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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i think the 2 deadliest canes to hitt louisiana were katrina then audrey what storm was number 3???
what caused that NE jog before the stall that helped to tip the balance?
That Central African disturbance has a good spin to it.
Hmm... A cat 4 in my area...
Cat 4 winds + a somewhat decaying and fragile power gird = no blog for me and for awhile. XD
geez go easy ;)
the crap was referring to all the banter and mayan joking etc, and i guess he doesnt like it.
you dont have to get so mad.
People are so sensitive nowadays
if ya keep that mindset nothing can stop you....best wishes....study study study and study more...
The 1893 Louisiana Hurricane killed 2,000 people.
wow that was a nola hit?
Seems like he was just expressing some anger if he was serious about his post, but I don't know why this blog deserves his anger.
The the Chenire Caminada Hurricane, also known as the Great October Storm, was a powerful hurricane that devastated the island of the Chenire Caminada, Louisiana in early October 1893.
It was one of two deadly hurricanes during the 1893 Atlantic hurricane season; the storm killed an estimated 2,000 people mostly from storm surge.
The hurricane wiped the community of Cheniere Caminada off the map, leaving a single, damaged home. Some survivors retreated to what is now Golden Meadow, and others migrated farther inland.
Impact
As a strengthening hurricane in the Gulf of Mexico, the Cheni%uFFFDre Caminada Hurricane brought a strong storm surge that flooded much of southeast Louisiana. 779 people died out of the town's 1500 residents from the high winds and flooding from the storm surge. The surge was up to 16 feet, with heavy surf above it. The hurricane caused about 2000 fatalities in total, making it among the deadliest American hurricanes.
The Gulf States were greatly affected by the hurricane. The orange and rice crop were greatly damaged, and combined with destruction of the wind, the hurricane caused about $5 million in damage (1893 USD, $102.6 million in 2005 USD)
Pretty much. It is called the 1893 Cheniere Caminada hurricane. For the town it destroyed. And for wiping out 779of the 1500 residents. This hurricane's death toll is actually higher than Katrina and Audrey.
what are your thoughts with the GOM this week??
thanks for sharing the info....
i guess back then you had to go by tidal surge to know if it was something different that just a reg storm coming off the gulf...our ancestors along the gulf coast back then were going to bed never really knowing when something would hitt them...
Well..it is Mid July so be wary, as things can and usually do surprise us.
Plus its still 2012 Mayan GOM "Swirl-a-palooza" too.
Gulf Of Mexico - Rainbow Loop
AXNT20 KNHC 142334
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUL 14 2012
TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.
BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.
...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 10N43W TO 16N49W MOVING W AT 15-20
KT. THE WAVE REMAINS ON THE LEADING EDGE OF A DEEP MOISTURE
SURGE AS DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY BETWEEN
45W-55W. NO SIGNIFICANT CONVECTION IS OCCURRING IN THE VICINITY
OF THE WAVE.
TROPICAL WAVE EXTENDS FROM 10N61W TO 19N63W MOVING W AT 20 KT.
THE WAVE IS EMBEDDED WITHIN A NARROW AREA OF DEEP MOISTURE
DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY BETWEEN 60W-65W
ACROSS THE EASTERN CARIBBEAN SEA. SCATTERED MODERATE CONVECTION
IS OCCURRING ON THE SOUTHERN EXTEND OF THE WAVE AXIS FROM
10N-13N BETWEEN 61W-63W.
...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO
10N21W TO 12N32W TO 11N42W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 10N47W TO 09N60W. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS FROM 11N-15N BETWEEN 11W-18W.
ISOLATED MODERATE CONVECTION IS FROM 08N-12N BETWEEN 23W-30W.
...DISCUSSION...
GULF OF MEXICO...
UPPER LEVEL TROUGHING EXTENDS FROM THE SW NORTH ATLC REGION NEAR
29N74W SOUTHWEST TO OVER THE STRAITS OF FLORIDA NEAR 24N82W TO
OVER THE NORTHERN YUCATAN PENINSULA NEAR 21N90W. CONSIDERABLE
BROAD SURFACE TROUGHING EXTENDS ACROSS THE SW NORTH ATLC REGION
AND WESTERN CUBA INTO THE NW CARIBBEAN SEA...WITH LOW TO MIDDLE
LEVEL ENERGY AND SURFACE TROUGHING EXTENDING FROM MOBILE BAY
NEAR 31N88W TO 26N89W IN THE CENTRAL GULF. WITH BROAD TROUGHING
IN PLACE...SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING
ACROSS PORTIONS OF THE WESTERN PENINSULA OF FLORIDA AND ADJACENT
COASTAL WATERS N OF 25N E OF 84W. MORE SCATTERED SHOWERS AND
ISOLATED TSTMS IN ASSOCIATION WITH THE CENTRAL GULF SURFACE
TROUGH ARE OCCURRING N OF 23N BETWEEN 86W-92W...INCLUDING INLAND
PORTIONS OF ALABAMA AND MISSISSIPPI. ELSEWHERE ACROSS THE
REMAINDER OF THE FAR WESTERN GULF...A WEAKENING SURFACE RIDGE
AXIS EXTENDS FROM WEST OF THE SURFACE TROUGH NEAR 27N94W TO A
1018 MB HIGH CENTERED OVER COASTAL EAST-CENTRAL MEXICO NEAR
22N98W. A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING W OF 95W
ON LIGHT EAST-SOUTHEASTERLY FLOW BETWEEN THE TROUGHING ACROSS
THE CENTRAL GULF AND HIGH OVER MEXICO.
