Greg Nordstrom's Hurricane Ike Chase Account

Greg has detailed a very interesting account of his Hurricane Ike chase on Galveston Island. I highly recommend reading it by going to his blog.

Greg Nordstrom on Weather Brains

Weather Brains is a weekly 30-minute Internet radio show that focuses on topics around the meteorology community. This show is hosted by James Spann, JB Elliot, and Brian Peters who are all affiliated with ABC 33/40 in Birmingham, AL. This week, one of their guests was my good friend Greg Nordstrom who recently chased Hurricane Ike in Galveston, TX. He shared his experiences with Ike and also participated in a roundtable discussion of other topics including the media coverage of Ike and a hurricane ranking scale. You can access the interview at http://weatherbrains.com/weatherbrains or download it directly at http://www.weatherbrains.com/audio/wb091508.mp3. I'll post final thoughts on Ike later today and look forward to the next couple of weeks in the tropics.

Galveston Taking a Pounding

Watching KHOU out of Houston and talking with Greg Nordstrom this evening, it sounds like Galveston has taken a beating this evening. The storm surge has now eclipsed the sea wall in Galveston and the eye has still not made landfall. If the eye does make landfall to the west of Galveston, the surge will easily inundate the island with water. Even if the eye does make landfall east of Galveston, the winds around the backside of the storm could drive the water in the bay onto the island. Judging by radar loops, it appears that the eye will go directly over Galveston and this may keep the worst surge just off to the east. However, much of the island will still be under water.


Ike now has the most impressive structure and satellite presentation it has had in several days. The good news is that it doesn't have very much longer over water and this will prevent significant strengthening. It's still possible that Ike becomes a Category 3 hurricane before making landfall in the next few hours, especially with the northern and northeastern eye wall convection beginning to intensify.

Ike Pulling Together?

Recent radar and satellite imagery and recon data suggests that Hurricane Ike may slowly be pulling itself together and becoming better organized. Radar loops within the past hour show Ike's eye width has shrunk nearly 30 miles. Why is this important? Well, Ike's energy may be getting compressed together as it approaches the coast. This will cause the pressure gradient to increase and will in turn increase the wind speed. In fact, recon data shows that maximum sustained winds are now up to 110 mph. While I don't think Ike will deepen significantly before landfall, I wouldn't be surprised to see Ike make landfall with winds of 115-120 mph. The track of Ike looks like it will make landfall just west of Galveston Island early tomorrow morning. I'll have more updates tonight.


Greg Nordstrom will be providing brief updates from Galveston, TX this evening. You can check those updates by going to http://twitter.com/LDCT

Status Quo

Ike has maintained its structure and intensity for a good part of today. The pressure has risen to 954 mb, but maximum sustained winds remain near 100 mph. Over the last 24 hours, the wind speeds reported by the recon plane have slowly risen and this may be a sign that the winds are slowly trying to catch up with the pressure drop. Additionally, recent satellite imagery suggests that Ike may slowly be getting stronger with deep convection beginning to develop around the southern eye wall and to the northeast of the center. Time will tell, but this may be the beginning of an intensification phase. If the deep convection can sustain itself, we will likely see Ike deepen overnight.


Ike continues to move WNW along the southern periphery of an upper-level ridge, and subsidence associated with this ridge has limited deep convection on the western half of Ike. Over the next 24 hours, this ridge should move eastward and Ike should be on the southwest side of the ridge. This may provide an enhanced outflow channel and may enable Ike to develop sustained convection on its western side.

The two intensity-related issues I discussed earlier today were the double eye wall structure and the expanded wind field. The double eye wall structure has dissipated, and Ike now only has the small eye wall (~9 miles wide) remaining. This eliminates one impediment to significant strengthening but others remain. Wind shear and dry air are still negative factors for intensification. However, the main issue still revolves around the broad wind field that resulted when Ike expanded in size yesterday. It remains to be seen whether Ike can pull itself together and tighten its pressure gradient before landfall. There is some speculation that as Ike moves closer to the coast, the land may act to locally "squeeze" the hurricane together and tighten the pressure gradient. This is actually common with hurricanes that make landfall at a 90 degree angle to the coast. If this occurs, the winds could spike very briefly as Ike moves ashore.

