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
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Yes it was. :(
HURRICANE FABIO ADVISORY NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL EP062012
800 PM PDT SAT JUL 14 2012
...CATEGORY TWO FABIO CONTINUES WESTWARD...
SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...16.4N 115.7W
ABOUT 585 MI...945 KM SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...972 MB...28.70 INCHES
NWS NATIONAL HURRICANE CENTER MIAMI FL EP062012
800 PM PDT SAT JUL 14 2012
FABIO HAS NOT CHANGED MUCH SINCE THE RELEASE OF THE SPECIAL ADVISORY
AROUND 0000 UTC. THE 20 N MI EYE REMAINS CIRCULAR AND DISTINCT IN
SATELLITE IMAGES...AND THE CONVECTIVE CLOUD PATTERN IS FAIRLY
SYMMETRIC. DVORAK CLASSIFICATIONS FROM TAFB AND SAB WERE BOTH 90
KT...THEREFORE THE INITIAL WIND SPEED IS HELD AT THAT VALUE.
IT SEEMS LIKELY THAT FABIO IS NEAR ITS PEAK INTENSITY...AS THE EYE
IS CLOSE TO THE 26C ISOTHERM. THE HURRICANE IS EXPECTED TO MOVE
OVER SUB-26C WATERS IN THE NEXT 12 TO 18 HOURS...AND THE SSTS ALONG
THE FORECAST TRACK STEADILY DECREASE BEYOND THAT TIME. THESE
UNFAVORABLE OCEANIC CONDITIONS...COMBINED WITH A DRIER AIR MASS
AHEAD OF FABIO SHOULD CAUSE SLOW BUT STEADY WEAKENING DURING THE
NEXT FEW DAYS. FABIO IS FORECAST TO BECOME A REMNANT LOW IN ABOUT 4
DAYS WHEN IT IS OVER WATERS OF ABOUT 20C AND ENCOUNTERS AND AN
INCREASE IN SOUTHERLY VERTICAL WIND SHEAR. THE OFFICIAL FORECAST IS
IDENTICAL TO THE PREVIOUS ADVISORY AND IN CLOSE AGREEMENT WITH
LGEM.
FABIO IS STILL MOVING WESTWARD AT ABOUT 8 KT. A WEST-NORTHWESTWARD
MOTION IS FORECAST DURING THE NEXT 24 HOURS AS MID-LEVEL RIDGING
HANGS ON TO THE NORTH OF THE SYSTEM. THEREAFTER...THE RIDGE IS
FORECAST TO BREAK DOWN AS A MID- TO UPPER-LEVEL LOW DIGS SOUTHWARD
OVER THE WESTERN UNITED STATES. THIS STEERING PATTERN SHOULD CAUSE
FABIO TO SLOW DOWN AND GRADUALLY TURN NORTHWARD. THE OFFICIAL TRACK
FORECAST LIES CLOSE TO THE TVCE CONSENSUS AND IS SIMILAR TO THE
PREVIOUS ADVISORY.
FORECAST POSITIONS AND MAX WINDS
INIT 15/0300Z 16.4N 115.7W 90 KT 105 MPH
12H 15/1200Z 16.7N 117.1W 85 KT 100 MPH
24H 16/0000Z 17.2N 118.7W 75 KT 85 MPH
36H 16/1200Z 18.0N 120.0W 65 KT 75 MPH
48H 17/0000Z 19.0N 120.8W 55 KT 65 MPH
72H 18/0000Z 21.5N 121.3W 35 KT 40 MPH
96H 19/0000Z 23.5N 121.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 20/0000Z 25.0N 121.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
$$
FORECASTER CANGIALOSI
will do i live in swla...
Oh well. :(
Tropical Cyclone Report may later increase the intensity of Fabio.
I was 17 during the WV floods. A lot of people, including me, experienced a defining moment that week, and will remember it for the rest of their lives. It was the first time (but not the last) that I realized a hurricane could affect an area that far inland.
A very impressive looking waterspout from Bradenton Bch. in Manatee County. a couple of miles off the coast about 3:30 in a Special Marine Warning (Credit: Meridith Garofalo.)
Right now, there are very few storms this evening. Near Captiva and Arcadia in SWFL. Near Palm Harbor/Dundein in Pinellas County, other than a small cluster of showers off the east coast of FL, you really have to look towards an area from Charlotte NC to the Piedmont Triad (Greensboro/High Point)
Over the next few day, the chances for a more severe storm over florida exists with higher PWAT columns and day time heating (higher temps 93-95F), any tornado (or tornado like) pictures I get I will pass them on to you.
Have a great nite
FM
BULLETIN
TROPICAL STORM EMILIA ADVISORY NUMBER 30
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052012
800 PM PDT SAT JUL 14 2012
...EMILIA WEAKENING...EXPECTED TO BECOME A TROPICAL DEPRESSION
SUNDAY...
SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...15.7N 134.5W
ABOUT 1675 MI...2700 KM WSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052012
800 PM PDT SAT JUL 14 2012
THE LOW-LEVEL CENTER OF EMILIA HAS CONTINUED TO MOVE AWAY FROM THE
REMAINING DEEP CONVECTION OVER THE PAST FEW HOURS. AN ASCAT PASS
AROUND 1800Z SUGGESTED THAT PEAK WINDS AT THAT TIME WERE AROUND 40
KT. GIVEN THE DECAY OF THE CLOUD PATTERN SINCE THE ASCAT PASS THE
INITIAL INTENSITY IS LOWERED TO 35 KT...IN AGREEMENT WITH A BLEND
OF THE LATEST TAFB AND SAB DVORAK ESTIMATES. THE OFFICIAL FORECAST
SHOWS EMILIA WEAKENING TO A TROPICAL DEPRESSION IN 12 HOURS AND
BECOMING A REMNANT LOW BY SUNDAY NIGHT...AS THE CYCLONE MOVES OVER
SSTS AROUND 24C AND THROUGH A VERY DRY ATMOSPHERIC ENVIRONMENT.
THE INITIAL MOTION IS WESTWARD AT 14 KT...AND THIS SHOULD CONTINUE
FOR THE NEXT NEXT FEW DAYS AS EMILIA IS STEERED BY THE LOW-LEVEL
TRADE WIND FLOW. THE NEW NHC FORECAST IS SIMILAR TO THE PREVIOUS
ONE AND IS CLOSE TO THE MIDDLE OF THE GUIDANCE ENVELOPE.
FORECAST POSITIONS AND MAX WINDS
INIT 15/0300Z 15.7N 134.5W 35 KT 40 MPH
12H 15/1200Z 15.7N 136.6W 30 KT 35 MPH
24H 16/0000Z 15.6N 139.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 16/1200Z 15.5N 142.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 17/0000Z 15.3N 145.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 18/0000Z 15.0N 150.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 19/0000Z 15.0N 156.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 20/0000Z...DISSIPATED
$$
FORECASTER BRENNAN
did ya move from there?
F U is not that easy
what?!!!!
really?
A very impressive looking waterspout from Bradenton Bch. in Manatee County. a couple of miles off the coast about 3:30 in a Special Marine Warning (Credit: Meridith Garofalo.)
Right now, there are very few storms this evening. Near Captiva and Arcadia in SWFL. Near Palm Harbor/Dundein in Pinellas County, other than a small cluster of showers off the east coast of FL, you really have to look towards an area from Charlotte NC to the Piedmont Triad (Greensboro/High Point)
Over the next few day, the chances for a more severe storm over florida exists with higher PWAT columns and day time heating (higher temps 93-95F), any tornado (or tornado like) pictures I get I will pass them on to you.
Have a great nite
FM
(Edited: Image was not formatted correctly post 1614) Sorry :(
Behind the times....
We got lucky- we took a drive to Dolly Sods this afternoon, and watched a thunderstorm pop up to the east and move down the valley below. I took it with a Samsung Galaxy tablet, so the quality is not the best but the storm still looks pretty cool.
Also, for some reason, WU thinks I took this in Antarctica. Rest assured I didn't drive that far today!
The total numbers are going to boil down to the strength of the El Nino effects right after the peak period.
The trajectory and potential landfall location of these storms (regardless of the numbers) is the main issue...................
Well said.
No- floods happen everywhere. Some may make fun of "mountain people", but how many complaints did you hear coming from us a couple weeks ago after the big storm knocked out power for days? We know how to deal with all kinds of adversity.
i don't knock mountain people, i am cajun so we probably sort of the same breed we know how to survive...
Here's a rainbow I was able to get on camera on the way home. I was in the backseat, so sorry about my bro's nasty foot getting into the picture. Just ignore that and gaze upon this giant rainbow. :-)
Very nice pics, thanks for sharing!
Good for you. Did you get a chance to have a few at the Flora-Bama Lounge?...............:)
Is it bad that the first thing that I noticed in the top picture were the girls on the beach?
Good pictures too anyway, better than a lot of those I have taken!
no, i did the same thing :)
1. It's not cheating unless you ACT on it, and I'm not going to do that...
2. And I was joking, calm down.
3. And welcome to my ignore list again JFV.
Thanks for the positive feedback and you are welcome!
Haha...Well, we were about a mile from the Flora-Bama, but we never went. We kinda had our own lounge in our beautiful condo. :-)
Thanks!
Haha thanks. Well, it is probably bad considering those girls are about 12 or 13. :-/
Who knows these days...
I see what you did there
I hear ya......Next time, rent a motorcycle (preferably a Harley) if you don't own one and roll on over there for some raw oysters and brews..... :)
I would say no, lol.
who is JFV???
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