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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pressure's dropping near cozumel..

while the pressure is rising near grand cayman, indicating the circular area of convection south of the cayman islands isn't developing for now..

the area east of cozumel though is possibly
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Taco,

Its good to see you back even its under a different name. it took me a while but I now know who you are. I should of known.... We have had some serious debates on here and doesnt look like you've missed a beat.... cheers to more debates....
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Quoting P451:Wait and see....instead of dropping the blog to DOOMCON 1 once again because of a few long range models.


DOOMCON 1 depends upon a person's proximity to the development. For example, when most people talk about "landfall", they mean the U.S. Us little crapsplat islands take these things seriously for good reason.

This time of year, systems develop often in the lower Caribbean and intensify quickly, leaving little time for response.

Just my $0.03 C.I. cheers
Member Since: January 20, 2005 Posts: 64 Comments: 9241
Slow development expected about 100miles east of cozumel,mx...looks to be nearly stationary for next 24hrs,maybe slight drift north or northeast imo
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Man, it's definately a Monday. I just hovered my mouse over the NHC map on post 389 and was trying to figure out why the info wouldn't pop up under the orange AOI! NEED MORE COFFEE!
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Quoting kwgirl:
Nope
I would say there is a chance the entire system could miss south and east of Florida. The combination of the front coming down and the flow becoming more southwest to northeast and eventaully more west to east. If nothing develops out of the very broad area of circulation this could turn into rainshowers for south florida and nothing more. There is always a possibilty of this occuring but not set in stone at this point. I have this feeling we are getting very close to the season winding down for the conus and certainly my area (northwest florida). Cold front will produce lows close to 60 next few days. No tropical activity up here in the current environment.
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85.5N and 19.5W seems to be the developing surface spin directly under the cluster of thunderstorms. Seems to be getting more define by the hour.
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Quoting CyclonicVoyage:
Reason being is forward speed is added to the strongest quadrant.


Gotchya! Thanks
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looks like convection is being displaced ene so there could be some windshear
Member Since: September 11, 2010 Posts: 1 Comments: 4717
Quoting CyclonicVoyage:


All the winds are converging to the area off Western Cuba. If it strengthens the blob to the east will be absorbed. The ULAC is not causing prohibitive shear so a relocation is unlikely, imo.


Gotcha! Thx for the input! Its kinda of crazy that some models had matthew doing what it did and now we have that area of interest in the Western Carribean just like the models were spitting out that broad weak low. Very complex, Seems like with the convection spread out as it is its going to take it awhile to get its act together expecially with 10-20kts of shear holding him in check. What do you see coming from this possibly down the road, strong tropical storm once it gets north of CUBA or maybe extratropical if it combines with the ULL over the Tennessee Valley?
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401. afj3
Quoting P451:


Sure. That front could dig down deeper into Florida and pick up this disturbance, bring it through Cuba and into the Bahamas.

The future of this disturbance is unknown.

Again, until it organizes and gets a well defined surface circulation it will be a tough call beyond expecting some breezy and rainy weather for Cuba and S Florida in the next 4-7 day period.


Thanks. We'll just have to wait...
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399. 7544
whatever if we get a td or not down i think it already is as it moves north over cuba it will weaken but as gets in the fla straight this could do a rapid intensifiation as tehre is no shear there and this could be stong as it gets closer to so fla so the way it looks now why would they cancel the flight it still ago ago for 2 pm stay tuned
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Reason being is forward speed is added to the strongest quadrant.
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397. unf97
Good morning everyone.

What a wet and wacky week in store for where I am here in Jax and my other fellow bloggers in Florida. The conveyor belt is now established for the Caribbean moisture to feed north and northeast not just for this week, but for the long term as this pattern is entrenched for at least the next 10 days.

Our developing Low Pressure area in the NW Caribbean Sea is definitely beginning to get its act together and based on satelitte imagery, I would find it very surprising if the Hurricane Hunters don't find that we at least have a tropical depression right now.

It has been a very hot and dry summer for most in Florida, but my goodness, we will see a drought buster potentially in the coming days. Looks as if this should be at least a moderate tropical cyclone (Nicole) as it approaches the state by Wednesday. We all will obviously keep monitoring this situation and hope that this system doesn't bomb out as we have seen many storms in the NW Caribbean have done in the past .
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OK, thank you!

I'll save my NE Quadrant question for tomorrow :)
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Quoting Seflhurricane:
can someone post a current vorticity map to see what going on. seems like we either have 2 lows forming/ competing to see which one is stronger


http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8vor4.html
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DID RECON DEPART ???
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Eastern area of convection is definately deeper...

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can someone post a current vorticity map to see what going on. seems like we either have 2 lows forming/ competing to see which one is stronger
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The strongest part of the eye wall usually the right side of the forward motion of the hurricane. If the hurricane is moving NW then the NE side of the eyewall would most likely be the strongest. If the hurricane is moving due north then the E side of eyewall. NE forward direction then the SE side.
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Quoting islander101010:
seems as if the area is the nw carib is stationary it looks like it is deeping
recon?
Member Since: September 11, 2010 Posts: 1 Comments: 4717
Hey Taco, you are beating a dead horse, OK?

