Dr. Jeff Masters' WunderBlog

July hurricane outlook

Posted by: Dr. Jeff Masters, 07:26 PM GMT del 02 Luglio 2009

Atlantic tropical cyclone activity typically picks up a bit during the first half of July. Since the current active hurricane period began in 1995, seven of 14 years (50%) have had a named storm form during the first half of July. The busiest first half of July occurred in 2005, when three hurricanes formed. These included Hurricane Dennis and Hurricane Emily--the strongest hurricanes ever observed so early in the season. As seen in Figure 1, most of the early July activity occurs in the Gulf of Mexico, Western Caribbean, and Carolina waters. However, a few long-track "Cape Verdes" hurricanes begin to occur. These are spawned by tropical waves that come off the coast of Africa. Tropical waves serve as the instigators of about 85% of all major hurricanes. Last year's Hurricane Bertha was one such rare early July Cape Verdes hurricane. Bertha's 120 mph winds made it the sixth strongest early-season Atlantic hurricane on record. Bertha also set the record for farthest east formation as a tropical storm, hurricane, and major hurricane, so early in the season.

Figure 1. Tracks of all tropical storms and hurricanes 1851 - 2006 that formed July 1-15. North Carolina and the Gulf of Mexico coast from the Florida Panhandle to Texas are the preferred strike locations. Oddly, the Florida Peninsula has been struck by only two storms that formed in the first half of July.

Sea Surface Temperatures
Sea Surface Temperatures (SST) anomalies have warmed slightly over the past two weeks, but are close to average over the tropical Atlantic between Africa and Central America (Figure 2). These are the are the coolest SST anomalies we've seen since 1994. The strength of the Azores-Bermuda high has been near average over the past two weeks, driving near-average trade winds. Stronger-than-average trade winds were observed through most of the period November 2008 - May 2009, which helped cool the tropical Atlantic substantially. Strong winds mix up colder water from the depths and cause greater evaporative cooling. The latest 2-week run of the GFS model predicts continued average-strength trade winds through mid-July, so SSTs should remain near average during this period.

Typically, July tropical storms form over the Gulf of Mexico, Western Caribbean, and Gulf Stream waters just offshore Florida. SSTs are about 1.0°C above average for this time of year in the Gulf of Mexico, but near average elsewhere. July storms typically 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. There will be one or two fronts moving off the U.S. coast over the next two weeks, and we will need to watch these for development. Wind shear is too high and SSTs are usually too cold in July to allow African tropical waves to develop into tropical storms. African tropical waves serve as the instigators of about 85% of all major hurricanes,

Figure 2. Sea Surface Temperature (SST) departure from average for July 2, 2009. SSTs were near 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
El Niño conditions continue to amplify over the tropical Eastern Pacific. Ocean temperatures there rose 0.5°C over the past two weeks, and are now 0.45°C above the threshold for El Niño, according to the Australian Bureau of Meteorology (Figure 3). NOAA's Climate Prediction Center issued an El Niño Watch in early June, saying "that conditions are favorable for a transition from neutral to El Niño conditions during June - August 2009". The pattern of changes in surface winds, upper-level winds, sea surface temperatures, and deeper water heat content are all consistent with what has been observed during previous developing El Niños, and latest set of mid-June runs of the El Niño computer models are almost universally calling for El Niño conditions to become well-established for the peak months of hurricane season, August - October. It is likely that Atlantic hurricane activity will be suppressed in 2009 due to the strong upper-level winds and resulting wind shear an El Niño event usually brings to the tropical Atlantic.

Figure 3. 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 June 28, 2009, SSTs in the Niño 3.4 region had risen to 0.95°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: Australian Bureau of Meteorology.

Wind shear
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's band of strong high-altitude winds is the main source of wind shear in July over the Atlantic hurricane breeding grounds, since the jet is very active and located quite far south this time of year.

The jet stream over the past two months has been locked into a pattern where a southern branch (the subtropical jet stream) brings high wind shear over the Caribbean, and a northern branch (the polar jet stream) brings high wind shear offshore of New England. This often leaves a "hole" of low shear between the two branches off the coast of North Carolina, which is where Tropical Depression One formed at the end of May.

