July Atlantic hurricane outlook

By: Dr. Jeff Masters , 12:55 PM GMT on July 13, 2012

Share this Blog
60
+

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

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: 1261 - 1211

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48Blog Index

1261. wxmod
Open water at the north pole. MODIS satellite photo today.

Member Since: Posts: Comments:
1260. LargoFl
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Member Since: March 16, 2012 Posts: 127 Comments: 7928
1257. LargoFl
..................nothing out there..
Member Since: Posts: Comments:
Member Since: March 16, 2012 Posts: 127 Comments: 7928
aspectre [inre 1204 LargoFl]: Where in the world did you find that dungheap of disinformation?
There ain't a scientist in the world, or any other place in the Universe, who'd endorse spouting such complete&utter nonsense.
1234 LargoFl: ...freedom of information act is a wonderful thing.

So you're sayin' you wrote it yourself?
Member Since: August 21, 2007 Posts: 0 Comments: 4860
Quoting WxGeekVA:
As promised the DOOM scenario of December 21st 2012, edited by WxGeekVA on MS Paint:



Enjoy thinking about what everything would be like if this happened.


should have moved 1 to houston, the fl one can hit NOLA
Member Since: February 11, 2012 Posts: 0 Comments: 9721
Member Since: Posts: Comments:
I'm enjoying the entertainment right now :).
Member Since: August 14, 2010 Posts: 10 Comments: 16437
Member Since: March 16, 2012 Posts: 127 Comments: 7928
1249. KEEPEROFTHEGATE (Mod)
all current solar warnings

Space Weather Message Code: WARPX1
Serial Number: 363
Issue Time: 2012 Jul 13 1633 UTC

WARNING: Proton 10MeV Integral Flux above 10pfu expected
Valid From: 2012 Jul 13 1630 UTC
Valid To: 2012 Jul 14 2300 UTC
Warning Condition: Persistence
Predicted NOAA Scale: S1 - Minor

Comment: This is an EXTENSION of the S1 Warning Issued at 12/1733Z. 10 MeV Protons are still above the S1 Alert threshold and expected to remain elevated with CME arrival.
Potential Impacts: Radio - Minor impacts on polar HF (high frequency) radio propagation resulting in fades at lower frequencies.

Space Weather Message Code: WARK04
Serial Number: 1972
Issue Time: 2012 Jul 14 1738 UTC

WARNING: Geomagnetic K-index of 4 expected
Valid From: 2012 Jul 14 1740 UTC
Valid To: 2012 Jul 15 0300 UTC
Warning Condition: Onset
Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

Space Weather Message Code: WARK05
Serial Number: 788
Issue Time: 2012 Jul 14 1738 UTC

WARNING: Geomagnetic K-index of 5 expected
Valid From: 2012 Jul 14 1740 UTC
Valid To: 2012 Jul 15 0300 UTC
Warning Condition: Onset
NOAA Scale: G1 - Minor
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

Space Weather Message Code: WARK06
Serial Number: 199
Issue Time: 2012 Jul 14 1914 UTC

WARNING: Geomagnetic K-Index of 6 expected
Valid From: 2012 Jul 14 1915 UTC
Valid To: 2012 Jul 14 2359 UTC
Warning Condition: Onset
NOAA Scale: G2 - Moderate
Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state

Space Weather Message Code: WATA20
Serial Number: 497
Issue Time: 2012 Jul 13 1313 UTC

WATCH: Geomagnetic A-index of 20 or greater predicted
NOAA Scale: Periods reaching the G1 (Minor) Level Likely
Valid for UTC Day: 2012 Jul 14
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting MAweatherboy1:

The CME from the 5.4 was not aimed directly at Earth like this one, I think. Either way, this won't be that big of a deal, no doom as some are suggesting.


Thanks... And I agree.
Member Since: Posts: Comments:
Quoting WxGeekVA:


I had nothing to do this afternoon so I figured why not?
Cool, hopefully that won't ever happen.
Member Since: March 16, 2012 Posts: 127 Comments: 7928
Quoting Pirate999:


I read an article that said on March 8th of this year Earth was hit by an X5.4. It also said that up to 95% was deflected back into space. I don't remember hearing about this but if it was a 5.4 why would we think the 1.4 would be more damaging? Am I missing something?

The CME from the 5.4 was not aimed directly at Earth like this one, I think. Either way, this won't be that big of a deal, no doom as some are suggesting.
Member Since: February 11, 2012 Posts: 82 Comments: 7635
Quoting LargoFl:
..the flare coming is supposed to be about as strong as the 1889 flare, gee i hope not but we will see, its still confusing the scientists..nasa says one thing,noaa says another..washington post has a great story on this very fact on the web


This Article?

