Hurricane season begins today; normal June activity expected

By: Dr. Jeff Masters , 1:38 PM GMT on June 01, 2009

Share this Blog
2
+

Hurricane season is upon us, and it's time to take a look at the prevailing conditions and 2-week forecast for tropical cyclone activity in the Atlantic. June is typically the quietest month of the Atlantic hurricane season. On average, we see only one named storm every two years in June. Only one major hurricane has made landfall in June--Category 4 Hurricane Audrey of 1957, which struck the Texas/Louisiana border area on June 27 of that year, killing 550. The highest number of named storms for the month is three, which occurred in 1936 and 1968. In the fourteen years since the current active hurricane period began in 1995, there have been eleven June named storms (if we include last year's Tropical Storm Arthur, which really formed on May 31). Five tropical storms have formed in the first half of June in that 14-year period, giving a historical 36% chance of a first-half-of-June named storm.


Figure 1. Tracks of all June tropical storms and hurricanes, 1851 - 2007.

Sea Surface Temperatures
Sea Surface Temperatures (SSTs) are close to average over the tropical Atlantic between Africa and Central America this year (Figure 2). These temperatures are some of the coolest we've seen since 1995, when the current active hurricane period began. This year's cool SSTs should prevent a repeat of the unforgettable Hurricane Season of 2005, which had the highest SSTs on record in the tropical Atlantic. Note also that SSTs along the Equatorial Pacific off the coast of South America are quite a bit above average, signaling the possible start of an El Niño episode. As I discussed in Friday's post, odds are increasing for a weak El Niño to form in time for hurricane season, and this should cut down on the number and intensity of Atlantic tropical storms and hurricanes this year. However, if an El Niño is developing, it shouldn't start affecting Atlantic hurricane activity until August.

Typically, June storms only form over the Gulf of Mexico, Western Caribbean, and Gulf Stream waters just offshore Florida, where water temperatures are warmest. SSTs are 26 - 28°C in these regions, which is about 0.5°C above average for this time of year. June storms typically form when a cold front moves off the U.S. coast and stalls out, with the old frontal boundary serving as a focal point for development of a tropical disturbance. African tropical waves, which serve as the instigators of about 85% of all major hurricanes, are usually too far south in June to trigger tropical storm formation. Every so often, a tropical wave coming off the coast of Africa moves far enough north to act as a seed for a June tropical storm. This was the case for Arthur of 2008 (which also had major help from the spinning remnants of the Eastern Pacific's Tropical Storm Alma). Another way to get Atlantic June storms is for a disturbed weather area in the Eastern Pacific Intertropical Convergence Zone (ITCZ) to push north into the Western Caribbean and spawn a storm there. This was the case for Tropical Storm Alberto of 2006 (which may have also had help from an African wave). SSTs are too cold in June to allow storms to develop between the coast of Africa and the Lesser Antilles Islands--there has only been once such development in the historical record--Ana of 1979, which coincidentally will be the name given to this year's first storm.


Figure 2. Sea Surface Temperature (SST) departure from average for June 1, 2009. SSTs were near average over the tropical Atlantic. Note the large region of above average SSTs along the Equatorial Pacific off the coast of South America, signaling the possible start of an El Niño episode. Image credit: NOAA/NESDIS.

Tropical Cyclone Heat Potential
It's not just the SSTs that are important for hurricanes, it's also the total amount of heat in the ocean to a depth of about 150 meters. Hurricanes stir up water from down deep due to their high winds, so a shallow layer of warm water isn't as beneficial to a hurricane as a deep one. The Tropical Cyclone Heat Potential (TCHP, Figure 3) is a measure of this total heat content. A high TCHP over 80 is very beneficial to rapid intensification. As we can see, the heat energy available in the tropical Atlantic has declined considerably since 2005, when the highest SSTs ever measured in the tropical Atlantic occurred. TCHP this year is similar to last year's levels, which were high enough to support five major hurricanes.


Figure 3. Tropical Cyclone Heat Potential (TCHP) for May 31 2005 (top), May 31 of last year (middle) and May 30 2009 (bottom). TCHP is a measure of the total heat energy available in the ocean. Record high values of TCHP were observed in 2005. TCHP this year is much lower, and similar to last year. Image credit: NOAA/AOML.