Greg Nordstrom, Jared Allen, and Michael Haynes are still in Galveston this evening. The gracious staff at the Holiday Inn provided them with three rooms, shelter, and meals as long as they need. If you travel anytime in the future, be sure to give Holiday Inn some business. I have only had excellent service provided to me when I needed data in crucial storm chasing situations. They have always come up clutch so big props to Holiday Inn! The three amigos scouted out the area today and plan to ride out Ike on the island. I'll have another update in the morning with potentially new thoughts on intensity.

Ike Continues Churning in Gulf

Hurricane Ike continues to look impressive this morning on satellite imagery with tight banding and good outflow. Most Texas residents probably are waking up this morning wondering why the rush to evacuate for a 100 mph hurricane? Don't focus on the wind, but instead, look at the pressure. I do note the latest recon data indicates the pressure has risen another millibar to 946 mb. However, that's still a very low pressure and certainly supports a strong Category 3 hurricane.


Why is this not a Category 3 then? Unfortunately, I have a limited understanding of hurricane and eye dynamics, but it appears that is what's currently controlling the hurricane. Recon data indicates that two eye walls are present. The smaller eye is about 9 miles wide and the larger eye is about 48 miles wide. Until the hurricane can concentrate itself into one eye, there won't be much strengthening that takes place. In fact, the hurricane may actually weaken some until one eye becomes dominant. In eye wall replacement cycles, the larger eye is usually the one that becomes dominant. Again, don't let this lull you into a false sense of security thinking that the competing eye walls will destroy the hurricane. It won't. When, not if, a dominant eye does become established within Ike, look for a steady amount of strengthening to take place. This will likely occur later this afternoon or tonight.

Another issue with the low central pressure not corresponding to the winds has to do with the actual size of Ike. When Ike emerged into the Gulf of Mexico, it really increased considerably in size. What this did was to space the isobars further apart. Although the pressure is low in the center, the isobars were spread further apart when Ike expanded. This meant that the wind speed could not increase appreciably. Remember from last week when Ike exploded from a Category 1 to a Category 4 hurricane within a matter of hours? It was a very small storm at that time and the isobars were packed much more closely together, and this is why there was a tremendous increase in wind speed. If Ike can "pull" itself back together to be more compact, the wind speeds will ramp up very quickly. It's possible this could also occur before landfall.

Again, don't be lulled into a false sense of security. Even though Ike is a Category 2 hurricane, the pressure dictates that this is potentially a strong Category 3 hurricane when these issues are resolved.

I have no changes to my thoughts on the intensity or track at this time. I'm still thinking Ike makes landfall as a Category 4 hurricane near Indianola, TX. However, if Ike doesn't pull itself together, expect a Category 3 at landfall.

Greg Nordstrom and crew are in Galveston, TX this morning and are planning to scout out the area today. I'll have an update from them later today.

**Attention Texas Coastal Residents**

The model guidance and the NHC track have shifted more to the right and are generally between Indianola and Galveston, TX. If you live along the coast from Indianola to Galveston, you need to evacuate tomorrow! I fear that when the sun rises in the morning, many residents along the Gulf Coast will be in a state of panic and shock to see what is coming. I heard an interview with the mayor of Galveston earlier this evening, and I was stunned to hear her nonchalant attitude about this storm. Yes, the entire island can probably be evacuated within 12-16 hours, but this is NOT the storm to ride out if you live along the coast! If you do ride out the storm and you live within 5 miles of the Gulf of Mexico in the areas I mentioned above, be warned that your area will likely be under water!

