Marine Weather and Tides
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.
|Sunrise 5:58AM||Sunset 5:50PM||Wednesday February 20, 2019 12:56 AM CST (06:56 UTC)||Moonrise 8:45PM||Moonset 7:24AM||Illumination 99%|
7 Day Forecast for Marine Location Near Arroyo, PRHourly EDIT Help
Area Discussion for - San Juan, PR  (on/off)  Help NOTE: mouseover dotted underlined text for definition
|Fxca62 tjsj 200135 aaa|
area forecast discussion... Updated
national weather service san juan pr
935 pm ast Tue feb 19 2019
Update Temperatures in the 20 00z sounding continue to show an
inversion from 5.0 kft to 8.5 kft with temperatures still above 10
degrees celsius at 12 kft. Relative humidities also fall off to
around two percent in that layer. Nevertheless pockets of showers
in the band of moisture settled over the area in strong trade wind
flow, will bring light showers to the area, though, for now, they
are dissipating as they reach the east coast of puerto rico. Will
continue with 20 to 40 percent chance of showers overnight in the
u.S. Virgin islands and eastern puerto rico and little or no
chance in the western part of puerto rico. Currently models are
showing the bulk of the showers forming of the u.S. Virgin islands
Wednesday and moving just south of puerto rico since flow is
expected to back slightly toward the northeast. Nevertheless there
is a good chance of light showers downstream from the usvi and
across puerto rico during the day Wednesday. This pattern is
expected to continue through early next week with a short break on
Saturday. Winds will decrease very slowly each day after Thursday
through mid week next week.
Aviation Vfr conditions are expected to prevail. Brief
MVFR -shra may occur at tncm tkpk tist tisx thru 20 20z. Winds
east 8-16 kt with hir gusts till 20 15z then winds 10-20g30 kt
thru 20 22z. Maximum winds E 25-35 kt til 20 12z btwn fl065-320.
Winds will diminish from the top aft 20 12z but a wnw jet will
begin forming and winds will increase up to 50 kt btwn fl350-400
btwn 20 18z-21 12z.
Marine Winds and seas will increase across the area through
Thursday night causing seas up to 6 to 8 feet in exposed local
atlantic and caribbean waters. Hazardous conditions will diminish
over the weekend but some areas will persist with seas of 7 feet
through early next week.
Prev discussion issued 513 pm ast Tue feb 19 2019
synopsis... Fair weather conditions are expected to prevail
through most of the forecast period. However, occasional
fragments of low level moisture will bring isolated to scattered
shower activity into the forecast area, but the presence of a
ridge aloft will limit any chance for significant rainfall
accumulations. A migratory surface high pressure will bring
breezy conditions Wednesday through Friday, holding a moderate to
locally fresh easterly through the rest of the forecast period.
Short term... Tonight through Thursday...
the combination of a surface high pressure and a ridge aloft will
result in fair weather conditions under a moderate to locally
fresh easterly wind flow tonight through Wednesday. As the surface
high moves into the northeastern atlantic, a stronger surface
high pressure is set to move over the western atlantic and build
north of the region Thursday through the rest of the short-term
forecast period, resulting in a fresh to locally strong east to
northeast wind flow. During this period, fragments of low level
moisture embedded in the trade winds will move across the
forecast area from time-to-time. This will result in showers
streaming over the waters into coastal areas of eastern puerto
rico and the u.S. Virgin islands, and if low-level moisture maxima
occurs at peak afternoon hours, convection can be expected
downwind from the local islands and over portions of the interior
and western puerto rico. Nevertheless, significant rainfall
accumulations are not expected.
Long term... Friday through Wednesday...
prev discussion... Issued 454 am ast Tue feb 19 2019
the aformentioned surface high pressure will promote breezy trade
winds especially across the local waters and coastal sections through
at least Friday. Surface winds will slowly diminish through the
Although a mid-to-upper level ridge will promote a fair weather
pattern through the forecast period, patches of moisture embedded
in the trades will result in passing showers across the windward
sections from time to time. Forecast soundings continues to
suggest the presence of a strong trade wind inversion which is
consistence with drier than normal conditions at mid-to-upper
levels as GFS continues to suggest.
Aviation... MainlyVFR conditions are expected to prevail across all
terminals during the next 24 hours. However, -shra across the region
with gusty winds could move at times across the local terminals.
Surface winds will continue from the east between 15-20 kt with
higher gusts through at least 23z, then decrease between 10-15 kt
overnight with a more ene component and occasional gusts up to 20
Marine... Small craft advisories continue in effect for the
outer caribbean waters and mona passage due to seas between 5 and
7 feet with occasional seas up to 9 feet. Elsewhere, mariners are
urged to exercise caution across most of the local waters due to
easterly winds between 15 and 20 knots and choppy seas up to 6
As a stronger surface high pressure builds north of the region,
marine conditions will continue to deteriorate and small craft
advisory conditions are expected to spread across the regional
waters by Wednesday morning and continuing through the upcoming
weekend. As a result, small craft advisories will be in effect.
Along with hazardous marine conditions, a moderate risk of rip
currents will continue for most of the local beaches through
Wednesday night, elevating to high for a few local beaches by
Preliminary point temps pops
Sju 74 82 74 84 20 20 20 30
stt 73 83 73 85 40 40 20 30
Sju watches warnings advisories
Pr... Vi... None.
Am... Small craft advisory from 8 am Wednesday to 8 pm ast Friday for
anegada passage southward to 17n-atlantic waters of puerto
rico and usvi from 10 nm to 19.5n.
Small craft advisory from 8 am Wednesday to 2 pm ast Friday for
coastal waters of southern usvi vieques and eastern puerto
rico out 10 nm.
Small craft advisory until 8 pm ast Friday for caribbean waters
of puerto rico from 10 nm to 17n-mona passage southward to
Small craft advisory from 8 am Wednesday to 8 am ast Friday for
coastal waters of southern puerto rico out 10 nm.
Short term... Ws
long term... .Icp
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