Area Forecast Discussion National Weather Service San Juan PR 519 AM AST TUE JUL 19 2016
.SYNOPSIS...Ridge aloft will build across the forecast area as an upper level trough moves west into the central and western Caribbean. The ridge aloft will hold through at least the end of the workweek. As this feature erodes, an upper level trough and associated low pressure will amplify into the eastern Caribbean from the tropical Atlantic Friday and the upcoming weekend. A broad surface high pressure will continue to prevail across the central Atlantic through Friday. A series of tropical waves will continue to moves across the eastern Caribbean through Thursday.
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.DISCUSSION...Partly to variably cloudy skies were observed across the local islands during the overnight and early morning hours. Scattered showers affected the local waters, with a few of them moving across the southeast sections of Puerto Rico as well as the USVI. The overnight temperatures were in the upper 70s to lower 80s across the lower elevations, and in the upper 60s to lower 70s across the higher elevations.
Continue to expect locally induced afternoon showers and Tstorms over and north of the Cordillera Central today. Showers and thunderstorms are expected as the result of available moisture, which is associated with a weak tropical wave moving across the area...and combined with local and diurnal effects. In addition, showers embedded in the prevailing southeast wind flow cant be ruled out across USVI and Eastern Puerto Rico.
The best moisture advection, with PWAT values increasing above two inches, as well as the highest chance for shower and thunder activity during the forecast cycle is still expected Wednesday afternoon and early Thursday as another tropical wave moves across the eastern Caribbean. This wave will be accompanied by a wind surge. Therefore, at this time, squally weather conditions are possible Wednesday afternoon and early Thursday mainly across the USVI and the eastern half of PR. As this feature moves away on Thursday afternoon, a drier and dusty air mass will then encompass the eastern caribbean. Although an upper level trough will return to the forecast area by the end of the week, there will be a lack in upper level dynamics. This will result in a seasonable weather pattern Friday through Sunday.
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.AVIATION...VCSH expected across the local terminals except TJBQ and TJMZ through 19/14Z. Winds will continue from the ESE at around 10kt across the Leewards and USVI but light and VRB over PR through 19/12Z. Thereafter...winds will increase to about 10-15kt and gusty but continuing from the ESE with sea breeze variations. Afternoon SHRA/TSRA development expected in the vicinity of TJMZ but possibly over TJBQ.
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.MARINE...Tropical waves combined with a surface high pressure across the central Atlantic will increase winds and seas across the regional waters. Choppy seas of 4-6 feet expected across most of the waters. A Small Craft Advisory is in effect for the Offshore Atlantic Waters as seas of 7 feet are forecast today and Wednesday.
Area Forecast Discussion National Weather Service San Juan PR 207 PM AST TUE JUL 19 2016
.SYNOPSIS...Mid to upper ridge will build across the forecast area for the next few days. A tutt low is forecast to develop on Thursday to the northeast of the area and move west across the islands through the end of the week. At low levels, broad surface high pressure will continue to prevail across the central Atlantic through at least Friday as it shifts slowly to the northeastern Atlantic during the weekend. A tropical wave will enter the eastern Caribbean by noon tomorrow and move across the forecast area through early Thursday. Hazy conditions due to SAL expected later on Thursday through Friday.
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.DISCUSSION...Sunny to partly cloudy skies prevailed across the islands Today, as a drier air mass filtered across the region. Thus, not much rainfall activity was observed across the islands as of 2 pm ast. However, diurnal effects and limited moisture could still induced showers and thunderstorms across the NW quadrant of the island. For tomorrow, a tropical wave will bring an increase in shower and thunderstorm coverage across the forecast area. Some thunderstorms are expected to produce strong gusty winds and create periods of urban and small stream flooding due to periods of moderate to heavy rainfall across the mountain ranges of the island. Fair weather conditions are expected following the passage of the wave as SAL and convergence aloft due to the position of the tutt to the northeast of the area.
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.AVIATION...VCSH but generally VFR conditions are expected to continue through 19/17z. Then sct-num SHRA and TSRA will develop mainly interior and northwestern PR with areas of mtn obscurations. Condtions will persist until arnd 20/00z. In the Leeward Islands VFR conds expected until at least 20/08z. SHRA to increase in advance of a tropical wave moving through the area later Wednesday. Winds alf: strongest winds 120/38 kt at FL120. Sfc winds 10 to 20 kt with some sea breeze influences and higher gusts in TSRA.
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.MARINE...Small craft advisory continues in effect for 7 feet seas in the offshore Atlantic waters through Wednesday night. Squally weather expected tomorrow and early Thursday due to the passage of a tropical wave. Small crafts should exercise caution across the rest of the water due to seas up to 6 feet and east winds up to 20 knots.