If you live in Houston, be prepared for Category 2 and possibly Category 3 winds that will be capable of producing extensive damage. If you live on the east or south side of Houston, you need to evacuate to higher ground. There will be at least a 10-15 foot storm surge in Galveston Bay that will be capable of flooding most of the south and east sections of Houston.

Coastal residents, evacuate inland tomorrow -- you won't regret it! I recommend going to Austin or San Antonio. For the latest on evacuations and other related news, go to http://twitter.com/hurricaneike

Ike Update

The visual presentation of Ike continues to become better defined this evening with a distinct eye wall beginning to form. The minimum pressure continues to drop fairly quickly this evening, and the latest recon data indicates the extrapolated pressure is now down to 940.5 mb -- that's a drop of 6 mb in the last few hours. Typically, there is about a 6-12 hour lag in the pressure drop and the wind speed increase. With that said, expect Ike to be a major hurricane later tonight and possibly near Category 4 intensity tomorrow morning.


Wind shear remains moderate (10-15 knots) around Ike, but the ambient environment has considerably moistened. Therefore, wind shear is the only impediment to rapid intensification at this point. However, if the inner core can resist the wind shear, it's possible Ike could undergo a rapid intensification period relatively soon. I still think this will hold off until tomorrow morning when a strong ridge becomes entrenched over the hurricane. At that time, Ike could explode into a Category 5 hurricane at some point within the next 48 hours.

LDCT's Greg Nordstrom, Jared Allen, and Michael Haynes are en route to Galveston, TX. They should be there tomorrow morning, and I'll provide updates when I hear from them.

Ike Poised to Srengthen

Hurricane Ike moved into the Gulf of Mexico last night and has already begun to strengthen. Maximum winds are up to 85 mph along with a minimum central pressure of 959 mb. Satellite imagery suggests that the core of Ike was well established even after two landfalls in Cuba. In fact, Ike developed an eye again shortly after moving into the Gulf and continues to maintain its eye. Although Ike is not as symmetrical as it was last weekend, it has grown in size and will significantly improve its structure over the next 24-36 hours. Even still, it has a good banding presentation along with good outflow in all quadrants.


Where is Ike headed? After trending sharply to the left Monday and Tuesday, the computer models shifted back to the right yesterday and now are mostly clustered around the Corpus Christi area. Notable outliers include the GFS (South Texas) and UKMET (Freeport, TX). This year's reliable models the GFDL and European foresee a landfall near Corpus Christi or Indianola, TX. A strong ridge is forecast to build over Ike today. The main question at this point revolves around how quickly the ridge breaks down as a strong trough approaches from the west. This trough is currently located over the Western U.S. states and is amplifying the ridge downstream. This ridge will have major effects on the track and intensity of Ike. With respect to the track, this ridge should steer Ike generally on a WNW heading, and most models agree that the ridge should hold strong at least until landfall.

A few models do break down the ridge and turn Ike more NW prior to landfall. This would present a major threat to Galveston and the Houston area. Due to the uncertainty, residents from Brownsville to Galveston need to pay very close attention to Ike over the next couple of days. However, I feel that the ridge will remain strong through landfall, and I'm sticking with a landfall near Indianola, TX.


The intensity forecast for Ike is somewhat difficult as it always seems to be. There are currently two main impediments to prevent rapid intensification. Wind shear, the largest impediment, is a bit on the moderate side with 10-15 knots over the center, and this shear may be responsible for the asymmetric structure of Ike. Second, dry air does surround the hurricane, but it does not appear to be getting entrained into the center. As long as the dry air is not entrained, it can't really be considered a true impediment. While I don't feel that dry air will be a problem in the next 24-36 hours, the presence of the dry air can't be completely neglected. The wind shear, on the other hand, is strong enough to prevent a rapid intensification period in the short term. However, when the upper-level anticyclone builds over Ike later this evening, wind shear will drop off to less than 5 knots and expect Ike to intensify.



