Hurricane Irene appears to be strengthening this afternoon over the Bahamas after pretty much holding steady for the last 24 hours. Relaxing wind shear, warm sea surface temperatures, and the completion of an eyewall replacement cycle will let Irene strengthen today and tonight.
The forecast track of Irene has become increasingly worrisome with an excellent model consensus right over or just west of Connecticut. The computer models are being augmented with tons of extra data from planes sampling the atmosphere near the storm and an unprecedented amount of weather balloon launches across the country ordered by the National Weather Service. The tight clustering and the added data give me increased confidence in the track forecast for 72 hours.
The 18z tropical models show the threat to Connecticut with a tight clustering over or just west of the state.
Here are some of the impacts that you should be concerned about assuming the storm remains on this track. It is completely possible that the storm wobbles west and weakens some over land or wobbles east and spares us the worst. At this time, however, the most likely scenario is a direct hit as severe or more severe than Gloria. Prepare for the worst, hope for the best.
Wind: If the storm follows the current National Hurricane Center track I expect wind gusts of 75 m.p.h. to 100 m.p.h. along the Connecticut shoreline. Inland, 60 m.p.h. to 80 m.p.h. wind gusts are likely. The wind will be of an unusually long duration for a Connecticut hurricane due to the unusually slow expected movement of the storm. This will increase the amount of wind damage potential. If the storm passes farther to the west over New Jersey and New York then the storm will be weaker and the wind threat will be lower. If the storm passes farther to the east the wind on the left side of the storm’s track will be less. At this point we should prepare for a direct hit – which is becoming the most likely scenario.
Winds of this magnitude will likely be as strong or stronger than what we experienced during Hurricane Gloria. The wet soil and long duration of winds will make trees very susceptible to either being uprooted or damaged. If a direct hit from a category 1 hurricane occurs the power infrastructure will suffer a devastating blow in many areas with power outages likely lasting for a week or longer.
Storm Surge: Tides are astronomically high on Sunday because of the new moon and in many cases will already be running a foot above normal. With the unusually long duration of winds the tidal piling into the sound will be substantial. Unless the track forecast varies significantly (which is still possible) we should prepare for a category higher of storm surge than would typically be expected from a cat 1 or 2 due to the aforementioned issues. I can’t emphasize enough the possible severe tidal flooding in the Sound given the unusually high tides and unusually long duration of the winds. We may get lucky and get this thing in here during low tide but we can’t count on that!
Flooding: At this point the fresh water flooding risk may be reduced somewhat by a track of the storm over western Connecticut. When hurricanes reach our latitude the distribution of precipitation becomes lopsided and the heaviest rain occurs west of the storm track. Up to 15″ of rain is possible west of the storm track but it’s unclear if that will be over the Litchfield Hills or over the Catskills. If you’re in an area on a river or stream that normally floods be prepared to move fast if waters rise.
Evacuations: If you’re asked to move… move! Even if Long Island Sound didn’t flood your neighborhood during Gloria this storm has the potential to produce a much higher surge. Remember that evacuations are for water and not for wind. Most people in the state won’t have to leave but some shoreline residents will. Be smart and use common sense.
Preparations: All preparations (and evacuations) should be completed by nightfall on Saturday. It looks like tropical storm force conditions will begin by Sunday morning. Hurricane conditions could develop by midday or afternoon. Prepare to be without power for a week and think of what you’ll eat, how you’ll cook, and what you’ll do during that week. Flashlights, batteries, water, games, etc. are all important things to have. Use common sense and discuss a plan with your family so you can take steps now to prepare.