The jet stream is forecast (Figure 4) to maintain this two-branch pattern over the coming two weeks. This means that the waters offshore of the Carolinas are the most likely place for a tropical storm to form during this period.

Figure 4. Wind shear in m/s between 200 mb and 850 mb, as forecast by the 06Z July 02, 2009 run of the GFS model. The position and strength of the subtropical jet stream is forecast to change little over the next two weeks, and this jet will bring high wind shear to the Caribbean and Gulf of Mexico into mid-July. There will at times be a region of low shear between the polar jet (northern set of arrows on the plots) and the subtropical jet, allowing for possible tropical development off the coast of North Carolina. Wind speeds are given in m/s; multiply by two to get a rough conversion to knots. Thus, the red regions of low shear range from 0 - 16 knots.

Dry air and African dust
June and July are the peak months for dust coming off the coast of Africa, and the Saharan dust storms have been quite active over the past month. Expect dust from Africa to be a major deterrent to any storms that try to form between Africa and the Lesser Antilles Islands in July.

Steering currents
The steering current pattern over the past few weeks has not changed much, and is typical for June and 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. At present, it appears that the coming two weeks will maintain the typical July pattern, bringing many troughs of low pressure off the East Coast capable of recurving any July storms that might form. 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 2006 steering current pattern that recurved every storm out to sea--or the unfavorable 2008 pattern, that steered Ike and Gustav into the Gulf of Mexico.

Summary
Recent history suggests a 50% chance of a named storm occurring in the first half of July. Given that none of the computer models are forecasting tropical storm formation in the coming seven days, and SST and wind shear patterns look pretty average, I'll go with a 20% chance of a named storm forming during the first half of July.

Vote for Mike Theiss as an Antarctica blogger
Extreme weather photographer Mike Theiss, who wrote our Ultimate Chase photography blog for two years until a new job took him to South America, wants your help. He's entering a Quark Expeditions competition to receive an expense-paid 2-week trip to Antarctica, where he will do some intensive photography and blogging. In order to go, he needs the votes to show that he's a popular blogger. So, if you liked his posts while he was blogging for wunderground, and want to see him blog for wunderground during this potential Antarctica voyage, go to http://www.blogyourwaytoantarctica.com/blogs/view /220 and cast a vote. It takes about 3 minutes navigate through the registration and voting process. Mike will be back chasing hurricanes this August, and has promised to post his excellent storm photos on wunderground should we help him secure the Antarctica gig.

Have a great holiday weekend, and I'll be back Monday with a new post.

Jeff Masters

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1851. stormpetrol 10:06 PM GMT del 05 Luglio 2009
interesting quikscat of former 94L, well defined system. Member Since: Aprile 29, 2007 Posts: 0 Comments: 6394

1852. Tazmanian 10:06 PM GMT del 05 Luglio 2009
Quoting AllStar17: nothing you cant this say nothing with out looking at all the new InFO like the SOI Member Since: Maggio 21, 2006 Posts: 5088 Comments: 111320

1853. stormpetrol 10:07 PM GMT del 05 Luglio 2009
Member Since: Aprile 29, 2007 Posts: 0 Comments: 6394

1854. extreme236 10:08 PM GMT del 05 Luglio 2009
Quoting Tazmanian: you cant this say nothing with out looking at all the new InFO like the SOI There isnt much more to say right now about el nino. Member Since: Agosto 2, 2007 Posts: 19 Comments: 19234

1855. stormwatcherCI 10:08 PM GMT del 05 Luglio 2009
Quoting stormpetrol: interesting quikscat of former 94L, well defined system. Have you noticed the wave E of Jamaica. We need to keep our eyes on this one. Member Since: Ottobre 9, 2008 Posts: 0 Comments: 8038

1856. AllStar17 10:09 PM GMT del 05 Luglio 2009
Quoting stormwatcherCI: Have you noticed the wave E of Jamaica. We need to keep our eyes on this one. We should also keep an eye on the wave just emerging off the African coast. Member Since: Giugno 29, 2009 Posts: 13 Comments: 5135

