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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Quoting Levi32:


All in the time-frame of late September and early October. We haven't hit the end of the month yet and we're already talking about one storm that is almost guaranteed. Don't expect nothing else to threaten before the season ends.


Thank you, Levi.
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Quoting mcluvincane:
Bunch of downcasters...


One thing you can't really deny though... Your 'downcasters' have the best forecast track record on the blog. They just keep on being right.

So what makes a good forecast anyway? The excitement it stirs? Or the accuracy of it?
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Quoting ecflweatherfan:


Agreed. Take a look at the XMLB radar. You will see strong storms also firing along the ECSB in Central FL... the ECSB will only add to the helicity values. Could get nasty (funny how points from Cape Canaveral south to Jupiter have only a 20% chance of rain)

Weather.com had us at a 60% chance for the day up to 80% tomorrow and 90% tomorrow night
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DISORGANIZED CLOUDINESS AND THUNDERSTORMS OVER THE NORTHWESTERN
CARIBBEAN SEA ARE ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE.
OBSERVATIONS FROM A NATIONAL SCIENCE FOUNDATION JET AIRCRAFT
INDICATE THAT THE LOW DOES NOT YET HAVE A WELL-DEFINED CENTER OF
CIRCULATION. HOWEVER...ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE
FOR GRADUAL DEVELOPMENT OF THIS SYSTEM DURING THE NEXT COUPLE OF
DAYS AS IT MOVES NORTHWARD OR NORTH-NORTHEASTWARD. THERE IS A
MEDIUM CHANCE...40 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL OR
A SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS. INTERESTS IN
CUBA...THE FLORIDA KEYS...AND THE SOUTH AND CENTRAL FLORIDA
PENINSULA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. CONSULT
STATEMENTS FROM YOUR NATIONAL WEATHER SERVICE FORECAST OFFICE AND
NATIONAL METEOROLOGICAL SERVICE FOR ADDITIONAL INFORMATION.
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Quoting Hurricanes101:


more like Karen part 25 lol


lol that's true to.
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Quoting Seflhurricane:
hey levi i continue to see that the Low continues to become better organized, in your opinion when do you expect this to become a TD


I suspect it may have acquired enough organization by tomorrow morning to be declared a TD, but we'll have to see how its convective organization looks tonight.
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Weather is wonderful here in Mobile today! Sunny and 76 Degrees. I hope were done here for the year, about having to worry about TCs.
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Quoting Jeff9641:
THe CMC model blast the FL penisula with pounding rain and wind on Thursday. Yikes!
I would say no matter what, Florida is in for flooding rains.
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655. unf97
Quoting FLWeatherFreak91:
Severe thunderstorm warning for western Duval right now.


Yes, that is a nasty looking cell approaching the Baldwin area and will be approcahing I-295 in a few minutes. That cell looks nasty on radar. I'm only about 15 miles or so away from that cell at the moment.
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Quoting reedzone:
Julie = Fred part 2.. Kind of funny.


more like Karen part 25 lol
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Julia = Fred part 2.. Kind of funny.
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does anyone know if there is any info out there as far as forecast model tracks once a storm has formed compared to where it actually tracked
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IMO 40% is way to low. Wow
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Quoting Levi32:


We're not talking about one tropical cyclone, but several. Multiple tropical cyclones in the NW Caribbean during October should theoretically have the same effect as a little stronger trades over a period of a month or so. If they are all weak storms then maybe not, but if we get a major in there and a couple hurricanes I could see the water cooling some.

I agree the CFS predicting hurricanes is iffy, but I wouldn't put it past the model that it could see the pattern of lower pressures and enhanced rainfall in that area of the world for the next couple months.
hey levi i continue to see that the Low continues to become better organized, in your opinion when do you expect this to become a TD
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Jacksonville had a very strong thunderstorm last night with winds gusting up to 55.
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Quoting Jeff9641:


Hey buddy, this is just the start of things to come later today and tonight across C FL. There is some pretty good shear across C and N FL today and this could cause storms to rotate. Also a good 3 to 5" rain is likely across most of C FL thru tomorrow.


Agreed. Take a look at the XMLB radar. You will see strong storms also firing along the ECSB in Central FL... the ECSB will only add to the helicity values. Could get nasty (funny how points from Cape Canaveral south to Jupiter have only a 20% chance of rain)
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Quoting stormwatcherCI:
Just on my lunch break but the blob south of the Cayman Islands is looking better and better. Got a feeling that is where we will see development. Very gusty conditions here today and rough seas.


If it consolidates there we might have a big problem on our hands
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Quoting RyanFSU:
This is highly unlikely. The reservoir of warm, deep water in the Caribbean cannot be depleted by a relatively short-lived tropical cyclone, even if it is very intense. It just does not last long enough.

A reconfiguration of the trades due to a record-strength La Nina would be my explanation.

