July Atlantic hurricane outlook
It's mid-July, and we have yet to see a named storm form in the Atlantic this month. The computer models are not predicting any development through at least July 20, and if we make it all the way to the end of the month without a named storm forming, it will be the first July since 2009 without a named storm. Since the current active hurricane period began in 1995, 13 of 17 years (76%) have had a named storm form during July. The busiest July occurred in 2005, when five named storms and two major hurricanes formed. These included Hurricane Dennis and Hurricane Emily--the strongest hurricanes ever observed so early in the season. Only eight major hurricanes have formed in July since record keeping began in 1851. As seen in Figure 1, most of the last half of July activity occurs in the Gulf of Mexico and waters off the Southeast U.S. coast. These type of storms 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 (as happened for Alberto, Beryl, Chris, and Debby in 2012.) There will be at least two cold fronts moving off the U.S. Mid-Atlantic coast over the next two weeks. The first of these fronts will push offshore around July 20, and we will need to watch the waters offshore of North Carolina for development then. Formation potential will be aided by ocean temperatures that are about 0.7°C (1°F) above average along the U.S. East Coast.
Figure 1. Tracks of all tropical storms and hurricanes 1851 - 2006 that formed July 16-31. The U.S. coast from North to Texas are the preferred strike locations. Only a few storms have formed in the tropical Atlantic and Caribbean in July. Wind shear is typically too high and SSTs too cool in July to allow African waves in the Caribbean and tropical Atlantic to develop into tropical storms. However, a few long-track "Cape Verdes" hurricanes have occurred in July, spawned by tropical waves that came off the coast of Africa. African tropical waves serve as the instigators of about 85% of all major hurricanes.
Figure 2. The seasonal distribution of Atlantic hurricane activity shows that July typically has low activity. Image credit: NHC.
Sea Surface Temperatures: slightly above average
The departure of Sea Surface Temperatures (SST) from average over the tropical Atlantic between Africa and Central America was about 0.3°C above average during June (Figure 3.) This figure has not changed much over the first two weeks of July. These temperatures are not warm enough to appreciably affect the odds of a July named storm or hurricane. The strength of the Azores-Bermuda high has been near average over the past two weeks, driving near-average trade winds. The latest 2-week run of the GFS model predicts continued average-strength trade winds through late-July, so SSTs should remain about 0.3°C above average during this period, due to average amounts of cold water mixing up from below due to the wind action on the water.
Figure 3. Sea Surface Temperature (SST) departure from average for July 12, 2012. SSTs were 0.3°C above average over the tropical Atlantic's Main Development region for hurricanes, from Africa to Central America between 10° and 20° North Latitude. Note the large region of above average SSTs along the Equatorial Pacific off the coast of South America, the hallmark of a developing El Niño episode. Image credit: NOAA/NESDIS
El Niño on the way?
For two consecutive weeks, ocean temperatures 0.5 - 0.6°C above average have been present in the tropical Eastern Pacific, which is right at the threshold for a weak El Niño episode. NOAA's Climate Prediction Center has issued an El Niño Watch, and gives a 61% chance that El Niño conditions will be present during the August - September - October peak of the Atlantic hurricane season. The likely development of a full-fledged El Niño episode means that Atlantic hurricane activity will probably be suppressed in 2012, due to the strong upper-level winds and high wind shear these events typically bring to the tropical Atlantic.
Figure 4. Sea Surface Temperature (SST) departure from average for the the equatorial Eastern Pacific (the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region"). El Niño conditions exist when the SST in this region rises 0.5°C above average. As of July 9, 2012, SSTs in the Niño 3.4 region had risen to 0.5°C above average. To be considered an "El Niño episode", El Niño conditions must occur for five consecutive months, using 3-month averages. Image credit: NOAA Climate Prediction Center.
Wind shear: above average
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 has two bands of strong high-altitude winds that are currently bringing high wind shear to the Atlantic. The southern branch (subtropical jet stream) is bringing high wind shear to the Caribbean, and the northern branch (polar jet stream) is bringing high wind shear to the waters offshore of New England. This configuration often leaves a "hole" of low shear between the two branches, off the Southeast U.S. coast and over the Gulf of Mexico. The jet stream is forecast to maintain this two-branch pattern over the coming two weeks. Wind shear has been about 10 - 20% higher than average over the first two weeks of July, and is predicted to be mostly above average for the coming two weeks. This will cut down on the odds of a July storm.
