Dean and Erin.

Tropical Depression 5 is now Tropical Storm Erin, as of 11:30 AM this morning. It’s expected to hit South Texas early tomorrow morning. The Houston Chronicle’s Eric Berger notes that this will be the first Texas landfall since 2003: “Rita (2005) and re-born Ivan (2004) both technically missed Texas by hitting near the Louisiana-Texas border.”

Some strengthening is expected, but Erin shouldn’t have time to get too strong. As Dr. Jeff Masters says: “Wind shear over Erin is only 5-10 knots, and an upper-level high pressure system has parked itself directly over the storm. This is an ideal situation for intensification, since the upper-level high provides very favorable outflow at the top of the storm, venting all the air forced up at the center of the storm. … Spiral banding is starting to occur, along with good upper level outflow. Erin could grow in strength rapidly. Fortunately, the storm only has about 24 hours over water, so it should not be able to become more than a 55 mph tropical storm. Heavy rains will be the main threat from [Erin].” That threat is nothing to sneeze at, though, considering that South Texas definitely doesn’t need rain. Flooding is likely.

Meanwhile, the bigger story in the grand scheme of things is Tropical Storm Dean, which has strengthened to 60 mph and, according to Bryan Woods, “is already showing the start of an eyewall structure and could become a hurricane at any time.” Luckily, a patch of Saharan dust north of storm should prevent rapid intensification in the immediate future. Says Alan Sullivan: “Some of this air will be entrained into the circulation from the north through the next day or two, and it will surely stunt Dean’s growth.” Dr. Masters “expect[s] that this dry air will impede Dean enough so that the storm passes through the Lesser Antilles as a Category 1 hurricane.” Sullivan, on the other hand, expects a burst of rapid intensification just before it reaches the islands (which is expected to happen on Friday).

Whatever happens before Dean reaches the islands, everyone seems to agree that afterward, conditions are ripe for rapid intensification. In Masters’s words, “the environment moistens, shear stays low, and the heat content of the ocean greatly increases. The 06Z run of new HWRF model is again very aggressive intensifying Dean after it crosses into the Caribbean, bringing the storm to 928 mb (Category 4) on Monday morning near Jamaica. The GFDL model is not nearly as aggressive, putting Dean at 964 mb (Category 2) Monday morning. I can’t see any reason why Dean wouldn’t become a Category 3 or 4 hurricane by the time it reaches the Cuba/Jamaica region, unless it passes very close to the mountainous island of Hispaniola.”

Berger, in Houston, is worried:

Given the warmer water and lessening wind shear, the official forecast calls for a 115-mph, category-3 hurricane [in five days], but then hastens to add that because of the favorable conditions, Dean could be “notably stronger” than this.

The bad news is that the Gulf of Mexico is still warmer (I’ll do a full analysis this afternoon), and if Dean reaches the Gulf the United States will likely face a blow from a major hurricane.

And it’s looking increasingly likely that Dean will indeed reach the Gulf. The computer models have come into general agreement on a west-northwest track, as you can see:

Again, cue Dr. Masters:

The trough of low pressure that will pass north of the islands on Saturday is now expected to be a bit weaker than earlier forecast, which should allow Dean to pass into the Caribbean on a west to west-northwest track. The trough is no longer forecast to spawn an upper-level low pressure system, which means that the danger to the U.S. East Coast north of the Carolinas is minimal. A ridge of high pressure is expected to build in after the first trough passes on Saturday, which should keep Dean on a west to west-northwest path into the middle of next week. The southernmost model solutions (GFDL, Canadian) take Dean into Honduras early next week. The more northerly solutions of the GFS and HWRF take Dean over Jamaica, then into the Gulf of Mexico. No models call for a threat to the east coast of Florida at present, but that could change once we see how strong Saturday’s trough of low pressure really will be. The NOAA jet is scheduled to make its first flight Thursday night, and by Friday morning we should have a good set of model runs that will give us a more reliable idea of Dean’s likely track. At present, it appears that Dean’s main threat to the U.S. will be to the Gulf of Mexico coast.

