Bermuda is stuck in a stream of moisture, this moisture is set to be in the picture in some form for at least the next three days! Both small and large scale forecast models show between 1-3″ of rain falling over this period – definitely going to help fill up our tanks, and help keep the vegetation looking fresh and green. Mid and upper level moisture has its origins in the Eastern Pacific through the sub-tropical jet stream, while low and mid level moisture is coming from the Central Atlantic and Caribbean – so there is a huge source region for this event.
A complex of surface and upper atmospheric low pressures (including the small and weak Tropical Storm Alberto) over the western Atlantic have been cut off from any significant steering currents for days, allowing copious amounts of moisture to pile up in the western Atlantic. This plume of convection has been streaming northwards for days and has finally inched its way eastwards enough to share its precipitation with Bermuda.
Unfortunately, rain is in the forecast for the 24th of May Bermuda Day holiday, so it may ruin some plans. Overall, the rain should be beneficial. As of May 20th, Bermuda was still about 10inches below average for the year, on top of ending 2011 over 16inches below average. 2012 marks the third year in a row of unusually dry conditions.