Figure 5. Vertical instability over the Caribbean Sea in 2012 (blue line) compared to average (black line.) The instability is plotted in °C, as a difference in temperature from near the surface to the upper atmosphere. Thunderstorms grow much more readily when vertical instability is high. Instability has been lower than average, due to an unusual amount of dry air in the atmosphere, reducing the potential for tropical storm formation. Image credit: NOAA/NESDIS/CIRA.
Dry air: above average
As seen in Figure 5, there has been an unusual amount of dry, stable air in the Caribbean this year creating low levels of vertical instability. This has occurred due to a combination of dry air from Africa, and upper-atmosphere dynamics creating large areas of sinking air that dry as they warm and approach the surface. The Gulf of Mexico and tropical Atlantic between the coast of Africa and the Lesser Antilles have also seen low vertical instability this summer. June and July are the peak months for dry air and dust coming off the coast of Africa, and the Saharan dust storms have been quite active over the past two weeks. Expect dry air to be a major deterrent to any storms that try to form in the tropical Atlantic during July.
Steering currents: average
The predicted steering current pattern for the next two weeks is a typical one for July. We have 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. 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 2010 and 2011 steering current pattern, which recurved most storms out to sea--or the unfavorable 2008 pattern, which steered Ike and Gustav into the Gulf of Mexico.
Summary: a below average chance of a July tropical storm
Given that none of the computer models are forecasting tropical storm formation in the coming seven days, SSTs are only slightly above average, and wind shear and vertical stability are above average, I'll go with a 30% chance of a named storm forming in the Atlantic during the remainder of July.
Figure 6. Hurricane Emilia over the Eastern Pacific at 20:35 UTC July 10, 2012. At the time, Emilia was a Category 3 hurricane with 125 mph winds. Emilia peaked earlier in the day as a Category 4 storm with 140 mph winds--the strongest hurricane in the East Pacific so far in 2012. Image credit: NASA.
An active Eastern Pacific hurricane season
It's been a very active start to the Eastern Pacific hurricane season, where we've already had six named storms, four hurricanes, and three intense hurricanes. A typical season has 4 named storms, 2 hurricanes, and 0 intense hurricanes by July 14. The formation of Tropical Storm Fabio on July 12 marks the 4th earliest formation of the Eastern Pacific's season's sixth storm. The record is held by the year 1985, when the season's sixth storm formed on July 2. Record keeping began in 1949.
Have a great weekend, everyone, and I'll be back Monday with a new post.
Jeff Masters
Reader Comments
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Really?
Ok...grandpa...let me give you some hip new information then. There's this thing called the internet which allows you to access a huge amount of information. For example, you can do searches and find out that the "ice age scare" was nothing more than a media myth trumped up because they could get some ratings out of it (then, like now, most climate scientist knew the planet was warming).
And food? If it wasn't for modern advances in technology we would have issues. Actually, check that. The world does have food problems. And poverty problems. And resource problems. And they aren't getting any better either and won't get any better with an ever growing population, diminishing natural resources, and a changing climate.
And no, scientists don't claim "Disease X is going to kill us all!!!!1!!!1!!". The media does that. Groups like the CDC bring communicable diseases to our attention to let us know things like unprotected sex or visiting countries that don't have proper vaccinations or poor health standards might not be such a good idea and to take precautions.
So, for the sake of your own sanity I suggest turning off Fox News, MSNBC, or whatever other supposed news network you watch and make a little effort to dig down to what the experts are really saying instead of what you you "think" you heard or what some well groomed talking head told you. Then you'll find out that when the TV says "It could kill millions!" you'll find the experts saying "Yeah, if we lived in the Dark Ages and we all started eating our own feces.".
Thanks Pat and yoboi. I'll bring my rubber boots and umbrella. Meeting up with a friend we were stationed with in Leavenworth, she's always wanted to visit NO. We'll have a great time no matter the weather.
CME (coronal mass ejection). Incoming solar storm projected for 14 July 2012 at 10:20 UT (+/- 7 hours).
Just as earth has cycles which we call seasons, the sun's energy output also changes on
a roughly 11-year basis. We call these changes the solar cycle.
We are now four years into a new solar maximum period. During the last solar minimum, there were few
magnetic storms on the sun, sunspots were rare, and geomagnetic disturbances here on earth
were nearly nonexistent. Aurora watchers had to travel to the polar regions to see
the Northern Lights. However, change is here. We are now in solar maximum.
