99L a heavy rainfall threat for Jamaica, Haiti, and Eastern Cuba

By: Dr. Jeff Masters , 2:35 PM GMT on October 21, 2012

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A tropical wave embedded in a large trough of low pressure (Invest 99L) covers a large portion of the Central Caribbean between Hispaniola and the northern coast of South America. This storm has the potential to be a dangerous rainfall threat for Haiti, Jamaica, and eastern Cuba. The disturbance is headed west at less than 5 mph, is over very warm waters of 29°C, and is in a moist environment. 99L has a large area of heavy thunderstorms that have a good degree of spin. These thunderstorms are beginning to organize into spiral bands, as seen on visible satellite loops. However, the amount of heavy thunderstorm activity is about the same as yesterday, and there are no signs of a surface circulation. An Air Force hurricane hunter aircraft is scheduled to investigate 99L this afternoon, but I expect this flight will be rescheduled for later.


Figure 1. Morning satellite image of Invest 99L.

Forecast for 99L
Wind shear is a low 5 - 10 knots, and is forecast to be in the low to moderate range, 5 - 20 knots, through Tuesday. This should allow for some steady development of 99L, and there has been a good deal of model support for 99L becoming a tropical depression by Wednesday. Steering currents favor a continued slow westward movement for 99L through Tuesday. On Wednesday, a strong trough of low pressure to the north of 99L is expected to turn the storm to the north or north-northeast, which should put 99L in the vicinity of Jamaica on Wednesday and Eastern Cuba on Thursday. By Friday, 99L should be in the Central or Eastern Bahamas. It is unclear at this point whether or not the trough pulling 99L to the north will be strong enough to pull the storm all the way out to sea to the northeast; a narrow ridge of high pressure has the potential to build in over 99L late this week and force the storm west-northwest, with a potential threat to the western Bahamas and U.S. East Coast by next weekend. In their 8 am EDT tropical weather outlook, NHC gave 99L a 70% chance of developing into a tropical cyclone by Tuesday morning. 99L will be capable of bringing heavy rains of 5 - 10 inches, with isolated amounts of up to 15 inches in mountainous areas, to Jamaica and Haiti, Monday through Wednesday. Heavy rains will begin on Tuesday in Eastern Cuba, and spread northwards into the Central and Eastern Bahamas by Wednesday.

Invest 90L in the middle Atlantic
A tropical wave (Invest 90L) about 830 miles east-northeast of the northernmost Lesser Antilles Islands is headed west-northwest at about 10 mph. The disturbance has a small amount of heavy thunderstorms, as seen on visible satellite images, and has gotten tangled up with an upper-level low pressure system. This upper-level low is providing 90L the spin it needs to become a tropical cyclone, but is also pumping cool, dry air into the disturbance, which will keep any development slow over the next few days. Wind shear is a moderate 10 - 20 knots, and is forecast to remain in the moderate range until Tuesday. This may allow for some slow development of 90L before it encounters high wind shear of 20 - 30 knots on Tuesday night through Thursday. None of the reliable computer models develop 90L into a tropical cyclone, and it's unlikely that 90L will affect any land areas. In their 8 am EDT tropical weather outlook, NHC gave 90L a 30% chance of developing into a tropical cyclone by Tuesday morning.

The next name on the list of Atlantic tropical storms for 2012 is Sandy.

Jeff Masters

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hr 75

Member Since: July 15, 2006 Posts: 163 Comments: 52096
Quoting Grothar:


I think a lot of rain and a lot of wind. Could be another Isaac type event, but more steady wind and a lot of beach erosion.


NO Gro NO,,...... Wilma was on the 25th?,,,.... okay. well I need to get my Hur did then!
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Well I kinda knew this was coming as our October has been pretty wet now.The last time we had a October this wet was 2009.It appears the NAO is negative(which I hope it stays through the winter).So it wouldn't be all to surprising if a big storm runs up the coast.
Member Since: August 14, 2010 Posts: 10 Comments: 15702
hr 69

Member Since: July 15, 2006 Posts: 163 Comments: 52096
Quoting Grothar:


Don't apologize for not forecasting, Doug. In my book you will always be a weenie. :)



When it comes to weather....Guilty as charged!
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Quoting 954FtLCane:

what r u talking about, are we gonna get rain....AGAIN!!


