Monday, March27, 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 5:38AMSunset 5:52PM Monday March 27, 2017 10:30 AM CST (16:30 UTC) Moonrise 6:17AMMoonset 6:53PM Illumination 0% Phase: New Moon; Moon at 0 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
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7 Day Forecast for Marine Location Near Arroyo, PR
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location: -34.81, -58.22     debug

Area Discussion for - San Juan, PR
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Fxca62 tjsj 271527
area forecast discussion
national weather service san juan pr
1127 am ast Mon mar 27 2017

Update A north northeast-south southwest band of showers moved
close to aguadilla during the early morning hours due to an area
of convergence associated with a boundary spiraling into the low
pressure north of the eastern dominican republic, but the focus of
the best activity in the band has shifted to the northern extreme
of the forecast area, leaving few traces of showers in the mona
channel where it has been much of the night. Good insolation over
northern puerto rico and relatively moist low levels have already
generated a few showers with low tops--one of which went just
northwest of the center of the airport in san juan. Minor amounts
of rain will have been left. More shower activity is expected to
develop over the favored area north of the cordillera central
this afternoon. Isolated showers are expected elsewhere.

Air parcels from the most recent sounding from san juan at 27/12z
will just clear the top of the inversion at 16-17 kft with
afternoon heating, and the air over the area has less than 20
percent relative humidity between 15 and 40 kft making convection
short lived. Low level directional shear is similar to yesterday
making the formation of isolated land spouts possible in the
heaviest showers.

Only minor updates to morning and evening pop/weather grids have
been made. Current synoptic reasoning holds.

Aviation Shra 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. Shra will also form over the cordillera
central with all hir terrain obscured. 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 continue to subside. Models are no longer bringing
in north northwest swell of 7 feet or more on Monday night, but do
bring in a brief episode of 6 foot seas Tuesday night.

Prev discussion /issued 401 am ast Mon mar 27 2017/
synopsis... A surface low over the atlantic waters northwest of
pr will continue to move north northeast into the western atlantic for
the next few days. A surface high will build across the western
atlantic just northwest of the surface low, spreading into the
local area by midweek as the surface low moves east into the
central atlantic. Drier air at mid levels is expected to continue
moving in through the end of the week. Light southerly winds will
continue until Monday, becoming very light on Tuesday, then
northerly and increasing on Wednesday and Thursday.

Short term... Today through Wednesday...

doppler weather radar indicated isolated to scattered showers
moving northward from the caribbean waters across the u.S. Virgin
islands, vieques, culebra as well as across the eastern sections
of puerto rico overnight and early this morning. However, no
significant rainfall amounts were measured. Elsewhere over land
areas not significant precipitation was detected.

A surface low pressure system to the north of hispaniola this
morning will continue to bring a relatively moist southerly wind
flow across puerto rico and the u.S. Virgin islands today. Less
cloud cover is expected today across the region and therefore
diurnal heating in combination with sea breeze convergence and
other local effects will induce the development of showers and
possible thunderstorms along and north of cordillera central,
including the san juan metro area during the afternoon hours.

Urban and small stream flooding are possible over northern puerto
rico. As the low moves further northeastward over the atlantic
waters, moisture will continue to decrease across the local
islands tonight and Tuesday. However, the lingering moisture in
combination with local effects will induce the development of
some convection each afternoon specially across the interior and
northern sections of puerto rico. Due to the expected southerly
wind flow, warmer than normal temperatures are possible across
the northern coastal municipalities of puerto rico during the
next few days.

Long term... Thursday through Monday...

the surface low will continue to move north into the north
central atlantic on Thursday and the ridge across the western
atlantic builds north of the islands through the end of the week.

This will generate a northerly wind flow from Wednesday through at
least Saturday. A much drier airmass will prevail over the region
from Thursday through late Friday... This will result fair weather
conditions through this period. East to southeast winds return
from early Saturday through Sunday with moisture increasing from
the southeast... Associated with remnants of the surface
low/frontal boundary.

Aviation... Brief periods of MVFR conds will remain possible at
the leeward and usvi TAF sites this morning. Shra/tsra expected
aft 27/16z in and around tjmz, tjbq and tjsj. Light and variable
winds are expected overnight. Latest tjsj sounding indicated a
south southwesterly wind flow at all levels, but very strong

Marine... Seas will continue to subside this morning. Early this
morning local buoy 41115 in rincon indicated seas of 5 feet while
bouy 41053 in san juan indicated also seas of 5 feet. The small
craft advisories were cancelled. A moderate risk of rip currents
will continue to prevail across some areas during the next few

Preliminary point temps/pops
Sju 88 75 86 77 / 60 40 40 10
stt 84 75 84 75 / 40 40 40 20

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

Vi... None.

Am... None.

Short term... Ws
long term... .Ws

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Wind Forecast for (12,3,4,5)
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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.