1857. Tazmanian 10:11 PM GMT del 05 Luglio 2009
Quoting extreme236: There isnt much more to say right now about el nino. well ok Member Since: Maggio 21, 2006 Posts: 5088 Comments: 111320

1858. Cavin Rawlins 10:14 PM GMT del 05 Luglio 2009
Alot of showers here in the islands. Probably the best indicator of shear is water vapor imagery which shows the convection being supported by upper divergence provided by the TUTT. The tropical wave in the vicinity may help to enhance this by providing mid-low level lift. There is mid-level turning evident along the wave but that has been apart of it since it emerged off the coast of Africa about 6-7 days ago. This is one of the first vigorous long-tracked wave (hard to believe this was the center of SAL). if wind shear was low, development would likely occur. Another expected around July 19-21, and models agree that conditions will be different then. Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076

1859. KEEPEROFTHEGATE (Mod) 10:15 PM GMT del 05 Luglio 2009
latest enhanced wv image Member Since: Luglio 15, 2006 Posts: 143 Comments: 40393

1860. PSLHokie 10:16 PM GMT del 05 Luglio 2009
Back to the inverted V cloud formation noted from the NHC discussion. Can someone tell me the significance of this formation? Some sources online say that it is an easterly wave interacting with a trough, some say it is cold core. Anyone? Buler...

1861. Patrap 10:17 PM GMT del 05 Luglio 2009
-- EMC Cyclogenesis Tracking Page -- Model Cycle: 2009070518 North America: Model Tracks for Mid-Latitude Cyclones .."Nuthing".. Member Since: Luglio 3, 2005 Posts: 370 Comments: 111244

1862. stormwatcherCI 10:19 PM GMT del 05 Luglio 2009
Quoting AllStar17: We should also keep an eye on the wave just emerging off the African coast. I know but the one in the Caribbean is closer to home for me and stormpetrol. We are in the Cayman Islands. Member Since: Ottobre 9, 2008 Posts: 0 Comments: 8038

1863. Dakster 10:19 PM GMT del 05 Luglio 2009
Stormpetrol - Can you post the link to that QuickScat pass? Member Since: Marzo 10, 2006 Posts: 0 Comments: 4922

1864. fishcop 10:21 PM GMT del 05 Luglio 2009
Quoting stormpetrol: very cool graphic Member Since: Settembre 16, 2008 Posts: 0 Comments: 70

1865. Cavin Rawlins 10:23 PM GMT del 05 Luglio 2009
Quoting PSLHokie: Back to the inverted V cloud formation noted from the NHC discussion. Can someone tell me the significance of this formation? Some sources online say that it is an easterly wave interacting with a trough, some say it is cold core. Anyone? Buler... An invert-V signature is a common feature of tropical waves and indicates the wave is well define. Cloud patterns along define tropical waves are roughly align to the low-level wind field associated with TW (SW-NE) which gives them a up-side V signature (inverted-V). It does not necessarily correlates to TC development but continuing amplification of the inverted V under favorable conditions leads from an open trough to closed circulation. Tropical waves are cold-core features (I know its hard to believe) since their greatest intensity is in the mid-levels and they weaken downwards. They become warm-core when their greatest intensity builds towards the low-levels and then weaken upwards. Tropical waves normally blow up when they enter the Eastern Caribbean as the interact with divergence ahead of the TUTT. Sometimes this is the initiation of TC development if the TUTT eventually weakens. Here's an inverted V signature of 2008's first tropical wave. For more info, you can check out my blog: Tracking Tropical Waves, June 8 2008 Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076

1866. Patrap 10:23 PM GMT del 05 Luglio 2009
WV loop of the Atlantic Basin Member Since: Luglio 3, 2005 Posts: 370 Comments: 111244

1867. fire635 10:24 PM GMT del 05 Luglio 2009
I'd be surprised if the wave coming off Africa stays as strong as it appears now. If Im not mistaken, its pretty common this time of year for them to come roaring off the coast like a lion and then cower down to kitten status within a day or two. Member Since: Giugno 24, 2006 Posts: 0 Comments: 478