Berger concurs: “Although the models remain unreliable forecasting longer than five days, and Dean probably wouldn’t reach the Gulf for a week, the storm’s trend is clearly in our direction. … It remains early in Dean’s life, but it’s becoming increasingly unlikely that the high-pressure system north of the tropical storm will weaken in time for it to re-curve northward and become a ‘fish’ storm, i.e. not affect land. Indeed, if the current trend continues the East coast will be out of the woods in a day or two for a possible strike. The Gulf, however, needs to remain quite alert and closely follow Dean’s progress.”

As an aside, the Space Shuttle Endeavour is scheduled to land on August 22 — assuming it’s deemed safe despite the gash in its heat shield. That’s right around the time Dean could be reaching the Gulf or Florida.

As of 11:00 PM, the National Hurricane Center has bumped Dean’s winds up to 50 mph — and the discussion says this estimate is “possibly conservative.” It also notes that the shear around Dean is “beginning to decrease,” so I think it’s fair to say that, after struggling to hold itself together this afternoon, Dean has now begun its intensification phase. The official forecast brings it to Category 3 status in five days — at which time the forecast track has it just offshore of Hispaniola. But of course, that’s subject to change. The computer models continue to be all over the map, as would be expected for a storm this far out at sea. The intensity models also disagree about just how fast it will intensify. The best advice is to continue to stay tuned.

Meanwhile, also at 11:00 PM, the NHC has designated Tropical Depression Five in the Gulf of Mexico. It is expected to become Tropical Storm Erin tomorrow, then make landfall along the Texas coast on Thursday. Tropical Storm Watches have been issued from Freeport, Texas south to Rio San Fernando, Mexico. Here’s a look at the track models and intensity models for it.

Last but not least, Category 2 Hurricane Flossie is passing due south of Hawaii as we speak:

The GFS computer model, one of the most commonly looked-at global models, can’t decide where it wants Tropical Storm Dean to go. That’s hardly unusual, given how far away it is; we’re talking about projected landfalls that are almost two weeks away. Besides, as Alan Sullivan points out, Dean is struggling so mightily against wind shear right now, the computers “can hardly even see such a weak system.” Even so, it’s entertaining to watch the GFS’s predicted landfall points bounce around the Eastern Seaboard and Gulf Coast. On his “Model Hype” blog, AccuWeather’s Jesse Farrell has posted an animated GIF showing the last two days’ GFS landfall predictions, which “started in Texas, moved up to the Canadian Maritimes, then back to Texas.” See for yourself:

And that, in a nutshell, is why you shouldn’t put any stock in individual computer model forecasts at this early date. Heh.

In my post below debunking the false notion that meteorologists have developed a habit in recent years of repeatedly “crying wolf” about the number of hurricanes that will form each season, several commenters raised an argument that I’ve heard several times before, and which, like the “cry wolf” perception, deserves some additional scrutiny. Their question is essentially this: If scientists can’t even reliably predict how many tropical storms will form each season (for instance, Dr. Gray’s forecasts were off by between 1 and 3 storms every year from 2000-2004, by 13 storms in 2005, and by 7 storms in 2006), how can we possibly trust their long-term predictions about climate change?

This question focuses on one obvious difference between seasonal hurricane projections and global-warming forecasts (namely, the much longer-term nature of the latter) but ignores other crucial differences — not least the difference between “climate” and “weather,” a distinction that both sides have a bad habit of conveniently ignoring when it suits their purposes. Most importantly, the question assumes that forecasts will always become less reliable as the forecasted time period becomes more remote, which while perhaps intuitively sensible, is a vast oversimplification.

You have to look at what is being forecasted, not just when the forecast is for. How precise, specific, and subject to random, unpredictable variations is the phenomenon at the heart of the forecast? For instance, a prediction for whether it will rain at some point tomorrow is probably going to be more accurate than a prediction for precisely what the rain rate will be at 3:47 PM today, even though the latter forecast deals with a more imminent event. Why? Because predicting whether something will happen during the course of 24 hours is easier than predicting exactly what will be happening at a particular moment in time. The latter is largely determined not just by big-picture meteorological phenomena (cold fronts, low pressure systems, etc.) but also by near-random localized events and tiny variations in timing, which are unpredictable and insignificant in the grand scheme of things, but can make all the difference when it comes to what the weather will be in a particular place at a particular time.

