Marine Weather and Tides
6/25/2017 - NOAA is having a major issue that impact the 7 day forecast load times. Many users are reporting problems. The issue has been reported.
5/23/2017 - Worked with NOAA again to speed up the 7 day forecast load times. Thanks to them for being responsive.
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.
|Sunrise 6:27AM||Sunset 6:08PM||Thursday October 19, 2017 10:21 AM AST (14:21 UTC)||Moonrise 6:15AM||Moonset 6:21PM||Illumination 1%|
EDIT (on/off)  Help
|AMZ742 Coastal Waters Of Northwestern Puerto Rico Out 10 Nm- 545 Am Ast Thu Oct 19 2017 |
Today..East winds around 10 knots. Seas 2 to 4 feet with occasional seas up to 5 feet. Dominant period 7 seconds.
Tonight..East winds 10 to 15 knots. Seas 2 to 4 feet with occasional seas up to 5 feet. Dominant period 8 seconds. Isolated showers.
Friday..East winds 5 to 10 knots. Seas 2 to 4 feet with occasional seas up to 5 feet. Dominant period 8 seconds.
Friday night..East winds 10 to 15 knots. Seas 2 to 4 feet with occasional seas up to 5 feet. Dominant period 8 seconds. Isolated Thunderstorms.
Saturday..East winds 10 to 15 knots. Seas 2 to 4 feet with occasional seas up to 5 feet. Dominant period 8 seconds. Isolated Thunderstorms.
Sunday..East winds 10 to 15 knots. Seas 2 to 4 feet with occasional seas up to 5 feet. Dominant period 8 seconds. Isolated Thunderstorms. Scattered showers.
Monday..East winds 10 to 15 knots. Seas 2 to 4 feet with occasional seas up to 5 feet. Dominant period 7 seconds. Isolated showers.
|AMZ700 545 Am Ast Thu Oct 19 2017 |
Synopsis for puerto rico and the uS. Virgin islands waters... A trade wind surge is producing choppy and hazardous seas particularly across the offshore waters and local passages. A tropical wave is forecast to move well south across the caribbean waters today.
7 Day Forecast for Marine Location Near RincÃ³n, PRHourly EDIT Help
Area Discussion for - San Juan, PR  (on/off)  Help NOTE: mouseover dotted underlined text for definition
|Fxca62 tjsj 190947|
area forecast discussion
national weather service san juan pr
547 am ast Thu oct 19 2017
High pressure in the central atlantic and a trade wind surge
across the caribbean will bring heavily dust-laden saharan air
over the area today. Drier air will continue through Sunday with
few showers, and thunderstorms unlikely. Moisture returns slowly
Monday through Wednesday, but rainfall accumulations will be
limited and flooding is not expected.
Short term Today through Saturday...
very dry air has moved into the area. It is heavily laden with
saharan dust that brought visibilities of less than 3 miles to
saint kitts yesterday and will likely be the worst dust episode
so-far of the year here. Visibilities are expected to range from
around 10 miles to as low as 3 miles in the local area.
Low pressure aloft has sunk as far south as the waters off the
coast of venezuela. It will continue to dissipate allowing high
pressure off the coast of costa rica to extend northeast and lean
over into the local area late Friday as an upper level trough
moves east southeast into the western atlantic. Once the trough
moves through flow at upper levels will turn northwest.
High pressure across the atlantic at lower levels will combine
with the stabilizing effects of the northwest flow behind the
upper level trough to keep very dry air over the area above the
850 mb level. This will continue well past Saturday. The GFS hints
at patches of weak moisture passing to the north of the area, but
this should have little effect on puerto rico or the u.S. Virgin
islands. Below 850 mb the very moist marine layer will persist in
a semi-capped fashion that will allow a few light showers to
develop in the windward slopes of the islands during the late
night and early mornings, but overall little convective
development is expected even in the afternoons over the higher
mountains mainly because once the cap is broken, drier air will
mix down and end cloud growth. The main effect will be clouds
capping the higher terrain and fair weather cumulus.
Mos did poorly on maximum temperatures for the north coast of
puerto rico yesterday, ostensibly because of the dense mid and
upper level cloud cover that kept skies cloudy. It is calling for
91 degrees for san juan again today, and should be much closer,
now that the cloud cover that prevented the heating yesterday is
gone and winds remain east southeast.
Minimum temperatures in the lower elevations will drop back into
the high 80s once winds turn more easterly during the weekend.
Minimum temperatures are holding in the upper 70s on the coast due
to the high dew points. This same moisture is also allowing some
patchy dense radiational fog to form in the valleys under clear
skies overnight. The dew points should return to more normal
values as the drier air is mixed down into the marine layer and
radiation fog should not return tonight except in narrow becalmed
Long term Sunday through Wednesday...
moisture begins the long road to recovery Sunday through
Wednesday, but columnar moisture does not rise much above 1.7
inches mid-week or the following Saturday. As low pressure at
upper levels digs down over the anegada passage the 40 kt jet
around the base of the low passes overhead on Sunday, but weak
dynamics prevail and little support for convection is found at
upper levels or in the drier air below them. Then, late on Monday
and Tuesday, a 70 kt jet develops around the southwest edge of the|
low, which moves little in the interim, and this brings better
dynamics. Modest moisture and low level instability will then be
able to increase the shower activity. At this time the model is
suggesting that showers will be centered over southeast puerto
rico Tuesday morning. The increase in moisture and instability
should increase the shower activity over the windward slopes in
the morning and the western valleys during the afternoon but dry
air between 500-300 mb will greatly limit the amount of
thunderstorms that can formï¿½if any. The upper-level low and the
accompanying jet move eastward Wednesday and shower activity will
then be almost totally driven by the moist lower layers,
orographic effects during the mornings and convergence in western
puerto rico in the afternoons as mid-level dryness continues
Breezy conds are expected to develop as the surface layer warms
and 20-30 kt winds are mixed down from as low as 600 feet.
