Tropical Depression Fifteen forms in the Caribbean
Tropical Depression Fifteen is here, and is destined to become Tropical Storm Matthew by late this afternoon or this evening. An Air Force hurricane hunter aircraft left the storm near 2pm EDT this afternoon, and on their final pass through the strong northeast quadrant of the storm, found a substantial area of surface winds of 40 - 45 mph with their SFMR instrument. Top flight level winds at 500 feet were 48 mph. These winds support upgrading TD 15 to Tropical Storm Matthew. Satellite loops show that TD 15's heavy thunderstorm activity continues to increase in intensity and areal coverage, with several respectable low-level spiral bands in evidence. There is some dry air to the northwest of TD 15, but it is currently not significantly affecting development.
Figure 1. TD 15 at 11:50am EDT 9/23/10, as seen by NASA's Terra satellite.
Forecast for TD 15
An upper-level high pressure system lies to the west of TD 15, near the coast of Nicaragua. The clockwise flow of air around this high will bring a moderate 10 - 20 knots of wind shear over TD 15 today and Friday. There is some dry continental air lying to the northwest of TD 15, and this shear may be able to drive dry air into the storm, slowing intensification and keeping TD 15 below hurricane strength through Saturday morning. By Saturday afternoon, TD 15 will move more underneath this upper-level high, causing the shear to decline. The SHIPS model forecasts that shear will fall to the low range, 5 - 10 knots, Saturday through Monday. This drop in shear should allow for intensification of TD 15 into a hurricane, if the center stays more than 50 miles offshore.
The future track and intensity of TD 15 depends critically upon the storm's interaction with land over the coming days. If TD 15 misses making landfall in Nicaragua and Honduras, and instead skirts the north coast of Honduras, the storm is likely to intensify into a hurricane by Sunday, as indicated in the official NHC forecast. However, if TD 15 spends significant time over or barely offshore of Honduras, the storm will likely stay below hurricane strength. TD 15 is being forced just north of due west by a strong ridge of high pressure. This ridge will keep the storm moving at 15 mph through Saturday. On Sunday, a trough of low pressure diving southwards over the Eastern U.S. will weaken the steering currents over the Western Caribbean and cause TD 15 to slow and turn more to the north. TD 15 will begin a period of slow and erratic movement on Sunday that may last many days, as the storm wanders in the Western Caribbean and over Belize, Honduras, and Mexico's Yucatan Peninsula. If the center of TD 15 spends significant time over water, the storm could easily develop into powerful and dangerous Hurricane Matthew. If the center remains mostly over land, TD 15 will still generate extremely heavy rains over Central America, but remain below hurricane strength. By late next week, the trough of low pressure over the Eastern U.S. may lift out, allowing a ridge of high pressure to build in and force TD 15 westwards across the Yucatan Peninsula and into the Gulf of Mexico's Bay of Campeche. Alternatively, the trough of low pressure over the Eastern U.S. may amplify, drawing TD 15 northwards across Western Cuba and into Florida. A complicating factor may be the development of a new tropical depression in the Central Caribbean 6 - 8 days from now, as predicted by both the GFS and NOGAPS models with their latest 12Z (8am EDT) runs. The uncertainties in the long-range fate of TD 15 are high, and depend strongly on slight variations in its track that determine how much time the storm spends over land. One thing that is virtually certain is that TD 15 will generate very heavy rains over Nicaragua, Honduras, Belize, and Mexico's Yucatan Peninsula Friday through Tuesday that will cause dangerous flooding rains and life-threatening mudslides.
Tropical Depression Lisa
Tropical Depression Lisa continues to churn the waters of the far Eastern Atlantic. By Saturday night, upper level winds out of the west are expected to increase, bringing high wind shear of 20 - 45 knots over Lisa. The high shear may be capable of destroying the storm by early next week. It appears unlikely that Lisa will affect any land areas.
Elsewhere in the tropics
The remnants of Hurricane Julia are still spinning over the far Eastern Atlantic, and are generating some sporadic heavy thunderstorm to the north of the center of circulation. Julia's remains are being given a 10% chance of re-developing by NHC.
Hurricane Karl's moisture causing flooding in Minnesota, Wisconsin
A plume of very moist air associated with what was Hurricane Karl last week has surged northwards over the Central U.S. over the past two days. This moisture is now being lifted over a warm front draped over Minnesota and Wisconsin, and has generated flooding rains in excess of six inches in southern Minnesota this afternoon. Flood warnings and flood watches are posted for a wide swath of the upper Midwest today, including most of southern Minnesota, northern Wisconsin, and Michigan's Upper Peninsula. 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. Radar estimated rainfall over Minnesota.