Global-warming forecasts are largely focused on determining the average temperature of the Earth at various points in the future. The average temperature of the Earth is about the broadest, most nonspecific measuring stick possible in meteorology and climatology. It isn’t subject to the sort of random variables that arise when predicting individual weather events, because the random events will generally even themselves out over the broad swaths of time we’re talking about. Thus, the computer models have a better chance of getting it right, because they only need to look at the big-picture factors. They don’t have to “sweat the small stuff,” if you will.

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It’s official. Tropical Depression 4 has become Tropical Storm Dean as of 11:00 AM EDT.

Hopefully “his” comment yesterday won’t come true: “I’m gonna go to Puerto Rico, and Hispaniola, and the Bahamas! And then I’m gonna go to Florida, and Alabama, and Mississippi, and Louisiana! And then my remnants are gonna recurve inland and rain on the White House! YARRRRH!!!”

Anyway, here’s what the discussion says, with a couple of key points boldfaced by yours truly:

SATELLITE IMAGES…MICROWAVE DATA AND QUIKSCAT MEASUREMENTS INDICATE THAT THE DEPRESSION HAS REACHED TROPICAL STORM STATUS AND ALSO THAT THE CENTER IS LOCATED FARTHER TO THE SOUTH AND WEST THAN PREVIOUSLY INDICATED. DEAN HAS DEVELOPED A SMALL CENTRAL DENSE OVERCAST OVER THE CENTER BUT MOST OF THE CONVECTION IS STILL LOCATED TO THE WEST AND SOUTH OF THE CENTER. THE OUTFLOW IS CONFINED TO THE WEST AND SOUTHWEST SINCE THE CYCLONE IS STILL EMBEDDED WITHIN EASTERLY SHEAR. THE SHEAR IS FORECAST TO DECREASE AND MOST OF THE INTENSITY GUIDANCE GRADUALLY STRENGTHENS DEAN. IN FACT…DYNAMICAL GUIDANCE SUGGESTS THAT DEAN COULD BE NEAR THE LESSER ANTILLES AS A HURRICANE WITH 100 TO 110 KNOTS IN FIVE DAYS. [That translates to 115 to 125 mph — a Category 3 major hurricane. -ed.]

DEAN APPEARS TO BE MOVING WESTWARD OR 265 DEGREES AT 20 KNOTS AROUND THE PERIPHERY OF A STRONG SUBTROPICAL RIDGE WHICH IS EXPANDING WESTWARD. IN THE SHORT TERM…2 TO 3 DAYS…DEAN SHOULD CONTINUE TO MOVE ON A GENERAL WESTWARD TRACK WITH A GRADUAL DECREASE IN FORWARD SPEED. THEREAFTER…THE FORECAST BECOMES HIGHLY UNCERTAIN SINCE SOME RELIABLE MODELS MAINTAIN A STRONG RIDGE TO THE NORTH AND KEEP THE CYCLONE MOVING WESTWARD ACROSS THE CARIBBEAN AND OTHERS SHOW A WEAKER RIDGE RESULTING IN A GRADUAL TURN TO THE WEST-NORTHWEST. THE OFFICIAL FORECAST FOLLOWS THE CONSENSUS AND IS A LITTLE BIT TO THE SOUTH OF THE PREVIOUS ONE…DUE TO THE REPOSITIONING OF THE CENTER…AND NOT BECAUSE WE HAVE CHANGED THE FORECAST REASONING.

Alan Sullivan, in South Florida, is more hopeful today than he was yesterday that Dean will steer clear of his area:

My birthday present his arrived. No, it’s not a camera — that comes tomorrow. It’s a new set of projections for future hurricane Dean, keeping it out to sea, well NE of Florida. The East Coast trough is digging again. Models have consistently over-estimated the Bermuda high this summer. It has been weak or absent to the east at all times. Now the digging trough seems likely to recurve Dean enough to make for landfall somewhere from the Carolinas to Nova Scotia. Or there may be no landfall at all. …

The current trough alone should turn Dean clear of the islands, but it will probably not persist long enough to recurve Dean entirely. It will take a second one to turn the storm decisively away from eastern North America. We still have at least a week of uncertainty. But the threat to the Caribbean and Florida is diminishing.

Dr. Jeff Masters has more on Dean, as well as information on the potential Tropical Depression Five in the Gulf of Mexico (proto-Erin??) and Hurricane Flossie in the Pacific. (He’s got a radar image of Flossie nearing the Big Island.)