Wind shear
Wind shear is usually defined as the difference in wind between 200 mb (roughly 40,000 foot altitude) and 850 mb (roughly 5,000 foot altitude). In most circumstances, wind shear above 20 knots will act to inhibit tropical storm formation. Wind shear below 12 knots is very conducive for tropical storm formation. High wind shear acts to tear a storm apart. The jet stream's band of strong high-altitude winds is the main source of wind shear in June over the Atlantic hurricane breeding grounds, since the jet is very active and located quite far south this time of year.

The jet stream over the past few weeks has been locked into a pattern where a southern branch (the subtropical jet stream) brings high wind shear over the Caribbean, and a northern branch (the polar jet stream) brings high wind shear offshore of New England. This leaves a "hole" of low shear between the two branches off the coast of North Carolina, which is where Tropical Depression One formed. The low shear "hole" has dipped down into the northern Gulf of Mexico a few times. Disturbance 90L, which almost developed into a tropical storm before it came ashore in Mississippi/Alabama on May 23, took advantage of one of these low-shear areas.

The jet stream is forecast to maintain this two-branch pattern over the coming ten days. This means that the waters offshore of the Carolinas are the most likely place for a tropical storm to form during this period, though the northern Gulf of Mexico will at times have shear low enough to allow tropical storm formation. The latest 16-day forecast by the GFS model (Figure 4) predicts that the subtropical jet will weaken and retreat northwards by the middle of June, creating low-shear conditions over the Caribbean. This is a typical occurrence for mid-June, and we need to start watching the Western Caribbean for tropical storm formation by the middle of the month.


Figure 4. Wind shear forecast from the 00Z GMT June 1, 2009 run of the GFS model for June 1 (left panel) and June 17 (right panel). Currently, the polar jet stream is bringing high wind shear to the waters offshore New England, and the subtropical jet is bringing high wind shear to the Caribbean. This leaves the waters off the coast of North Carolina under low shear, making this area the most favored region for tropical storm formation over the next 7 - 10 days. By June 17, the subtropical jet is expected to weaken and move northwards, leaving the Caribbean under low shear, and favoring that region for tropical storm formation. Wind speeds are given in m/s; multiply by two to get a rough conversion to knots. Thus, the red regions of low shear range from 0 - 16 knots.

Dry air and African dust
It's too early to concern ourselves with dry air and dust coming off the coast of Africa, since these dust outbreaks don't make it all the way to the June tropical cyclone breeding grounds in the Western Caribbean and the Gulf of Mexico. Developing storms do have to contend with dry air from Canada moving off the U.S. coast; this was a key reason why 2007's Subtropical Storm Andrea never became a tropical storm. Dr. Amato Evan of the University of Wisconsin will issue his dust forecast for the coming hurricane season later this week, and I'll be discussing his forecast in an upcoming post.

Steering currents
The steering current pattern over the past few weeks has been typical for June, with an active jet stream bringing many troughs of low pressure off the East Coast of the U.S. These troughs are frequent enough and strong enough to recurve any tropical storms or hurricanes that might penetrate north of the Caribbean Sea. Steering current patterns are predictable only about 3-5 days in the future, although we can make very general forecasts about the pattern as much as two weeks in advance. At present, it appears that the coming two weeks will maintain the typical June pattern, bringing many troughs of low pressure off the East Coast capable of recurving any June storms that might form. There is no telling what might happen during the peak months of August, September, and October--we might be in for a repeat of the favorable 2006 steering current pattern that recurved every storm out to sea--or the unfavorable 2008 pattern, that steered Ike and Gustav into the Gulf of Mexico.

Summary
Recent history suggests a 36% chance of a named storm occurring in the first half of June. The current conditions in the atmosphere and ocean are near average, so expect about a 1/3 chance of a named storm between now and June 15. The computer models are currently not forecasting development of any tropical storms over the next seven days.

I'll have an update Tuesday afternoon, when I'll discuss the Colorado State University June Atlantic Hurricane season forecast by Dr. Phil Klotzbach and Dr. Bill Gray, which will be issued Tuesday morning.

My next analysis and 2-week outlook for hurricane season is scheduled for June 13.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 594 - 544

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18Blog Index

593. IKE
Quoting WPBHurricane05:
Ahh...David...back when we would "tape" our windows. oops.


LOL....that stuff don't all come off. I found that out.

I was in Panama City,FL. when Camille hit. We had winds to 50+ mph.

What a total beast!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting IKE:


One month after that I went into kidney failure and almost died....7-11-2005. Doctor told me I waited a week too long:(

I was on dialysis from July of 2005 to January 1st of 2007.

