November Atlantic hurricane season outlook
A small area of disturbed weather in the extreme southern Caribbean has brought heavy rains of up 4-6 inches to Costa Rica and southern Nicaragua over the past two days. This disturbance should persist for the next 3-5 days, and the UKMET and NOGAPS models continue to forecast that a tropical depression could form in this region 4-7 days from now. Steering currents are weak in the area, and any storm forming there would move slowly. Nicaragua would be at greatest risk from such a storm.
Late season Atlantic tropical storms
What are the odds of getting a late-season November or December tropical storm? In the active hurricane period that began in 1995, we've had nine tropical storms in November, and four in December, for an average of one late season storm per year. Six of these late season storms have become hurricanes. The record for late season named storms is four, which occurred in 2005, when three November and one December storm formed. The typical formation location for these late-season storms is the Western Caribbean or the middle Atlantic (Figure 1). The Western Caribbean storms are the most dangerous. There have been two Category 4 hurricanes that have formed in November in that region, Hurricane Lenny of 1999 (the strongest late-season hurricane on record, with 155 mph winds), and Hurricane Michelle of 2001. November storms are primarily a theat to Central America, Cuba, the Cayman Islands, the Bahamas, and the Gulf Coast of Florida.
Figure 1. Historical tropical cyclone tracks in the Atlantic for storms that formed in the first half of November. The Western Caribbean is the preferred formation region.
Sea Surface Temperatures
Sea Surface Temperatures (SSTs) are cooling, but are still warm enough to support a tropical storm over the Caribbean (Figure 1). The Gulf of Mexico will cool significantly in the coming week, due to the presence of cold air and northwesterly winds. It is now too late for the Gulf to spawn a tropical storm, and any hurricane or tropical storm that passes into the Gulf will likely weaken due to the cool SSTs there. The total heat content of the ocean is still high enough to support a major hurricane in the Caribbean.
Figure 2. Sea Surface Temperatures (SSTs) on October 29, 2008. The 26 °C isotherm (red line that separates blue colors from yellow colors) marks the boundary where SSTs are warm enough to support a tropical storm. Image credit: NOAA/AOML.
Wind shear
High wind shear is main reason we don't get many November tropical storms. Wind shear is currently very high north of the Caribbean Sea, and is forecast to remain high for the next two weeks (Figure 3). However, shear is low over the Caribbean, and is forecast to remain low for at least the next two weeks.
Figure 3. Forecast wind shear (in meters per second) for Friday, November 7, at 06 GMT. This is an 8-day forecast generated by the 12Z GMT run of the GFS model on Thursday, October 30. The Caribbean is forecast to remain under low shear for the first half of November, while the U.S. will be protected by very high shear, thanks to the presence of the jet stream.
MJO
We are currently in the phase of the Madden-Julian Oscillation (MJO) that suppresses Atlantic tropical storm formation. The MJO is a pattern of enhanced rainfall that travels along the Equator, and can act to boost hurricane activity when it propagates into the Atlantic. The MJO has a period of about 30-60 days. According to the latest 15-day GFS model forecast and the MJO discussion from the National Weather Service's Climate Prediction Center, we are expected to remain in the inactive phase for the MJO for the next two weeks. By mid-November, we may transition to a positive MJO again. This year, the active phase of the MJO has been strongly correlated with formation of named storms in the Atlantic. Thus, the chances for a late-season named storm may increase by mid-November.
Summary
Given past climatology, warm SSTs in the Caribbean, and forecast low wind shear over the Caribbean for the first half of November, I put the odds at 50% we will see a named storm in the western or south-central Caribbean in the first half of November. Given the recent history of such storms, there is a 50% chance that such a storm would become a hurricane.
I'll update this blog over the weekend if there's any developments in the tropics worth reporting.
For those interested, the portlight.org charity now features a blog that details the recent Hurricane Ike relief effort they undertook.
Jeff Masters
Reader Comments
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Sweet dreams all. :) LOL!
LOL
at least if there was ever any question, I could go here and show my girl where I was while she was out of town!
ROFL - seriously, the dog is running for the other room - thinks I've lost it...
on that note I'll say goodnight friends...I really do appreciate all of you...for your weather wisdom, but just as much for the good times!