I’d post more, but I have baby shopping to do. :)

At the risk of starting another blog brushfire, I need to correct the record about something that keeps coming up in the debate about hurricanes and (ugh) global warming.

There is a perception, repeated numerous times here and elsewhere, that meteorologists and climatologists have developed a habit of “crying wolf” about the number of storms that they expect to form in the Atlantic each year. This perception is understandable, for reasons that I’ll explain after the jump, but it’s also entirely incorrect. And I mean flatly, facially false.

The perception is based on one data point, namely the 2006 season, which is obviously not enough to demonstrate a trend or pattern. Between 2000 and 2005, the preseason forecasts actually underestimated the number of named storms every single year. And of course, as I’ve pointed out before, it’s laughably early in the 2007 season to be asking, “Where are all the hurricanes?”; the vast majority of the season still lies ahead, in terms of expected activity. It’s impossible to accurately assess the seasonal forecasts until mid-October at the earliest. So the only season the “cry wolf” crowd is really talking about is 2006.

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As expected, the vigorous tropical wave off the African coast has been designated Tropical Depression Four as of 11:00 AM EDT. It “could become a tropical storm during the next 24 hours,” but initially at least, strengthening will likely be slow due to wind shear today and tomorrow. There’s even a chance, as Eric Berger points out, that it could fall apart. But if it holds together until the shear abates, then it could be Katie bar the door:

THE EASTERLY WIND SHEAR WILL PROBABLY LIMIT INTENSIFICATION DURING THE NEXT COUPLE OF DAYS. THEREAFTER…THE GLOBAL MODELS…EVEN THOSE THAT DO NOT HAVE A STRONG REPRESENTATION OF THE TROPICAL CYCLONE ITSELF…FORECAST AN UPPER-LEVEL RIDGE TO BUILD OVER AND NEAR THE LESSER ANTILLES. COMBINED WITH WARM SEA-SURFACE TEMPERATURES ALONG THE TRACK…CONDITIONS APPEAR CONDUCIVE FOR STEADY STRENGTHENING LATER IN THE FORECAST PERIOD.

Of course, if those conditions actually materialize — low wind shear, high SSTs, and no other inhibiting factors like dry air or Saharan dust — the intensification probably won’t be “steady,” it’ll probably be rapid. Given the inherent limitations of intensity forecasting, the NHC would never predict such an eventuality this far in advance… but Alan Sullivan would, and does: “When the easterly sheer quits kicking its butt, rapid intensification is probable.”

In the discussion, the NHC points out, “IT IS IMPORTANT TO REMEMBER THAT SIGNIFICANT UNCERTAINTIES EXIST IN BOTH THE TRACK AND INTENSITY FORECASTS…ESPECIALLY AT LONG RANGES.” That’s very true. But it isn’t stopping the weather nerds from speculating. For instance, Berger writes: “[D]ynamics in the upper atmosphere are such that T.D. Four is unlikely to curve poleward any time soon… In other words, the system’s most likely destination now is the Caribbean Sea, where waters are extremely warm.” On the other hand, Sullivan, who lives in South Florida, “think[s] early recurvature is still possible,” but is “also concerned about a mere leftward wobble that gets our storm north of Puerto Rico, followed by just enough building high pressure to head the cyclone west again. This is the Andrew scenario, and it is plausible for this system.” He concludes: “I feel exceptional uncertainty about the future course of our Atlantic cyclone. Destinations from Tampico to Halifax are plausible. The worst-case scenario of a first landfall in South Florida is plausible, too.” For what it’s worth, here’s what the computer models say, out to 120 hours:

Needless to say, it is waaaaay too early to put any stock in any particular forecast “line,” whether from the official forecast track, or from any particular computer model… such as, for example, the GFS, which shows Hurricane Dean moving up the Eastern Seaboard toward New England in 12 days:

What was I saying? Oh, right, don’t take any of these computer models seriously. :) Case in point: just a few days ago, the same GFS model was predicting a New Orleans landfall. (”I’m no Brendan Loy but the GFS does have a Category 2 Hurricane hitting New Orleans on August 23rd,” Jesse Ferrell wrote on Friday. Heh.) So just stay tuned, and if you’re in a coastal area anywhere along the Atlantic or Gulf coasts, brush up on your basic hurricane preparations — the ones that should always be in place this time of year anyway.