Ike will also be traversing the Loop Current and other clockwise loop eddies as it makes its way across the central Gulf. The Loop Current and eddies are extra sources of heat for the hurricane to ingest. One way you can think of it is that in a normal situation, the hurricane is just eating a steak from Applebee's. Sure, it's good but it's not top quality. When a hurricane passes over the Loop Current or a loop eddy, it's like eating a high grade Kansas City steak. This warm, deep reservoir of water and low wind shear will likely result in a rapid intensification period tomorrow. In fact, it should be no surprise if Ike is at least a Category 4 hurricane by tomorrow night.

The landfall intensity is a little more problematic due to the uncertainty of dry air, eye wall replacement cycles, and the approach of the trough. The one constant that will remain is the oceanic heat content will remain high, especially with a loop eddy just off the central Texas coast. However, dry air from the higher elevations of Mexico is always present, and it wouldn't take much to pull this dry air toward the hurricane. The approaching trough could also increase wind shear near Ike as it approaches the coast. I'm not banking on this scenario as much because I think the ridge will hold strong enough until landfall, but any increase in wind shear could disrupt the circulation and cause Ike to weaken. Lastly, the most difficult to forecast, eye wall replacement cycles dictate the strength of hurricanes. When a hurricane replaces its eye wall, it typically goes through a period of weakening. When the eye wall is replaced, the hurricane usually re-gains its strength quickly. Eye wall replacement cycles usually take ~6-12 hours to complete but can be as long as 24 hours.

If dry air is not a problem at landfall, Ike could certainly be a Category 4 hurricane. On the other hand, if dry air or wind shear are present at landfall, Ike will probably be a Category 3 hurricane. At this point, I think Ike will be a Category 4 hurricane with 135 mph winds at landfall. I may have another update later today.

For information on evacuations and other related news, check http://twitter.com/hurricaneike

Ike Emerges Into Caribbean

The strong ridge of high pressure has steered Ike a little further west and south than previously thought, and the center emerged into the Caribbean Sea late this morning. Ike was expected to move over Cuba for almost 36 hours before finally emerging into the Gulf of Mexico. Now, it appears that Ike will mostly stay over the very warm, deep waters of the northwest Caribbean and may actually intensify again before moving over the western tip of Cuba. Strengthening is highly dependent upon the how severe the core of Ike was disrupted as it moved over land. Unfortunately, I don't have the tropical forecasting experience to know how the core of small but strong hurricanes fares as it traverses land. My best guess is that it they aren't impacted as severely as large, strong hurricanes. However, since Ike was wound up when it moved over land, it's certainly possible it may take some time before the core is repaired. It will be a learning experience for me regardless. Even with limited experience, I can confidently say that the structure of Ike looks very solid with tight banding, good inflow, and excellent outflow.


If the core is intact, it will likely strengthen quickly given the very low shear, moist ambient air, and high oceanic heat content. In fact, if this is the case, Ike could be a Category 3 hurricane again when it moves over the western tip of Cuba. This brings up another situation that deals with the interaction of the inner core and land. How will the second landfall impact the core of Ike? At this point, given my limited experience with tropical forecasting, it's best to play the conservative road and forecast Ike to be a Category 1 or perhaps 2 hurricane when it does emerge into the Gulf of Mexico.

Once into the Gulf of Mexico, strengthening will be contingent upon Ike's inner core after its second landfall in Cuba. If the core remains intact, conditions will be primed for modest and perhaps rapid intensification. Ike will be traversing the loop current and with low wind shear forecast by the models, this spells the potential for a quick ramp-up if Ike's core is intact. If it is not intact, it may take up the 48 hours before the core is repaired. This would leave Ike with approximately a 24-48 hour window to strengthen prior to landfall. In this time frame, Ike will have somewhat favorable conditions for strengthening with low shear and high oceanic heat content. The only potential caveat would be whether dry continental air becomes entrained into the circulation. This seems to happen more often than not when tropical systems approach the Texas coast. If dry air is not a problem, look for Ike to potentially become a Category 4 hurricane in the central Gulf of Mexico.