Sustained winds of 15 to 20 kt with gusts to 30 kt are expected at
most coastal sites. Although few if any shra are expected, MVFR
and ocnl ifr vsbys are psbl in saharan dust today. Prevailing
vsbys should remain at or above 5 miles, however. Maximum winds:
east southeast 20-30 kt from fl040-120 til byd 20 12z. Winds will
be easterly up through fl350 till 20 12z.
The wind surge in the east southeast trade winds is causing seas
to rise to 7 to 8 feet in the outer waters and funnel points
around the local islands. These conditions should persist until
Monday when winds and seas begin to abate. Winds of 20 to 25 knots
are possible where winds are strongest around the islands through
Preliminary point temps pops
Sju 90 79 90 79 20 10 10 20
stt 90 81 90 81 10 10 10 20
Sju watches warnings advisories
Pr... High rip current risk through Friday afternoon for central
interior-northeast-ponce and vicinity-southeast-southwest-
Small craft advisory until 8 am ast Friday for southeast.
Vi... High rip current risk through Friday afternoon for st croix.
Small craft advisory until 8 am ast Friday for st.Thomas... St.
John... And adjacent islands.
Am... High rip current risk through Friday afternoon for coastal
waters of southwestern puerto rico out 10 nm-coastal waters
of southern puerto rico out 10 nm.
Small craft advisory until 8 am ast Friday for coastal waters of
southern puerto rico out 10 nm-coastal waters of southern
usvi vieques and eastern puerto rico out 10 nm.
Small craft advisory until 8 pm ast Saturday for caribbean
waters of puerto rico from 10 nm to 17n-mona passage
southward to 17n.
Small craft advisory until 2 pm ast Friday for anegada passage
southward to 17n-atlantic waters of puerto rico and usvi
from 10 nm to 19.5n.
Short term... Ws
long term... .Tw
Weather Reporting StationsEDIT (on/off)  Help NOTE: Click on distance to see the station location on a map
|Stations||Dist||Age||Wind||Air Temp||Water Temp||Waves||Pressure||DewPt|
|MISP4 - 9759938 - Mona Island, PR||70 mi||51 min||85°F||83°F||1016.4 hPa|
Wind History for Mayaguez, PR(wind in knots) EDIT (on/off)  Help
Airport ReportsEDIT (on/off)  Help Click EDIT to display multiple airports
|Aquadilla, Rafael Hernandez Airport, PR||78 mi||31 min||E 11 G 15||5.00 mi||Clear with Haze||84°F||71°F||66%||1017.6 hPa|
Wind History from JBQ (wind in knots)
|1 day ago||NE||E||E||E||E||E||E||E||E||Calm||E||Calm||Calm||SE||SE||SE||SE||Calm||E||E||E||NE|
|2 days ago||E||E||NE||E|
EDIT RT Ports Option Weekend mode (on/off) (on/off)  Help One Week of Data
|Mona Island |
Click for Map
Thu -- 02:39 AM AST 0.19 feet Low Tide
Thu -- 06:12 AM AST Moonrise
Thu -- 06:26 AM AST Sunrise
Thu -- 07:49 AM AST 0.62 feet High Tide
Thu -- 10:53 AM AST 0.55 feet Low Tide
Thu -- 12:36 PM AST 0.57 feet High Tide
Thu -- 03:12 PM AST New Moon
Thu -- 04:21 PM AST 0.40 feet Low Tide
Thu -- 06:06 PM AST Sunset
Thu -- 06:20 PM AST Moonset
Thu -- 07:04 PM AST 0.48 feet High Tide
Thu -- 11:44 PM AST 0.14 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
EDIT (on/off)  Help One Week of Data
Click for Map
Thu -- 01:39 AM AST -0.01 feet Low Tide
Thu -- 06:09 AM AST Moonrise
Thu -- 06:23 AM AST Sunrise
Thu -- 08:01 AM AST 1.33 feet High Tide
Thu -- 02:20 PM AST 0.08 feet Low Tide
Thu -- 03:12 PM AST New Moon
Thu -- 06:03 PM AST Sunset
Thu -- 06:16 PM AST Moonset
Thu -- 08:08 PM AST 1.07 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Weather Map and Satellite Images(on/off)  Help
|Weather Map ||IR Satellite Image from GEOS|
GOES Local Image of Puerto Rico EDIT
Wind Forecast for (10,2,3,4)(on/off)  Help
Ad by Google
The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerious of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.