P.S. Ferrell points out that it might not be Dean: “Don’t assume that this will be Tropical Storm ‘Dean’ however… it could be ‘Erin’… some models are still talking about the system in the Caribbean becoming a tropical storm this week as well.”

P.P.S. Ferrell has added an update, pointing out the same thing I did: “The GFS now has the hurricane hitting New York City, after three consistent model runs hitting the Texas Coast.”

UPDATE: Dr. Masters has posted an update, in which he writes of T.D. 4’s future:

The total heat content of the ocean stays relatively low through the next 48 hours (Figure 1), so no rapid intensification is likely until Thursday, when the storm approaches the Lesser Antilles Islands. The 12Z (8am EDT) run of the GFDL model intensifies TD 4 into a Category 2 hurricane five days from now. …

The big question is how strong the trough of low pressure predicted to pass north of TD 4 on Friday will be. If the trough is stronger than currently forecast, it may be able to pull TD 4 far enough north so that it misses the Lesser Antilles. This would be good for the islands, but potentially bad for the U.S. East Coast. The trough will likely not be strong enough to recurve TD 4 harmlessly out to sea, and the storm would then be forced westwards again by the next ridge of high pressure. A landfall along the U.S. East Coast as a hurricane–possibly a major hurricane–could result, unless the next trough of low pressure is strong enough to recurve the storm out to sea. The latest (12Z) run of the UKMET model has TD 4 passing through the very northernmost Lesser Antilles Islands. The 12Z GFDL, GFS, and HWRF have TD 4 jogging just far enough north that it would likely miss the islands. Some of these runs are considerably slower, delaying the possible impact to the islands to Saturday or Sunday. What may happen after 5 days is highly uncertain. Last night’s GFS model run had TD 4 eventually making landfall south of Brownsville, Texas. This morning’s run had it eventually hitting New England–a difference of about 2000 miles in landfall location!

Dr. Jeff Masters believes that “Invest 90L” will become Tropical Depression 4 tomorrow or Tuesday, and he thinks it will ultimately become Hurricane Dean, and a threat to North America. In a post this morning, he writes:

Watching the computer model runs for 90L is not for the faint of heart. All the major models except the NOGAPS develop the system into a tropical storm or hurricane that tracks westward over the Atlantic, reaching the lesser Antilles Islands as early as Thursday night, August 16. There are four possible scenarios to consider:

1) A strong trough of low pressure is forecast to move off the East Coast of the U.S. at that time, and this trough may deflect 90L northwards so that it misses the Lesser Antilles Islands, and then recurves harmlessly out to sea.

2) In keeping with the steering pattern we’ve observed since late July, the trough is expected to rapidly move onward, allowing a ridge of high pressure to build in. If the trough is not strong enough to recurve 90L out to sea, the storm will be forced to the west once more and eventually hit the East Coast of the U.S. This is the solution of last night’s ECMWF model.

3) 90L will be far enough south and next weekend’s trough will be weak enough that 90L will plow through the Caribbean, and not be deflected north of the Lesser Antilles Islands. The storm would eventually track into the Gulf of Mexico. This is the solution preferred by this morning’s GFS model.

4) 90L will never develop, or will never become more than a weak tropical storm, due to unfavorable wind shear, dry air, or other factors. This is the solution of the NOGAPS model.

Of the four scenarios, I believe #2 or #3 are most likely to occur–90L will develop into a tropical storm or hurricane that will affect the Caribbean and/or U.S. East Coast. Residents throughout the Caribbean and U.S. should anticipate the possibility that 90L may become a hurricane–and possibly a major hurricane–that will not recurve.

With regard to scenario #3, recall that the Gulf of Mexico is really, really warm right now, so it would be seriously bad news if any well-organized storm were to reach it.

Meanwhile, out in the Pacific, monster Category 4 Hurricane Flossie is expected to pass 50-100 miles south of the Big Island of Hawaii late Tuesday or Wednesday. She will have weakened by then, though, probably to a Cat. 1.

A tropical wave off the African coast has the potential to develop into the first serious tropical system of the season. For now, it’s just a disorganized mass of clouds with a moderately low pressure, but the computer models are predicting that it’ll become Tropical Depression 4 as early as Monday. For now, it’s known only as Invest 90L.

