Monday, December16, 2019
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Marine Weather and Tides
Arroyo, PR

Version 3.4
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.
6/2/2019. Many thanks to a user for reporting an error on one of the Edit pages. The switch to PHP 7.2 caused many pages that previously worked to quit working. I fixed many but I still depend on users to report ones I missed. Please report errors HERE or send an email to me at Allen

Sunrise 5:50AMSunset 5:21PM Monday December 16, 2019 7:04 AM CST (13:04 UTC) Moonrise 12:00AMMoonset 9:51AM Illumination 77% Phase: Waning Gibbous; Moon at 19 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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Area Discussion for - San Juan, PR
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Area Forecast Discussion National Weather Service San Juan PR 421 AM AST Mon Dec 16 2019


A strong mid to upper-level ridge will hold over the area through the middle of the week. The surface ridge will cause fresh easterly wind flow across the area, thus resulting in hazardous seas and breezy conditions. The middle of the week a weak trough will cause the surface high to become elongated as it slides to the northeast of the area. As the high weakens and moves northeast of the region a east to southeast wind flow will prevail over Puerto Rico. This flow will usher in patches of moisture across the region from time to time.

SHORT TERM. Today through Wednesday . A strong high-pressure building north of the islands is promoting breezy and windy easterly trade winds across the region of the U.S. Virgin Islands and Puerto Rico. This wind surge, pushing a patch of moisture, will bring occasional pesky showers from the regional waters into the Virgin Isles and the eastern half of PR throughout the day. However, periods of sunshine will be observed too. These showers will makes their way into the interior and western section by the afternoon hours. The low- to mid-high pressure ridge will be the main weather feature across the North Atlantic Ocean through the short term period.

A trade wind perturbation will shift winds from the ESE Tuesday and more from the SE by Wednesday. This wind shift could increase somewhat the maximum temperatures along the northern sections of the islands. Moisture will erodes by Wednesday, although quick passing showers should not be ruled out at times.

LONG TERM. Thursday through Tuesday . A strong mid to upper-level ridge is forecast to hold over the area Thursday through the weekend. Thursday, a weak perturbation, is forecast to will transverse the southern Caribbean waters and pull deep tropical moisture across Puerto Rico and adjacent islands through Friday. Guidance shows precipitable water values reaching 1.50 inches during this time. The deep tropical moisture is progged to combine with local and diurnal effects to yield isolated to scattered showers across the U.S. Virgin Islands and eastern Puerto Rico during the mornings. Followed by scattered showers across southern, interior, western areas of Puerto Rico during the afternoons. As for thunderstorm development due to the mid to upper- level ridge suppressing the vertical development of showers, as well as limited divergence aloft. Therefore thunderstorms are not forecast to develop at this time. Daytime high temperatures may exceed the daily record as a result of the east to southeast wind flow, which typically causes temperatures to soar.

Saturday and Sunday, the weak perturbation in the easterly flow is progged to continue to move west, and away from the region, however, moisture behind the feature may pool over the area through early Sunday morning. However, patches of moisture in the easterly flow could induce showers during the afternoon on Sunday. The GFS shows precipitable water values falling to the 1.2 inches on Sunday; this ranks near the 50th percentile for December. Also, several weak boundaries and their associated moisture are forecast to stall well north of Puerto Rico through the weekend and early next week.

Monday through Tuesday, the beginning of the week is were the GFS and ECMWF diverge. The GFS shows an upper-level low deepening near Nova scotia with the base of the trough reaching the central Atlantic waters. As the trough deepens well north of the area, its progged to push a weak front through the region. The GFS shows abundant moisture ahead of the front, with the moisture filtering into the U.S. Virgin Islands and Puerto Rico. Also, the GFS develops a low which as warm-core characteristic similar to a tropical cyclone over the central Atlantic waters.

On the other hand, the ECMWF shows a low getting cutoff from the main flow across the southern coastal areas of the U.S. on Monday. As the low transverse, the coastal locations of the northern Gulf of Mexico the ECMWF has it undergo cyclogenesis while it continues to sink south across the Peninsula of Florida. The ECMWF shows the low east of the Florida Peninsula by Tuesday afternoon with the bulk of the remaining moisture positioned northeast of Puerto Rico. At this time a wait and see approach to should be taken with the long-term forecast. The forecast picture should become clear over the next several days. Nevertheless, an increase in showers is progged can on Monday and Tuesday as moisture increases across the region.

AVIATION. VFR conditions will prevailed today. Gusty easterly winds are expected at times across the islands. Therefore, expect E to ENE winds at 15 to 20 kt gusting between 25 and 30 kt. SHRA/+SHRA will move en route from the Leeward islands and E-PR throughout the day, spreading into central and western PR between 16/16z-20z.

MARINE. Hazardous marine conditions will continue to prevail through the middle of the week. A surface high pressure is creating fresh easterly trade winds across most of the regional. As a result, small craft advisories are in effect for the offshore and nearshore waters except for the southern nearshore waters of Puerto Rico. Seas will range from 7 to 9 feet with seas occasionally reaching 10 feet. A high risk of rip currents continues in effect for the northern, eastern and southeastern beaches of Puerto Rico. There is a high risk of rip currents for the beaches of Culebra and Saint Croix.

PRELIMINARY POINT TEMPS/POPS. SJU 86 75 86 74 / 50 60 60 40 STT 88 76 85 75 / 50 60 50 20

SJU WATCHES/WARNINGS/ADVISORIES. PR . High Rip Current Risk through Wednesday afternoon for Culebra- North Central-Northeast-Northwest-San Juan and Vicinity- Southeast.

Small Craft Advisory from 2 PM this afternoon to 8 PM AST Wednesday for Southeast.

High Rip Current Risk through Wednesday afternoon for Central Interior.

High Rip Current Risk from this evening through Wednesday afternoon for Vieques.

VI . High Rip Current Risk through Wednesday afternoon for St Croix.

AM . Small Craft Advisory from 2 PM this afternoon to 8 PM AST Wednesday for Coastal Waters of Southern Puerto Rico out 10 NM.

High Rip Current Risk until 2 PM AST this afternoon for Coastal Waters of Southern Puerto Rico out 10 NM.

Small Craft Advisory until 8 PM AST Wednesday for Caribbean Waters of Puerto Rico from 10 NM to 17N-Coastal Waters of Northern Puerto Rico out 10 NM-Mona Passage Southward to 17N.

Small Craft Advisory until 2 PM AST Thursday for Anegada Passage Southward to 17N-Atlantic Waters of Puerto Rico and USVI from 10 NM to 19.5N-Coastal Waters of Northern USVI and Culebra out 10 NM-Coastal Waters of Southern USVI Vieques and Eastern Puerto Rico out 10 NM.

Small Craft Advisory from 2 PM this afternoon to 2 AM AST Wednesday for Coastal Waters OF Northwestern Puerto Rico out 10 NM.


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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 (8,2,3,4)
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