The landfall destination will have a major impact on the final intensity of Ike. A landfall along the Louisiana coast would likely result in a Category 3 hurricane as a worst case scenario. In fact, Ike would likely be weakening when it makes landfall. Conversely, a landfall in Texas could mean that Ike doesn't weaken significantly and could potentially be a Category 3 or 4. That's impossible to say at this point given the multitude of factors that govern intensity. However, the point is that a Texas landfall would imply a stronger hurricane and a Louisiana landfall would imply a weaker hurricane.

Where exactly Ike is going to make landfall is somewhat problematic, and the model guidance flip-flops are certainly not bolstering any confidence. Last night's model runs were targeting mostly Texas and Louisiana, but this morning's model runs are generally targeting Texas. The early 18Z suite of guidance is rolling in, and it generally agrees with a Texas hit. Given the strong ridge in place, and the unexpected southward jump of Ike today, it seems like Texas is a better idea at this point. Very reliable models such as the ECMWF, GFDL, UKMET, and NOGAPS now all suggest a central or south Texas coast landfall. Given the superior track record of the GFDL this season, I think landfall will be between Corpus Christi and Indianola, TX as a Category 3 hurricane.

Ike Threat Growing

After quickly ramping up to a Category 4 in a matter of hours on Wednesday, Hurricane Ike has weakened somewhat due to strong wind shear and some dry air. However, don't let that lull you into thinking that Ike has reached its maximum intensity. Unfortunately, it likely hasn't. Recon got into Ike early this afternoon and generally confirmed what satellite estimates have known -- it is a major hurricane with top winds of 115 mph and a minimum pressure of 958 mb. Wind shear still remains on the high side (20 knots), but the large expanse of dry air observed earlier today has since moistened considerably. Therefore, shear is the only factor preventing Ike from strengthening. Furthermore, satellite images do show that outflow along the northern half of Ike is still being restricted due to the strong shear. The eye of Ike has been visible briefly throughout the afternoon but is eroded on the northwest side. The temperature difference between the eye and just outside of the eye wall is somewhat low (5 C), which indicates to me that Ike is not currently a very efficient hurricane. This temperature is normally at least 10 C in mature hurricanes.


The wind shear is forecast to weaken in the next 24-36 hours, and when this occurs, look for Ike to intensify again. One caveat to rapid intensification is the cool waters (80-82 F) just east of the Bahamas that were upwelled by Hanna earlier this week. However, once Ike moves west of the 75 deg W meridian, rapid intensification could commence. Wind shear is forecast to be quite low at that time along with a moist environment and high oceanic heat content. In fact, it should be no surprise if Ike quickly becomes a Category 4 hurricane again by early Monday. Ike should be a very powerful hurricane by Monday and will still remain in a low shear and high oceanic heat environment. However, eye wall dynamics come into play and it's somewhat difficult to forecast the intensity of Ike once it becomes a steady-state mature hurricane. Yes, the environment will be highly supportive of strengthening, but eye wall replacement cycles can create periods of intensity fluctuations. Another dillemma with intensity forecasting past Monday morning involves the potential impacts of land.


This opens up a big can of worms, especially trying to forecast the track of Ike. The easy part of the track deals with the next 48 hours. There is decent model agreement that Ike will move just south of due west during this time frame and should be south of Long Island Sunday afternoon. After this, there is a large amount of spread in the models. The 18Z GFDL, HWRF, UKMET, and 12Z Euro and UKMET all forecast Ike to interact with Cuba and even move over Cuba for nearly 24 hours. Other models like the 18Z GFS and 12Z NOGAPS either show Ike interacting very little with Cuba or moving just north of Cuba. This is a very difficult track forecast because it will also dictate the intensity of Ike. Earlier today, I was leaning with the idea that Hanna would create enough of a weakness in the ridge to keep Ike from moving over Cuba. However, there is very reliable model support for this idea, and I'm now leaning toward the idea of Ike interacting with northern Cuba. I think it will be brief, but it will be enough to at least disrupt the circulation of Ike. Just how much remains to be seen. However, Ike should then pop out into the Straits of Florida on Tuesday and will likely pass just south of Key West if my idea is correct. If Ike does not interact with Cuba, the Florida Keys could be in the direct path of a potential Category 4 or 5 hurricane. I'll stop with the track forecast at this point, but most of the models do agree that Ike enters the Gulf of Mexico next week and could be a major hurricane depending on how much land it encounters.