The SHIPS intensity model has “90L” approaching hurricane strength — it would be named Hurricane Dean — in 120 hours. The track models show it moving in the general direction of the Antilles islands, as storms in that part of the ocean tend to do, but the computers diverge wildly in predicting the hypothetical hurricane’s ultimate destination: “At one extreme, a harmless course recurving up the North Atlantic. At the other, a duplicate of the 1998 hurricane Georges — grinding over all the Greater Antilles, crossing the Florida Keys to the Gulf, then heading for Mobile Bay.” I believe this is where Fark.com would insert the headline “EVERYBODY PANIC.” But seriously, folks, it’s waaaay too early to put any stock whatsoever in such forecast details, with regard to either track or intensity. For now, this is simply an area of disturbed weather worth watching, but certainly not yet worth hyping, let alone panicking about oil prices over. (Seriously, WTF?) Invest 90L could very easily turn out to be nothing. Or something. It’s far, far, far too early to say. Just stay tuned.

If the wave does develop, it’ll be the season’s first Cape Verde system… just what you’d expect around mid-August. The 2007 hurricane season continues to evolve right on schedule, or a tiny bit ahead of it, despite what Drudge and other agenda-driven conservative websites would have you believe. Here’s an update of the climatology-versus-reality chart that I posted last month:

Just FYI.

P.S. Incidentally, Charles Fenwick — who is way more knowledgeable about this stuff than I am — also published a post last month, similar to mine, criticizing the “slow season” nonsense that Drudge and others have been peddling. This isn’t about global warming, people; it’s about telling the truth.

Tropical Depression Three has formed off the East Coast. It may become Tropical Storm Chantal later today, but it’s a race against the clock — or more precisely, against extratropical transition. Will the NHC name T.D. 3 before it’s too late? She (if it isn’t premature to call her “she”) is already moving north-northeast at 16 mph, and will soon accelerate into colder waters. In just over a day, she’s expected to be near Newfoundland. So this will be a short-lived entry in the Atlantic tropical logs for 2007, whether it earns a name or not.

Margie Kieper, back from the blogging dead, has more over at Jeff Masters’s place.

UPDATE BY MIKE QUINN: According to CNN, Tropical Storm Chantal has been born.

The report that was compiled by a team from National Oceanic and Atmospheric Administration sent to investigate the festering mistrust of Bill Proenza by many of the hurricane forecasters that work for him was released today:

“The current TPC director should be reassigned and not be allowed to return to his position at the center. This should be done due to his failure to demonstrate leadership within the TPC,” according to the report obtained by ABC News.

The report harshly criticizes Proenza and notes the rift between him and his staff compromised the work being done at the center — a potential public safety issue.

“The short term ability of the TPC to provide accurate and timely information was put at risk due to the TPC director’s disruptive conduct and the lack of trust between many staff and the director,” according to the report. “The negative work environment, exacerbated by the director, has had — and is likely to continue to have — a major deleterious impact on the center’s ability to fulfill its mission, if he is allowed to return to his position.”

Despite the reports findings Proenza told congress he wants his job back. (More after the jump.)

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Today, ousted National Hurricane Center director Bill Proenza told his side of the story before two congressional subcommittees. From 10am until 12pm EDT, the House Committee on Science and Technology held a hearing called, “Tracking the Storm at the National Hurricane Center”. You can check out some of the press releases and listen to a webcast of the hearing at the Committee web site.

Dr. Jeff Masters lists all those who are testifying in todays hearings and points out that it appears to be a little one sided:

The list of people testifying include Bill Proenza; QuikSCAT expert Dr. Robert Atlas; emergency management officials who worked with Proenza; and the head of NOAA, Admiral Lautenbacher. With the exception of Lautenbacher, all these witnesses are likely to be allies of Proenza. Also testifying will be Dr. Jim Turner, deputy director of the federal agency NTIS (National Technical Information Service), who led the inspection team that showed up at NHC without notice on July 2. Dr. Turner’s report was scheduled to be completed this Friday, July 20, but is now scheduled to be released to the Congressional panel today. Notably absent from the list of people called to testify is anyone from the National Hurricane Center. Also absent is a QuikSCAT science expert besides Dr. Atlas, who has thus far not addressed in his public comments, that I have seen, the very high uncertainties surrounding the impact of QuikSCAT data on track forecasts of landfalling hurricanes. In fact, in comments published in the Orlando Sentinel, Dr. Atlas claimed that Proenza’s statement that loss of the loss of QuikSCAT could reduce the accuracy of hurricane-track forecasts by as much as 16 percent represents “the consensus of the scientific community.” Well, that is not the case, as myself and senior hurricane specialists at the National Hurricane Center will attest to.