Area Forecast Discussion National Weather Service San Juan PR 429 AM AST WED JUL 20 2016
.SYNOPSIS...Tropical wave is expected to move into the local area today with the highest amount of moisture moving in after noon. Surface high pressure over the Central Atlantic will continue to promote a moderate easterly wind flow for the next few days. Weak upper level ridge is present over the local islands but a TUTT is expected to develop on Thursday to the northeast of the Leewards and it is expected to move to the southwest into the local area by Saturday. Saharan dust expected to affect the local area late Thursday into Friday.
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.DISCUSSION...Widely scattered showers have been observed during the overnight hours across the local forecast area. This is due to the steady increase in moisture as a tropical wave approaches. The deepest moisture associated with the tropical wave is expected to move in after noon...causing showers and thunderstorms to move in and affect the local islands. Also...when combined with the local effects...thunderstorms are expected across western PR. Moderate to heavy rain with occasional lightning and gusty winds can be expected with the thunderstorm activity. The deep moisture is expected to linger into Thursday morning...which is the reason why the forecast calls for numerous showers and isolated thunderstorms into Thursday morning.
Gradual improvement is expected on Thursday...especially in the afternoon as drier air and Saharan dust begins to move into the local area. By Friday...the drier air and Saharan dust is still expected to be over the local area. There is also the TUTT to the northeast by then which will cause subsidence due to its positioning...so shower and thunderstorm activity on Friday and Saturday afternoon is expected to be limited.
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.AVIATION...VCSH but generally VFR conditions are expected to continue through 20/16z. Then sct-num SHRA and TSRA will develop mainly interior and northwestern PR with areas of mtn obscurations. Condtions will persist until 20/22z. SHRA/TSRA to increase at the Leeward and USVI terminals during the afternoon and evening hours respectively. These SHRA/TSRA expected to reach PR aft 21/00z. Sfc winds 10 to 20 kt with some sea breeze influences and higher gusts in TSRA.
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.MARINE...Showers and thunderstorms with gusty winds expected over the waters today into Thursday as the tropical wave passes. Small craft advisory continues in effect for 7 foot seas across the offshore Atlantic waters through this evening. Small craft operators should exercise caution across the rest of the waters due to seas up to 6 feet and east winds up to 20 knots.
Area Forecast Discussion National Weather Service San Juan PR 205 PM AST WED JUL 20 2016
.SYNOPSIS...Tropical wave is expected to move into the local area through tomorrow. Surface high pressure over the Central Atlantic will continue to promote a moderate easterly wind flow for the next few days. Weak upper level ridge is present over the local islands but a TUTT is expected to develop on Thursday to the northeast of the Leewards and it is expected to move to the southwest into the local area by Saturday. Saharan dust expected to affect the local area late Thursday into Friday.
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.DISCUSSION...Showers with thunderstorms developed this afternoon across most of the area...with the heaviest weather affecting the western section of Puerto Rico. Activity was associated with the leading edge of a tropical wave just over the Eastern Caribbean this afternoon. The moisture associated with the wave...will continue to combine with daytime heating and local effects to induce the development of scattered to numerous showers and isolated to scattered thunderstorms across central, interior, and western Puerto Rico as well as across the USVI and the surrounding coastal waters.
This activity is expected to continue overnight and into Thursday. After the passage of the wave, a drier air mass is then expected to move across the local islands from the east, limiting the shower activity to the typical early morning showers over eastern Puerto Rico, followed by some afternoon convection across western and interior Puerto Rico.
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.AVIATION...Brief periods of MVFR conditions will affect the leeward, USVI and Eastern Puerto Rico taf sites until at least 20/21Z. Scattered to numerous SHRA and TSRA will continue to develop mainly across interior and northwestern PR with areas of mtn obscurations until 20/22Z. SHRA/TSRA will increase again at the Leeward and USVI terminals this evening. SHRA/TSRA expected to reach again PR after 21/02Z. Sfc winds 10 to 20 kt with higher gusts near thunderstorms.
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.MARINE...Showers and thunderstorms with gusty winds expected over the waters tonight into Thursday as the tropical wave passes. Small craft advisory continues in effect for 7 foot seas across the offshore Atlantic waters through this evening. Small craft operators should exercise caution across the rest of the waters due to seas up to 6 feet and east winds up to 20 knots.
Area Forecast Discussion National Weather Service San Juan PR 425 AM AST THU JUL 21 2016
.SYNOPSIS...Tropical wave is continues to move west and out of the local area but lingering moisture will remain through the early afternoon hours. Surface high pressure over the Central Atlantic will continue to promote a moderate easterly wind flow for the next few days. A TUTT is expected to develop today just northeast of the Leewards and it is expected to move to the west southwest approaching the local area by Saturday. Saharan dust expected to affect the local area this afternoon into Friday. Relatively dry conditions expected on Friday and Saturday with the chance of rain increasing slightly for Sunday.
