Monday, August 17, 2009

HE'S GOT THE LOOK

Hurricane Bill 5:00 PM EDT 8-17-09

6:00 pm MONDAY, 8-17-09 This headline is a slight take-off of the 1988 pop hit "She's Got The Look" by the artist/group Roxette, but I think we can all agree Bill is starting to get "the look" himself. Recent NOAA satellite scans this afternoon suggest the hurricane is starting an eye-wall replacement cycle (ERC) which is usually followed by rapid intensification. Category 3 status seems very likely in 24 hours or less. All those with weekend plans for the coasts of the Carolinas, DelMarVa or New Jersey may be faced with a lot of unexpected beach closures. Yes, I know some of you made a deposit on that beachfront rental back last October. But Mother Nature is probably going to beat the Route 50 Bay bridge traffic Friday afternoon, and be waiting for you just across the dunes with a little surprise in big red letters: BEACH CLOSED.

AND SO IT BEGINS...

7:00 am MONDAY, 8-17-09 With a rush of headlines and three storms forming in two days, it's apparent the Atlantic basin has awoken from a long summer slumber. The real questions for tropical watchers are simple:


1. Does Hurricane Bill pose a threat to the East Coast?
Early indications of the projected path suggest that Bermuda may feel more direct effects from this storm, whereas the US East Coast could experience several days of dangerous rip currents.


This week, two upper level features will be of primary influence to Bill's track: The 500 millibar Atlantic Ridge as shown on this forecast map from the Ocean Prediction Center (OPC), and an upper level trough sliding across the central US. While the hurricane travels around the southern pheriphery of the Atlantic ridge, it will enter a confluence zone created by the clockwise flow around that ridge, and the counter-clockwise southerly flow generated by the trough. The combined effect of these two features is likely to veer Bill from the current westerly track to more northwest as shown in the NHC graphic, and eventually north-northwest by the weekend. This expected turn is also reflected in the tropical cyclone early-track guidance provided by Colorado State University and depicted on the interactive site StormPulse.com. Based on this analysis, some media forecasters suggest that Bermuda is more likely to experience effects of this storm.


References:
Kimberlain (2009): Hurricane Bill Discussion 8 from National Hurricance Center's 500 AM EDT 8-17-2009 update. Retrieved August 17, 2009 from http://www.nhc.noaa.gov


By Friday, rip currents and swells will increase along the southeast coast, and by Saturday affect the entire Eastern seaboard from Florida to Maine. This will pose a significant hazard to swimmers, beachgoers and lifeguards. You can monitor the progress of swell heights with the OPC's Wind/Wave Analysis. Hopefully local and national media will convey the shoreline's hidden dangers enhanced by a passing hurricane. Of particular concern will be ocean-going cruises departing from or returning to East coast ports. If you are among those hopeful travelers, be prepared for changes in the itinerary, or at least be cautious in how much you consume at the dining hall! (I assume you understand the connection.)


2. Do these storms signal the start of an active period heading into September and the all-important Labor Day Weekend? As you can plainly see from the StormPulse visible satellite image below, a series of tropical waves is in the queue ready to keep forecasters busy for at least the next 2 weeks.

African Waves 8-17-09


Answers to those in addition to your questions will be posted in the next day or two.

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