CARIBBEAN SEA...
UPPER LEVEL TROUGHING EXTENDS FROM OVER THE SW NORTH ATLC REGION
NEAR 29N74W SOUTHWESTWARD TO OVER THE NW CARIBBEAN SEA AND
NORTHERN YUCATAN PENINSULA NEAR 21N90W. SOUTHWESTERLY MIDDLE TO
UPPER LEVEL MOISTURE ADVECTION EAST OF THE UPPER LEVEL TROUGHING
IS PRODUCING A FAVORABLE ENVIRONMENT FOR SHOWERS AND TSTMS THIS
EVENING. AT THE SURFACE...A BROAD SURFACE TROUGH AXIS EXTENDS
FROM CENTRAL CUBA NEAR 23N79W TO 19N84W PROVIDING FOCUS FOR
SCATTERED SHOWERS AND TSTMS FROM 18N-23N BETWEEN 75W-85W...
INCLUDING A LARGE PORTION OF CUBA. THE REMAINDER OF THE
CARIBBEAN BASIN S OF 17N BETWEEN 57W-85W IS UNDER THE INFLUENCE
OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 12N68W.
THE UPPER LEVEL HIGH IS PROVIDING FOR OVERALL STABLE CONDITIONS
THIS EVENING WITH ONLY A FEW PASSING HIGH LEVEL CLOUDS S OF 14N
BETWEEN 68W-82W. ONE EXCEPTION TO CONVECTIVE-FREE SKIES IS A
TROPICAL WAVE ANALYZED ALONG 62W WHICH IS GENERATING SCATTERED
SHOWERS AND ISOLATED TSTMS FROM 10N-13N BETWEEN 61W-63W AND IS
EXPECTED TO TRACK WESTWARD OVER THE NEXT 24 TO 36 HOURS.
ATLANTIC OCEAN...
UPPER LEVEL TROUGHING EXTENDS ACROSS MUCH OF THE SW NORTH ATLC W
OF 67W WITH AN UPPER LEVEL LOW CENTERED NEAR 29N74W TO ANOTHER
UPPER LEVEL LOW CENTERED OVER THE FLORIDA STRAITS NEAR 24N82W.
THIS TROUGHING RESULTS IN A BROAD SURFACE TROUGH AXIS AT THE
SURFACE ANALYZED FROM 32N65W TO 25N75W. PLENTY OF MIDDLE TO
UPPER LEVEL MOISTURE CONTINUES TO ADVECT NORTHWARD FROM THE
WESTERN CARIBBEAN SEA INTO THE SW NORTH ATLC REGION PRODUCING
SCATTERED SHOWERS AND ISOLATED TSTMS OVER A LARGE AREA FROM
23N-29N BETWEEN 69W-79W...AND FROM 18N-23N BETWEEN 75W-83W.
FARTHER EAST...A BROAD SURFACE RIDGE CONTINUES TO DOMINATE THE
REMAINDER OF THE ATLC BASIN ANCHORED BY A 1029 MB HIGH CENTERED
NEAR 35N48W. MOSTLY FAIR CONDITIONS ARE NOTED ON SATELLITE
IMAGERY N OF 15N E OF 60W AND ARE FURTHER ENHANCED BY SUSPENDED
SAHARAN DUST COVERING MUCH OF THE EASTERN AND CENTRAL ATLC S OF
30N.
FOR ADDITIONAL INFORMATION PLEASE VISIT
WWW.HURRICANES.GOV/MARINE
$$
HUFFMAN
Bud (115mph, category 3):
Carlotta (105mph, category 2):
Daniel (115mph, category 3):
Emilia (140mph, category 4):
Fabio (105mph, category 2):
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
807 PM EDT SAT JUL 14 2012
GMZ830-150100-
807 PM EDT SAT JUL 14 2012
...STRONG THUNDERSTORMS APPROACHING THE WATERS...
AT 806 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS...PRODUCING STRONG WINDS UP TO 33 KNOTS 5 NM SOUTH OF
TAMPA BAY...MOVING NORTHWEST AT 20 KNOTS.