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.DISCUSSION...Widely scattered showers were observed during the overnight hours across the local forecast area. This is due to the lingering moisture of the tropical wave that passed over the area yesterday. The available moisture is now gradually decreasing and it is expected to continue into the early afternoon hours. However...when combined with the local effects...thunderstorms are possible across western and northwestern PR. Moderate to heavy rain with occasional lightning and gusty winds can be expected with the thunderstorm activity.
Gradual improvement is expected by late this afternoon and tonight...as drier air and Saharan dust begins to move into the local area. By Friday...the drier air and Saharan dust is still expected to be over the local area. There is also the TUTT to the northeast by then which will cause subsidence due to its positioning...so shower and thunderstorm activity on Friday and Saturday afternoon is expected to be limited. A slight increase in moisture is expected for Sunday...which is expected to aid in the development of morning showers across the local waters...USVI...and eastern PR and then showers and thunderstorms across western PR on Sunday afternoon.
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.AVIATION...VCSH at the Leeward and USVI terminals as well as JSJ early this morning...but generally VFR conds expected to prevail. SHRA/TSRA will develop over the interior and northwest PR with areas of mtn obscurations between 21/16-22z...this also may result in MVFR conds at JBQ. Sfc winds 10 to 20 kt with some sea breeze influences and higher gusts in TSRA.
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.MARINE...Winds between 15 to 20 knots expected over most exposed waters. In the outer Atlantic waters...seas are expected to be at around 7 feet. Therefore there is a small craft advisory through 8 PM AST tonight. Seas up to 6 feet are expected elsewhere so small craft operators should exercise caution today.
Area Forecast Discussion National Weather Service San Juan PR 200 PM AST THU JUL 21 2016
.SYNOPSIS... A TUTT it is expected to move to the west southwest approaching the local area by Saturday. Saharan dust expected to affect the local area through Friday. Relatively dry conditions expected on Friday and Saturday with the chance of rain increasing slightly for Sunday.
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.DISCUSSION...A very drier air mass has moved across the area today. This area of drier air is accompany by Saharan air which is suppressing the shower activity across the region. However...available moisture combined with strong daytime heating and local effect to produced some showers and thunderstorms over the western interior and northwest sections of Puerto Rico.
For the remainder of the work week and into the weekend...dry air will continue dominating the local region. Although a TUTT it is expected to move west southwest approaching the local area by Saturday...it is expected to remain east of the area...without any significant impact expected over the region.
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.AVIATION...VCSH at the Leeward and USVI terminals as well as TJSJ this morning...but generally VFR conditions expected to prevail. SHRA/TSRA will develop over the interior and northwest PR with areas of mtn obscurations between 21/16-22z...this also may result in MVFR conditions at tJBQ. Sfc winds 10 to 20 kt with sea breeze influences and higher gusts in TSRA.
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.MARINE...Winds between 15 to 20 knots expected over most exposed waters. Latest buoy observations indicated seas have decreased below 7 feet in the Atlantic waters. Therefore there is a small craft advisory through 8 PM AST tonight. Seas up to 6 feet are expected elsewhere so small craft operators should exercise caution.
Area Forecast Discussion National Weather Service San Juan PR 519 AM AST FRI JUL 22 2016
.SYNOPSIS...Fair weather pattern will prevail across the local islands through at least Saturday. An upper level low/TUTT will move over the region on Sunday...increasing the instability and the chance of showers across Puerto Rico and the U.S. Virgin Islands. Another surge of moisture is expected on Tuesday next week.
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.DISCUSSION...A relatively dry and stable air mass will prevail across the islands today. Saharan dust particles embedded in this stable air mass will produce hazy skies and somewhat reduce visibilities. Strong subsidence will keep the chances of showers generally low and the rainfall accumulations will be mainly light. Moderate showers still possible over Southwest Puerto Rico during the afternoon due to the sea breeze convergence.
Stable pattern will prevail through Saturday as Saharan Air Layer remains over the area...limiting the development of showers across the local region. A few bands of moisture embedded in the trade winds will bring light showers at night and early in the morning. An upper level trough/TUTT will move over the area late Saturday into Sunday...increasing the moisture and instability across the local islands. The coverage and intensity of the afternoon convection will increase somewhat due to the influence of the TUTT. The next surge of moisture is associated with a tropical wave. At this time...operational models suggest that the moisture associated with the wave will likely reach the local region on Tuesday. As a result...showers and a few thunderstorms are likely with the wave.
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.AVIATION...Mainly VFR conditions are expected to prevail through the rest forecast period. HZ due to Saharan dust expected Today across the flying area. From 17Z-22Z, SHRA/Isolated TSRA expected to develop over western interior/southwestern PR creating brief mvfr and areas of mtn obscurations thru at least 22Z, impacting mainly TJMZ and the vicinity of TJPS/TJBQ. Low level winds from the ENE at 10-20 knots with sea breeze variations and higher gusts after 14Z.