My kidneys came back:)))


Good Lord!! Glad your alright now!!
Member Since: Posts: Comments:
Ike is one tough Guy.
He wears and tears and comes back swinging.

And we glad to have him when the going gets Rough here.



My Local NWS Radar, Slidell Office from August 28-29 2005
Member Since: Posts: Comments:
Ahh...David...back when we would "tape" our windows. oops.
Member Since: Posts: Comments:
Quoting Patrap:
Hurricane David in the Atlantic



Beautiful Storm
Member Since: Posts: Comments:
It may be a slow season..but always be aware...

Hurricane Ike
Member Since: Posts: Comments:
Quoting Patrap:
LARGE Image of David near Georgia



0____________o wow over winter you forget how scary a full blown major hurricane is
Member Since: Posts: Comments:
The best "blown" storm forecast I recall was Betsy. Which actually is the first one I can remember. I was in Pats area. Slidell. To young to fear, but I could show you where every tree fell. Camille was the first blow that meant work for me, (Ocean Springs, Ms ). From then on, a whole different perspective.
Member Since: Posts: Comments:
GOM IR loop
Member Since: Posts: Comments:
582. IKE
Quoting StSimonsIslandGAGuy:
SevereHurricane, Ike made this post 2 hours earlier:

25. IKE 8:24 PM GMT on June 10, 2005 Hide this comment.
I live in Defuniak Springs, Florida and believe me...we DON'T need any rain any time soon. We've had enough to last for awhile. Interesting forecast in that our winds aren't suppose to be much above 20 mph...maybe 30 in gusts, but the NEXT county over...Okaloosa County/Crestview has a forecast of gusts to possibly 70 mph! There can't be that much difference in 25 miles of location....someone will be right and someone will be wrong.


One month after that I went into kidney failure and almost died....7-11-2005. Doctor told me I waited a week too long:(

I was on dialysis from July of 2005 to January 1st of 2007.

My kidneys came back:)))
Member Since: June 9, 2005 Posts: 23 Comments: 37858
LARGE Image of David near Georgia

Member Since: Posts: Comments:
Quoting Patrap:
Hurricane David in the Atlantic




That's a nice looking storm.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Hurricane David in the Atlantic

Member Since: Posts: Comments:
Good evening all...Here's to a tranquil season with no hardships or tragedy for anyone.
Member Since: Posts: Comments:
576. IKE
Quoting CaneWarning:


What were you talking about?


There was a storm, I forget which, that was forecast to make landfall close to where I live. All of the forecasts for areas near me...Crestview, Fort Walton Beach, Destin, Milton...had winds forecast 20 mph higher than my Defuniak Springs,FL. forecast.

My unprofessional opinion I thought the forecast winds for my area was too low.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting SevereHurricane:
Category 4 Hurricane Audrey Radar Loop


Radar has come a long way.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
I didn't realize this blog was so young. I learned of this site from Paul & Young Ron Brewer @ Zeta 4 rock & roll in S Fl. mid to late 90's. Have turned many a soul on to Dr M over the years. Thought ya'll had been yakin' a little longer though.
Member Since: Posts: Comments:
Will the low dissipating to the north of our AOI affect development at all? Also Dvoraks were issued earlier on this "invest" but I seem to have a malfunctioning link for NOAA's Dvoraks can someone post one for me? Thanks in advance!
Member Since: Posts: Comments:
Category 4 Hurricane Audrey Radar Loop
Member Since: Posts: Comments:
Quoting CaneWarning:


What were you talking about?


6-10-2005...had to have been TS Arlene.
Member Since: Posts: Comments:
Quoting StSimonsIslandGAGuy:
Patrap, you have images of the eye of Donna in the northeastern USA? I've also always wanted to see radar images of hurricane David off the Georgia coast, but never been able to find them.






Donna in the Keys

Water Obs




Member Since: Posts: Comments:
Quoting IKE:


I remember saying that:)


What were you talking about?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting kmanislander:


Hopefully they will find the black box and figure this one out. Electrical failure followed by a cabin depressurization sounds like several redundant systems failing in a cascading series of events.


...I posted earlier

So what happened to Air France Flight 447?

Miles O'Brien is a pilot, airplane owner
and freelance journalist who lives in Manhattan.
His blog is located here:
http://trueslant.com/milesobrien/

"...here is what we do know for sure.
Keep this in mind as you process
the often inaccurate reporting on aviation that is so prevalent..."

