Yesterday, I gave you the following information:

In 1969, Cat. 5 Hurricane Camille struck the Louisiana-Mississippi border and produced a deadly storm surge of 24 feet.  Almost 40 years later, Cat. 3 Hurricane Katrina, following almost the exact same path and landfall point as Camille, produced a record storm surge of nearly 30 feet in the same area!

And then I asked:

How did Hurricane Katrina, a Cat. 3 at landfall, obliterate Cat. 5 Hurricane Camille’s surge record?

c) Intense development in the Gulf Coast Region between 1969 and 2005 lowered the mean elevation of the coast, making it more vulnerable to surge.

Thanks to all who participated in my second hurricane trivia poll question of this season!  Congratulations to those of you who chose the correct answer, “a”.

This was intended to be a tough question! 

Many of you responded “b” – and I understand your thinking.  Tide cycles do matter, at least marginally, in storm surge situations.  However, Gulf Coast tide levels typically fluctuate a mere 1 to 3 feet from low to high cycles – not enough to account for the 25% increase in storm surge Katrina produced over Camille. 

Most of you did not answer “c”, but it might have been attractive to you in that it fits with the narrative that man adversely alters nature.  Studies have suggested that, at least in Louisiana, manmade levees built to divert Mississippi River floodwaters have compromised the coastal wetlands of the Mississippi Delta Region.  But, less wetlands cannot account for the six foot increase in storm surge in Katrina over Camille.  What’s more, Mississippi’s coast is independent of Louisiana’s levees.  The great increase in storm surge Katrina brought to Mississippi would have happened regardless of how many homes, hotels or casinos came to the state’s coast since 1969.

Indeed, “a” is the best answer.  The magnitude of a storm’s surge is directly dependent on the strength of the hurricane’s wind and the size of the hurricane’s wind field.  Despite Katrina’s Category 3 landfall status (with winds between 111mph and 130mph), the storm had been a monstrous Category 5 hurricane (with winds greater than 155mph) just 24 hours before it came ashore.  And not only was Katrina strong, it was enormous.  Satellite estimates and other data suggest that Katrina’s hurricane-force wind field was at least twice the aerial size of Camille’s.  Katrina was able to amass an incredible storm surge in its trek across the Gulf of Mexico.

Thanks again for your participation in hurricane trivia!

At a most unlikely time - right in the heart of September - the tropical Atlantic Basin (including the Caribbean Sea and Gulf of Mexico) is free of tropical storms and hurricanes.  Despite that mid-September is the statistical peak of Atlantic Hurricane Season storm activity, strong upper-level winds over critical regions of the Atlantic Basin are preventing clusters of showers and thunderstorms from organizing this Monday morning.  Tropical storm formation is not expected in the Atlantic Ocean, Caribbean Sea or Gulf of Mexico in the next 24 to 36 hours.

The official end of Atlantic Hurricane Season is November 30, but North Carolina rarely sees hurricane activity beyond mid October.  Monster Category 4 Hurricane Hazel struck Eastern North Carolina on October 15, 1954.  Early North Carolina records indicate that a hurricane struck on November 17, 1825 (a tid-bit I picked up from Wikipedia).  Usually, however, upper-level winds become too strong during the fall season for tropical storms and hurricanes to survive to the North Carolina coast. 

Thanks for checking into my blog!

... I will be including updates on Gustav, Hanna, and the rest of the tropical Atlantic Ocean in my main forecast segment on the weather page.

I hope you’re enjoying the Labor Day weekend thus far!  Let’s get you updated on the tropics…

Gustav: Major hurricane Gustav is slamming Cuba as I type this report Saturday evening.  Gustav will likely maintain itself as a major - perhaps Category 3, 4 or even 5 - hurricane through tomorrow and Labor Day.  Northwest-bound Gustav will very likely impact the coast of Louisiana late on Labor Day or perhaps Upper Texas coast early Tuesday.  New Orleans’ levees would likely be inundated with a direct hit or even a near-miss from Gustav if it stays a Category 4 or 5 hurricane.  If Gustav hits the central or western Louisiana coast or the coast of Upper Texas as a Category 4 or 5 hurricane, New Orleans may just barely be spared and said areas to the west would be inundated with an epic storm surge of 15 to 20 feet (perhaps locally higher at and just east of the point of landfall).  Unfortunately, the legacy of Gustav is likely to be similar to that of 2005’s Katrina and Rita.  Keep the residents of the Gulf Coast in your thoughts and prayers this Labor Day weekend.

