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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135 NM EITHER SIDE OF A LINE FROM 20.7N 142.4E TO 24.4N 136.2E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS
IN THE AREA ARE ESTIMATED TO BE 15 TO 20 KNOTS. METSAT IMAGERY AT
150000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 20.9N
142.2E. THE SYSTEM IS MOVING NORTHWESTWARD AT 07 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 18.9N
144.1E, IS NOW LOCATED NEAR 20.9N 142.2E, APPROXIMATELY 235 NM
SOUTH-SOUTHEAST OF IWO TO. RECENT ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS DEEP CONVECTION FLARING ALONG THE EASTERN PORTION
OF A SLIGHTLY ELONGATED LOW-LEVEL CIRCULATION CENTER EVIDENT IN A
150042Z ASCAT PASS. THIS SCATTEROMETER DATA SHOWS 15 TO 20 KNOT
WINDS ALONG THE EASTERN AND NORTHERN PORTIONS OF THE CIRCULATION
CENTER WITH STRONGER 30 TO 35 KNOT WINDS NORTHEAST OF THE CENTER
INDUCED BY THE PRESSURE GRADIENT BETWEEN THE DISTURBANCE AND THE
SUBTROPICAL RIDGE TO THE NORTHEAST. A TROPICAL UPPER TROPOSPHERIC
TROUGH (TUTT) CELL PREVIOUSLY SUPERIMPOSED OVER THE LLCC HAS MOVED
RAPIDLY WESTWARD, DECREASING VERTICAL WIND SHEAR AND UPPER-LEVEL
SUBSIDENCE AND ALLOWING A POLEWARD OUTFLOW CHANNEL TO DEVELOP.
ADDITIONALLY, A NEW TUTT CELL THAT HAS FORMED TO THE EAST OF THE
DISTURBANCE HAS INTRODUCED A SECOND OUTFLOW CHANNEL. MAXIMUM
SUSTAINED SURFACE WINDS NEAR THE CIRCULATION CENTER ARE ESTIMATED AT
15 TO 20 KNOTS, WITH STRONGER GRADIENT-INDUCED WINDS OF 30 TO 35
KNOTS OBSERVED TO THE NORTHEAST OF THE CENTER. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. BASED ON A PERSISTENT LOW-
LEVEL CIRCULATION AND RAPIDLY IMPROVING UPPER-LEVEL SUPPORT, THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH.
...UNSETTLED WEATHER THROUGH TUESDAY WITH STRONG TO PERHAPS
ISOLATED SEVERE TSTORMS, LOCALIZED HEAVY RAIN...
...INCOMING SAHARAN AIR LAYER WEDNESDAY THROUGH LATE WEEK
RESULTING IN HAZY SUNSHINE, FEWER TSTORMS BUT ISOLATED SEVERE
STILL POSSIBLE...
Anything trying to develop from a trough split will at least have a fighting chance.
It's a nice day for a green wedding - as two frogs got married in front of over 2,000 wedding guests in India.
I thought the picture WAS of the girls on the beach....
Link
all 2011 tornado outbreaks during high SOI times
Falling SOI = 1 tornado outbreak in March and April and no more.
The power of El Nino/La Nina
Link
Where did you get these rain totals from? We have had almost 10" here in Edna and the majority fell last Tuesday and Wednesday. Just curious
Could have been moving very fast.
ROFLMBO
I bet you I do more...my..dad..he's horrible, whenever we go to the beach, and get a hotel, he always grabs a pair of binoculars to stare...at..you know what
Help NASA Find the Alphabet - From Space
By Betsy Mason July 15, 2012 | 7:00 am
NASA says this looks like the letter "V" but I say it looks like a "Z."
Photo: NASA
I know there aren't many people who spend as much time looking at images of Earth from space as I do. But there some out there, and NASA wants your help.
Adam Voiland of NASA's Earth Observatory found the photo above that looks like a huge, cloudy "V."...
But what about the rest of the alphabet? Voiland would like to assemble the entire alphabet from space, so if you've seen a letter, let us know and perhaps your contribution will be featured by NASA or Wired. He suggests looking for letter-shaped clouds, smoke, dust, ice or phytoplankton blooms. I imagine there may be literary glaciers, rivers, islands, forests, faults and mountain ranges as well. Just make sure the letter stands out clearly against the background.
http://www.wired.com/wiredscience/2012/07/alphabe t-from-space/
Rain's held up over NP for now.... looks like Freeport's getting it.
Its vector had changed from 18.8mph(30.3km/h) West West to 22.2mph(35.7km/h) West
MaxSusWinds had held steady at 30knots(36mph)56km/h
And minimum pressure had held steady at 1004millibars
For those who like to visually track TS.Emilia's path...