-rob
Stay safe, all..
The number of trolls is directly proportional with the square to the danger a storm presents to land.
Yes yes, Pottery, feel free to have your 5 minutes of gloating. ;)
Now, with 2/3 of my sports teams losing this weekend, my Ravens better not let me down today....
000
ABNT20 KNHC 020542
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT SUN NOV 2 2008
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE NEXT 48 HOURS.
$$
FORECASTER BEVEN
Not even a ripple out there.
Let me quote that DST has ended and the NHC has made a tiny mistake on time change. It should be 100 AM EST, not 200 AM EDT.
Hi Vort, 530 is really early!!
Good morning all
Get out the fork, I think this season is done for the U.S.
I have been wondering about this term but wanted to wait until nothing much was going on. What is a troll? Some one that says something you don't like? Someone off topic? Some one lying about who they are? Some one being mean and just trying to start some S.....!
I have learned much about tropical weather this year from this site. Especially Storm. He makes things simple.
Will read the blog again after church.
One has nothing to with the other....different entities....
As far as McCain/Palin.....2 1/2 more days and no more ads.....
Thank God.
What will network news(CNN,MSNBC and FOX noise), talk about then...
(1)Why did so and so lose?
(2)2012.
After 2 weeks...mid-Nov.....
(1)Back to the economy.
(2)Sales down/Xmas shopping.
Thanksgiving not important this year? :P
To my stomach it is...lol.
Not news though....oops....forgot Thanksgiving/Macy's day parade.....
I realize that Ike....but I'm glad you got the point.
Though, no matter how much change Obama or McCain advocates, those who suffered at the hands of Ike et al have gone under more change than either could ever create.
Though, whichever candidate is elected, let's hope it's a positive step.
Can't be healthy to be up this early on Sunday!
Can clearly see the ULL near PCola now on WVLoop.
NWS Ruskin has an interesting discussion this am concerning this feature.
Mirror Site
Present Satellite, Area of Interest Southern Caribbean
Think Pottery's going to find me before I busy myself?
Know he's been looking...shouldn't thrash you too bad though.
The ESL is a satellite data receiving station and image processing facility for environmental data from six unique earth observing sensor systems. ESL specializes in real-time access to satellite imagery and measurements of the atmosphere, oceans and coastal areas within the Gulf of Mexico / Caribbean Sea region, data which they obtain directly from satellite transmissions to three antennas on LSU rooftops. These data have many applications for research, education, and state emergency response.
Sounds like I missed all the fun again ....
Heh, we're talking sports at least. ;)
Ike,
Have you ever thought of being an i reporter for CNN?
I would never flag a message like that.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
359 AM CST SUN NOV 2 2008
.DISCUSSION...
UNAUTHORIZED SHOWERS HAVE DEVELOPED THIS MORNING ACROSS NE TX/SE OK...AND
ARE POISED TO DRIFT E INTO EXTREME SW AR IN THE NEXT HR OR SO.
ORIGINALLY THOUGHT THE CURRENT 88-D ECHOES WERE AP...BUT A CHECK
UPSTAIRS WITHIN THESE ECHOES VERIFY...AND OK MESONET STATIONS IN MT
HERMAN HAS MEASURED...WITH TRACE AMOUNTS RECORDED THUS FAR IN BROKEN
BOW. NOT QUITE SURE HOW THESE SHOWERS ARE FORMING...
That's too funny! Yes, went and checked, it's real.
Wouldn't mind visiting there someday. Sounds a nice place.
Me too, lots of Scandinavian blood in my veins. would have to be summer though...
LOL - it is a sign of wisdom, knowing when to keep one's mouth shut!
How are things in the keys this AM
Good to know, the ULL in the NE gulf will be setting up a more swesterly flow so we'll probably be seeing some cloudyness and increased chances of showers/tstorms before it lifts out. Jury is still out on the speed/strength of next weekends front but you should be good for a few days of "sockless" weather!
some of the models certainly think so...hard to say what comes of it though, although almost certainly more rain for folks who don't need it. That alone is mischief enough.
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