Danny hangs on by a nail, begins northward motion
August 28, 2009
Tropical Storm Danny has begun its northward motion based on the latest reconnaissance. Winds have dipped in many areas of the storm, however one region did record sustained winds of 40-45 mph, thus holding on to the “tropical storm” designation.
Danny may strengthen slightly as it moves under an area of moderate upper level convergence over the next 24 hours. However the system will then encounter strong shear associated with a surface front measuring around 35 knots, which will eventually convert Danny to an extra-tropical system at roughly 36 hours.
The chance of the east coast experiencing sustained tropical storm forced winds (35+ mph) is relatively low at this time.
You can see from the image below from Wunderblog just how much the storm has struggled with the shear affecting the convection. The areas of heaviest activity are well east of the central rotation, which has caused multiple reformations thus far.
Danny rests overnight, track shifts further east
August 28, 2009
Tropical Storm Danny continues to exhibit strange behavior and shape, but aircraft recon is still recording sustained winds around 40 mph in the strongest quadrants to the East of the low pressure center. Significant wind shear has kept most of the convection from forming around the low and hindered possible strengthening overnight.
Danny will encounter an upper level ridge which should provide enough stability to increase winds to 50 mph over the next 24 hours. However a deep surface trough will begin to overtake the storm and its forward, or rather northeastward motion will pick up speed.
Tropical Storm Watches remain in effect for the Outer Banks, but the probability of experiencing TS winds is relatively low at 20-30%. The TS wind speed probabilities for Cape Hatteras have decreased a bit as well for the weekend. Rip tides will again be present, though the wave activity is not as large as Bill, which was a strong Cat-2 (and growing) at a similar latitude last week.
GOES Floater 090828 1145UTC
Slightly weaker Danny begins slow movement North
August 27, 2009
The most recent hurricane aircraft recon has indicated that the winds from Tropical Storm Danny have become somewhat better organized in the western front. However the overall max sustained winds have weakened slightly to 50 mph.
Satellite imagery shows a strong presence of dry air to the west of the system. This will hold Danny’s intensity steady over the next 24 hours. The system will then unite with an upper level high which will provide a small window for potential strengthening in 24 – 36 hours.
Although some models are in disagreement, most do not predict Danny to reach hurricane strength.
The NHC forecast track has not changed significantly, and Tropical Storm Watches have been issued for the Outer Banks of NC. The forecast still brings Danny to Cape Hatteras late Saturday afternoon.
Water Vapor Image -click for loop-
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Unusual Danny continues to gain steam
August 27, 2009
Tropical Storm Danny continues to strengthen with sustained winds up to 60 mph as of 5:00 AM Thursday morning. Danny is displaying some odd wind fields, with the strongest winds being observed well North and East of the central low.
Satellite imagery indicates heavy convection in this area, with good counter-clockwise flow at the upper levels in the NE and NW. There is still no clear central rotation at the lower levels.
Despite the odd current configuration, the NHC is still forecasting Danny to reach hurricane status early Saturday morning east of the Outer Banks
The system will then increase in forward speed as it turns north and encounters a strong cold front over the Eastern US.
JSL Satellite Image -click for loop-
Bill weakens, waves dont as storm heads to Nova Scotia
August 21, 2009
The latest guidance from the NHC shows Bill has weakened slightly to a strong Cat-2 hurricane after encountering some moderate shear. There is a good chance the system will reorganize as shear diminishes and hits warmer waters Friday. However the forecast shows Bill slowing to a weak Cat-2/strong Cat-1 as Saturday progresses.
The forecast models are in good agreement on the track, taking Bill due North Friday night, before making a NE turn into Sunday.
The greatest threat to the US will be in the form of coastal erosion as high seas will affect the eastern seaboard from Florida to Maine. The highest expected seas will occur near Cape Cod, which could experience 20′ waves. The threat from rip currents is moderate and expected to increase as Bill travels North.
We will continue to monitor the system and provide updates as necessary.
Bill Makes the Turn as a Strong Cat-3
August 20, 2009
Hurricane Bill is forecasted to track NW over the next 24 hours (early Friday morning), with a slight northward turn in the next 48 hours while maintaining sustained winds in excess of 111 mph (Cat-3).
The current National Hurricane Center’s 3-day forecast has Bill approximately 360 miles due-East of Delaware by early Sunday morning. However the system is forecasted to remain a category 3 storm through until Sunday where it will weaken due to cooler waters and increased shear velocity.
The forecast models are showing disagreement on where Bill will track in the coming days. Though most agree that Cape Cod will experience weak-to-tropical storm force (35+ mph) sustained winds over the weekend. Significant wave activity is also expected all along the Eastern Seaboard due to Bill’s immense size and strength.
The image below shows the AOML satellite-derived wind speeds as of 930 EST this morning. The HU strength wind radius has shrunk slightly, but should increase again today as the surrounding air warms.
AOML 8/20/09 1330 UTC Satellite Derived Winds
We will continue to monitor the situation and provide updates as necessary.
Claudette lands softly; Bill still Looming
August 17, 2009
Tropical Storm Claudette made landfall overnight with little affect on the Florida panhandle and Alabama coast. Sustained winds of 48 mph were recorded, with slightly higher gusts. The National Weather Service has not reported any major damage or flooding.
Meanwhile, Hurricane Bill continues to spin in the Atlantic just east of the Antilles. The NHC is forecasting winds to reach 110 knots (SS-3) by Thursday night. The forecast models have shifted the expected track slightly W/NW from yesterday’s runs.
Bill will be closely observed over the next few days to monitor forecast track and intensification.
Three’s Company; Ana, Bill, and Claudette
August 16, 2009
After a slow start, the 2009 Atlantic hurricane season has begun, and in grand fashion. On Saturday the 15th, the first and second tropical systems of the season, Ana and Bill, developed. By early Sunday morning, Claudette had strengthened from a depression to a tropical storm, and is making landfall along the Florida panhandle and Alabama coast.
The main threat from Claudette will be inland flooding, as 3 – 5 inches of precipitation are forecast with areas of heavier precip possible. Sustained winds around 6o mph are expected, with higher gusts also present.
Ana is weakening due to a strong influence from dry Saharan air. Organization is fading quickly and forecasters do not expect the storm to redevelop at this time.
Last, but far from least, is Tropical Storm Bill. Bill is likely to strengthen to a hurricane overnight, and reach “intense” status by Friday afternoon. The models are in good agreement over the next 3 days, but then diverge. A developing low pressure system over the US is expected to develop, and may steer Bill away from land. Model plot from Colorado State below shows the predicted tracks. These are used for guidance only and can quickly change with each run.