In both an article published in the Houston Chronicle and in an Orlando Sentinel article from Wednesday, you can see just how unhappy the staff at the NHC was with Proenza. (More after the jump.)

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The hurricane season hasn’t given us anything to fear yet in the tropical Atlantic, but there is some cause for concern looking forward, particularly along the Gulf Coast. The Houston Chronicle’s SciGuy looks at the Tropical Cyclone Heat Potential maps, and notes that the Gulf and Western Caribbean are warmer than they were this time in 2005 — and the “heat potential generally should only increase during the next few months unless a major storm passes through and stirs up cooler water from below.”

So what does this tell us? I’m certainly not saying there’s another Rita or Katrina in store for this summer. But given the heat potential in the Gulf it’s possible, and coastal residents ought to be quite wary of tropical systems that develop in the Caribbean or reach the Gulf of Mexico.

So let us hope that wind shear, Saharan dust or other factors ensure that they do not.

Unfortunately, according to Dr. Jeff Masters, one of those “other factors” — the global steering currents — are about to shift in a way that would make a Gulf hurricane more likely:

[T]here is there a major development to report–it appears likely that a major shift in the weather pattern will occur in late July across the Northern Hemisphere. If the GFS model is correct, the trough of low pressure that has been consistently in place over the Eastern U.S. will finally move off, to be replaced by a ridge of high pressure. This would bring a hurricane steering pattern much like we saw in 2004 and 2005, with increased risk for the Gulf of Mexico and reduced risk for the U.S. East Coast from the Carolinas northward. The east coast of Florida would remain at normal risk. The GFS model has been inconsistent in its prediction of the timing of this shift, but has been persistent enough about it that I’m forecasting a 70% likelihood of this major pattern shift occurring by the end of July. Such a shift would bring the western U.S. some relief from the current heat wave, and bring high heat and air pollution problems to the Midwest and East Coast. How long such a shift might last is impossible to predict–it could last for a week, or could remain in place for the remainder of hurricane season.

If you’re along the Gulf coast, there’s obviously no need to freak out — we’re talking about purely hypothetical hurricanes at this point, not even a twinkle in Mother Nature’s eye — but don’t get complacent, either, amid all this fallacious slow-season talk.

P.S. Alan Sullivan has more on the expected steering pattern shift:

The Dog Days may come early this year. Though the GFS model has been varying from run to run, the trend is unmistakeable. The hot western high pressure ridge spreads east over the next couple of weeks and merges with a strong Atlantic high to bring sultry weather for much of the US. Only the Great Lakes and the Northeast seem likely to retain a cooler flow from the persistent trough over eastern Canada.

This is hurricane weather. Such a pattern will steer tropical waves westward under the flank of the Atlantic high. They will tend to turn into the zone of weakness between high plains and Atlantic ridge axes. With such a pattern in place, any Atlantic or Caribbean hurricane is likely to strike Florida, the Gulf Coast, or both.

Fortunately there are no tropical disturbances at the threshold right now. Upper winds remain unfavorable over most of the tropical Atlantic. Any storm that does form will have to fight through numerous upper vortices. Surely one of more of the waves will organize in the next few weeks, but the storms should remain weak unless the swirly flow unkinks.

In response to Bill Proenza’s departure from the National Hurricane Center, Glenn Reynolds says, “Good thing it seems to be a slow season.”

I like and respect Glenn, but I can’t let his misimpression go uncorrected, especially when this false notion that it’s been a “slow season” is already being used by global-warming skeptics to press their political agenda. (Not that global-warming alarmists don’t also sometimes use false or distorted facts to press their agenda, mind you, but two wrongs don’t make a right!)

