Area Forecast Discussion
Issued by NWS San Juan, PR
FXCA62 TJSJ 011727
Area Forecast Discussion
National Weather Service San Juan PR
127 PM AST SAT OCT 1 2016
.SYNOPSIS...Surface high pressure centered in the northern
Atlantic will maintain an easterly wind flow through the rest of
weekend across the region. The winds are expected to become more
southerly early in the week as Hurricane Matthew moves northward
over the Bahamas. The moisture advecting over Hurricane Matthew
will have an impact on the local weather early next week.
.DISCUSSION...Doppler radar indicated scattered to numerous trade
wind showers across the surrounding coastal waters, the USVI,
Vieques, Culebra as well as across most sections of Puerto Rico
this afternoon. Few thunderstorms were also developed across
western and interior sections of Puerto Rico by mid afternoon.
This activity was associated with the moisture left behind
Hurricane Matthew, currently about 365 miles SSW of Port Au Prince
Haiti, is expected to move north tonight and Sunday. As this
happens the local low level wind flow will become more from the
south in association with the outer circulation of Matthew. This
humid southerly wind flow will bring deep tropical moisture across
the forecast area starting on Sunday and continuing until the
middle of the week. A slight shift to the right of the projected
path of Matthew will bring more moisture influx across the region.
An increase in showers and thunderstorms are expected across
interior and northern sections of Puerto Rico early next week. As
of now, the days with the moist amount of moisture appears to be
Monday and Tuesday. The GFS model guidance suggests PWAT values
of around 2.10 inches on Monday increasing to around 2.25 inches
Monday afternoon, decreasing again to around 2.10 by Tuesday.
.AVIATION...Trade wind showers with tops around FL200 will
continue across the local waters with VCSH/-RA across the leeward
islands, USVI and eastern PR terminals through this evening.
TSRA/SHRA will continue to affect the western interior portions
of PR with few tempo MVFR conditions mainly over TJMZ/TJBQ until
01/22Z. Low level winds will remain E-ESE at 10-15 kt overnight
increasing to 15 to 20 after 02/14Z.
.MARINE...Seas up to 6 feet and winds up to 20 knots will continue
across most of the local waters tonight and Sunday. Small craft
should exercise caution. Moderate risk of rip currents will
continue for most of the local beaches.
.PRELIMINARY POINT TEMPS/POPS...
SJU 78 89 79 90 / 10 20 10 50
STT 79 88 79 88 / 10 10 30 30