Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Juan PR
529 am AST Sat Dec 7 2013
Synopsis...surface high pressure will remain across the Atlantic
to the north northeast of the local islands through early next
week...maintaining windy conditions through the weekend and into
early next week. Middle to upper low will retrogress into the
Caribbean waters and meander over that area through early next
week. Good moisture will remain over the islands through the
weekend causing showers across the U.S. Virgin Islands as well as
north and eastern Puerto Rico this weekend.
Discussion...shower activity has gradually increased across the
local waters through the overnight hours. This shower activity is
expected to continue affecting the local waters and gradually
become more persistent across the islands as well through the day.
Latest guidance suggests that the USVI as well as northern and
eastern PR may observe scattered to numerous showers with isolated
thunderstorms today as these showers...associated with the middle to
upper low and the available moisture...continue to move west and
into our area today. By late this afternoon and into this
evening...the shower activity over land areas is expected to
diminish somewhat but still scattered showers are
expected...across many sectors in our forecast area.
Unsettled weather with scattered showers is once again expected
for Sunday. For Sunday night into Monday...shower activity should
be mostly across the Caribbean waters with much drier air to the
immediate north of the local islands according to the GFS model.
Aviation...periods of MVFR conditions and mountain obscurations
will remain possible today in and around tjsj/tist/tisx and
tncm/tkpk in rain showers and isolated thunderstorms and rain. Elsewhere...mostly VFR
conds expected. Main concern will be strong NE winds 20-25 kts.
Marine...seas will continue to deteriorate today as northeasterly
swell invades the local waters and winds continue to increase.
This will cause seas of up to 8 feet across most of the local
waters by tonight. Currently...buoy 41053 just north of San
Juan...is reporting seas of over 6 feet. Buoy 41043 in the
Atlantic...just under 200 miles north-northeast of San Juan is
reporting seas of over 10 feet. The period is fairly
short...around 8 to 9 seconds so at this time it does not meet
high surf advisory criteria.
Preliminary point temps/pops...
sju 83 73 82 74 / 60 40 0 10
stt 85 75 86 76 / 60 30 0 10
coastal waters...Small Craft Advisory until 2 am AST Tuesday for Atlantic waters of
Puerto Rico and USVI from 10nm to 19.5n-coastal waters of
northern Puerto Rico out 10 nm-coastal waters of northern
USVI and Culebra out 10 nm-coastal waters of northwestern
Puerto Rico out 10 nm-Mona Passage southward to 17n.
Small Craft Advisory from 9 am this morning to 2 am AST Tuesday
for Anegada Passage southward to 17n-Caribbean waters of
Puerto Rico from 10 nm to 17n-coastal waters of southern
USVI Vieques and eastern Puerto Rico out 10 nm.
Small Craft Advisory from 3 PM this afternoon to 2 am AST
Tuesday for coastal waters of southern Puerto Rico out 10