1868. HurricaneSwirl 10:26 PM GMT del 05 Luglio 2009
Weather456: I agree that the shear is prohibiting development right now, but as you probably saw, the wave put up with extreme environments that would kill most waves ever since it got off of africa. do you think that the wave will survive the shear until it gets into a more favorable environment (if there will even be a more favorable environment at all) Member Since: Luglio 7, 2008 Posts: 2 Comments: 3237

1869. stormwatcherCI 10:26 PM GMT del 05 Luglio 2009
Quoting Weather456: An invert-V signature is a common feature of tropical waves and indicates the wave is well define. Cloud patterns along define tropical waves are roughly align to the low-level wind field associated with TW (SW-NE) which gives them a up-side V signature (inverted-V). It does not necessarily correlates to TC development but continuing amplification of the inverted V under favorable conditions leads from an open trough to closed circulation. Tropical waves are cold-core features (I know its hard to believe) since their greatest intensity is in the mid-levels and they weaken downwards. They become warm-core when their greatest intensity builds towards the low-levels and then weaken upwards. Tropical waves normally blow up when they enter the Eastern Caribbean as the interact with divergence ahead of the TUTT. Sometimes this is the initiation of TC development if the TUTT eventually weakens. I have googled inverted-v pattern numerous times and got no information to help me understand what it meant. Thank you very much. Member Since: Ottobre 9, 2008 Posts: 0 Comments: 8038

1870. stormpetrol 10:28 PM GMT del 05 Luglio 2009
Quoting stormwatcherCI: Have you noticed the wave E of Jamaica. We need to keep our eyes on this one. Yep, I been looking at it this afternoon, appeared to have held together pretty well since it came off Africa,I think it might have been the first one to make it this far west since the season started.I wouldn't turn my back on it, so far it has shown itself to be a survivor. Member Since: Aprile 29, 2007 Posts: 0 Comments: 6394

1871. fishcop 10:29 PM GMT del 05 Luglio 2009
another very hot one in the Cayman Islands. Rain is in the forecast for tuesday. Would be very nice to have a cool down. My AC has been running non stop for about a week Member Since: Settembre 16, 2008 Posts: 0 Comments: 70

1872. plywoodstatenative 10:30 PM GMT del 05 Luglio 2009
What we all have to remember is that there was actually talk of a less active CV season and that's what we are seeing. Fire365, the item that you bring up is true, most if not all the activity that we will see will come from these waves but it will occur once the TUTT leaves the Caribbean basin, once it does so then we should see a ramp up in activity. If you have been taking in what some of the regulars and trusted bloggers have been saying in here since the season started, the shear values in the Caribbean, Gulf of Mexico, and even the BOC have been extremely high based on the TUTT being around. Get rid of it, and you will see that the waves that come off of Africa will as you said fire, die out, but once they hit the Caribbean basin you will see them once again fire up. Its basically as a lot have said in here, a repeat of the conditions that we saw during 04-05 where the waves coming off of Africa were weak in nature until they came close to land. That is my synopsis of whats going on with the tropics and what we should see for the rest of this month. Member Since: novembre 15, 2005 Posts: 16 Comments: 4147

1873. stormwatcherCI 10:30 PM GMT del 05 Luglio 2009
Quoting fishcop: another very hot one in the Cayman Islands. Rain is in the forecast for tuesday. Would be very nice to have a cool down. My AC has been running non stop for about a week Are you in Cayman and if so where ? Member Since: Ottobre 9, 2008 Posts: 0 Comments: 8038

1874. MississippiWx 10:30 PM GMT del 05 Luglio 2009
Hey everyone. I'm sure it has been well noted on the blog lately, but does it scare anyone other than me at how clear the Gulf of Mexico has been for almost an entire month? Winds really haven't been that high across the Gulf either since high pressure has been over it. I just have a really bad feeling that once the high moves and allows a system to come into the Gulf, the system will have unlimited potential to "bomb out." Obviously, atmospheric conditions have to be favorable as well, but the potential is there. The website I normally use for SSTs and TCHP is the AOML site from NOAA. For some reason, it has been down for over half a month. Anyone know why? Also, what is another good site for viewing TCHP and SSTs? Thanks. Hopefully my feelings are wrong! I don't mean to be the doom and gloom guy! =/ Member Since: Luglio 15, 2006 Posts: 13 Comments: 8507

