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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Those form when High Cirrus,ice crystals refract the sunlight O believ ..
I shot one here in NOLA a few weeks back as well.
what kind of weather radio do ya have??
Whenever both sun and clouds are in the sky, be sure to look up--you may behold rings, arcs, and other marvels!
I havent one,but I tune in VIA the web a lot.
http://www.eham.net/
It is not caused by the CME.
They are produced by the ice crystals in cirrus clouds high (5–10 km, or 3–6 miles) in the upper troposphere. The particular shape and orientation of the crystals is responsible for the type of halo observed. Light is reflected and refracted by the ice crystals and may split up into colors because of dispersion. The crystals behave like prisms and mirrors, refracting and reflecting sunlight between their faces, sending shafts of light in particular directions.
TXC071-201-291-339-473-131945-
/O.NEW.KHGX.FF.W.0046.120713T1643Z-120713T1945Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1143 AM CDT FRI JUL 13 2012
THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A
* FLASH FLOOD WARNING FOR...
SOUTHWESTERN LIBERTY COUNTY IN SOUTHEAST TEXAS...
EXTREME NORTHWESTERN CHAMBERS COUNTY IN SOUTHEAST TEXAS...
HARRIS COUNTY IN SOUTHEAST TEXAS...
SOUTHWESTERN MONTGOMERY COUNTY IN SOUTHEAST TEXAS...
NORTHEASTERN WALLER COUNTY IN SOUTHEAST TEXAS...
* UNTIL 245 PM CDT
* AT 1136 AM CDT...DOPPLER RADAR INDICATED THUNDERSTORMS PRODUCING
HEAVY RAIN ACROSS THE WARNED AREA. FLASH FLOODING IS EXPECTED TO
BEGIN SHORTLY. A BAND OF SHOWERS AND THUNDERSTORMS ALONG THE I-10
CORRIDOR SHOULD DEVELOP NORTHWARD AND WILL BE CAPABLE OF RAINFALL
RATES 1.5 TO 2" PER HOUR AND ON TOP OF THE SATURATED GROUND WILL
RUNOFF PRODUCING FLOODING. ROADWAYS WILL BE SEVERELY IMPACTED.
HARRIS COUNTY FLOOD CONTROL DISTRICT HAS REQUESTED THAT PEOPLE
IN THE WARNED AREA STAY INDOORS AND NOT TO ATTEMPT TO TRAVEL.
* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
HOUSTON...CHANNELVIEW...CLOVERLEAF...ALDINE...WEST UNIVERSITY
PLACE...GALENA PARK...JACINTO CITY...LIBERTY...HIGHLANDS...JERSEY
VILLAGE...TOMBALL...DAYTON...HUNTERS CREEK VILLAGE...BUNKER HILL
VILLAGE...SPRING VALLEY...PINEHURST...PINEY POINT VILLAGE...
BARRETT...HEDWIG VILLAGE...CROSBY...SHELDON...SOUTHSIDE PLACE...
AMES...HILSHIRE VILLAGE AND STAGECOACH.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND
UNDERPASSES AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.
i have a portable one and a mobile one both midland brand. the portable one misses about 30% of alerts. might just be a louisiana thing idk. my advice if your going to buy one go with the mobile not the portable one....
This is the one I got . Inexpensive and has about a 95% "catch" rate from my experience.
Midland WR 120
yeah thats the mobile one, the potable must get about 65% of alerts....and i exchanged it for another one and same problem...
I think what's even more disturbing about this post is that you got five "plusses"..........
It kind of makes you wonder if ignorance is celebrated.
it's celebrated daily in DC......on the hill..
I got something similar to one of those not too long ago. Really neat little bugger. I especially like it when I'm driving through storms/storm chasing.
Think it was plussed by some, cause it made them laugh...
spinning?
i wish ya could choose the voices on them, i have had times when an alert went off and i was having a really good dream and that noaa dude voice really killed the mood. i want a frech accent lady voice....
To all deniers: Even if climate change isn't real, the least that could happen is that we create a better world to live in.
Whats left of Fabio heading for Southern California......probably just make it muggy again.....but with the moisture infusion T Storms will be possible.
ya should have some breaks in weather... but ya will get some rain
NATIONAL WEATHER SERVICE SAN JUAN PR
1237 PM AST FRI JUL 13 2012
PRC003-005-013-027-065-071-081-099-115-131-141-13 1930-
/O.NEW.TJSJ.FA.Y.0276.120713T1637Z-120713T1930Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
HATILLO PR-LARES PR-MOCA PR-UTUADO PR-SAN SEBASTIAN PR-ARECIBO PR-
AGUADILLA PR-ISABELA PR-CAMUY PR-AGUADA PR-QUEBRADILLAS PR-
1237 PM AST FRI JUL 13 2012
THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED AN
* URBAN AND SMALL STREAM FLOOD ADVISORY
FOR THE FOLLOWING MUNICIPALITIES...
IN PUERTO RICO
HATILLO...LARES...MOCA...UTUADO...SAN SEBASTIAN...ARECIBO...
AGUADILLA...ISABELA...CAMUY...AGUADA AND QUEBRADILLAS
* UNTIL 330 PM AST
* AT 1230 PM AST...DOPPLER WEATHER RADAR INDICATED AN AREA OF
SHOWERS AND THUNDERSTORMS WITH VERY HEAVY RAIN IN THE ADVISORY AREA.
RAINFALL AMOUNTS OF AROUND 1 INCH HAVE FALLEN ACROSS THESE
MUNICIPALITIES IN THE LAST HOUR AND ADDITIONAL 1 TO 2 INCHES ARE
POSSIBLE IN THE NEXT FEW HOURS.
MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.