Needless to say, everyone from Louisiana to Miami needs to pay very close attention to Ike in the coming days. This could be a very powerful hurricane with a major threat to impact the U.S. within the next week. I'll have an update tomorrow morning.

Hanna Strengthening, Headed Toward Coast

Dry air still surrounds Hanna, but its center of circulation has enveloped itself around healthy convection overnight. With moderate wind shear and warm SSTs, expect Hanna to be strengthening is it makes landfall near Wilmington, NC tomorrow. I note the latest recon data shows a minimum pressure of 980 mb, which is down 5 mb from earlier this morning. I believe the NHC will likely updgrade Hanna to a hurricane at some point today. If you live anywhere east of the center, you can expect Hanna to be stronger than expected when it moves onshore. The reason is that deepening systems more efficiently mix stronger winds down to the surface. I'm thinking Hanna will still make landfall as a Category 1 hurricane with winds of 80-85 mph tomorrow.

Big update on Ike to come later today. Most models have shifted west and now indicate a threat to Florida or even the Gulf of Mexico.

Threat #1 -- Hanna

I've got new thoughts on Hanna this morning, and if you've seen the water vapor imagery, you'll understand why. A vast area of continental air has infiltrated the center of Hanna and has completely disrupted the convection. Unless the ambient environment around Hanna moistens considerably, I don't think it will be a Category 2 hurricane at landfall. I do think that the environment will moisten over the next 24 hours, but I've lowered my intensity down to a strengthening Category 1 hurricane (80-85 mph winds) at landfall. My landfall idea has still not changed with a projected landfall between Wilmington and Morehead City, NC on Saturday.


I'll have another update later today focusing on the larger threat that looms -- Hurricane Ike. My gut feeling is that Ike will target South Carolina, but I'll be doing a lot of analysis today to get a better feel for the track.

Busy Tropics

The recent MJO pulse that moved into the Atlantic has created a flurry of activity not seen since 2005. On Tuesday, we had four named systems in the Atlantic basin: Gustav, Hanna, Ike, and Josephine. Gustav's dissipated on Wednesday, but we still have three systems to deal with.

JOSEPHINE
Let's deal with Tropical Storm Josephine, the system furthest east and least threat to the U.S., first. Josephine doesn't look that impressive, but maximum sustained winds are 65 mph and a minimum pressure of 994 mb. It's somewhat surprising that Josephine has strengthened as much as it has with high wind shear (20 knots). Still, water temperatures are plenty warm (82 - 84 F) and there is very little dry air around the storm. I don't expect much strengthening with the high wind shear near the center and even stronger wind shear to its northwest. With a ridge to its north, Josephine should move WNW over the next few days. As it does so, it should move into cooler waters and this will also limit the amount of strengthening. I agree with the NHC's intensity forecast with minimal short-term strengthening followed by weakening on Friday. I believe Josephine will be a re-curving storm before it can get too close to the U.S.

HANNA
The system closest to home is Tropical Storm Hanna, which has taken a Muhammad Ali-like beating at the hands of an upper-level low. The low is slowly weakening and lifting out to the northeast of Hanna. However, wind shear is still high enough to prevent significant short-term strengthening and Hanna's inflow is probably being disrupted by Haiti. By tomorrow, Hanna should be moving away from Haiti and wind shear should relax enough to promote strengthening. The shear should still be strong enough to prevent rapid intensification, but some modest intensification is possible. I expect Hanna to become a hurricane late Thursday or possibly Friday. After that, it will be in an environment supportive of slight intensification with high oceanic heat content being the main positive factor. Some dry air and moderate wind shear will likely prevent significant strengthening. Still, I expect Hanna to be a strengthening Category 2 hurricane at landfall Saturday morning.