I think a lot of rain and a lot of wind. Could be another Isaac type event, but more steady wind and a lot of beach erosion.
Member Since: July 17, 2009 Posts: 63 Comments: 23672
Levi is back - and just in time. This looks too much like a Hazel-type repeat.....and you-know-who will mention it over and over......
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hr 60

Member Since: July 15, 2006 Posts: 163 Comments: 52096
hr 48

Member Since: July 15, 2006 Posts: 163 Comments: 52096
42 hr

Member Since: July 15, 2006 Posts: 163 Comments: 52096
36 hr

Member Since: July 15, 2006 Posts: 163 Comments: 52096
Member Since: July 15, 2006 Posts: 163 Comments: 52096
24hr

Member Since: July 15, 2006 Posts: 163 Comments: 52096
Quoting Grothar:


Yes, we across "the Pond" still using the old dates and measuring systems. I read about the rains in France, but I didn't realize how bad it was in Spain.


I didn't realize those living on the other side of Lake Okeechobee do their dates and measurements differently than the rest of us... :)

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18hr
Member Since: July 15, 2006 Posts: 163 Comments: 52096
The FIM9




Member Since: July 17, 2009 Posts: 63 Comments: 23672
18z gfs to hr 144

Member Since: July 15, 2006 Posts: 163 Comments: 52096
325 Grothar: Bryan Norcross just did a blog here on the tropics. Interesting read. For those in Florida and the East Coast I think you should take a look.

StuOstro's newest blog on US weather also has items of interest. Amongst others, "...a satellite image from Friday is something you don't see every day: a cloud of dust which got kicked up by powerful winds in the Plains blowing over extremely dry soil and carried all the way almost to Atlanta!

Didn't realize what a huge scar that Atlanta projects upon the landscape (the "hub&spokes" to the right&middle overlaps the freeway system).
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Quoting KEEPEROFTHEGATE:


event detected


Is that an M or X class event?
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Quoting Grothar:


Thanks, nc. Right over my house.

what r u talking about, are we gonna get rain....AGAIN!!
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Quoting ncstorm:


but what about your neighbor:)
And his neighbors neighbor's?.Then their neighbors!
Member Since: August 14, 2010 Posts: 10 Comments: 15702
.
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Quoting Grothar:


Thanks, nc. Right over my house.


but what about your neighbor:)
Member Since: August 19, 2006 Posts: 13 Comments: 13418
Quoting ncstorm:
JMA Model

Florida, Bahamas-120 hours


and then for those other states who are called the east coast-144 hours..last frame


Thanks, nc. Right over my house.
Member Since: July 17, 2009 Posts: 63 Comments: 23672
Quoting PensacolaDoug:


But not So Cal.


It never rains in Southern....California!
Member Since: July 17, 2009 Posts: 63 Comments: 23672
A Night to Remember

All of the houses on Raymore Drive, on the Etobicoke side of the river just south of Lawrence Avenue, were washed into the Humber River, killing 32 residents in a less than one hour. The entire five-man pumper crew from the Lambton-Kingsway fire department died when their vehicle was swept into the raging river; one of the bodies was never recovered. In fact, the water in the river moved so swiftly that some bodies were eventually found on the other side of Lake Ontario on the shores of New York state.

Bridges at Bloor Street, Dundas Street, Old Mill, and Albion Road on the Humber River were badly damaged, while the bridge at Lawrence Avenue in Weston was washed out. All the flats were inundated, and roads and buildings were damaged.

To the north of Toronto, over 3,000 people abandoned their homes in the Holland Marsh area as the floodwaters engulfed the farmland. The water levels rose so quickly that sandbagging efforts failed, dykes overflowed, and residents were instructed to seek higher ground.

Most of those who lost their lives were swept away by the raging waters of the Humber River and its tributaries, creek-like under normal conditions – but on this night, conditions were far from normal.

Many people can still clearly recall their personal experiences of Hurricane Hazel as if it was yesterday. Winnie McLean, a former Legion Branch president asked me quite a few years ago to write about what happened to her and her family when Hurricane Hazel swept in from the south.

A Night to Remember

Nelson and Winnie McLean, their 4-month-old daughter Sue, and 14-month-old son Calvin were living in a rented two-bedroom house in Islington, where the usually placid and meandering Black Creek ran past the back end of their property. Here’s Winnie’s account about what happened on that Godforsaken night when whole families were swept away to their deaths in the muddy, raging waters:

“There are two things that sneak up on you, one is old age and the other is a huge flood. In this case it was the latter. Nelson and I were sitting in our living room watching TV when suddenly the screen went blank. I went outside to see if the aerial had blown off the roof, but when I stepped out the door, there was a calmness, a stillness in the air much like after a storm. As we couldn't watch our favourite programs on TV, and since the storm appeared to be over, we retired for the night, unaware of the terrible events that were soon to unfold.

We were awakened at 1a.m. by loud banging on our window and someone shouting: ‘Get out!, Get out!’ We went out to take a look at what was going on and were surprised to see water in the front and back yard running fast and deep, and people yelling, ‘Get out, there's a flood!’