Aurora Borealis Page
The Solar Maximum has arrived early. According to some end of the world enthusiasts, it wasn't supposed to arrive until Dec. 21, 2012.
Steady decline:
El Ninos are supposed to be wet and cool, but that didnt help in 2007, and after this trough passes, we arent supposed to get much more rain for a long time, and eventually the high is supposed to come back.
Even the normal popup tstorms have found a way to not come without forcing this year.
Hurricane Nate of last year:
maybe this isnt the maximum :O
mabye the end of the world is when a gigantic solar flare explodes with all its got into a massive off the charts CME and fries the earth.
How the dark side of the earth dies we still have to figure out
jk
weak wave, and then its gone
I gotta hand it to you...almost as many plusses as the Doc.
Northern lights are extremely difficult to predict but may be visible from the far north US tomorrow.
we know you are around. :)
Huh? There's plenty of permafrost. The mountains in the area (also home to many glaciers) are covered in permafrost.
The attribution to warming being the culprit is pure speculation at this point. While studies have shown a recent increase in these types of landsides due to warmer temperatures, there a other things that can trigger such an event. The analysis of the debris should give a good indication of what the culprit was.
I imagine *something* will happen. I intend, for instance, to drop a hot dog with the works in a busy intersection.
That's something.
What I was trying to say is the model has shown this since the 10th.
But sadly, looking at the new modle runs, that wont happen soon. Are we diving or jumping off?
The northern u.s. might be able to see the auroras at night around sunset, but to the untrained eye you won't notice them. This far south they will be red and blend in with the sunset.
Whoa... looking good there, Fabio... I can see u are trying to earn that Fab Fab nomen...
Geez. Maybe she just wanted to.
Don't mean to brag, but we've been getting something every little while... It's great to see everything so green this summer.
Course, Mr. Ford doesn't look so much like that anymore these days... lol
Wonder if he blogs on the Wunderground...
Hey, if u can't have a little fun on a Friday p.m. when can u... lol
Very interesting. Goes back to the story I read yesterday about the snow slip near Chamonix, France.
being a swimmer i choose jumping, wouldnt want to associate any of the blogs follies with swimming and diving
you would think the dark side would be spared or at least not as fried
I would go with jumping. We need something to track already.
just makin' sure :)
Current Auroral Oval
Observers in North America should watch for aurora on the nights of the 14th and 15th local time. Depending on the configuration of the disturbance, auroras may be visible as far south as the middle tier of states.
Activity may remain high also on the 16th.
my grandfather will celebrate his birthday. thats something. otherwise winter starts right around there.
LOL!
It's funny how during El-Nino years you get all of these ULL's all over the place.
NATIONAL WEATHER SERVICE SAN JUAN PR
254 PM AST FRI JUL 13 2012
THE TUTT LOW AND THE ASSOCIATED TROUGH ARE EXPECTED TO DRIFT SLOWLY
WESTWARD DURING THE NEXT FEW DAYS. THE TYPICAL AFTERNOON SHOWERS
WILL BE ENHANCED BY THIS FEATURE THROUGH SUNDAY. THIS SHOWERS AND
THUNDERSTORMS WILL CONCENTRATE OVER THE WESTERN PORTIONS OF PUERTO
RICO BUT WINDS WILL HAVE A SLIGHT SE COMPONENT THEREFORE SHOWERS
COULD ALSO AFFECT SOME NORTHERN PORTIONS OF PUERTO RICO.
A TROPICAL WAVE NOW LOCATED AT AROUND 54 W...WILL CONTINUE TO MOVE
WEST...REACHING OUR LOCAL FORECAST AREA LATE SUNDAY.
no booze.
Anything capable of making your brain functions impaired probably isnt wise to intake.
Remember, everything is poisonous, good things just require a higher dosage.
Something that gets you drunk in 5 bottles isnt quite a good thing
just saying, dont get mad at me
who sang that song????
382 GTcooliebai: That's cool, my birthday is the 20th, so you know I will be stacked with the booze. Might as well go out with a bang!
And an efficient way to never become a grandfather.
Its a saying when I was growing up when we school people who dip into conversations and dont know the whole story..
Hurricane Fabio is loking decsent as of right now:
posting on this site at times can impair ya.....
Simple. The flare lasts 24 hours. 12:12:12 in every time zone....
Diving is more fun, especially if u can do a backflip on the way out...
We see your Low.
um, diving is fun most of the time.
have several friends with back injuries from diving of 3m boards and landing "off".
since he wants ease and no pain, he should jump
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