HPV is Hanalei,Kauai :: HNL is Honolulu,Oahu :: OGG is Kahalui,Maui :: ITO is Hilo,Hawaii
The kinked line represents the 1st day of TS.Emilia's path after it became a TropicalStorm again
Easternmost dot on the longest line is TS.Emilia's most recent position
The longest line is a straightline projection through TS.Emilia's 2 most recent positions to its closest approach to Hawaii
14July6pmGMT: TS.Emilia had been headed toward passing 322miles(519kilometres)South of Hawaii
(dot south of the straightline)
15July12amGMT: TS.Emilia had been headed toward passing 105miles(169kilometres)South of Hawaii
(dot north of the straightline)
15July6amGMT: TS.Emilia had been headed toward passing 289miles(465kilometres)South of Hawaii
(bottom half of the blob on the straightline)
15July12pmGMT: TS.Emilia was heading toward passing 276miles(444kilometres)South of Hawaii
in ~2days4hours from now
Copy&paste hpv, hnl, 14.25n155.154w, 17.382n155.718w, 14.732n155.261w, ogg, ito, 15.3n124.2w- 15.5n125.4w- 15.5n126.7w- 15.5n127.9w- 15.5n129.3w, 15.5n129.3w-15.5n130.6w, 15.5n130.6w-15.5n132.2w, 15.5n132.2w-15.7n133.7w, 15.7n133.7w-15.7n135.4w, 15.7n135.4w-15.7n137.4w, 15.7n135.4w-14.913n155.317w, 18.911n155.681w-14.913n155.317w into the GreatCircleMapper for more information
The previous mapping for comparison
really?
thats wierd
T-storms
70% chance of precipitation
Tomorrow
T-storms
70% chance of precipitation
Not really. O_o
He calls the binoculars his bikini binoculars. LOL
looks like a surface low is still trying to form with the tropical wave off the SE coast
I cant post images this morning but if you go to the current HPC surface low map, you will see a weak one is trying to form
That's not just weird, that's kinda...stalker-ish. Lol.
5.8 / 954.3mb/109.8kt
Final T# Adj T# Raw T#
5.7 5.5 5.5
de ol' guy wit a kid and de binoculars. he-he
POST-TROPICAL CYCLONE EMILIA ADVISORY NUMBER 32
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052012
800 AM PDT SUN JUL 15 2012
...EMILIA IS NOW A POST-TROPICAL CYCLONE...THIS IS THE LAST
ADVISORY...
SUMMARY OF 800 AM PDT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...15.6N 138.2W
ABOUT 1150 MI...1845 KM ESE OF HILO HAWAII
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES
------------------------------------------------- -------------------------------
8:00 AM PDT Sun Jul 15
Location: 15.6°N 138.2°W
Moving: W at 18 mph
Min pressure: 1005 mb
Max sustained: 35 mph
FORECAST POSITIONS AND MAX WINDS
INIT 15/1500Z 15.6N 138.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
12H 16/0000Z 15.5N 140.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 16/1200Z 15.4N 143.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 17/0000Z 15.3N 146.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 17/1200Z 15.2N 149.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 18/1200Z 15.0N 155.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 19/1200Z 15.0N 161.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 20/1200Z...DISSIPATED
yahoo!!!!
now only fabio is left
------------------------------------------------- -------------------------------
8:00 AM PDT Sun Jul 15
Location: 16.9°N 117.4°W
Moving: WNW at 9 mph
Min pressure: 972 mb
Max sustained: 105 mph
FORECAST POSITIONS AND MAX WINDS
INIT 15/1500Z 16.9N 117.4W 90 KT 105 MPH
12H 16/0000Z 17.4N 118.7W 85 KT 100 MPH
24H 16/1200Z 18.3N 120.2W 70 KT 80 MPH
36H 17/0000Z 19.4N 121.1W 55 KT 65 MPH
48H 17/1200Z 20.6N 121.5W 40 KT 45 MPH
72H 18/1200Z 23.3N 121.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 19/1200Z 25.2N 121.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 20/1200Z 26.0N 121.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
40 is not old to me.
My thoughts are your not old until your a senior.
how?
lol
Oh wow....they are way off. After 2 hours of rain Tuesday morning, we realized the rain gauge was not put back out after we mowed and dumped 5.5 inches. We dumped another 3.75 inches on Wednesday and another 1.1 from rains Friday and Saturday. I wonder where they get their information from here in Edna
.DAY ONE...TODAY AND TONIGHT
THUNDERSTORMS: NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED
ACROSS ALL OF SOUTH FLORIDA TODAY. THE MAIN IMPACTS WILL BE FREQUENT
LIGHTNING STRIKES...LOCALLY HEAVY RAINFALL AND GUSTY WINDS.
WIND: THE STRONGEST STORMS TODAY WILL CAPABLE OF PRODUCING WIND
GUSTS TO 40 TO 50 MPH.
FLOODING: SLOW STORM MOTION WILL ALLOW FOR LOCALLY HEAVY RAINFALL
WITH AMOUNTS IN EXCESS OF 2 INCHES POSSIBLE IN A SHORT PERIOD OF
TIME, POTENTIALLY RESULTING IN TEMPORARY FLOODING OF LOW LYING AND
POORLY DRAINED AREAS.
RIP CURRENTS: SOUTHEASTERLY WINDS AT 10 TO 15 MPH WILL RESULT IN A
MODERATE RISK OF RIP CURRENTS ALONG THE ATLANTIC BEACHES TODAY.
Looking Good Lucy!
Serial Number: 202
Issue Time: 2012 Jul 15 1145 UTC
EXTENDED WARNING: Geomagnetic K-Index of 6 expected
Extension to Serial Number: 201
Valid From: 2012 Jul 15 0730 UTC
Now Valid Until: 2012 Jul 15 1500 UTC
Warning Condition: Onset
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.
Good morning Hydrus. :]
Viewing: 1751 - 1801
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