We quickly threw winter suits and a blanket on our babies. I managed to get into only a slip and skirt, while Nelson got his hip-boots on and a jacket over his pajamas. We stuffed blankets into the bath to keep the water out; this all took place in less than five minutes. I didn't have time to rescue any valuable items, but managed to grab the babies' bottle-sterilizer, but then discovered there were no bottles in it.

We slipped out the back door and stepped into waist deep water where two burly firemen took our babies, tied ropes around our waists, steered us to another rope that enabled us to climb up the muddy embankment to safety.

From there we were we could see the two-storey Scarlett Road Hotel, with the floodwater running through the upper windows and out through the back. The most pathetic and heart-rending sight we saw were the cars floating by with people clinging desperately on top crying out for help.

Other people were halfway up hydro poles waiting to be rescued, but before long the surging waters claimed them.
On that night of terror and death, a radio news announcer, in a casual voice, mentioned that there was flooding on Toronto's west side, and that people who owned a motorboat could assist in the rescue operation.

Five minutes later came another announcement that only boats of 20 H.P. would be needed. Five more minutes went by and again an announcement that now it had to be boats of 50 H.P. The last request was for boats having 100 H.P. motors, the only size that could navigate the seething, tumbling, fast-flowing water. The requests for help from boat owners, I have to say in hindsight, today seems rather comical.

A new steel bridge over Black Creek, a block from our house, stopped several houses from being carried out into Lake Ontario. It was so sad to look into their upper rooms and see all the possesions destined to be lost forever. Roofs were gone and there were big holes in buildings’ sides. The houses had floated down from Raymore Drive where so many had drowned.



To the north of Toronto, over 3,000 people abandoned their homes in the Holland Marsh area as the floodwaters engulfed the farmland.

Our street was a circular one, with all new houses on it, and those homes that formed a circle in the centre became an island, trapping the families on the rooftops. Those who tried to swim to safety never made it.

Not far from the hotel, a hook and ladder fire-truck with a full complement of five volunteer firemen was swallowed up by the raging waters. It wasn't until 35 years later that the truck was found at the bottom of Lake Ontario, some four or five miles from where it went under.

The power of the floodwater was so great, the pressure it exerted forced many furnaces right up through the roofs of the houses. After the flood waters abatted, and we were able to come back to where we lived, we were stunned at what our eyes took in. Where Nelson had parked his truck on the road, the water had eroded the gravel base and the soil underneath – our truck was sitting some 20 feet down in a great pit. What saved it from being carried away like so many other vehicles was the weight of steel loaded into the back.



Hurricane Hazel

by Stan Scislowski
Member Since: July 15, 2006 Posts: 163 Comments: 52096
Quoting Levi32:


Don't you know, I always walk the path of least resistance :)

It's been quite busy for me lately, but doing well. How are things for you?


Busy, but good. I know this may come as a shock to you, but I agree with you pretty much on this one. I've already sent a "blob" alert to my family and friends in the NE.
Member Since: July 17, 2009 Posts: 63 Comments: 23672
Quoting Levi32:
Good afternoon.

Blog update:

Tropical Tidbit for Sunday, October 21st, with Video


Good to see ya Levi! Thanks for the Tidbit!
Member Since: July 2, 2011 Posts: 0 Comments: 1176
Levi!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!:):) lol!!!!!!!!:)
Member Since: May 23, 2012 Posts: 0 Comments: 4207
Quoting Grothar:


Oh, sure. Now you show up, after we did all the work. How you doing, Levi?


Don't you know, I always walk the path of least resistance :)

It's been quite busy for me lately, but doing well. How are things for you?
Member Since: November 24, 2005 Posts: 628 Comments: 26452
Quoting ncstorm:


LOL..if the model runs pan out from today and hopefully dont shift any farther west, NONE of the east coast including the bahamas wont be trick or treating but actually dipping and dodging..
Member Since: August 14, 2010 Posts: 10 Comments: 15702
Quoting Levi32:
Good afternoon.

Blog update:

Tropical Tidbit for Sunday, October 21st, with Video


Oh, sure. Now you show up, after we did all the work. How you doing, Levi?
Member Since: July 17, 2009 Posts: 63 Comments: 23672
Quoting washingtonian115:
The models have a "wanted" sign on my head after I made fun of the cmc.Hey ncstorm you got your trick-or-treak cand available in case so you and your family can feast?.


LOL..if the model runs pan out from today and hopefully dont shift any farther west, NONE of the east coast including the bahamas wont be trick or treating but actually dipping and dodging..
Member Since: August 19, 2006 Posts: 13 Comments: 13418
Good afternoon.

Blog update:

Tropical Tidbit for Sunday, October 21st, with Video
Member Since: November 24, 2005 Posts: 628 Comments: 26452
337. beell
Quoting Tropicsweatherpr:
18z Surface Analysis.