There is simply no valid basis for calling this a “slow season” thus far. Quite the opposite, actually. We’ve already had two tropical storms, Andrea and Barry, which puts us ahead of schedule. In the “average Atlantic season” between 1944 and 2005, the first named storm formed on July 10 — tomorrow — according to NOAA’s Tropical Cyclone Climatology page. The second named storm formed on August 6, and the first hurricane didn’t form until August 14. So we’ve got a loooong ways to go before the activity we’ve experienced so far would qualify this as a “slow season.” (And even if, as some folks believe, Barry wasn’t really a tropical storm, we’re still ahead of schedule!) Here’s a graphical representation of this season compared to the average season:

Glenn is presumably basing his statement on the ridiculous LiveScience article that he linked last month. The article, published on June 25, asked, “Where are All the Hurricanes?” Given that the season’s first hurricane wouldn’t be expected to form until 50 days after the article’s publication date, I think it’s pretty clear how ridiculous that question was. As I wrote previously:

A website called “LiveScience” shouldn’t be misinforming the public in this way. Not to put too fine a point on it, but anyone who “might wonder where all the action is” is completely ignorant of the climatological reality. … Two tropical storms, and no hurricanes, as of June 27, makes for an unusually active season so far, not an unusually inactive one! (On average, there is approximately one tropical storm every two years prior to June 30.) That’s not to say it won’t ultimately be a below-average season…but “Where are All the Hurricanes?” is, at this point, completely and utterly the wrong question. It would be like asking, on November 1 in New England, after two small October snowstorms, “Where are All the Blizzards?” It just makes no damn sense.

Confusion along these lines by Glenn and other non-weather-nerds is somewhat understandable, given the insanely active seasons of recent years. (It’s less understandable when “scientists” are the ones confused.) But let’s be clear. If the implicit comparison is to 2005 — when, by this point in the season, we’d had four named storms, two of them hurricanes, one of those a Category 4 — that’s just ridiculous. 2005 was the most active Atlantic hurricane season in history, by far. Calling this a “slow season” because it’s behind 2005’s pace is like calling Andy Roddick a bad tennis player because he hasn’t won as many tournaments as Roger Federer.

It might end up being another below-average season. But the jury is very much still out, and at any rate it isn’t a “slow season” thus far. Moreover, studies have repeatedly shown that there is virtually no correlation between the level of tropical activity through July and the level of tropical activity from August onward. A couple of illustrative examples are 2004 — the year of Charley, Frances, Ivan and Jeanne — when no tropical storms formed until July 31; and 1992, when the first storm didn’t form until August 16. Its name? Andrew.

UPDATE: Glenn has posted a correction.

UPDATE 2: I just wrote in an e-mail to Glenn:

It could be argued that this season isn’t significantly “ahead of schedule,” but rather that it’s roughly on schedule, given that storms like Andrea and Barry might not have been named at all in prior years, especially in the pre-satellite era. What can’t really be argued is that it’s behind schedule. In fact, it’s pretty much impossible for a season to be behind schedule until at least July 11. :)

UPDATE 3: As with seemingly all weather-related posts these days, the only thing anybody wants to talk about in comments is… global warming. Apropos of which, a hearty Amen to Scientizzle’s comment:

It’s worth reiterating:

Yearly very small fractional increases in average global temperature and, in particular, regional oceanic temperatures would not simply manifest its effects in the integer value of the variable number of tropical storms that meet an arbitrarily defined human threshold. If anthropogenic global climate change exists, and if that climate change does result in the oft-predicted increase in the number and/or intensity of tropical storms, it certainly cannot be reliably determined by any one year of activity. It likely cannot be reliably determined by a decade’s worth of activity.

Long-term trends, people! Only controlled long-term analysis will support or refute this hypothesis. Why is that hard to understand?

Lots of people on both sides of the argument seem to have a hard time understanding it. Some folks on the “skeptics” side seem to think that the deceptive rhetoric of Al Gore & co. on this front somehow justifies their own deceptive fact-fudging for rebuttal purposes. Which is odd, because I thought the Right was anti-relativism. In any event, when substantial numbers of people on both sides of the debate are deceptively or ignorantly conflating weather with climate, short-term occurrences with long-term trends, the whole public discourse on this important issue suffers greatly. It’s time we all made a commitment to do our part to raise the discourse, regardless of what others might be doing.

Margie Kieper says National Hurricane Center director Bill Proenza is likely to resign soon.