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Fred is born; storm surge survival misconceptions

By: Dr. Jeff Masters, 1:29 PM GMT on September 08, 2009

Tropical Storm Fred sprang to life yesterday off the coast of Africa, but is not a threat to any land areas for at least the next week. Satellite imagery from the European satellite shows a well-organized circulation with plenty of low-level spiral bands and high cirrus clouds streaming away from the storm at high levels, indicating good upper level outflow. There is dry air of the Saharan Air Layer to the north of Fred, but it is far enough away so as not to be a major impediment to development. Wind shear is moderate, 10 - 15 knots, and ocean temperatures are 1 - 2°C above the threshold needed for tropical cyclone formation.

Figure 1. Morning satellite image of Fred, off the coast of Africa. Note the layer of low stratocumulus clouds to Fred's north, a sign of relatively dry, stable air there.

The forecast for Fred
Wind shear this afternoon is expected to drop to the low range, 5 - 10 knots, and continue to remain low until Thursday morning, when it will rise to the moderate range again. Given Fred's current improving appearance, the storm should be able to attain hurricane status by Thursday. At that time, a strong trough of low pressure traversing the North Atlantic will bring higher shear, weakening the storm. The trough will also pull Fred to the northwest and then north. Most of the models foresee that this trough will not be strong enough to fully recurve Fred to the northeast and out to sea. However, with the steering pattern for this year continuing to feature plenty of deep troughs of low pressure moving off the U.S. East Coast, the odds of Fred making it all the way across the Atlantic to threaten land areas appear low at this time.

Elsewhere in the tropics
An area of concentrated thunderstorms has developed off the North Carolina coast in association with the remains of an old cold front. This system is under about 20 - 30 knots of shear, and is not tropical. However, it will bring heavy rain to eastern North Carolina and Virginia today and Wednesday, as the storm slides north-northeastward along the coast.

A strong low pressure system is expected to move into the central U.S. by this weekend, dragging a cold front into the western Gulf of Mexico. In several of their runs over the past few days, the GFS and ECMWF models have been predicting a tropical system may develop along this front in the western Gulf of Mexico by Sunday or Monday. The latest GFS phase space analysis of the predicted storm confirms that this would be a tropical cyclone, and not extratropical. There is currently not an area of disturbed weather in the Gulf, but we will have to keep an eye out there beginning this weekend, when the front moves offshore.

I'll have an update Wednesday, when I'll also announce the release of wunderground's excellent new series of storm surge pages. The new storm surge section provides more than 500 detailed, zoomed-in storm surge maps from the official storm surge model used by the National Hurricane Center--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The Weather Underground has created SLOSH model worst-case flood maps for Category 1, 2, 3, 4, and 5 hurricanes for the entire U.S. Atlantic coast, plus Hawaii, Puerto Rico, the Virgin Islands, and the Bahamas. Zoom-in maps of fifteen important cities such as Miami, New York City, Boston, Tampa, and Corpus Christi are included. To help coastal residents see how past storms have affected their region, the wunderground storm surge pages also include SLOSH model animations of the surge for more than 30 historic storms--from the Great Colonial Hurricane of 1635 to Hurricane Ike of 2008. Included here is one section from the new storm surge pages, "Storm Surge Survival Misconceptions".

Storm Surge Survival Misconceptions
The storm surge is usually the most dangerous threat of a hurricane. The ten deadliest U.S. hurricane disasters, including the Galveston Hurricane of 1900 (8000 killed), the Lake Okeechobee Hurricane of 1928 (2500 killed), and Hurricane Katrina of 2005 (1833 killed), were all primarily storm surge disasters. The Biloxi-Gulfport Sun Herald ran a series of stories in 2005 on people who were lucky enough to survive Hurricane Katrina's record storm surge. There were some common misconceptions that were touched on in these stories, and are reproduced here from Margie's Kieper's blog on the Hurricane Katrina storm surge.

Figure 2. A man wearing a tiny life jacket and clutching a neon green noodle and a pet dog floats on the remains of a house in Waveland, MS, during Hurricane Katrina. The photo was taken from the second floor window of a home, and the water is close to the roof line of the first floor. The home was at an elevation of about 17 feet, and the surge is close to ten feet deep here. There are electric lines running down from a pole to a home from left to right. In the distance on the right is a home with water up to the roof line. The eye is probably overhead, as the water is relatively calm and there appears to be little wind or rain, even though the pine trees are bent from the recent force of the eyewall winds. The photo was taken by Judith Bradford. Her husband, Bill Bradford, swam out and rescued the man and his dog, and two other people who floated by. He reported that the water was nothing like white water, but was a gentle, continuous flow. He was lucky. In the nearby Porteaux Bay area, a woman watched her fiance get pulled from a tree by the force of the current. The man was washed out into the Gulf and drowned. The image above is described in more detail on Margie Kieper's Katrina storm surge web page.

