National Weather Service San Juan PR
556 AM AST Tue Mar 14 2023
...New SYNOPSIS, AVIATION, MARINE...
.SYNOPSIS...
Issued at 505 AM AST Tue Mar 14 2023
A recent pulse of swell will peak this morning along our coasts.
A second, stronger pulse will come in on Thursday night and
persist well into the weekend. Some moisture has moved in from the
south overnight and will bring a few more showers to the interior
of Puerto Rico and the local waters this afternoon. This moisture
will persist and then be met on Thursday by a cold front
advancing from the northwest. Drier weather is expected for the
weekend and beyond, but scattered showers from a shallow layer of
moisture will continue in the normal diurnal pattern.
&&
.SHORT TERM...Today through Thursday
A surface high pressure over the central Atlantic will maintain a
southeasterly wind pattern across the Islands. Under this east-
southeast wind pattern influence, patches of Caribbean moisture will
reach the local islands, increasing the water content across the
region. According to the satellite derived imagery, Pwat values
across the Caribbean sea are around 1.5 inches, which is near or
slightly above climatological normals. This pattern will continue
to result in cloudiness across the region with some afternoon
showers across the northwestern quadrant of Puerto Rico. Minimal
rainfall accumulations are expected today. The latest model
guidance agrees with a more unstable and wet pattern from late
Wednesday into Thursday. At the surface, an increase in moisture
from a frontal boundary moving southward into the region is seen
and some instability aloft will be provided by an upper-level
trough moving just north of the area. As the front approaches, a
reduction in the pressure gradient will create more light and
veering winds. This wind flow will enhance the development of
shower activity in the afternoon hours across the interior
sections of Puerto Rico. Regardless of the increase in showers,
rainfall accumulations will not be sufficient for any flood threat
except for some localized ponding of water in roadways where the
heaviest activity occurs.
Daytime temperatures will warm slightly across the north-central
sections due to the southeasterly component.
&&
.LONG TERM...Friday through Wednesday...
The cold front will arrive on Thursday night. Good vertical motion
will begin on Thursday and moisture will deepen on Thursday night.
Drier air will spread into the area above 6 or 7 thousand feet on
Friday, but a moist layer will remain through the end of the
period. It will thin, however, as clouds erode and provide some
heating from the ground. Showers will likely spread over most of
Puerto Rico and the other islands on Thursday night and Friday
morning, continue on the windward side Friday afternoon through
Saturday morning and then gradually diminish through Wednesday.
By Friday, the upper level trough will have moved to our northeast
with high pressure across Panama. The sub-tropical jet will hover
over or just north of the area until a second and weaker trough
crosses through on Sunday. The ridge to our west will finally
arrive on Wednesday, but the trough that moved over the southern
Windward Islands on Monday will remain in place causing flow to
become more northerly over the local area.
Mid levels will become quite dry after Friday and remain so beyond
the end of the period, again limiting most shower activity.
&&
.AVIATION...
(12Z TAFS)
Issued at 505 AM AST Tue Mar 14 2023
VFR conditions will prevail for all the TAF sites during the period.
Winds will remain VRB at 5 kts or less until 14/14Z, increasing to
12 kts from the E-SE with sea breeze variations. Some VCSH is
possible at TJPS & TISX around 14/23Z-1503Z with the approach of
cloudiness. Winds will revert to VRB around 14/22Z. Maximum winds
W 60-70 knots btwn FL325-440, strongest at FL370.
&&
.MARINE...
Issued at 505 AM AST Tue Mar 14 2023
Seas at the outer buoy (41043) peaked around midnight at nearly 10
feet and 17 seconds and have now diminished to just above 7 feet
at 13 seconds. As of 5:00 AM AST seas were approaching 7 feet at
14 seconds. Some of the highest waves will be arriving on the
north coasts of Puerto Rico and the northern U.S. Virgin Islands
this morning and will fade tonight. Unfortunately, marginally
hazardous seas will persist through Wednesday night. Another
stronger swell will enter our Atlantic waters on Thursday night
with seas up to 12 feet expected. Seas are expected to remain
hazardous with small craft advisories not ending before Monday.
The local Caribbean waters south of Puerto Rico will remain the
most favorable for navigation.
High surf will impact the area today and tonight--generally between
10 to 12 feet. High surf will subside to just below thresholds
for all but the northwest zone of Puerto Rico before hazardous
surf is again encountered beginning Thursday night. This time up
to 14 foot breaking waves are expected.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through late Friday night for PRZ001-002-
005-008-010-012.
High Surf Advisory until 6 AM AST Thursday for PRZ001-002-005-
010-012.
High Surf Advisory until 8 AM AST Saturday for PRZ008.
High Rip Current Risk through late Friday night for PRZ011-013.
VI...High Rip Current Risk through late Friday night for VIZ001-002.
High Surf Advisory until 6 PM AST Wednesday for VIZ001.
AM...Small Craft Advisory until 8 AM AST Saturday for AMZ711-742.
Small Craft Advisory until 8 PM AST Wednesday for AMZ712-723.
Small Craft Advisory until 2 PM AST Wednesday for AMZ716.
Small Craft Advisory from 8 PM this evening to 8 AM AST Saturday
for AMZ741.
&&
$$
SHORT TERM/AVIATION...LIS
LONG TERM/FIRE WEATHER....WS
PUBLIC...RVT