Also, the ability of CFS to generate tropical cyclones is, uh, a bit on the unproven side.



We're not talking about one tropical cyclone, but several. Multiple tropical cyclones in the NW Caribbean during October and November should theoretically have the same effect as a little stronger trades over a period of a month or two. If they are all weak storms then maybe not, but if we get a major in there and a couple hurricanes I could see the water cooling some.

I agree the CFS predicting hurricanes is iffy, but I wouldn't put it past the model that it could see the pattern of lower pressures and enhanced rainfall in that area of the world for the next couple months.
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644. srada
Quoting largeeyes:


Work in New Bern, live near Havelock.


should be an interesting week for us..
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Quoting 1992Andrew:
Can't tell where the center will be... yesterday it looked as if it was situated underneath the northwest blob. But today the much larger (south east) blob may win out. The exact position of the center will factor into the eventual strength and path of the storm.
Yes..We were saying yesterday that these"monsoonal lows" tend to have multiple centers until one finally dominates. It is starting to fan out more...
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this area of low pressure has still not been tagged ?????? and is recon going to go in as planned even though the science foundation already did ???
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1. DISORGANIZED CLOUDINESS AND THUNDERSTORMS OVER THE NORTHWESTERN
CARIBBEAN SEA ARE ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE.
OBSERVATIONS FROM A NATIONAL SCIENCE FOUNDATION JET AIRCRAFT
INDICATE THAT THE LOW DOES NOT YET HAVE A WELL-DEFINED CENTER OF
CIRCULATION. HOWEVER...ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE
FOR GRADUAL DEVELOPMENT OF THIS SYSTEM DURING THE NEXT COUPLE OF
DAYS AS IT MOVES NORTHWARD OR NORTH-NORTHEASTWARD. THERE IS A
MEDIUM CHANCE...40 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL OR
A SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS. INTERESTS IN
CUBA...THE FLORIDA KEYS...AND THE SOUTH AND CENTRAL FLORIDA
PENINSULA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. CONSULT
STATEMENTS FROM YOUR NATIONAL WEATHER SERVICE FORECAST OFFICE AND
NATIONAL METEOROLOGICAL SERVICE FOR ADDITIONAL INFORMATION.

2. CLOUDINESS AND SHOWERS ASSOCIATED WITH A SMALL LOW PRESSURE AREA
LOCATED ABOUT 800 MILES WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS
HAVE BECOME LESS ORGANIZED TODAY...AND THERE IS A LOW CHANCE...NEAR
0 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

3. ANOTHER AREA OF LOW PRESSURE...THE REMNANT OF TROPICAL DEPRESSION
JULIA...IS LOCATED ABOUT 350 MILES SOUTHEAST OF BERMUDA AND IS
MOVING WESTWARD NEAR 15 MPH. CONDITIONS ARE NOT CONDUCIVE FOR
SIGNIFICANT DEVELOPMENT AND THERE IS A LOW CHANCE...10 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH/CANGIALOSI
NNNN
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638. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting 1992Andrew:
Can't tell where the center will be... yesterday it looked as if it was situated underneath the northwest blob. But today the much larger (south east) blob may win out. The exact position of the center will factor into the eventual strength and path of the storm.
Just on my lunch break but the blob south of the Cayman Islands is looking better and better. Got a feeling that is where we will see development. Very gusty conditions here today and rough seas.
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Quoting Jax82:


Yeah I probably should have taken down my umbrellas in my back yard, lol, we'll see what happens, sometimes these lines die out before they hit here.
Severe thunderstorm warning for western Duval right now.
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hurricane hunter joe been trying to post an image for like 2 weeks now. lol
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Quoting PSUweathermet:


I just got dell's 15r and i love it, now i got it at a student price so im not sure how much it would cost you. Great sound and graphics card, 4GB ram, and 500GB HD


I'll check it out. thanks.
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Can't tell where the center will be... yesterday it looked as if it was situated underneath the northwest blob. But today the much larger (south east) blob may win out. The exact position of the center will factor into the eventual strength and path of the storm.
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From "PREDICT":

Science Director Summary for Sep 27.

We are focused today on the the broad area of cyclonic
circulation in the Northwestern Caribbean. The GV is currently
flying research flight 24, with an east-west oriented lawnmower
pattern



Wonder who's right?
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Quoting PSUweathermet:

Atlantic Tropical Weather Outlook


000
ABNT20 KNHC 271731
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT MON SEP 27 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

DISORGANIZED CLOUDINESS AND THUNDERSTORMS OVER THE NORTHWESTERN
CARIBBEAN SEA ARE ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE.
OBSERVATIONS FROM A NATIONAL SCIENCE FOUNDATION JET AIRCRAFT
INDICATE THAT THE LOW DOES NOT YET HAVE A WELL-DEFINED CENTER OF
CIRCULATION. HOWEVER...ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE
FOR GRADUAL DEVELOPMENT OF THIS SYSTEM DURING THE NEXT COUPLE OF
DAYS AS IT MOVES NORTHWARD OR NORTH-NORTHEASTWARD. THERE IS A
MEDIUM CHANCE...40 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL OR
A SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS. INTERESTS IN
CUBA...THE FLORIDA KEYS...AND THE SOUTH AND CENTRAL FLORIDA

PENINSULA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. CONSULT
STATEMENTS FROM YOUR NATIONAL WEATHER SERVICE FORECAST OFFICE AND
NATIONAL METEOROLOGICAL SERVICE FOR ADDITIONAL INFORMATION.

