over the northwestern Caribbean, including Jamaica. Radar indicates that widespread showers and thunderstorms affected the island especially sections of southern and northeastern parishes last night into this morning. The forecast is for showers and thunderstorms to continue through today, tonight and Tuesday. Deteriorating conditions are expected to persist over the island into Wednesday as this disorganized area of Low Pressure drifts northward away from Jamaica. There is a chance of this system becoming a Tropical cyclone during the next 48 hours as conditions become favorable for gradual development. As a result a Flash Flood Watch is now in effect for all parishes. Fishers and other marine interests are being advised to exercise caution as strong, gusty winds are likely in areas of showers and thunderstorms mainly over inshore and offshore areas of the south coast. The Meteorological Service will continue to monitor the progress of this system. pef Member Since: 17 août 2008 Posts: 0 Comments: 670

2852. nrtiwlnvragn 14:00 GMT le 28 septembre 2010
09/28/2010 01:54PM 952 invest_al162010.invest AL 16 2010092812 BEST 0 202N 828W 30 1001 TD Member Since: 23 septembre 2005 Posts: 11 Comments: 8918

2853. Keys99 14:02 GMT le 28 septembre 2010
WIll The HH fly over Cuba to try and locate a center? If the Low center is Between The Isle of Youth and Grand Cayman,The Area of lowest preasure will be over land by the time they get their at 18z 2pm Est. Member Since: 16 août 2007 Posts: 0 Comments: 132

2854. barotropic 14:03 GMT le 28 septembre 2010
Quoting reedzone: Clearly a circulation there, I don't think it's Subtropical yet, still fully Tropical to me. Looks like a Tropical Storm. Nicole should be here shortly, maybe 5 p.m. at the latest. Plus I've never seen a Subtropical Storm in the Caribbean before. Deep convection almost around the center = Fully Tropical to me. Yes but there is no deep circulation around the center though. Of course you didnt point out the lat long of where you think the center is, which is?? Member Since: 22 août 2010 Posts: 0 Comments: 652

2855. dolphin13 14:03 GMT le 28 septembre 2010
Quoting Neapolitan: Nice sunrise in Naples a short while ago. Love the inverted over-the-horizon cloud shadows. (And please forgive the poor resolution; I shot this with a low-quality cellphone camera while stopped at a red light [Airport & Orange Blossom].) Absolutely gorgeous!! Thank you Neapolitan! Member Since: 10 septembre 2007 Posts: 0 Comments: 33

2856. weaverwxman 14:03 GMT le 28 septembre 2010
HH will probally not fly over Cuba atleast not without permission Member Since: 17 novembre 2009 Posts: 0 Comments: 332

2857. nrtiwlnvragn 14:04 GMT le 28 septembre 2010
NEW BLOG Member Since: 23 septembre 2005 Posts: 11 Comments: 8918

2858. mcluvincane 14:04 GMT le 28 septembre 2010
Quoting nrtiwlnvragn: 09/28/2010 01:54PM 952 invest_al162010.invest AL 16 2010092812 BEST 0 202N 828W 30 1001 TD Is there such thing as a sub tropical depression lol Member Since: 2 juin 2010 Posts: 0 Comments: 1315

2859. StormChaser81 14:05 GMT le 28 septembre 2010
Jamaican Radar Met Service of Jamaica Member Since: 11 août 2008 Posts: 0 Comments: 2315

2860. barotropic 14:06 GMT le 28 septembre 2010
go to new blog Member Since: 22 août 2010 Posts: 0 Comments: 652

2861. sailingallover 14:08 GMT le 28 septembre 2010
Quoting utilaeastwind: This is what it was like here when Matthew passed a couple days ago. This photo was a real crowd pleaser. This is the Chief of Police with his speed boat. Sorry Fidi. More photos of Matthew at www.utilaeastwind.com Glad to hear it was not so bad you can't make fun of it! Look like he got caught by the wind switch.. Member Since: 1 septembre 2009 Posts: 23 Comments: 982

2862. WarEagle8 14:09 GMT le 28 septembre 2010
Quoting Bordonaro: The NHC named Bonnie, Fiona, Gaston & Hermine as Tropical Storms this year. Bonnie looked awful, meanwhile this 96L has a central pressure of 1002 MB and id producing much more tropical storm force winds and rain than Bonnie did and it's still NOT a TD?? I think the system needs to have all ingredients (coc, winds, pressure, convection, outflow, etc.) for a minimum of 6 hrs to go from A.O.I to TD or TS. Member Since: 19 août 2008 Posts: 0 Comments: 89

2863. watercayman 14:18 GMT le 28 septembre 2010
I thought ST was the Supreme Terror factor. Shows what I know. Conditions in Cayman about the same as reported a few hours ago: Light rain & about 9kts wind. Member Since: 13 septembre 2007 Posts: 0 Comments: 77

2864. charlestonscnanny 14:43 GMT le 28 septembre 2010
Quoting Chucktown: Understood, but the other side of the coin is that if you name this, the worst of the storm will be on the east side and away from land. When the general public hear tropical storm they think winds 40-50 and a lot of rain. This will not be the case with this storm, heavy rain yes, winds not so much. The Bahamas are going to see the worst of this. Thank you for a calm voice here in Summerville, SC Member Since: 5 août 2010 Posts: 0 Comments: 106

2865. kmanislander 19:29 GMT le 28 septembre 2010
NEW BLOG Member Since: 19 août 2006 Posts: 0 Comments: 14939

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