Hanna: Tropical Storm Hanna will not enjoy the same favorable atmospheric or ocean conditions for intensification purposes that Gustav will.  Nonetheless, Hanna will likely maintain its integrity as a tropical storm through Labor Day weekend and into early next week.  A high pressure system building over the Eastern U.S. will guide Hanna toward the Bahamas in the coming days.

Good Friday morning, tropical weather watchers!  Here’s an update on my thinking about the evolution of Gustav and Hanna:

Tropical Storm Gustav: Gustav will still likely become a hurricane - as early as later this Friday.  Models are unanimous in bringing an intense (perhaps Category 3 or higher) Gustav to the northern Gulf of Mexico Coast later on Labor Day or next Tuesday.  A strong high pressure system that will build over the Eastern U.S. by this time will steer Gustav on this said course.  New Orleans and other storm-vulnerable Gulf Coast communities are right to be concerned! 

Tropical Storm Hanna: Hanna is still about 300 miles north of Puerto Rico and is still weak.  An upper level low pressure system is shearing Hanna’s structure a bit more than I anticipated yesterday, but still, the storm will likely maintain its integrity as it moves northwest in the coming days.  Computer forecast models have come into better agreement regarding Hanna’s track since yesterday.  Their general solution: The same high pressure system that will steer Gustav into the Gulf will likely block Hanna from having a clear path to the Carolina Coast!  Most models predict Hanna will turn left - toward the Bahamas - three to five days from now.  Only a small camp of models predict Hanna turning toward Bermuda with time.  Not one major model brings Hanna to North Carolina within the next 7 days.  We will have plenty of time to watch Hanna, but for now, the latest trends are certainly encouraging.

I’ll have more updates into next week!

Tropical Storm Gustav: As of Thursday morning (8/28), Gustav is a strong tropical storm near Haiti and Jamaica, and all indications suggest the storm will intensify greatly as it crosses the northwest Caribbean Sea and Gulf of Mexico in the coming days.  Gustav poses a significant threat to the northern Gulf of Mexico Coast of the United States early next week as it could become a major hurricane by that time.

Challenges in Forecasting Gustav: Computer forecast models are almost unanimous in tracking an intensifying Gustav through the northwestern Caribbean Sea and into the Gulf of Mexico this weekend.  Pinning the exact landfall location for Gustav on the Gulf Coast will be a major forecast challenge in the coming days.  Forecasting the exact intensity of any tropical system is inherently challenging, but given the wealth of warm water Gustav will pass over as well as favorable upper-atmosphere conditions, Gustav has a good chance of becoming the second major hurricane of the 2008 Atlantic Hurricane Season.

Tropical Storm Hanna: Located in the Atlantic Ocean about 500 miles northeast of Puerto Rico, Tropical Storm Hanna was born out of Tropical Depression Eight late this Thursday morning (8/28).  T.S. Hanna will slowly strengthen next 24 to 48 hours and it’s even possible that the system could graduate to hurricane status over the Labor Day weekend.  Storm Team 9 will closely watch Hanna as it slowly moves northwest through this weekend.  It’s possible that this system will stay over the ocean through its lifetime, but it’s also possible that this system will ultimately impact the Southeast U.S. Coast.  Even if the latter occurs, however, direct impacts from Hanna wouldn’t happen for at least seven days from now, so Storm Team 9 will have plenty of time to track the storm’s evolution. 

Challenges in Forecasting Hanna: Hanna will likely enjoy many of the same atmospheric and ocean conditions in the Atlantic that Gustav will in the Caribbean and Gulf - warm sea surfaces, moist ambient air and relatively low high-altitude wind shear - so it’s likely the storm will graduate to hurricane status within a few days.  Hanna’s ultimate track is a far more challenging forecast.  The timing and intensity of surface cold fronts moving off the East Coast often have a direct effect on where Atlantic hurricanes go, and Hanna’s case is no exception.  One such cold front will work off the eastern U.S. coast by this coming Sunday (this front will almost certainly bring Eastern Carolina drier weather for Labor Day).  Some computer models suggest that this front will even be strong enough to continue into the Atlantic Ocean and steer Hanna on a more eastern course toward, say, Bermuda.  On the other side, a large camp of computer models suggest that this front will not be strong enough to steer Hanna, and that the storm will slow to a halt - or perhaps drift west to Florida - in time.  The models’ differences in the strength and timing of this cold front may be only slight, but the resulting effect on Hanna will be huge. 