.........
above blog server appears to be overwhelmed, so read the text here:

http://www.reuters.com/article/idUSTRE5505BF20090602?virtualBrandChannel=10531


CRS
Member Since: Posts: Comments:
Quoting kmanislander:


Water temps around the CV islands still pretty cool but remember that the aircraft was on a North Easterly heading from Brazil.

A night time ditching is a low survival event at the best of times. The water temps could be survivable depending on where it went down but from cruise altitude to the surface at night probably meant the aircraft totally disintegrated on impact.

Hopefully they will find the black box and figure this one out. Electrical failure followed by a cabin depressurization sounds like several redundant systems failing in a cascading series of events.

yes i agree
Member Since: Posts: Comments:
I just looked back through this site's tropical archives from 1930-2008. The closest to 40n/25w that i could find a storm forming is T.S. Edouard 38n/23w, Aug. 2-3, 1990. The only other storm i could find forming in the last 78 years east of 35 w. and north of 35 n was T.S.11 36.5n/35w Sept. 24-30 1969. Edouard was moving n/n.w. at time of formation. T.S. 11 was moving s.w. Couldn't find any that were moving like our low.
Member Since: Posts: Comments:
Ike Radar Image from Ellington FIeld

Member Since: Posts: Comments:
563. IKE
Quoting SevereHurricane:

The 1st Post I could find that IKE made.


I remember saying that:)
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting IKE:
I understand about the differences in small locations....20 or 30 miles...east vs. west of the center...it's just the forecast for every area around where I live is for winds at least 20 mph higher than where I reside. I think the forecaster goofed...but oh well. Looks like Pensacola might be a bullseye for the worst weather...and points eastward too...hopefully in a lesser degree!

The 1st Post I could find that IKE made(June 10,2005)
Member Since: Posts: Comments:
Quoting AussieStorm:

The CV waters are on 24degrees c atm. is that right?


Water temps around the CV islands still pretty cool but remember that the aircraft was on a North Easterly heading from Brazil.

A night time ditching is a low survival event at the best of times. The water temps could be survivable depending on where it went down but from cruise altitude to the surface at night probably meant the aircraft totally disintegrated on impact.

Hopefully they will find the black box and figure this one out. Electrical failure followed by a cabin depressurization sounds like several redundant systems failing in a cascading series of events.
Member Since: Posts: Comments:
Radar Image of DONNA ,1960
Member Since: Posts: Comments:
I'm gone till later. Been nice looking back and seeing how far we've come. Night all.

June Outlook
Member Since: July 24, 2005 Posts: 407 Comments: 19076
557. MahFL
I signed up :

2004-06-08 21:45:55

:)
Member Since: Posts: Comments:
Good evening all! Hope everyone is doing well.

I've moved to Dallas but still following the tropics. Just praying for a pretty tame year.

Member Since: Posts: Comments:
Wilma!!! A day of prep, a few days of drinkin' & waitin', another day of prep and drinkin'. 7' atlantic surge before sunrise, 9' gulf late morn' @ my shop. Ford & GM could use that now!
Member Since: Posts: Comments:
Quoting StSimonsIslandGAGuy:
Rita did not surpass Gilbert's record. Wilma did.


Yea I know. I was quoting a blogger from the past. During that time some speculate that Rita would surpass Gilbert's record. This was long before Wilma.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Don't remind me!I tried to stay up all night.Unfortunately I fell asleep and woke up in 3 hours near 5 am when the power went out and got really bad.
Member Since: Posts: Comments:
Quoting StSimonsIslandGAGuy:
Me nash28 and a few others were hanging out on lefty's blog during the night of Wilma.


Do you remember someone with the name a lego guy ?
Member Since: Posts: Comments:
Quoting AussieStorm:

The CV waters are on 24degrees c atm. is that right?


SSTs won't begin warming up in the vicinity of the Cape Verde Islands until around August.
Member Since: Posts: Comments:
Quoting Weather456:
The morning of Wilma, and I could not sleep


Oh God I nearly had a heart-attack that day. I could not believe what I was seeing.
Member Since: November 24, 2005 Posts: 635 Comments: 26611
This is an incredibly compact, amazingly intense hurricane, the likes of which has never been seen in the Atlantic. The Hurricane Season of 2005 keeps topping itself with new firsts, and now boasts three of the five most intense hurricanes of all time--Katrina, Rita, and Wilma.

Four years later, this still sends chills up my spine.
Member Since: July 24, 2005 Posts: 407 Comments: 19076

Viewing: 594 - 544

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18Blog Index

Top of Page

About

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

Local Weather

Overcast
72 °F
Overcast