And it says NOTHING about being as bad as 1889....
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Looks like the poles are starting to light up
Member Since: Posts: Comments:
Quoting LargoFl:
..actually its not crap and is coming, but with the lack of hurricanes and this IS..weather related, i dunno where your coming from, but one more post on this and I will finish,lets go back to the boring non-weather talk


I think your tin-foil hat is constricting your blood flow to your head.
Member Since: Posts: Comments:
If the internet did go down for a long time, lots of regular bloggers around the world might have a tough time adjusting to "real" life.............:)
Member Since: Posts: Comments:
Member Since: Posts: Comments:
1239. LargoFl
Quoting VAbeachhurricanes:


You understand that alignment happens every December 21st? Talk to Neil Degrasse Tyson... and please stop posting that crap in here.
..actually its not crap and is coming, but with the lack of hurricanes and this IS..weather related, i dunno where your coming from, but one more post on this and I will finish,lets go back to the boring non-weather talk
Member Since: Posts: Comments:
Quoting wxchaser97:
I didn't think you would actually go and add 2 more doom-canes, great job.


I had nothing to do this afternoon so I figured why not?
Member Since: Posts: Comments:
1237. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #1
TROPICAL DEPRESSION 08
3:00 AM JST July 15 2012
=====================================

SUBJECT: Tropical Depression Near The Marianas

At 18:00 PM UTC, Tropical Depression (1006 hPa) located at 18.8N 143.0E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving west northwest slowly.

Dvorak Intensity: T2.0

Forecast and Intensity
=========================

24 HRS: 21.0N 139.0E - 35 knots (Tropical Storm/CAT 1) - South Of Japan
Member Since: Posts: Comments:
Quoting LargoFl:
..the flare coming is supposed to be about as strong as the 1889 flare, gee i hope not but we will see, its still confusing the scientists..nasa says one thing,noaa says another..washington post has a great story on this very fact on the web


No it is not, would you stop posting lies. My goodness gracious.
Member Since: Posts: Comments:
Quoting WxGeekVA:
As promised the DOOM scenario of December 21st 2012, edited by WxGeekVA on MS Paint:



Enjoy thinking about what everything would be like if this happened.
I didn't think you would actually go and add 2 more doom-canes, great job.
Member Since: March 16, 2012 Posts: 127 Comments: 7928
1234. LargoFl
Quoting aspectre:
Inre comment1204 LargoFl,
Where in the world did you find that dungheap of disinformation? There ain't a scientist in the world, or any other place in the Universe, who'd endorse spouting such complete&utter nonsense.
..freedom of information act is a wonderful thing
Member Since: Posts: Comments:
Dec. 22, 2012, I sit here still waiting for the world to end...
Member Since: Posts: Comments:
WXGVA Our coastal cities would be wiped out.Huge population shifts would occur.Their would be gas and food shortages and flooding with tornado's everywhere..did I miss anything?.Ah yes the economy would crash.
Member Since: August 14, 2010 Posts: 10 Comments: 16437
1231. KEEPEROFTHEGATE (Mod)
it is what it is
and what it will be
Member Since: July 15, 2006 Posts: 169 Comments: 53296
How often does WU update its EasternPacificSeaSurfaceTemperature map.
I'd almost swear that Emilia and Fabio were sitting on the same spots 12hours ago.
Member Since: August 21, 2007 Posts: 0 Comments: 4860
1229. LargoFl
Quoting Pirate999:


I read an article that said on March 8th of this year Earth was hit by an X5.4. It also said that up to 95% was deflected back into space. I don't remember hearing about this but if it was a 5.4 why would we think the 1.4 would be more damaging? Am I missing something?
..the flare coming is supposed to be about as strong as the 1889 flare, gee i hope not but we will see, its still confusing the scientists..nasa says one thing,noaa says another..washington post has a great story on this very fact on the web
Member Since: Posts: Comments:
International cooperation in Pac NW atmospheric sounding exercise.

Link

Hopefully there are no casualties...
Member Since: Posts: Comments:
Quoting WxGeekVA:
As promised the DOOM scenario of December 21st 2012, edited by WxGeekVA on MS Paint:



Enjoy thinking about what everything would be like if this happened.
Member Since: August 14, 2010 Posts: 10 Comments: 16437
As promised the DOOM scenario of December 21st 2012, edited by WxGeekVA on MS Paint:



Enjoy thinking about what everything would be like if this happened.
Member Since: Posts: Comments:
Quoting LargoFl:
I guess there is no REAL way of saying WHAT is going to happen when the full pulse hits us tomorrow sometimes, but i did read..if it IS strong and wipes out the electricial generators the utilities use..the really big ones..there are NO spares available..can you imagine that..no electric for 5 years maybe...forget hurricanes..this space crap is so much more scary huh..and you know what..its REAL and COULD happen..this isnt science fiction..and nasa etc have planned for it TO happen..sometime