The track of Hanna is not terribly tricky, but there is still quite a bit of disagreement with the models. Hanna should be moving along the western periphery of a ridge and this should shoot it NW and make landfall in South Carolina or North Carolina. Due to the slightly unexpected eastward movement today, I'm leaning towards a landfall between Wilmington and Morehead City, NC.

IKE
Wow is all I can say. Within six hours, Ike has gone from a minimal Category 1 hurricane to a major Category 4 hurricane! This intensification was not forecast by anyone or any model this quickly. Yes, Ike is surrounded by moist air and very low wind shear, but the thermodynamic state of the ocean isn't typically what you would see with such a rapid intensification period. It just goes to show you that as advanced as our technology is and as smart as we think we are, God still controls the weather. Given the expected conditions over the next 24 hours, it shouldn't be a surprise if Ike continues to intensify and possibly gains Category 5 intensity. I don't think that will happen given the oceanic heat content, but I didn't think it would be a Category 4 hurricane this soon either. Still, expect Ike to remain a powerful hurricane for another day or so. After that, wind shear associated with the upper-level low near Hanna is forecast to increase and may halt any strengthening. However, the upper low should pull away from Ike by Saturday as a ridge builds in. This should decrease the shear and make conditions favorable again for strengthening.


Ike should begin to move more WNW and NW tomorrow as it begins to feel the effects of the upper-level low. After it passes on Saturday, a ridge builds in and should push Ike slightly south of due west for almost 48 hours. After this time, models diverge on keeping the ridge strong or breaking it down. This results in Ike maintaining a westerly motion or turning more NW. Regardless, a powerful hurricane will likely be approaching the western Bahamas by the end of the weekend. Everyone from Florida to North Carolina needs to watch this extremely closely. We may not get off lucky this time...

Gustav Thoughts

Residents along the northern Gulf Coast can thank Cuba for severely disrupting Hurricane Gustav. The powerful hurricane's core was disrupted as it passed over the very small strip of land in western Cuba. That small strip of land was enough to weaken the core and allow wind shear to tilt the eye. Remember that hurricanes are warm core and want to keep their eye as vertical as possible to achieve maximum efficiency. Tilted eyes caused by wind shear typically prevents strengthening. Well-defined and major hurricanes are more susceptible to core disruption when they move across land than weaker tropical cyclones. Furthermore, it typically takes 24-48 hours for the core of major hurricanes to become re-established after they move over land and back into water. Weaker tropical cyclones often keep their core intact as they pass over land, but it may only take 12 hours for some weak cyclones to fully recover their core.

Two excellent examples to compare are Gustav and Katrina. Gustav was a well-organized Category 4 hurricane when it moved over Cuba early Saturday afternoon. After its passage and subsequent movement into the Gulf of Mexico, the core was severely disrupted until late Sunday night. In this case, it took nearly 36 hours for Gustav to re-establish its core, and when it did, it wasn't in an environment favorable for significant intensification. Katrina, on the other hand, made its first landfall in South Florida as a Category 1 hurricane. Since it didn't have a mature core, it wasn't severely impacted as it moved over land. Once it emerged in the Gulf of Mexico, it quickly re-intensified into a hurricane.

I like to compare this concept to football players. Think of a big offensive lineman as a mature hurricane with a well-defined core and a small wide receiver as a weak tropical storm or hurricane with a developing core. Now let's introduce a tackler to serve as a landmass. If the wide receiver is tackled, he will get back up rather quickly. On the other hand, it's going to take a little while longer for the big offensive lineman to pick himself up after he is tackled.

Again, we can be very thankful that Cuba saved the Gulf Coast from a potential Category 4 hurricane. I'll have an update later today on Hanna, Ike, and Josephine.