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Kyle not strengthening

By: Dr. Jeff Masters, 8:31 PM GMT on September 26, 2008

Tropical Storm Kyle continues to struggle with wind shear as it heads northwards towards Nova Scotia, Canada. Visible satellite loops show little change in the appearance of Kyle today, and wind shear of 15-20 knots is keeping any heavy thunderstorm activity from developing on Kyle's west side. Unless the shear relaxes, allowing Kyle's heavy thunderstorms to wrap all the way around the center, intensification into a hurricane will be difficult.The Hurricane Hunters measured top surface winds around 55 mph so far this afternoon, and Kyle's central pressure was a rather high 1003 mb at the 3:33 pm EDT center fix.


Figure 1. Current satellite image of Kyle.

The forecast
Wind shear is forecast to change little over the next 36 hours. This gives Kyle some time to intensify into a Category 1 hurricane, which the GFDL and HWRF models have been consistently predicting will happen. However, given the storm's current struggle to organize, I doubt Kyle will ever attain hurricane strength. By Saturday night, wind shear is forecast to increase to 25-35 knots, and the sea surface temperatures plunge from 26°C Saturday night to 13°C Sunday night. If, as I expect, Kyle is still a sheared 50-60 mph tropical storm at that point, it will probably decay to a 40 mph tropical storm by landfall. The latest strongest Kyle is likely to be at landfall is a 60 mph tropical storm, as predicted by the 12Z (8 am EDT) run of the GFDL model.

Storm surge should not be a major issue with Kyle. If it makes landfall in the Maine/New Brunswick region as a Category 1 hurricane, it would likely generate a storm surge in the 3-5 foot range, according to NOAA's SLOSH model. Given that the range between low tide and high tide is at least 12 feet in the region, Kyle would have to hit very close to high tide to cause any storm surge flooding. Kyle's likely impact as a tropical storm makes surge flooding problems improbable. Hurricane Edna of 1954, which hit just west of Eastport, Maine, as a Category 1 hurricane with 90 mph winds, generated a storm surge of just 3.4 feet at Eastport. If Kyle hits Nova Scotia as a Category 1 hurricane or tropical storm, a storm surge of 1-3 feet is likely. Hurricane Juan of 2003, which hit Halifax, Nova Scotia as a Category 2 hurricane with 100 mph winds, generated a storm surge of 4.9 feet in Halifax.

Kyle's cone of uncertainty covers the eastern coast of Maine and the western half of the coast of Nova Scotia. Recent model runs have trended to take Kyle a little more to the east, over Nova Scotia. This province will probably get Kyle's worst winds and rain, since wind shear is keeping Kyle's heaviest thunderstorms on the east side of the storm. My best guess is a landfall in western Nova Scotia as a tropical storm with 40-45 mph winds. According to the forecast wind radius images from NHC, tropical storm force winds of 39 mph and higher will miss Massachusetts, but may affect eastern Maine. Tropical storm force winds are also expected to miss Bermuda. (Use the wundermap with "wind radius" turned on to see the expected radius of tropical storm force winds).

Kyle's main threat is heavy rain. Kyle's rains will primarily affect Nova Scotia and New Brunswick at landfall on Monday morning. However, Kyle should pull copious amounts of tropical moisture and the remains of the unnamed storm that hit South Carolina last night northwards into Canada and northern New England. This will create potential serious flooding problems early next week in the region. NOAA is forecasting up to eight inches of rain could fall in New England over the next five days (Figure 2). The latest 12Z (8 am EDT) UKMET model run is forecasting that Kyle will stall after landfall. If this forecast verifies, there is the possibility that extremely heavy rains in excess of twelve inches will fall over northern New England, New Brunswick, and Nova Scotia next week. Near-record flooding with heavy damage would likely result. However, the other models do not go along with this scenario, and rain amounts in the 6-8 inch range are more likely for northern New England, New Brunswick, and Nova Scotia.


Figure 2. Forecast rain amounts for the 5-day period ending 8 am Wednesday 10/1/08. Image credit: NOAA/HPC.

Middle Atlantic disturbance
An area of disturbed weather in the middle Atlantic, near 12N 42W, has changed little today. This morning's QuikSCAT pass showed an elongated surface circulation and top winds in the 20-30 mph range. Wind shear is 10-20 knots, but is expected to increase to 20-30 knots Saturday and increase further on Sunday, which should destroy the struggling circulation. NHC is giving this system a low (<20% chance) of developing into a tropical depression by Sunday.

Gulf of Mexico disturbance may threaten western Florida next week
An area of disturbed weather in the southern Gulf of Mexico, just west of Mexico's Yucatan Peninsula, has changed little today. Visible satellite images show a modest-sized area of heavy thunderstorms moving east-southeast, towards the Yucatan Peninsula. Wind shear is about 15 knots over the region, which is marginal for development. The system should move ashore over the Yucatan Peninsula by Saturday before development into a tropical depression can occur. NHC is giving this system a low (<20% chance) of developing into a tropical depression by Sunday. Early next week, we will have to watch the waters on either side of the Yucatan for possible development of this system. Some of the models are predicting that a tropical depression could form off the coast of the Yucatan Peninsula early next week, then move northeastwards to a landfall in western Florida as early as Wednesday.

The Hurricane Ike relief effort continues
Thanks to everyone who has contributed to the portlight.org charity! We raised enough money to send another truck with relief supplies to Winnie and Bridge City, Texas, where traditional relief efforts have fallen short. Wunderground member Presslord (AKA Paul Timmons, Jr.), who is coordinating this effort, has announced that if we raise an additional $10,000 mark, he will pose in a dress for our wunderphoto gallery. We're up to $2500 so far.


Figure 3. The town of Bridge City was inundated with a massive storm surge even though it was far displaced from Ike's landfall point. This speaks to just how massive Ike was. The people of Bridge City, Winnie, and other small towns in Ike's path will need help for a long time to come: www.portlight.org. Image credit: Storm Junkie.

You can read more about the effort at at stormjunkie's blog.

Jeff Masters
Nor' Easter on the Outer Banks, Kitty Hawk, NC
Nor' Easter on the Outer Banks, Kitty Hawk, NC
Unnamed northeastern storm in Kitty Hawk, NC about one hour after high tide.

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