I read an article that said on March 8th of this year Earth was hit by an X5.4. It also said that up to 95% was deflected back into space. I don't remember hearing about this but if it was a 5.4 why would we think the 1.4 would be more damaging? Am I missing something?
Member Since: Posts: Comments:
Member Since: Posts: Comments:
1223. KEEPEROFTHEGATE (Mod)
Quoting LargoFl:
I guess there is no REAL way of saying WHAT is going to happen when the full pulse hits us tomorrow sometimes, but i did read..if it IS strong and wipes out the electricial generators the utilities use..the really big ones..there are NO spares available..can you imagine that..no electric for 5 years maybe...forget hurricanes..this space crap is so much more scary huh..and you know what..its REAL and COULD happen..this isnt science fiction..and nasa etc have planned for it TO happen..sometime
those that can adapt to there surroundings will be fine the key is to be one of the 10 percent the other 90 will be gone
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Member Since: Posts: Comments:
Inre comment1204 LargoFl,
Where in the world did you find that dungheap of disinformation? There ain't a scientist in the world, or any other place in the Universe, who'd endorse spouting such complete&utter nonsense.
Member Since: August 21, 2007 Posts: 0 Comments: 4860
Quoting LargoFl:
May 13, 2012 - We have a very alarming update and are still working to have more details ASAP. News that even has the full attention of the National Academy of Sciences along with NASA and other world scientist are quite concerned as they are not sure just what to expect, if they do, they are not talking. Simply said... the earth will soon start to cross through the absolute center of the dark rift of the Milky Way around 12.21.12. The rift is dark because it's littered with lots of space debris that consists of stationary rocks and boulders, even asteroids, and some objects which are planet size. This "dark rift" is the galactic gravitational plane of the Milky Way which traps all of this space debris. As the Earth passes through this plane, we may very well see a meteorite storm producing thousands of rocks that come raining out of the sky with hundreds, possibly thousands of meteorites making it all the way to the ground. We will just have to see what really happens. Keep in mind that countries around the world have long since built massive deep underground survival bunkers for 2012 and beyond. See Milky Way photo above.

Additionally, solar scientist are concerned that this gravitational plane (that is the backbone to the Milky Way's dark rift) may send the sun on a rampage which sets off powerful x-class solar storms and CMEs. (coronal mass ejections) It's these x-class storms that have the ability to generate an EMP event (electromagnetic pulse) like the one that hit the Earth in 1859. Once that happens again with today's technological world of electronics, the United States will go dark in about three minutes or less, along with the rest of the world.

Food trucks will no longer be able to supply stores with food, cell phones and computers will no longer work, and without power from the grid most factories will no longer work. Within three days or so, what food that's in your local store will be gone. Since most cars and trucks today require electronic ignition to work, most likely most vehicles will not work, however non-electric trains most likely would continue to work.

It's estimated that it will take at least six months to repair the grid. But the National Academy of Sciences estimates it will be closer to five years to repair it all. However populations in third world countries are use to growing their own food and should survive such an event much easier.


You understand that alignment happens every December 21st? Talk to Neil Degrasse Tyson... and please stop posting that crap in here.
Member Since: Posts: Comments:
Member Since: March 16, 2012 Posts: 127 Comments: 7928
Fabio:

Member Since: Posts: Comments:
Post 1204. LargoFl do you have a link to that article?
Member Since: Posts: Comments:
CI# /Pressure/ Vmax
5.2 / 967.8mb/ 94.8kt


Final T# Adj T# Raw T#
5.2 5.8 5.8

Estimated radius of max. wind based on IR : 16 km

Center Temp : +4.0C Cloud Region Temp : -64.0C

Scene Type : EYE

Positioning Method : RING/SPIRAL COMBINATION

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : PACIFIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

Member Since: March 16, 2012 Posts: 127 Comments: 7928
Member Since: Posts: Comments:
Quoting hurricanehunter27:
Sorry to tell you this but Daniel died quite a long time ago.
I meant it's remnants are still around.And look my hater has put a plus by your comment.So lovely :).
Member Since: August 14, 2010 Posts: 10 Comments: 16437
Member Since: March 16, 2012 Posts: 127 Comments: 7928
Here is my new blog entry Link
Member Since: Posts: Comments:
Western Pacific Invest 91W

Member Since: Posts: Comments:

Viewing: 1261 - 1211

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48Blog 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

Light Rain
67 °F
Light Rain