Give it a rest and watch our new AOI develop.
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Quoting Katelynn:
Good Morning everyone!

I have another dumb question today :)

It's about the 'Northern Eyewall'

What if a hurricane is coming in sideways (horizontal) to a location.

Is the northern eyewall on the 'north' (top) or is it on the east or west side, as it's coming into land.

Gah, I don't know how to word that! Does anyone know what I'm trying to ask?!

Hurricane approaching land at a right angle Oooo-------> |Florida|

so is the 'northern eyewall' ^ up top (north on compass), or is the 'northern eyewall' considered facing/heading east, because the hurricane is on it's 'side' as it approaches land.

Say there was a TC /above/ PR, and it headed south into SJ. Then would SJ get the 'northern eyewall', although it's approaching from the north and the eyewall is actually on the south side of the blob? (rare, but I think it's happened?) (i think i just answered my question)

aaaah, I could've summed it up in one easy question:

Is the 'northern eyewall' always on the leading edge of a hurricane, no matter what compass direction it's coming from or approaching?

Thanks, only 1 dumb question a day from me :)




No.

From the East = NE Quad

From the West = SW Quad
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seems as if the area is the nw carib is stationary it looks like it is deeping
Member Since: September 11, 2010 Posts: 1 Comments: 4717
most of the convergence is developing with the area near the cayman islands

but there's a stronger low near the yucatan near the surface
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Quoting BobinTampa:


we're all getting pedicures. be patient.


Speak for yourself. Nobody touches my feet but me.
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looks like somthing if forming near the caymen islands looks impressive
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Good Morning everyone!

I have another dumb question today :)

It's about the 'Northern Eyewall'

What if a hurricane is coming in sideways (horizontal) to a location.

Is the northern eyewall on the 'north' (top) or is it on the east or west side, as it's coming into land.

Gah, I don't know how to word that! Does anyone know what I'm trying to ask?!

Hurricane approaching land at a right angle Oooo-------> |Florida|

so is the 'northern eyewall' ^ up top (north on compass), or is the 'northern eyewall' considered facing/heading east, because the hurricane is on it's 'side' as it approaches land.

Say there was a TC /above/ PR, and it headed south into SJ. Then would SJ get the 'northern eyewall', although it's approaching from the north and the eyewall is actually on the south side of the blob? (rare, but I think it's happened?) (i think i just answered my question)

aaaah, I could've summed it up in one easy question:

Is the 'northern eyewall' always on the leading edge of a hurricane, no matter what compass direction it's coming from or approaching?

Thanks, only 1 dumb question a day from me :)


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not a lot going on in here despite possible development close to florida.. quite a surprise lol
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As Matthew's remnants move further off to the west, conditions should improve a bit for our AOI.
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Quoting 69Viking:


I ended up with 1.25" of rain this weekend in the FL Panhandled, much needed rain after over 3 weeks of 90 degree temps and no rain. It's going to be nice to see highs only in the low 80's and lows in the upper 50's and low 60's, fall has arrived in the FL Panhandle today!


I hear you on the no rain thing...and like you, relief came last night when we got a 1.67" gullywasher over a period of an hour. Rain rates on the weather station were hitting over 5"/hr for brief periods...good stuff...here in SWFL though I think it can be attributed to tropical moisture leaching up from the AOI's and ex-Matthew...
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372. 7544
our aoi is getting a bigger red ball at this hour maybe we just might see a td at 2pm when the plane gets in it imo
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Quoting ILwthrfan:


So the remenants of Matthew still effecting this area then?

I would think the blob to its southeast would be in a better environment to spin up at least in proximity to other convection around 17N 82W?


All the winds are converging to the area off Western Cuba. If it strengthens the blob to the east will be absorbed. The ULAC is not causing prohibitive shear so a relocation is unlikely, imo.
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Good morning all (what's left of it anyways)... Looks like a decent spin around 20.5N 86W... not sure if it is surface yet, since winds at sites to the W (Cozumel and Cancun) are still out of the E/SE
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Quoting 69Viking:


I ended up with 1.25" of rain this weekend in the FL Panhandle, much needed rain after over 3 weeks of 90 degree temps and no rain. It's going to be nice to see highs only in the low 80's and lows in the upper 50's and low 60's, fall has arrived in the FL Panhandle today!


I'm envious. I don't think that front is going to make it far enough south to cool me down. Lots of rain, though.
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368. HadesGodWyvern (Mod)
Japan Meteorological Agency

DEVELOPED LOW, FORMER MALAKAS (T1012)
54.0ºN 173.0ºE - 972 hPa

SUBJECT: In Sea Around Aleutian Islands
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Quoting weatherwart:
The entire southeastern seaboard is going to get soaked, looks like.







I ended up with 1.25" of rain this weekend in the FL Panhandle, much needed rain after over 3 weeks of 90 degree temps and no rain. It's going to be nice to see highs only in the low 80's and lows in the upper 50's and low 60's, fall has arrived in the FL Panhandle today!
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Quoting afj3:
Any chance of this thing passing east of Florida entirely???
Nope
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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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