Updates on Irene

While the forecasted "worst" of Hurricane Irene has yet to arrive, if you had told me nothing about what was coming, and I just made observations based on what I saw today, I would say that today was nothing but an ordinary rainy day.  Now, it's a much different story on the coast.  Ocean City and most of the other major Delmarva, Virginia, Carolina, and New Jersey ocean resorts have ordered mandatory evacuation.  Only about 300 people have chosen ride out the storm in Ocean City, and police demanded that they give them contact information for next of kin (scary?).  In the words of New Jersey governor Chris Christie, "Get the hell off the beach!"  New York city has ordered a mandatory evacuation for neighborhoods in low-lying areas (including the Ground Zero site) affecting 370,000 people.  Public transportation and airports in many of these major metropolitan areas have either already shut down or will do so very soon.  Public officials are taking this storm very seriously, which is good to see.  It is even good to see most people heed the warnings and get out.  This was Ocean City's first mandatory evacuation in 26 years. 

Meteorologically, Irene has been much less of a monster than what was previously forecast, but this is understandable.  Don't get me wrong, Irene is nothing to sneeze at (it's still a Hurricane as of 7:00), but the forecasts of major hurricane landfall were grossly overestimated, as they usually are.  Media outlets, including the NHC itself, are always prone to overexaggerating the potential effects of tropical systems.  The reason is simple.  If you UNDERESTIMATE, and the storm ends up being worse than predicted, well, you can figure out how that would turn out.  Bottom line is that by the time the eye gets to Ocean City (it is over Norfolk, VA at the moment and moving offshore), it will be over water and a minimal hurricane at worst.  Another thing to keep in mind is areas such as New England and even Maritime Canada, are not used to any sort of tropical event, so these people need to be vigorously warned in advance of a system that is heading their way.  So in that respect, I can totally appreciate the way this storm has been presented in the media, and it should even be encouraged.   You can never take these types of storms too sereiously.  Normally, I criticize media outlets for oversensationalizing stories simply to get ratings, but in this case, it is definitely a good thing.

Let's take a look at the infrared satellite imagery (at of 6:45PM on August 27th)

Let me tell you a little bit about this picture.  You've probably seen these enhanced satellite photos before.  What the colors actually represent is cloud top temperature.  Infrared imagery looks for thermal signatures in the clouds.  It is kind of ironic, but the hotter colors (yellow and orange) refer to COOLER cloud top temperatures.  What does this mean?  Cool cloud tops indicates very TALL clouds, high in the atmosphere.  Tall clouds indicates that there is a high degree of convection going on which allows the clouds to build.  Lots of convection means that there is lots of moisture in the cloud, which means that thunderstorms embedded within the clouds are much stronger.  At its peak intensity, you would have seen reds thrown in with the oranges and yellows.  This was when the storm was over the warmest waters of the ocean. 

Since the storm has been over land, that convection has decreased, shortening the clouds, and interrupting the rotation of the clouds, which increases the central pressure and weakens the storm.  It's about the reemerge over water again, but at these latitudes the water is not nearly warm enough to maintain a strong hurricane.  However, it will not weaken nearly as quickly over water as it would over land.  That's why people in New York and New England should prepare for a category 1 landfall.  Not only is it not going to weaken as fast, it is increasing in forward speed so it will not have much TIME to weaken. 

Right now, however, it is only moving at about 12 mph.  This is giving it plenty of time to dump all of that moisture that has convected into the clouds.  Flash floods are being reported all over the region.  Damage reports are already coming in from North Carolina and Southern Virginia.  Storm surge has already overrun the barrier islands and beach erosion is taking place at rapid rates.  There have been several reports of tornadoes in Virginia as well.  Spinning hurricanes have a high tendency to drop tornadoes.  In Maryland, the Bay Bridge has been shut down due to the high winds.  The state of Delaware has even shut down major highways except for emergency vehicles.  The best thing to do is just stay home for the night and enjoy the rain.  Follow NOAA's public advisories for the latest on Irene...and we'll have more on Caputo's Corner too of course.