Misconception: Call 911 and you can be rescued, while the water is pouring into your home.
How? No one will be able to get to you. Water rises quickly--sometimes six to ten feet within minutes; cars can't drive in it, and it is usually unnavigable by boats when it is coming ashore.

Misconception: Just stuff towels under the door jambs. Then rush around to start picking up things that are close to floor level, so you can save them.
Bad idea. In a minute or so the surge will burst open the door, and instead of standing in a room with four inches of water, you'll be knocked off your feet and into whatever piece of furniture is closest, and will suddenly be in three or four feet of moving water that you can't make any headway into...just before the refrigerator, quickly rushing through the water towards you, knocks you cold.

Misconception: You'll be able to maneuver around in the rushing water.
Probably not. Some people who drowned were not even able to get out of the room they were in, when the water started pouring into the home. The speed of water in surge can be equivalent to a Class III or IV rapids (Class V is hardly navigable by expert kayakers and canoers, and Class VI is not navigable at all).

Misconception: You'll know in time.
The surge is usually not a wall of water as is often assumed, but rather a rapid rise of water of several feet over a period of minutes. It can sneak in unexpectedly, on little cat feet. Most people that were not completely taken by surprise simply happened to look out the window at the right time.

Misconception: You can outrun the storm surge in your car.
Here's an email I got last year from a resident in the Florida Keys who ignored the evacuation order for Hurricane Ike in 2008: I hate to bother you again, but we live on Marathon in the Florida Keys on the Atlantic side, and my husband says that if we see water coming up from storm surge and have an inch of water in our house, that we can outrun the storm surge in our car. Can you please tell me if there is any way this can possibly be true? P.S., I don't know of anyone who lives down here who is planning on evacuating for Ike. Everyone says they are staying. If you wait until the water is an inch high before trying to outrun the surge, the odds are that the surge will rise to over a foot high before you get your car out of the driveway. If the water is a foot high, the typical 10 - 15 mph speed of the storm surge's current has enough force to sweep a car away. In many places along the coast, there is only one road out of a low-lying region prone to storm surges, and the surge will cut off one's only escape route. The Keys have only one road, and the storm surge will likely be moving perpendicular to the road, cutting off the only escape route. One of these days, there are going to be a lot of people who fail to evacuate caught and killed in the Keys by the storm surge from a major hurricane.

How to Survive a Storm Surge
People who survived Katrina's storm surge did one of several things: they floated out an open window, and managed to hang onto debris, a tree, or some other structure above the water, until the surge receded, hours later. Or, they were able to pull themselves into an attic, or make it up to a second floor, where water did not reach, and luckily the home was not swept away. It is common in many flood-prone regions behind levees to keep an axe fastened to the wall of the attic. Then, if water comes in unexpectedly, you can get into the attic and chop a hole through the roof to escape. Don't forget to keep a length of rope there that you can use to tie yourself to a sturdy part of the house (don't tie yourself to the steel beams of the house, as these will sink).

The best way to survive a storm surge is to heed evacuation orders and leave before the surge arrives!

Storm Surge Safety Actions
- Minimize the distance you must travel to reach a safe location; the further you drive the higher the likelihood of encountering traffic congestion and other problems on the roadways.

- Select the nearest possible evacuation destination, preferably within your local area, and map out your route. Do not get on the road without a planned route, or a place to go.

- Choose the home of the closest friend or relative outside a designated evacuation zone and discuss your plan with them before hurricane season.

- You may also choose a hotel/motel outside of the vulnerable area.

- If neither of these options is available, consider the closest possible public shelter, preferably within your local area.

- Use the evacuation routes designated by authorities and, if possible, become familiar with your route by driving it before an evacuation order is issued.

- Contact your local emergency management office to register or get information regarding anyone in your household whom may require special assistance in order to evacuate.

- Prepare a separate pet plan; most public shelters do not accept pets.

- Prepare your home prior to leaving by boarding up doors and windows, securing or moving indoors all yard objects, and turning off all utilities.

- Before leaving, fill your car with gas and withdraw extra money from the ATM.

- Take all prescription medicines and special medical items, such as glasses and diapers.

- If your family evacuation plan includes an RV, boat or trailer, leave early. Do not wait until the evacuation order or exodus is well underway to start your trip.

- If you live in an evacuation zone and are ordered to evacuate by state or local officials, do so as quickly as possible. Do not wait or delay your departure, to do so will only increase your chances of being stuck in traffic, or even worse, not being able to get out at all.

- Expect traffic congestion and delays during evacuations. Expect and plan for significantly longer travel times than normal to reach your family's intended destination.

- Stay tuned to a local radio or television station and listen carefully for any advisories or specific instructions from local officials. Monitor your NOAA Weather Radio.

Source: NOAA

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.