Tropical Storm Danny is one of those systems that could have or not have been declared tropical at the flip of a coin. There are reasons to say it’s not tropical and there are reasons to say it is. Nonetheless, the NHC upgraded the system yesterday and the storm is continuing to struggle as of this morning. It’s unclear of Danny will take on a resemblance to Bill – a well-organized system (Danny will never be as strong as Bill – fact) or will Danny take on more of a resemblance to Ana – struggling daily with the environment around it. If you’re a gambler, pick the latter. Danny’s in trouble.Though Danny does have a closed surface circulation as evidenced by the QuickSCAT image below, it is at a bare minimum and Danny is currently closer to being a tropical wave than a tropical storm. This earlier QuickSCAT pass recorded two rain-contaminated areas of 50kt winds over 100 miles from the center of circulation. This is in the heavier convection which is also well away from the center. Nearer the center the highest surface winds are about 20kts. Even the National Hurricane Center noted this is not a typical tropical cyclone structure.
Tropical Storm Danny QuickSCAT - Aug 27, 2009
Tropical Storm Danny Ship Obs - Aug 27, 2009 courtesy CIMSS
As mentioned, the heaviest convection is off to the northwest of the center. Danny has made several attempts at reforming it’s center beneath the convection but still hasn’t quite accomplished this task. Currently, Danny is in an area of relatively weak wind shear but this is expected to turn for the worse in the next day or so. While several models are emphatic about Danny having hurricane-force winds by the end of this week, the NHC questions whether those winds are from Danny itself or as a result of tight pressure gradients between Danny, the high to the east and a trough to the east. Especially as Danny picks up forward speed going into the weekend, hurricane-force conditions may be felt but not entirely attributable to Danny.
Tropical Storm Danny IR Enhanced - Aug 27, 2008 - courtesy CIMSS
Tropical Storm Danny Shear/SST Map - Aug 27, 2009 courtesy CIMSS
The official forecast has shifted east with the NHC now thinking Danny won’t make landfall until it gets near Nova Scotia or Newfoundland – if at all. However, the NHC also cautions that any slight deviations in the forecast track or additional relocations of Danny’s center can adjust the forecast track either way. Essentially, residents all along the mid-Atlantic and New England coasts should be prepared for a potential landfalling hurricane.
Tropical Storm Danny Forecast #4
This forecast track is generally inline with the GFS, GFDL, HWRF and UKMET for now. The CMC is a bit further west calling for two landfalls – one over the Outer Banks and the second of a much stronger hurricane over Long Island/Massachusettes.
Tropical Storm Danny - CMC 60HR Model Forecast - Aug 27, 2009 0Z courtesy FSU
Meanwhile, Ignacio is still considered a tropical cyclone (depression) but has lost most of it’s convections with little flare-ups here and there. Advisories will be discontinued later today.