1875. Cavin Rawlins 10:31 PM GMT del 05 Luglio 2009
Vigorous tropical waves that do not develop in the tropical Atlantic becuz of shear, cool SSTs and SAL pose the dangerous threat. I don't have to look far for examples - Hurricane Katrina 2005, Hurricane Dennis 2005, Hurricane Charley 2004, Hurricane Felix 2007, Hurricane Gustav and Dolly 2008. I remember a forecaster was surprise that Jeanne developed considering the hostile environment left by Ivan across the tropical Atlantic. Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076

1876. stormpetrol 10:31 PM GMT del 05 Luglio 2009
Quoting Dakster: Stormpetrol - Can you post the link to that QuickScat pass? Link Member Since: Aprile 29, 2007 Posts: 0 Comments: 6394

1877. SomeRandomTexan 10:31 PM GMT del 05 Luglio 2009
thanks for the explanation Weather456!!! Member Since: Agosto 30, 2007 Posts: 0 Comments: 1814

1878. PSLHokie 10:32 PM GMT del 05 Luglio 2009
Great answer Weather... It'll take me a little while to digest! Thats the sort of information I enjoy getting from this blog.

1879. plywoodstatenative 10:33 PM GMT del 05 Luglio 2009
Storm petrol, It might appear interesting on satellite, but the real deal happens when the National Hurricane Center takes interest in it by applying one of the multicolored boxes that they use to tell you whether its believed that a storm will develop. Now if you were to pull up buoy's in the area and take a look at the pressure in the area, then you might have a valid point. Member Since: novembre 15, 2005 Posts: 16 Comments: 4147

1881. Cavin Rawlins 10:35 PM GMT del 05 Luglio 2009
Quoting HurricaneSwirl: Weather456: I agree that the shear is prohibiting development right now, but as you probably saw, the wave put up with extreme environments that would kill most waves ever since it got off of africa. do you think that the wave will survive the shear until it gets into a more favorable environment (if there will even be a more favorable environment at all) Shear does not kill tropical waves. Shear kills tropical cyclones. Even weak tropical waves can survive shear. Convection maybe prohibited but the wave axis is always there. Once they enter a favorable environment then they stand a chance. In fact, interaction with the TUTT amplifies tropical waves and this is something they develop over Africa since tropical waves form within the African Easterly Jet. Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076

1882. Patrap 10:36 PM GMT del 05 Luglio 2009
1874. MississippiWx 5:30 PM CDT on July 05, 2009 The WAVCIS Lab by ESL has a Great GOM, SST's ,Surface currents,wind and wave models. WAVCIS page GOM 60 Hour Surface Current Forecast Model Also,the "Tropical Weather" listing on the Left of the WAVCIS page is the wundergounds Tropical Page. Member Since: Luglio 3, 2005 Posts: 370 Comments: 111244

1883. Dakster 10:38 PM GMT del 05 Luglio 2009
StormPetrol - Thanks... Member Since: Marzo 10, 2006 Posts: 0 Comments: 4922

1884. stormpetrol 10:40 PM GMT del 05 Luglio 2009
Quoting plywoodstatenative: Storm petrol, It might appear interesting on satellite, but the real deal happens when the National Hurricane Center takes interest in it by applying one of the multicolored boxes that they use to tell you whether its believed that a storm will develop. Now if you were to pull up buoy's in the area and take a look at the pressure in the area, then you might have a valid point. I totally agree, but living here in The Caymans "hurricane alley" especially after the Ivan 2004 experience and even Paloma last year, I don't turn my back on anything that might be suspicious, though I do have the deepest respect for the forecasters at the NHC, the sure know alot more than me or probably everyone else here for that matter, but you know what I've learned even the best can make errors in judgement and sometimes a fool can offer valid advice to even the experts. Member Since: Aprile 29, 2007 Posts: 0 Comments: 6394

