Southern US Virgin Islands, Vieques and Eastern Puerto Rico out 10nm Marine Forecast
|Tonight...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Up To 5 Feet. Dominant Period 10 Seconds. Isolated Showers Through The Night.|
|Friday...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Up To 5 Feet. Dominant Period 10 Seconds. Isolated Showers.|
|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 Showers.|
|Saturday...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Up To 5 Feet. Dominant Period 8 Seconds. Isolated Showers.|
|Saturday Night...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Up To 5 Feet. Dominant Period 10 Seconds. Isolated Showers.|
|Sunday...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Up To 5 Feet. Dominant Period 11 Seconds. Scattered Showers.|
|Monday...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Up To 5 Feet. Dominant Period 10 Seconds. Scattered Showers.|
|Tuesday...East Winds 10 To 15 Knots. Seas 1 To 3 Feet. Dominant Period 8 Seconds. Isolated Showers.|
| Area Forecast Discussion|
National Weather Service San Juan PR
750pm AST Thu May 19 2022
Skies became mostly clear to partly cloudy across the region with little or no shower activity noted across the forecast area. A few showers were noted earlier in the afternoon across the west interior around Utuado, but were of short duration with no significant rainfall accumulations observed or reported. An overall dry and stable air-mass will remain in place at least through Friday with hot and hazy conditions expected to continue. Limited showers activity is forecast so far as a deep layered high pressure ridge and a moderate concentration of suspended Saharan dust particulates in an extensive Saharan Air Layer spread across the Tropical Atlantic and eastern Caribbean, will persist for the next several days favoring the hot and hazy conditions as previously mentioned. Otherwise no change to the previous inherited forecast grids and reasoning at this time.
ht to moderate east southeast winds between 5 to 15 knots will continue across the regional water and local passages overnight with seas of 4 feet or less. No change to the previous marine discussion. Recent model guidance continued to suggest the arrival of a small northerly across the local Atlantic waters over the upcoming weekend.
/issued 500pm AST Thu May 19 2022/
SYNOPSIS...The Saharan Air Layer (SAL) affecting our region will continue to promote hazy skies into the weekend, lulling on Saturday. The mid-level ridge and drier air entering our region has inhibited any development of shower activity in our area, and should continue to do so by the end of the week. Warmer temperatures and heat indices in the low 100s are also possible each day.
SHORT TERM...Tonight through Saturday... The weather pattern for most of the short term period will continue to be influenced by a mid-level ridge and the Saharan Air Layer (SAL) filtering into our region. The ridge and the drier air, with suspended Saharan dust particulates, entering our region have mostly limited afternoon convective activity to short-lived showers in areas in or near the Utuado and Lares municipalities. Conditions are expected to continue to be unfavorable for any convective activity during the short term period, with hazy skies and deteriorated air quality. Satellite precipitable water values are around 1.60 in and are expected to continue drying through the short term period, staying within normal values for this time of the year. General wind flow will continue to be from the southeast due to the surface ridge that will be over the central Atlantic during the short term period. This will continue to promote warmer temperatures with maximum heat indices across northern (Friday and Saturday) and western portions (on Friday) of PR reaching the mid 100s during the day. Hot, dry and hazy conditions will continue through the short term period. Filtering SAL (Saharan Air Layer) into our forecast area should lull on Saturday, according to the GEOS aerosol model, leaving slightly more favorable conditions for convective development. By the end of the short term period, on Saturday night, the mid level ridge should start to collapse, making way for a deepening upper level trough. This could also lead to slightly more favorable conditions for convective development.
Long Term...Sunday through Thursday... FROM /issued 508am AST Thu May 19 2022/
A TUTT-low is expected to develop over the central Atlantic by Sunday and hold through midweek. The base of the trough is forecast to meander for much of the long term period over the northeastern Caribbean. Meanwhile at the surface, the associated low pressure over the central Atlantic and a building ridge over the western Atlantic will promote a northeasterly wind flow and a cool advective pattern across the local area. PWAT (Precipitable Water) content is forecast to increase between 1.75-2.00 inches through the period, and 500 mb temperatures are expected to drop to around -8C. Therefore, a more seasonable weather pattern is expected during the long term period. Expect trade wind showers to increase during the nighttime and early morning hours between the USVI and north/eastern sections of PR, followed by diurnally induced afternoon showers over portions of the interior and western PR each day. Isolated thunderstorms are possible during the afternoon hours, but were not included in the official forecast at this moment.
AVIATION... Hazy conditions will cont for at least the next 24 hours, yet VSBYs should remain P6SM exc for a few hrs around sunset/sunrise when VSBYs could be 6 SM in Saharan dust. Some mtns may be lcly topped with low- topped clouds. Surface winds east 10-15 kts with hir gusts in sea breezes near the coasts. Aft 19/23Z, winds diminishing to less than 7 kt in land breezes. Aft 20/13Z surface winds to bcm ESE 12-18 kt with some hir gusts in sea breezes. Maximum winds NW 45-50 kts between FL420- 480.
Seas will remain at 4 feet or less across the local waters and passages through the rest of the workweek except areas with 5 feet driven by very localized winds around Puerto Rico. A surface high pressure over the central Atlantic will maintain gentle to moderate east to southeast winds across the local waters and passages. A small northerly swell is forecast to arrive across the local Atlantic waters this upcoming weekend.
.SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None.