MARINERS CAN EXPECT GUSTY WINDS UP TO 33 KNOTS...LOCALLY HIGHER
WAVES...AND DEADLY CLOUD TO WATER LIGHTNING STRIKES. BOATERS SHOULD
SEEK SAFE HARBOR IMMEDIATELY UNTIL THIS STORM PASSES.
STRONG THUNDERSTORMS CAN PRODUCE WATERSPOUTS WITH LITTLE OR NO
ADVANCE WARNING. SEEK SAFETY IMMEDIATELY.
LAT...LON 2769 8252 2768 8250 2767 8250 2766 8254
2759 8256 2756 8261 2777 8275 2770 8266
2771 8263 2781 8263 2783 8261 2786 8264
2788 8262 2791 8270 2799 8270 2771 8248
$$
NATIONAL WEATHER SERVICE STATE COLLEGE PA
841 PM EDT SAT JUL 14 2012
PAC111-150330-
/O.NEW.KCTP.FA.Y.0036.120715T0041Z-120715T0330Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
SOMERSET PA-
841 PM EDT SAT JUL 14 2012
THE NATIONAL WEATHER SERVICE IN STATE COLLEGE PA HAS ISSUED A
* FLOOD ADVISORY FOR...
SOUTHERN SOMERSET COUNTY...
* UNTIL 1130 PM EDT...
* AT 837 PM EDT DOPPLER RADAR INDICATED HEAVY RAIN WAS FALLING DUE TO
SLOW MOVING THUNDERSTORMS. DOPPLER RADAR ESTIMATES THAT OVER 2
INCHES OF RAIN HAS FALLEN IN THE LAST TWO HOURS. EXPECT FLOODING
TO BEGIN SHORTLY.
* LOCATIONS THAT MAY EXPERIENCE MINOR FLOODING INCLUDE BUT ARE NOT
LIMITED TO EAST OF SALISBURY TO NEAR WELLERSBURG WHERE THE
HEAVIEST RAIN HAS ALREADY FALLEN.
HEAVY RAIN HAS ALREADY FALLEN BETWEEN SALISBURY AND WELLERSBURG IN
SOUTHEASTERN SOMERSET COUNTY. MORE RAIN IS MOVING IN FROM THE WEST.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A FLOOD ADVISORY MEANS THAT ALTHOUGH STREAMS AND CREEKS MAY BE
ELEVATED OR EVEN RISE OUT OF THEIR BANKS...PROPERTY DAMAGE WILL BE
MINIMAL. INCONVENIENCES CAN BE EXPECTED BUT THE FLOODING WILL NOT BE
IMMEDIATELY LIFE THREATENING.
EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE ELEVATED LEVELS ON
SMALL CREEKS AND STREAMS...AND PONDING OF WATER IN URBAN AREAS...
HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER POOR DRAINAGE
AREAS AND LOW LYING SPOTS.
BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODS.
&&
LAT...LON 3973 7941 3982 7937 3985 7940 3990 7938
3984 7879 3974 7879 3972 7881 3971 7894
$$
FORECASTER: RHG/DM
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
856 PM EDT SAT JUL 14 2012
MDZ501-502-WVZ050-504-150145-
HAMPSHIRE WV-EXTREME WESTERN ALLEGANY MD-
CENTRAL AND EASTERN ALLEGANY MD-EASTERN MINERAL WV-
856 PM EDT SAT JUL 14 2012
...THUNDERSTORM WITH VERY HEAVY RAIN TO AFFECT HAMPSHIRE...EXTREME
WESTERN ALLEGANY...CENTRAL AND EASTERN ALLEGANY AND EASTERN MINERAL
COUNTIES...
AT 855 PM EDT...A THUNDERSTORM WAS LOCATED OVER MIDLAND...MOVING
EAST AT 10 MPH.
LOCATIONS IMPACTED INCLUDE LA VALE...RIDGELEY...CUMBERLAND AND FORT
ASHBY.
THIS STORM IS PRODUCING FREQUENT CLOUD TO GROUND LIGHTNING. MOVE
INDOORS IMMEDIATELY FOR YOUR SAFETY. IF YOU CAN HEAR THUNDER...YOU
ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING.
HEAVY RAIN WITH THIS STORM WILL REDUCE VISIBILITIES TO BELOW ONE MILE
AND MAY CAUSE PONDING OF WATER ON ROADWAYS. RAINFALL AMOUNTS OF UP
TO 2 INCHES CAN BE EXPECTED.
&&
LAT...LON 3943 7862 3951 7906 3971 7895 3973 7893
3973 7860
TIME...MOT...LOC 0055Z 268DEG 10KT 3960 7892
$$
KONARIK
Date 15 July 2003
Fabio becomes a Category 2 hurricane, may briefly become a major while Emilia weakens
does fabio the person live in calif???
Viewing: 1501 - 1551
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