Monsoon trough attached to the low on that one.
Member Since: September 11, 2007 Posts: 137 Comments: 15297
Quoting Grothar:


I think you've got it!


But not So Cal.
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not sure if anyone posted this but from the 12z GFS run

thru 120 hours-precip map


thru 240 hours


thru 360 hours..something is coming up thru Cuba again
Member Since: August 19, 2006 Posts: 13 Comments: 13418
Quoting PensacolaDoug:
I've been sitting on the sidelines watching the models and the speculation as this unfolds. It's starting to get very very interesting. A true test of the models. I don't forecast but I do follow the the official and (un-official) forecasts. I can't wait to see how this all plays out but the situation is ripe to get all of us weather weenies in a dither! Very cool set-up!


Don't apologize for not forecasting, Doug. In my book you will always be a weenie. :)
Member Since: July 17, 2009 Posts: 63 Comments: 23672
Quoting ncstorm:
JMA Model

Florida, Bahamas-120 hours


and then for those other states who are called the east coast-144 hours..last frame
The models have a "wanted" sign on my head after I made fun of the cmc.Hey ncstorm you got your trick-or-treak candy available in case so you and your family can feast?.
Member Since: August 14, 2010 Posts: 10 Comments: 15702
Quoting CaicosRetiredSailor:


...mainly on the plain.


I think you've got it!
Member Since: July 17, 2009 Posts: 63 Comments: 23672
Quoting Grothar:


Yes..... I read about the rains in France, but I didn't realize how bad it was in Spain.


...mainly on the plain.
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18z gfs starts in about 15 minutes
Member Since: July 15, 2006 Posts: 163 Comments: 52096
Quoting ncstorm:
JMA Model

Florida-120 hours


and then for those other states who are called the east coast-144 hours..last frame


i feel like iam about to witness the hazel effect
Member Since: July 15, 2006 Posts: 163 Comments: 52096
Good evening... VORT from 850MB to 500MB is almost stacked a couple hundred miles S/SSE of Jamaica. There's quite a bit of deep moisture pooling up in the C/W Carib as well with should take care of modifying any dry air intrusion (at least a low levels).
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JMA Model

Florida, Bahamas-120 hours


and then for those other states who are called the east coast-144 hours..last frame
Member Since: August 19, 2006 Posts: 13 Comments: 13418
Quoting PlazaRed:

Things quiet with a bit of drizzle in my Zone, south of Seville but horrendous floods in the north and Barcelona area of Spain lots of damage and houses washed away.
Big storm came up of the Sahara of all places, red dust all over the place in Valencia which is no doubt red mud by now. The sort of Biblical stuff with Moses and raining blood etc.
Some areas are having worst rainfall and damage in over 50 years, more to come tomorrow.
There will be plenty to moan about cleaning up in the next few days.
Do all the ex-colonies in the Americas use the "non backward" system of applying dates? I suppose it would have worked OK on 11,11,11? For all of us.


Yes, we across "the Pond" still using the old dates and measuring systems. I read about the rains in France, but I didn't realize how bad it was in Spain.
Member Since: July 17, 2009 Posts: 63 Comments: 23672



Bryan Norcross just did a blog here on the tropics. Interesting read. For those in Florida and the East Coast I think you should take a look.
Member Since: July 17, 2009 Posts: 63 Comments: 23672
Quoting Grothar:


They give the year first, 12 then month and date.

2012 10-29

We don't put our dates backwards like you do in Europe. :) How you doing Plaza?

Things quiet with a bit of drizzle in my Zone, south of Seville but horrendous floods in the north and Barcelona area of Spain lots of damage and houses washed away.
Big storm came up of the Sahara of all places, red dust all over the place in Valencia which is no doubt red mud by now. The sort of Biblical stuff with Moses and raining blood etc.
Some areas are having worst rainfall and damage in over 50 years, more to come tomorrow.
There will be plenty to moan about cleaning up in the next few days.
Do all the ex-colonies in the Americas use the "non backward" system of applying dates? I suppose it would have worked OK on 11,11,11? For all of us.
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I've been sitting on the sidelines watching the models and the speculation as this unfolds. It's starting to get very very interesting. A true test of the models. I don't forecast but I do follow the the official and (un-official) forecasts. I can't wait to see how this all plays out but the situation is ripe to get all of us weather weenies in a dither! Very cool set-up!
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Quoting whitewabit:


Don't feel bad .. I predicted 15/8/3 and thought I would be high when I posted it ...
Whitewabit, you were high when you posted? One pill makes you larger and one pill makes you small.
Member Since: August 30, 2010 Posts: 0 Comments: 317
18z Surface Analysis.

Member Since: April 29, 2009 Posts: 75 Comments: 13256

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.