1885. Levi32 10:41 PM GMT del 05 Luglio 2009
Evening all. Member Since: novembre 24, 2005 Posts: 586 Comments: 25441

1886. Cavin Rawlins 10:42 PM GMT del 05 Luglio 2009
Caribbean Coral Reefs and Climate Change Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076

1887. beell 10:44 PM GMT del 05 Luglio 2009
1881. Shear does not kill tropical waves. Shear kills tropical cyclones. Even weak tropical waves can survive shear. Convection maybe prohibited but the wave axis is always there. Once they enter a favorable environment then they stand a chance. A great point, W456! Member Since: Settembre 11, 2007 Posts: 124 Comments: 12849

1888. stormwatcherCI 10:44 PM GMT del 05 Luglio 2009
Quoting stormpetrol: I totally agree, but living here in The Caymans "hurricane alley" especially after the Ivan 2004 experience and even Paloma last year, I don't turn my back on anything that might be suspicious, though I do have the deepest respect for the forecasters at the NHC, the sure know alot more than me or probably everyone else here for that matter, but you know what I've learned even the best can make errors in judgement and sometimes a fool can offer valid advice to even the experts. Up until the Saturday I think before Ivan hit we were being told(by the NHC) it would miss us. My daughter works at the EOC and called me to tell me to go to the shelter because Ivan was going to give us a direct hit and basically no information from TWC which is why I have no more confidence in them. Member Since: Ottobre 9, 2008 Posts: 0 Comments: 8038

1889. stormwatcherCI 10:45 PM GMT del 05 Luglio 2009
Quoting Levi32: Evening all. Evening. What is your input on the wave in the Caribbean please ? Member Since: Ottobre 9, 2008 Posts: 0 Comments: 8038

1890. HurricaneSwirl 10:46 PM GMT del 05 Luglio 2009
upper level divergence on the increase lower level convergence on the decrease and the shear tendencies are falling like rocks where the wave is right now, but that won't help it because its rising to the north and to the west of the wave Member Since: Luglio 7, 2008 Posts: 2 Comments: 3237

1891. Cavin Rawlins 10:46 PM GMT del 05 Luglio 2009
Tropical Waves are the 2nd most interesting features of the tropics and what's make then so interesting is they are unique to the Atlantic. No other areas across the globe can produce tropical waves, though Australia, the closest candidate lacks a mid level jet. Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076

1892. fire635 10:46 PM GMT del 05 Luglio 2009
Quoting plywoodstatenative: What we all have to remember is that there was actually talk of a less active CV season and that's what we are seeing. Fire365, the item that you bring up is true, most if not all the activity that we will see will come from these waves but it will occur once the TUTT leaves the Caribbean basin, once it does so then we should see a ramp up in activity. If you have been taking in what some of the regulars and trusted bloggers have been saying in here since the season started, the shear values in the Caribbean, Gulf of Mexico, and even the BOC have been extremely high based on the TUTT being around. Get rid of it, and you will see that the waves that come off of Africa will as you said fire, die out, but once they hit the Caribbean basin you will see them once again fire up. Its basically as a lot have said in here, a repeat of the conditions that we saw during 04-05 where the waves coming off of Africa were weak in nature until they came close to land. That is my synopsis of whats going on with the tropics and what we should see for the rest of this month. Thanks for the insight Member Since: Giugno 24, 2006 Posts: 0 Comments: 478

1893. Levi32 10:49 PM GMT del 05 Luglio 2009
Quoting stormwatcherCI: Evening. What is your input on the wave in the Caribbean please ? Sheared right now. Convection being enhanced by the TUTT not by any particular effort by the wave itself. The trade winds are too strong in the Caribbean right now to let any tropical waves slow down and amplify. Strong easterlies in there ruin convergence. All the tropical waves are bound for the east Pacific and Central America right now. This is the kind of pattern we'll likely see for most of the hurricane season. Member Since: novembre 24, 2005 Posts: 586 Comments: 25441

