Wednesday, March29, 2017

Marine Weather and Tides
Arroyo, PR

Version 3.4
What's New / NOTES
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.
3/12/2015 - Added section for Gulf current for users in the GMZ marine zones.
This was requested by a user. If you have requests, please let me know.

Sunrise 5:37AMSunset 5:52PM Wednesday March 29, 2017 1:14 AM CST (07:14 UTC) Moonrise 8:31AMMoonset 8:13PM Illumination 3% Phase: Waxing Crescent; Moon at 2 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
    EDIT      (on/off)   Help
7 Day Forecast for Marine Location Near Arroyo, PR
   Hourly   EDIT   Help
location: -34.81, -58.22     debug

Area Discussion for - San Juan, PR
      (on/off)   Help   NOTE: mouseover dotted underlined text for definition
Fxca62 tjsj 290120
area forecast discussion
national weather service san juan pr
920 pm ast Tue mar 28 2017

Update Forecast on track... Partly cloudy skies with a few
passing showers possible overnight; mainly across the local
waters as well as the east and southeast coastal areas.

Environmental conditions will remain favorable for shower and
thunder development. Therefore expect another round of showers
with isolated thunderstorms possible late in the morning and into
the afternoon hours. Low level winds are expected to become more
northerly; therefore afternoon showers and thunderstorms will be
focused over and south of the cordillera central. A fair weather
pattern with limited shower activity is expected Thursday and
Friday as a drier air mass moves across the forecast area.

Aviation Vfr conds expected overnight at all TAF sites through
the forecast period. Tsra/shra with MVFR/ifr conds expected at
jps after 29/16z. Light and variable winds expected overnight.

Marine Seas 3 to 5 feet will continue to prevail across
the atlantic waters, with seas 2 to 4 feet across the caribbean
waters. A moderate risk of rip current will continue across the
atlantic shoreline of puerto rico during the next few days. A
northerly swell will arrive across the local waters late Wednesday
into Thursday with seas increasing up to 6 feet.

Prev discussion /issued 341 pm ast Tue mar 28 2017/
synopsis... Sfc low to the north of the local area will continue
to promote a southerly wind flow across the local area, bringing
moisture, which is helping the development of showers across the
local islands, especially across central and northern pr when the
moisture combines with the local effects and favorable upper level
conditions. North swell is expected to affect the local waters
late Wednesday and Thursday.

Short term... This afternoon through Wednesday...

a surface low is about 380 miles north of punta cana and is
moving northeast at about 15 mph. This motion will continue and
perhaps accelerate during the next 48 hours. Bands of convection
will form in the southwest flow around the islands today and
tomorrow, but moisture has diminished somewhat and convection has
been weaker in strength and coverage. There is little consensus in
the models as to where a band might form in the flow tonight, the
gfs wants to have convection form northwest of puerto rico after
28/00z and shift to southeast of puerto rico aft 28/06z. Hires
models have scattered showers on both sides of the island. It is
likely that a band will form parallel to the flow however--and
over water-- leaving better than one quarter to one half inch of
rain over smaller islands-- if any are in its path and nearby

On Tuesday a plume of moisture at 700 mb will form an arc that
travels from colombia north to the local caribbean waters from the
west southwest. This plume will enhance the moisture over the area.

Then, during the day Tuesday, with moisture higher and the upper
level jet and trough a little closer conditions will be a little
better even though the GFS is still not putting much divergence
aloft over the forecast area. With strong directional shear near the
surface and good speed shear above 700 mb--albeit decreasing with
time--small showers could develop with land or water spout
potential, once diurnal heating gets underway.

Currently the model trend has been to peak the moisture on Tuesday
but the GFS has been raising its moisture forecast for Wednesday.

Therefore cannot expect too much improvement until Thursday when
drier air will move in from the north. Temperatures on Tuesday will
continue above normal for the north coast despite afternoon
cloudiness, but on Wednesday winds should shift to more northerly as
the low pressure moves east across our longitude and temperatures on
the north coast will return to normal and temperatures on the south
coast will rise by even as much as 5 degrees.

Long term... The latest guidance is now suggesting that Wednesday
will not be as dry as it had suggested in the past few days. So
even though the winds are expected to shift to a northerly
direction, this means that the interior and southern sections of
pr have the better chance for afternoon showers. The rest of the
the forecast area should have isolated to briefly scattered
showers. Then fair weather overnight Wednesday into Thursday with
afternoon showers on Thursday afternoon developing across the sw
quadrant of pr, and once again isolated showers elsewhere,
including the usvi. However for Thursday, the latest guidance
still suggests drier air over the local area as a possible frontal
passage pushes through. Fair weather mainly on Friday, then the
front may retrograde on Saturday, increasing moisture
significantly and so will the shower activity over the forecast
area over the weekend.

Aviation... Shra are forming along a sea breeze front in NRN pr and
will generate very localized brief MVFR conds in cigs/vsbys. Shra
will diminish aft 28/00z. Some areas of hir terrain will be
obscured. Aft 28/06z areas of moisture will move thru the usvi and
leeward islands from the SE to bring brief pds of MVFR in shra to
tisx/tncm/tkpk. Sfc winds se-s 10 to 15 kt. Maximum winds wsw 55
knots btwn fl290-420, but winds will incrs to SW 30 kt as low as
fl120 by 28/06z.

Marine... Seas generally of 3 to 5 feet are to be expected across
the atlantic waters and local passages, 2 to 4 feet across
southern pr and south of the usvi. The northerly swell expected
late Wednesday into Thursday may cause seas to go up to 6 feet
across the atlantic waters and local passages.

Preliminary point temps/pops
Sju 77 85 75 83 / 40 20 20 10
stt 74 85 73 83 / 40 40 20 20

Sju watches/warnings/advisories
Pr... None.

Vi... None.

Am... None.

Update... .Om

Weather Reporting Stations
   EDIT       (on/off)   Help   NOTE: Click on distance to see the station location on a map

Airport Reports
    EDIT      (on/off)   Help   Click EDIT to display multiple airports
Click EDIT to select an airport
Tide / Current Tables for
   EDIT   RT Ports Option   Weekend mode (on/off)   (on/off)   Help
Tide / Current Tables for
   EDIT      (on/off)   Help
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 (3,6,7,8)
      (on/off)   Help

Ground Weather Radar Station Puerto Rico,Virgin Islands
   (on/off)   Help
weather_mapweather_map weather_map

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 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 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.