Area Forecast Discussion
Issued by NWS San Juan, PR
FXCA62 TJSJ 221425
Area Forecast Discussion
National Weather Service San Juan PR
1025 AM AST Sat Oct 22 2016
.UPDATE...Stable weather conditions prevailed across the local
islands this morning as a ridge aloft remains over the region.
Doppler weather radar indicated only light isolated showers across
the surrounding coastal waters, but not precipitation was detected
over land areas. the limited low level moisture will combine with
daytime heating and local effects this afternoon to induce some
showers and a couple of thunderstorms over western interior and
northwest sections of Puerto Rico. This relatively dry weather
pattern is expected to persist until early next week.
.AVIATION...VFR conditions are expected to prevail across the
local flying area through the rest of the morning. After 22/16Z,
brief periods of MVFR conditions with mountain obscurations can be
expected across TJMZ and TJBQ in SHRA/isolated TSRA. Low level
winds will continue mainly from the southeast at 10 kts.
.MARINE...Quiet marine conditions are expected to continue through
the next several days with seas up to 5 feet and winds up to 15
.PREV DISCUSSION... /issued 558 AM AST Sat Oct 22 2016/
Ridge pattern aloft across the eastern Caribbean will continue to
hold through the weekend. As a polar trough moves across the
Western Atlantic on Sunday, the ridge pattern is expected to
weaken by early next week. At lower levels, a frontal system is
expected to moves across the Western Atlantic and remain to the
north of the local islands during the weekend and early next week.
As a result, moisture is expected to pool across the local area.
Therefore, expect passing showers across the windward sections of
the U.S. Virgin Islands and Puerto Rico during the overnight and
early morning hours, followed by afternoon showers and
thunderstorms mainly across the interior and to the west of Puerto
Rico each day. Although, easterly winds are expected to return,
light winds and warm/hot temperatures are expected through the
Satellite imagery showed a layer of mid to upper level clouds over
the islands. Also, the Doppler radar detected a showers across the
surrounding waters, but some of them moved across the windward
sections of the U.S. Virgin Islands and Puerto Rico. However,
rainfall accumulations were minimal. Once again, the minimum
coastal temperatures were around low 80s.
Under a ridge pattern and enough low level moisture, continue to
expect a few passing showers across the windward areas, followed
by locally induced afternoon showers and thunderstorms. The
afternoon activity should focused across the interior and
northwestern sections of Puerto Rico, as well as downwind from the
U.S. Virgin Islands. In addition, some showers could develop
downwind from El Yunque to affect the San Juan Metro Area late
this morning and into the afternoon. By this afternoon a
southeasterly wind flow will result in warm to hot temperatures
along the northern slopes of Puerto Rico.
A frontal boundary is expected to remain to the north of the local
area through the early part of the upcoming week. A strong surface
high pressure behind this front is expected to establish across
the western Atlantic. This pattern will shift winds from the
northeast Sunday-Monday. Although, trade winds will return to the
forecast area by Sunday, light winds will continue to result in
warm/hot temperatures, with afternoon showers and thunderstorms
focusing across and to the west of the Cordillera Central by early
VFR conditions are expected to prevail at all TAF sites
through 22/16z. After 22/16Z, brief periods of MVFR conditions with
mountain obscurations can be expected across TJMZ and TJBQ in
SHRA/isolated TSRA. Low level winds will continue mainly from the
southeast at 10 kts.
Tranquil seas are expected through the next several days with
guidance indicating seas no higher than 5 feet. Winds will remain
below 15 knots.
.PRELIMINARY POINT TEMPS/POPS...
SJU 91 78 90 79 / 20 30 30 50
STT 89 82 89 82 / 20 30 30 50