&&
LAT...LON 1852 6701 1850 6696 1850 6694 1849 6689
1844 6669 1826 6678 1839 6721 1842 6717
1849 6718 1852 6714 1852 6710
$$
FIGUEROA
I hope so. With all this tension between denialists and AGW "believers", I have a hard time interpreting it as sarcastic humour.
I wont say it, but the Slidell boyz might er, dampen yer hopes atad.
Area forecast discussion
National Weather Service New Orleans la
949 am CDT Friday Jul 13 2012
Update...
Sounding discussion...
Problems with sounding getting into d2d this morning. Ncf fixed
the problem and sounding is now available in d2d. Otherwise...a
successful flight this morning. A continued moist and unstable
sounding with a precipitable water of 1.95 inches and and an Li of -5.8. Very high
cape values around 3600 this morning as well. A light to moderate
southerly flow continues to dominate from the lower levels up to
the upper levels.
&&
Previous discussion... /issued 359 am CDT Friday Jul 13 2012/
Short term...
the boundary stalled just to the north of the County Warning Area remains the
driving factor in the forecast. This boundary will weaken over the
next few days. Expect conditions to reflect conditions from
yesterday except initial rainfall this morning is on our door
step. Latest infrared imagery shows a numerous clouds just off to the
west. Another interesting feature being depicted on the imagery
is a weak low just off to the northwest of the area across extreme
west Mississippi. This could help increase convection this
morning. In fact showers and thunderstorms have been developing
west of Baton Rouge this morning. Some of the short range models
increase convection during the morning hours especially areas from
Baton Rouge westward. For this reason and also for ongoing
precipitation near the western border of the County Warning Area this morning have
increased probability of precipitation over the western areas of the forecast area this
morning to near 100 percent. Areas to the east have maintained the
likely wording from last package. Coverage of showers and storms
will increase this morning...a few models suggest that the bulk of
the rainfall expected today will fall during the morning hours.
However have continued to carry likely probability of precipitation through the afternoon
and evening hours despite a possible dry trend in the afternoon.
Temperatures today should remain at or below normal today due to
convection and cloud cover.
Long term...
the boundary continues to weaken and the atmosphere still is very
moist through the weekend. Precipitable water values still around the 2 inch mark
and a moderately unstable atmosphere should allow for showers and
storms to develop each day though the weekend. Have kept likely
wording in though Sunday. Upper level ridge over eastern rockies
stubbornly tries to move eastward by the middle of next week. We
can expect a more normal pattern next week as convection should be
more diurnal in nature. Have probability of precipitation in the 30 to 40 percent range
each day next week. With increased subsidence aloft taking
hold and drier air working into the area...temperatures will begin to
warm across the region. Near normal to slightly above normal
temperatures by weeks end as upper level ridge over the High
Plains slowly flattens and slides eastward.
the rain is headed down I-10 eastbound next stop the cats meow....
Looks like a derecho coming together
Flash Flood Warning in effect until 2:45PM CDT FRI
THE NATIONAL WEATHER SERVICE IN LEAGUE CITY Â HAS ISSUED A Â
FLASH FLOOD WARNING FOR
SOUTHWESTERN LIBERTY COUNTY IN SOUTHEAST TEXAS
EXTREME NORTHWESTERN CHAMBERS COUNTY IN SOUTHEAST TEXAS
HARRIS COUNTY IN SOUTHEAST TEXAS
SOUTHWESTERN MONTGOMERY COUNTY IN SOUTHEAST TEXAS
NORTHEASTERN WALLER COUNTY IN SOUTHEAST TEXAS
UNTIL 245 PM CDT Â
AT 1136 AM CDT
DOPPLER RADAR INDICATED THUNDERSTORMS PRODUCING Â HEAVY RAIN ACROSS THE WARNED AREA. Â FLASH FLOODING IS EXPECTED TO Â BEGIN SHORTLY. A BAND OF SHOWERS AND THUNDERSTORMS ALONG THE I-10 Â CORRIDOR SHOULD DEVELOP NORTHWARD AND WILL BE CAPABLE OF RAINFALL Â RATES 1.5 TO 2" PER HOUR AND ON TOP OF THE SATURATED GROUND WILL Â RUNOFF PRODUCING FLOODING. ROADWAYS WILL BE SEVERELY IMPACTED. Â HARRIS COUNTY FLOOD CONTROL DISTRICT HAS REQUESTED THAT PEOPLE Â IN THE WARNED AREA STAY INDOORS AND NOT TO ATTEMPT TO TRAVEL. Â
SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE
HOUSTON
CHANNELVIEW
CLOVERLEAF
ALDINE
WEST UNIVERSITY Â PLACE
GALENA PARK
JACINTO CITY
LIBERTY
HIGHLANDS
JERSEY Â VILLAGE
TOMBALL
DAYTON
HUNTERS CREEK VILLAGE
BUNKER HILL Â VILLAGE
SPRING VALLEY
PINEHURST
PINEY POINT VILLAGE
BARRETT
HEDWIG VILLAGE
CROSBY
SHELDON
SOUTHSIDE PLACE
AMES
HILSHIRE VILLAGE AND STAGECOACH. Â PRECAUTIONARY/PREPAREDNESS ACTIONS
EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL Â CREEKS AND STREAMS
URBAN AREAS
HIGHWAYS
STREETS AND Â UNDERPASSES AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS. Â
Link
You shouldnt have to explain why you plussed a comment..this blog gets more outrageous every day..
Of course it's going to be outrageous!
He was baiting you..thats what they do..its hard to not say something..I know for a fact..
the bait don't always taste good....
And it keeps on coming on...
Everyone has different opinions but to question someone on why they plussed a comment is obsurd.
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