Thanks for checking into my blog!  I’ll have updates on these forecasting challenges as the days progress.  Comments and questions from you are welcome!

Yesterday, I asked: Which states are least hurricane-prone?

a) Maine, Massachusetts, and Rhode Island

b) New Hampshire, Massachusetts, and Connecticut

c) New Hampshire, Delaware, and Maryland

If you said “c”, you are correct!  But just why are New Hampshire, Delaware, and Maryland stand-out states for their low hurricane risk?  The answer lies in their geography.

First, the Atlantic coastlines of NH, DE, and MD are very small.  Only one county in each of these states borders the ocean, so they are inherently tiny - and therefore rare - hurricane targets.

What’s more, the Atlantic coasts of NH, DE, and MD are oriented north-south.  Since East Coast hurricanes generally move from south to north, the storms will often move parallel to the coastlines of these states rather than moving straight into them.

States like Maine, Massachusetts, Rhode Island, and Connecticut are historically susceptible to northbound Atlantic hurricanes because they have south-facing shorelines (much like North Carolina’s hurricane-vulnerable south-facing coast).

Zero hurricanes have made landfall in New Hampshire, Delaware, or Maryland in the past 60 years, while in the same span, nearly 20 hurricanes made landfall in North Carolina.

Thanks for all who participated in hurricane trivia!  I will post more questions periodically through the season.

A rare breed of summer day might occur Wednesday, the 13th of August - an August day in which temperatures climb no higher than the 70s.  I should note that average high temperatures for mid August are upper 80s to around 90.

Cool August days in the 70s are so rare because it takes an unseasonable day-long combination of thick clouds and persistent rain showers to hold daytime temperatures down.  These factors may indeed come together Wednesday, August 13th, as a storm system approaches Coastal Carolina from the southwest.

Right now, the official Storm Team 9 Forecast has a high of 80 for Wednesday, but this reflects a degree of uncertainty in how thick morning clouds will be and how soon rain showers will arrive.  If clouds begin the day thin, and filtered sunshine breaks through them, temperatures will climb fast.  Also, if rain showers don’t arrive until Wednesday afternoon, their cooling presence will be delayed as well.  But, if clouds stay thick for the entire day and/or rain showers arrive early in the day, temperatures will likely climb no higher than the 70s.

The last time daytime temperatures were held to the 70s in August was in 2004 - when it happened 4 times!  August 6th, 14th, 15th and 29th, 2004 all featured high temperatures in the 70s - and every one of those days featured clouds and measurable rainfall.

To check past weather like I did for this blog, visit the Storm Team 9 Almanac here at wnct.com.  Join me tomorrow for an updated forecast for the showers and the temperatures, too!  In the meantime, thanks for checking out my blog!

Nearly two weeks ago, Hurricane Dolly lashed Deep South Texas with whipping winds and torrential rain.  Today, the Lone Star State braces for a potential Hurricane in Edouard.  As I type, Edouard is a tropical storm, but it will have a chance to deepen into a hurricane before impacting the Upper Texas Coast on Tuesday. 

Why may Texas see two hurricanes in as many weeks?  There are two main reasons.

One reason is almost a given this time of year: warm sea surface temperatures.  Bouys show that the Gulf of Mexico water temperatures near Texas and Louisiana are in the mid to upper 80s - plenty warm to sustain a developing tropical storm system.  Dolly intensified to a hurricane in these waters.  Edouard will likely maintain its tropical storm status and may develop into a hurricane as well.

Another reason that Dolly/Edouard was/is guided to Texas is a westerly mid-level atmospheric wind flow, or “steering wind flow” over the Gulf of Mexico.  Clockwise wind flow around a persistent high pressure system over the Central Plains has meant a prevailing westerly wind flow across the Gulf of Mexico for many recent days and weeks.  Any tropical storm or hurricane caught in these steering winds moves west - toward Texas.

Thanks for checking into my blog.  I look forward to reading any questions/comments you may have.  Be sure to stay with Storm Team 9 in the coming days for the latest on Edouard!