Next post
I'll have an update on TD 15 Friday morning.
Jeff Masters
Neighbors help a driver to move his vehicle from the flood waters
Reader Comments
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rofl, geeze thank a lot!
you are correct, here in my area, Broward County, very few homes had real hurricane shutters before 2004/2005,
(we had to use plywood) but after those years, we all have shutters and most of us now have accordian shutters that we can close up the entire house in about 15 mins.
but that does not mean we want all the hard work preping before the storm and replacing and relandscaping after the storm.. plus the days without power..and the money it all costs! LOL
Oh what a thoughtful comment for the people living in C. A. Many of them have no means of protection. At least Florida doesn't get devastating mudslides that destroy entire towns.
What;s the topography like? A fairly significant portion of your country is forecast to be in the tropical storm force wind field, and that means a significant area will receive rain:
True enough, but even an offshore Hurricane will put more rains into Central America and I'd be shocked if no one loses their life from Matthew. 100's will probably be lost due to mudslides and flash-flooding if Matthew was 50 miles offshore or 50 miles inland. It's still going to be very bad.
I'm sorry I totally did not understand what you said lol.
Is any eastward component likely (upper keys SE Florida)?
That's looking at the bright side!
definite wishcasting, as I hope it interacts with land (but sparing all lives and property).
I don't think my wishes matter one bit. Mother nature will do what mother nature will do.
That's just mean. What about all the people in Florida that want a storm?
*facepalm* Ah the famous "Not In My Backyard" syndrome.
Next time, as a suggestion, perhaps wishing "I hope this just fizzles out, the last thing we need is another hurricane making landfall."
They can go to Central America!
In the Bible, the apostle Matthew is sometimes known as Levi. I wouldn't have made the connection until he/she said that.
Zing! Gotta give you props for that one.
Yeah, unless you live in Central America.
We will have to see. It all depends on how the upper low/trough behaves over the southern US. At this point, if Matthew goes through the Yucatan Channel, I don't think he will acquire enough angle to track over SE Florida, but that is based on a couple assumptions.
We have to take the track forecast one step at a time. What we're doing is setting up the main idea that a storm is going to be drawn north out of the western Caribbean and threaten the area from the central GOM eastward, with Florida probably at the most risk at this point. From this idea, we can start constructing specifics as the situation evolves. The first hurdle we have to get past is what TD 15 does around central America.
Do either of you know if they are talking about evacuating the Cayes yet? Since it is daytime only operation, doesn't it take about two and a half days to move everyone?
That is what it will most likely do..
Oh ya, thought about mentioning it lol. I wish I was still in Homer....it's going to be epic there, but I'm now in the interior where we will see little weather from that. It's going to be one heck of a winter here, probably the worst in decades for some parts of the state.
I don't think people wouldn't want their roof to collapse or get torn off and then their walls falling down and crushing them to death...
Matthew to be, will stall, according to the NHC, over the highest area of TCHP.
Not good.
Another Wilma?
.
.
Seems a little low to me.
I'll wait for the words between the words in the first full discussion coming up soon.
I'll ask again I guess, why is Matthew forecasted to become a major over land?
Member Since: September 22, 2010 Posts: 0 Comments: 0
Again it's hard to say how he will behave near the Yucatan, but right now my feeling is he will stay near the eastern coast of the Yucatan and slowly turn NNE towards the Yucatan Channel. If he is far enough offshore he could potentially bomb into a rather strong hurricane, but if he's too close to land or onshore, he will be a broad, weak system when he comes out.
Right now I think he will stay more over water than over land, but that could change depending on when the weakness opens up in the ridge. Either way, heavy rains will be causing major problems for central America.
Matthew is not forecast to become a major hurricane over land.
So true. The trees and mother nature are just getting back to normal after Wilma 5 yrs ago.
What????
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Just don't want him to think we are ignoring his/her comment. That is rude.
1203. seflagamma 3:43 PM EDT on September 23, 2010
Quoting mx3gsr92:
I asked this yesterday but was not successful in getting any feedback. I'm heading to Cozumel/Cancun for a week vacation starting Sunday. Could someone give me an idea of what to expect? Should I not go? Anybody have a similar experience? Sorry for asking again. Thanks.
From me:
not sure if anyone has answered you yet but sounds iffy to me, if the storm misses that area there is no need to miss your vacation.
just wait and watch a few more days.. this storm could possibly fizzle out, who knows at this point. Most resorts will allow you to cancel at the last minute if they go under a warning. At least give it until Sat morning until you make your decision. By then we should know something more...
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