Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 241549
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
1149 AM AST Tue Jan 24 2017

.DISCUSSION...
Warmer conditions are still expected mainly across the northern
half of Puerto Rico as southerly winds will prevail through the
afternoon hours. A frontal boundary across the northern Bahamas
should approach the local Atlantic waters later tonight or early
Wednesday morning and this could bring an increase in clouds and
showers.

&&

.AVIATION...VFR conditions will continue to prevail across all
terminals through 25/12z. Light southerly or variable winds
expected morning, becoming mostly S-SW at 5-10 kts aft 16z.


&&

.MARINE...North northeast swell continue to affect the local
Atlantic waters and passages. Small craft operators should
exercise caution as seas are between 4 to 6 feet and winds up to
20 knots. A higher northwesterly swell is expected to invade the
local waters by Wednesday night, causing an increase in seas and
possibly meeting small craft advisory criteria. There is a high
risk of rip currents today for the north and northwest coast of PR
and Culebrita beach in Culebra.


&&

.PREV DISCUSSION... /issued 434 AM AST Tue Jan 24 2017/

SYNOPSIS...Surface low across the western Atlantic will promote
a light to moderate southerly wind flow today, then a surface high
moves in just north of the local islands, shifting winds to a
northerly direction on Wednesday. Relatively dry air expected
today with an increase in moisture mainly for the USVI. Upper
trough developing to our west by Wednesday. Slightly warmer than
normal daytime temps expected today across the San Juan area and
other portions of the northern half of PR due to dry air and
southerly winds.

DISCUSSION...Fair weather prevailed overnight across the local
area with a light and variable wind and variably cloudy skies.
Overnight temperatures dipped into the mid 60s to lower 70s
across the lower elevations and around 60 to the mid 60s across
the higher elevations. For today, we can expect southerly winds
once again and therefore warmer than normal temperatures for
portions of the northern coastal municipalities of PR including
the San Juan Metro Area, where temperatures are expected to reach
the upper 80s today. The rest of the local area should remain with
temps in the low to mid 80s. Very little shower activity is
expected today since the airmass is relatively dry, however there
is some moisture moving in from the south but it appears that it
will stay over the USVI briefly then move away. This may cause
isolated showers in the afternoon and then scattered showers
tonight around the local waters and particularly just to the east
of the USVI.

Surface low across the western Atlantic is causing the southerly
wind flow today, then there is a SFC high that will move over the
Bahamas on Wednesday. This will cause winds to shift direction
from southerly to westerly late tonight into Wednesday morning
then to northerly winds on Wednesday afternoon. This rare wind
shift for our area will also bring a patch of moisture on
Wednesday, which means that scattered showers are expected across
the local waters tonight into Wednesday morning then scattered
showers expected across the northern USVI and the northern half of
PR. However, the accumulations are expected to be modest.

For the latter part of the week, the light to moderate winds will
be from the NE on Thursday and mainly easterly by Friday.
Relatively dry airmass to prevail on those days as well so the
shower activity is expected to be minimal. In fact, predominantly
fair weather, with brief moments of clouds and showers, is
expected into the weekend.

AVIATION...VFR conditions will continue to prevail across all
terminals through 24/24z. Light southerly or variable winds expected
early this morning, becoming mostly S-SW at 5-10 kts aft 14z.

MARINE...North northeast swell continue to affect the local
Atlantic waters and passages. Small craft operators should
exercise caution as seas are between 4 to 6 feet and winds up to
20 knots. A slightly stronger northwesterly swell is expected to
invade the local waters by Wednesday night, causing an increase in
seas and possibly meeting small craft advisory criteria. There is
a high risk of rip currents today for the north and northwest
coast of PR and Culebrita beach in Culebra.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  88  75  82  72 /  20  20  30  30
STT  83  74  81  72 /  20  20  30  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk until 6 PM AST this evening for Culebra-
     Mayaguez and Vicinity-North Central-Northeast-Northwest-San
     Juan and Vicinity-Southeast-Western Interior.

VI...None.
AM...None.
&&

$$

10/72



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