Area Forecast Discussion
Issued by NWS San Juan, PR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
FXCA62 TJSJ 260135

Area Forecast Discussion
National Weather Service San Juan PR
935 PM AST Thu May 25 2017

.UPDATE...A few light showers persisted across western PR through
the early evening hours. While isolated showers from streamers
from the northern USVI made it inland across Culebra and eastern
PR. Also, light trade wind showers were noted over the Caribbean
waters and over portions of St. Croix. However, no significant
rainfall accumulation`s were observed. Overall, fair weather
conditions should prevail overnight with a few showers moving from
time to time across the USVI/eastern portions of PR. Minor changes
were made to short term grids.


.AVIATION...Mainly VFR across all terminals through the forecast
period. Light trade wind showers could briefly affect the
Leeward/USVI/Eastern PR terminals through early Friday morning.
HZ due to Saharan dust will continue but VSBY P6SM. Latest 26/00z
TJSJ upper air sounding indicated E winds below FL100 at 7-20
kts...bcmg N above.


.MARINE...No change from previous discussion. High rip current
risk continues overnight across the northwest to north central
coast of PR. Moderate risk of rip currents expected on Friday
across much of the beaches of the islands.


.PREV DISCUSSION... /issued 449 PM AST Thu May 25 2017/

SHORT TERM...Today through Saturday...
Mostly sunny and hazy skies prevailed across the region once again
today. Only a few light showers were noted over the west interior
of Puerto Rico during the late afternoon hours. However, the activity
was of short duration. Expect mostly clear skies during the overnight
hours with little or no measurable precipitation expected across the
forecast area.

A very dry and stable airmass will continue to dominate the local
region for the next few days as a strong low to mid level ridge
will dominate the region. Saharan dust will continue across the
region during the rest of the evening but lesser concentrations is
expected during the next few days. An east to southeast wind flow
will prevail through Saturday promoting near or slightly above normal
temperatures along the northern slopes of Puerto Rico. Elsewhere temperatures
will be near normal. On Friday, the upper level ridge will gradually
erode allowing for a slight increase in low level moisture transport
through Saturday. This should allow a better chance for early morning
showers followed by some afternoon showers and possibly isolated thunderstorm
development mainly over the interior and west sections of Puerto Rico.

LONG TERM...Sunday through Friday...
An upper level low and an associated trough just east northeast of the
region is forecast to retrogress north northwest across the area
while weakening Sunday through Monday. However, another short wave
trough is expected to develop and move across the southwestern Atlantic
and reinforce the previously mentioned lingering trough. Surface
high pressure across the central Atlantic is forecast to maintain
moderate trade winds across the region through early. However,
winds are to become east to northeast by mid week and once again
east southeast for the rest of the period. All in all, expect
relatively dry weather pattern across the local islands during
most of the weekend with typical diurnally and locally induced
afternoon convection mainly over parts of the interior and west
sections of Puerto Rico. A tropical wave is still forecast to
approach to the Lesser Antilles Sunday and Monday and move across
the eastern Caribbean Tuesday through Wednesday. This feature in
combination with the proximity of an upper trough should bring an
increase in tropical moisture transport and consequently increase
the chance for showers and thunderstorms over the local islands
and surrounding waters early next week.

AVIATION...Suspended saharan dust will result in slight Hz with
slant VSBY btwn 6-9 nm durg prd. Some SHRA/-SHRA are possible in
the VCTY of TJMZ btwn 25/18-23z, then VFR conditions will prevail
during the next 24 hours. Surface winds E-ESE at 10-20 knots with
higher gusts. Light and variable overnight.

MARINE...A northerly swell at 3 to 5 feet continued to move across
the local Atlantic waters. This swell will continue to subside
during the rest of the evening hours. The nearshore buoys
continued to suggests easterly winds at 15 to 20 knots. Mariners
can therefore expect seas between 3 and 6 feet and winds at 15
knots or less.


SJU  78  89  77  89 /  10  40  40  40
STT  78  87  77  88 /  10  40  40  40


PR...High Rip Current Risk until 6 AM AST Friday for North Central-
     Northwest-Western Interior.



LONG TERM....RAM is the U.S. government's official web portal to all federal, state and local government web resources and services.