Sunday, July5, 2020
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Marine Weather and Tides
Arroyo, PR

Version 3.4
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 5:21AMSunset 6:08PM Sunday July 5, 2020 1:12 AM CST (07:12 UTC) Moonrise 6:26PMMoonset 8:25AM Illumination 100% Phase: Full Moon; Moon at 15 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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Area Forecast Discussion National Weather Service San Juan PR 930 PM AST Sat Jul 4 2020

UPDATE. After the afternoon shower and thunderstorm activity across western PR, the weather became fairly benign with a few light to moderate showers across the local waters, USVI and eastern PR. The showers have been moving quickly to the west, and therefore fairly brief at any one place. The patch of moisture over the area will cause these isolated to scattered showers over the area overnight into Sunday morning, then in the afternoon the moisture will combine with the local effects and somewhat favorable upper level conditions to induce the development of showers and thunderstorms across the central and western sections of PR, while isolated to scattered showers continue for the USVI. A dry slot with Saharan dust will move in late on Sunday, ahead of a tropical wave that is expected late on Monday.

AVIATION. VCSH across the TIST, TISX, and TJSJ terminals overnight into Sunday morning but otherwise VFR conds with winds from the east at 10KT or less. SHRA/TSRA expected after 05/16Z across central and western PR will cause at least VCSH at TJPS and VCTS at TJBQ, although there is a possibility of the TSRA actually affecting the TJBQ terminal, causing brief MVFR conds, especially after 05/18Z. Winds will be from the east at around 15KT with sea breeze variations after 05/13Z.

MARINE. No changes from the previous discussion. Seas will be up to 5 feet across the local waters through Sunday morning, increasing slightly thereafter up to 6 feet by late Sunday. Winds will be mainly between 10 and 20 knots for the next few days. There will be a moderate risk of rip currents across some of the local beaches, otherwise a low risk. Please see the Surf Zone Forecast SRFSJU for details on the specific beaches of interest.

PREV DISCUSSION. /issued 357 PM AST Sat Jul 4 2020/


Showers and possibly isolated thunderstorms are possible during the afternoon through Sunday. A weak tropical wave will increase rain chances across most of the region on Monday. Then a more substantial wave is forecast to enter the area on Wednesday, then a dry Saharan air mass will filter in from the east during the middle of the week.

SHORT TERM . Rest of the day through Monday .

Doppler radar shows showers and isolated thunderstorms across the western areas of Puerto Rico this afternoon. Currently, TJUA dual-pol total shows rainfall amounts of less than half of an inch. Also, a few showers have develop across the U.S. Virgin Islands and Saint Thomas this afternoon. The shower activity is a result of local and diurnal effects; this activity will wane as the surface begins to cool later this evening.

Sunday, a patch of drier air is progged to move through the area and limit the development of afternoon convection, nevertheless showers and isolated thunderstorm are possible as a result of significant surface heating, and local effects. Forecasting in the tropics can be tricky, and if the drier air mass moisten during the overnight, or tomorrow rain chances may need to be increased.

Monday, a weak tropical wave is progged to move into the area and increase rain changes for the U.S. Virgin Islands and Puerto Rico. The GFS shows precipitable water values peaking at 2.0 inches during the afternoon. However, at this time the GFS keeps the moisture confined between the 1000 mb to 800 mb leve; and keeps the mid-levels of the atmosphere rather dry. The GFS has mid- level RH values ranging from 30 to 50 percent. Additionally, the amount of cloud cover over the area will play a roll in the development of showers and isolated thunderstorms. Temperatures are forecast to be near the upper 80s to the lower 90s in lower elevations, and the lower to the middle 80s in higher elevations during the short-term period.

PREV DISCUSSION . /issued 447 PM AST Sat Jul 4 2020/

LONG TERM . Tuesday through Saturday .

Latest model guidance is indicating that another tropical wave will move across the eastern Caribbean and near the vicinity of the forecast area later Tuesday evening through at least the first half of Wednesday. However, there are differences in terms of timing as well as positioning of this wave amongst the guidance. The ECMWF model is the fastest as it brings the wave in late Tuesday afternoon and exiting the forecast area by early Wednesday morning. This model also shows the heaviest activity associated with this wave remaining to the south, therefore, the rainfall activity would not be that significant if this solution would to verify. The GFS model on the other hand is slower with bringing the wave in as it brings it in during the overnight hours of Tuesday into Wednesday with the moisture not exiting the area until Wednesday evening. This model is farther north with the moisture axis, therefore, more significant rainfall activity would be more likely under this solution. Given the varying solutions, confidence on the timing and how much of an impact the wave will have on the region is low at this time and we will need to wait for additional model cycles during the next couple of days for a better consensus.

After the wave passage, drier conditions as well as another episode of suspended Saharan Dust particulates will follow by the latter half of the work week. Therefore, fair weather conditions along with hazy skies can be expected. Afternoon convection will be possible across western Puerto Rico due to local and diurnal effects.


VFR conditions with showers and thunderstorms across the interior and western sections of Puerto Rico. This activity could affect JMZ/JBQ. This activity is expected to diminish by 05/02Z with VRF conds continuing. Elsewhere sunny to partly cloudy with a few VCSH. Winds will continue from the E-ESE at 10 to 15 knots.


Choppy seas up to 5 feet will continue through Sunday, then seas are forecast to increase to 6 feet across the outer Atlantic waters on Monday.Small craft should exercise cautions across the local and outer waters. Winds will be from the east to southeast at 15 to 20 kts with higher gusts. There is a moderate risk of rip currents for the northern beaches of Puerto Rico, and the northeastern beaches of Culebra, Vieques and the U.S Virgin Islands.

PRELIMINARY POINT TEMPS/POPS. SJU 79 90 80 90 / 40 30 30 60 STT 79 90 80 90 / 30 30 30 50



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NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
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Wind Forecast for (3,6,7,8)
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Ground Weather Radar Station Puerto Rico,Virgin Islands
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