Weather Nerd

T.S. Nana forms, but will be short-lived; Omar next?

The National Hurricane Center designated a disturbance in the Eastern Atlantic as Tropical Storm Nana Sunday afternoon — and immediately announced its imminent demise:

THE LONG-TERM SURVIVAL OF NANA SEEMS BLEAK AS STRONG UPPER-LEVEL WESTERLIES ARE FORECAST TO CONTINUE. ALL THE INTENSITY GUIDANCE SHOWS WEAKENING AND SO DOES THE OFFICIAL FORECAST. THE OFFICIAL FORECAST SHOWS NANA DEGENERATING INTO A REMNANT LOW IN ABOUT 48 HOURS…BUT IT WOULD NOT BE SURPRISING IF IT OCCURRED SOONER.

Alan Sullivan mocks the NHC’s decision as an example of count-padding. Whether he’s right about that is above my pay grade, but regardless, Nana is expected to weaken to a tropical depression or even a remnant low on Monday.

Meanwhile, Sullivan wonders whether the NHC will similarly designate the sheared disturbance in the Eastern Caribbean — currently “Invest 98L” — as Tropical Storm Omar tomorrow. Perhaps so; the Tropical Weather Outlook gives 98L a better than 50% chance of becoming a tropical depression in the next 48 hours.

Dr. Jeff Masters has a full update on both storms, albeit written Sunday afternoon when Nana was still “97L.”