CLOUDINESS AND SHOWERS ASSOCIATED WITH A SMALL LOW PRESSURE AREA
LOCATED ABOUT 800 MILES WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS
HAVE BECOME LESS ORGANIZED TODAY...AND THERE IS A LOW CHANCE...NEAR
0 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

ANOTHER AREA OF LOW PRESSURE...THE REMNANT OF TROPICAL DEPRESSION
JULIA...IS LOCATED ABOUT 350 MILES SOUTHEAST OF BERMUDA AND IS
MOVING WESTWARD NEAR 15 MPH. CONDITIONS ARE NOT CONDUCIVE FOR
SIGNIFICANT DEVELOPMENT AND THERE IS A LOW CHANCE...10 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

shes backkkkk!!
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wow 40% chance and no invest tagged

someone overslept lol
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627. unf97
I know all of us is focused on the action in the NW Caribbean rightnow, but I wanted to mention as a sidenote how the low level swirl of ex-Julia keeps spinning out in the Central Atlantic. That system has been around for quite sometime and even ahad a flare up of convection within the past 12 hours before being sheared off again. Just an interesting and fascinating little feature that's still out there.
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Atlantic Tropical Weather Outlook


000
ABNT20 KNHC 271731
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT MON SEP 27 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

DISORGANIZED CLOUDINESS AND THUNDERSTORMS OVER THE NORTHWESTERN
CARIBBEAN SEA ARE ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE.
OBSERVATIONS FROM A NATIONAL SCIENCE FOUNDATION JET AIRCRAFT
INDICATE THAT THE LOW DOES NOT YET HAVE A WELL-DEFINED CENTER OF
CIRCULATION. HOWEVER...ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE
FOR GRADUAL DEVELOPMENT OF THIS SYSTEM DURING THE NEXT COUPLE OF
DAYS AS IT MOVES NORTHWARD OR NORTH-NORTHEASTWARD. THERE IS A
MEDIUM CHANCE...40 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL OR
A SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS. INTERESTS IN
CUBA...THE FLORIDA KEYS...AND THE SOUTH AND CENTRAL FLORIDA
PENINSULA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. CONSULT
STATEMENTS FROM YOUR NATIONAL WEATHER SERVICE FORECAST OFFICE AND
NATIONAL METEOROLOGICAL SERVICE FOR ADDITIONAL INFORMATION.

CLOUDINESS AND SHOWERS ASSOCIATED WITH A SMALL LOW PRESSURE AREA
LOCATED ABOUT 800 MILES WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS
HAVE BECOME LESS ORGANIZED TODAY...AND THERE IS A LOW CHANCE...NEAR
0 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

ANOTHER AREA OF LOW PRESSURE...THE REMNANT OF TROPICAL DEPRESSION
JULIA...IS LOCATED ABOUT 350 MILES SOUTHEAST OF BERMUDA AND IS
MOVING WESTWARD NEAR 15 MPH. CONDITIONS ARE NOT CONDUCIVE FOR
SIGNIFICANT DEVELOPMENT AND THERE IS A LOW CHANCE...10 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

shes backkkkk!!
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Quoting BobinTampa:
Sorry for being off-topic but since the tropics are semi-dead and since this place is full of tech geeks, I need some help. I'm looking for a new laptop. Any suggestions on which brand?

I've heard Sony VAIO's are decent. Any feedback on that or any other recommendations? I don't need anything special. Mostly Internet and email access.



I just got dell's 15r and i love it, now i got it at a student price so im not sure how much it would cost you. Great sound and graphics card, 4GB ram, and 500GB HD
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now cant wait for the ECMWF
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ipad takes care of everything i do takes some time getting use to
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Quoting bwi:
Good afternoon. I'm liking these new gridded forecast links from NHC, off of their main marine forecast page. Gives an idea of their thinking ahead of TD formation:

Pressure

Wind

Wave Height
Great post and links, thank you for them. Rainbow showing a good amount of convection.
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Hello. What chances do the Tampa area see from these systems? Rain and wind wise.
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Quoting srada:



Largeeyes: Where are you located?..Im in Wilmington


Work in New Bern, live near Havelock.
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HERE IS THE 12Z NOGAPS Link.

Very interesting set up in the ATL east of the lesser antilles and in the caribbean
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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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