1894. stormpetrol 10:50 PM GMT del 05 Luglio 2009
Quoting stormwatcherCI: Up until the Saturday I think before Ivan hit we were being told(by the NHC) it would miss us. My daughter works at the EOC and called me to tell me to go to the shelter because Ivan was going to give us a direct hit and basically no information from TWC which is why I have no more confidence in them. Correct, I remember that, I knew Ivan was going hit Grand Cayman too,remember Ivan was forcasted hit Cayman Brac and Paloma Grand Cayman, vice versa happened, I knew after Paloma wobbled late that evening that the Brac was going to get a direct hit and we were going to be spared the brunt, I even posted my thoughts here regarding Paloma. Member Since: Aprile 29, 2007 Posts: 0 Comments: 6394

1895. antonio28 10:50 PM GMT del 05 Luglio 2009
Good Evening all. Member Since: Luglio 15, 2008 Posts: 0 Comments: 799

1896. HurricaneSwirl 10:51 PM GMT del 05 Luglio 2009
Quoting Weather456: Shear does not kill tropical waves. Shear kills tropical cyclones. Even weak tropical waves can survive shear. Convection maybe prohibited but the wave axis is always there. Once they enter a favorable environment then they stand a chance. In fact, interaction with the TUTT amplifies tropical waves and this is something they develop over Africa since tropical waves form within the African Easterly Jet. good point, i have never thought about that too deeply. but the wave has survived the extremely stable/dry area in the central atlantic so i was wondering if since it is such a vigorous wave, would it spin up quickly in a favorable environment once it gets there? because right now i only see a small pocket of low shear in the nw caribbean. the central caribbean, east caribbean, and all of the gulf of mexico have harsh shear. Member Since: Luglio 7, 2008 Posts: 2 Comments: 3237

1897. Cavin Rawlins 10:54 PM GMT del 05 Luglio 2009
Quoting Levi32: Sheared right now. Convection being enhanced by the TUTT not by any particular effort by the wave itself. The trade winds are too strong in the Caribbean right now to let any tropical waves slow down and amplify. Strong easterlies in there ruin convergence. All the tropical waves are bound for the east Pacific and Central America right now. This is the kind of pattern we'll likely see for most of the hurricane season. I don't think that would be the pattern of the entire hurricane season, since trades across the Caribbean is currently near to below average due to a continuing negative NAO. Probably the number 1 reason disrupting the formation of circulation is vertical shear. Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076

1898. stormwatcherCI 10:56 PM GMT del 05 Luglio 2009
Quoting stormpetrol: Correct, I remember that, I knew Ivan was going hit Grand Cayman too,remember Ivan was forcasted hit Cayman Brac and Paloma Grand Cayman, vice versa happened, I knew after Paloma wobbled late that evening that the Brac was going to get a direct hit and we were going to be spared the brunt, I even posted my thoughts here regarding Paloma. When Ivan was halfway across the Atl I told my co-workers I had a bad feeling about it. I told them it was going to hit GC and hit us hard. They called me a fool. Now they all ask my opinion about whatever makes it into the Caribbean.. I guess I am not such a fool after all. Member Since: Ottobre 9, 2008 Posts: 0 Comments: 8038

1899. Levi32 10:56 PM GMT del 05 Luglio 2009
Quoting Weather456: I don't think that would be the pattern of the entire hurricane season, since trades across the Caribbean is currently near to below average due to a continuing negative NAO. I'd like to see it if you have an image showing the trade wind speed relative to normal. Right now they're too fast. The Columbian Low is stronger than normal right now and the surface ridge is squashed further south than normal, which is also pushing the wave train to the south. On the ECMWF when you see yellows like that in the Caribbean that's bad news for tropical waves. Member Since: novembre 24, 2005 Posts: 586 Comments: 25441

1900. CybrTeddy 11:01 PM GMT del 05 Luglio 2009
REMEINDER for all Floridians! Space Shuttle Endeavour will launch this upcoming Saturday @ 7:39 PM, Going to be 6 miles from the pad during liftoff. Member Since: Luglio 8, 2005 Posts: 253 Comments: 20195

1901. Cavin Rawlins 11:02 PM GMT del 05 Luglio 2009
Levi, Trades were also higher 2005 2005 2009 Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076

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