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.MARINE...Seas have subsided across the local waters. Mariners can expected seas of 3-5 feet and winds around 10-15 knots through at least midweek next week. No Small Craft Advisories are anticipated over the next 5-7 days.
Area Forecast Discussion National Weather Service San Juan PR 153 PM AST FRI JUL 22 2016
.SYNOPSIS...Surface high pressure will continue to dominates the local region through the Saturday night. An upper level trough will approach the local area Sunday.
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.DISCUSSION...Very dry conditions prevailed across the local area today. No shower activity was observed over land areas. Drier air will continue across the region until at least Saturday. However...the limited available moisture will combine with strong daytime heating...sea breeze convergent and local mountains effects to produce some showers and a couple of thunderstorms across western interior and southwest sections of Puerto Rico tomorrow afternoon. A slight increase in moisture is expected by Sunday as an upper level trough moves close to the region. Better moisture...with GFS computer model suggesting precipitable water values up to 2.0 inches are forecast on Tuesday. Therefore...an increase in shower and thunderstorm activity is expected by early next week.
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.AVIATION...Mostly VFR conditions are expected to prevail through the forecast period across the local flying area. HZ due to Saharan dust also expected to continue across the flying area. Low level winds from the ENE at 10-20 knots with sea breeze variations and higher gusts this afternoon diminishing after 22Z.
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.MARINE...Seas up to 5 feet and winds up to 20 knots are expected. Small Craft should exercise caution across the coastal waters of southern Puerto Rico.
Area Forecast Discussion National Weather Service San Juan PR 505 AM AST SAT JUL 23 2016
.SYNOPSIS...An upper level low/TUTT just northeast of Puerto Rico will move over the local islands later today. This will help to increase the instability and the chance of showers across Puerto Rico and the U.S. Virgin Islands during the weekend. Another surge of moisture is expected on Tuesday next week. Then...drier and more stable pattern will return to the islands by midweek.
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.DISCUSSION...A generally stable air mass will prevail across the islands most of today. Saharan dust particles will continue to diminish throughout the day. Subsidence cap will gradually weaken as the TUTT moves over the local islands. This will allow moderate showers to develop over portions of the Cordillera Central and Southwest Puerto Rico during the afternoon due to the sea breeze convergence and orographic effects.
The upper level trough/TUTT over the area on Sunday will promote moisture transport across the local area. In addition...the unstable environment will help to increase the coverage and intensity of the showers and thunderstorms. Although...no significant rainfall accumulations are expected during the weekend...periods of heavy rainfall can`t ruled out.
The next surge of moisture is associated with a tropical wave. At this time...operational models suggest that moisture associated with the wave will likely reach the local region on Tuesday. As a result...showers and a few thunderstorms are likely with the wave. Stable pattern is forecast from midweek to the end of next week. Another pulse of Saharan Dust will likely reach the local islands by midweek.
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.AVIATION...Mainly VFR conditions are expected to prevail during the next 24 hours. However, SHRA developing over western interior/southwestern PR could create brief mvfr conditions and mtn obscurations through at least 22Z, impacting mainly TJMZ and the vicinity of TJPS/TJBQ. Low level winds will continue from the ENE at 10-20 knots with sea breeze variations and higher gusts after 14z.
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.MARINE...Typical seas are forecast across the local waters. Mariners can expect seas of 3-5 feet and winds around 10-15 knots over the next several days. No Small Craft Advisories are anticipated over the next 5-7 days.
Area Forecast Discussion National Weather Service San Juan PR 118 PM AST SAT JUL 23 2016
.SYNOPSIS...An inverted upper level trough over the region will move to the west on Sunday. This feature will increase the instability and the chance of showers across Puerto Rico and the U.S. Virgin Islands during the rest of weekend. Another surge of moisture associated with a tropical wave expected to reach the region late Monday and Tuesday next week.
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.DISCUSSION...Saharan dust particles diminished considerably across the region today. Doppler weather radar indicated isolated to scattered showers across eastern sections of Puerto Rico as well as across the surrounding waters this morning and early in the afternoon. This moisture is associated with an inverted upper level trough across the region this afternoon. The instability provided by the trough in combination with daytime heating and local effects resulted in the development of showers across western and southwest sections of Puerto Rico this afternoon. This activity is expected to diminish rapidly after sunset.
Tonight, the upper trough will move to a position more favorable for the development of showers and thunderstorms and therefore, isolated to scattered showers will develop overnight and early Sunday across USVI, Vieques, Culebra and Eastern sections of Puerto Rico followed by showers and thunderstorms across Western and interior PR Sunday Afternoon. Although...no significant rainfall accumulations are expected on Sunday...periods of heavy rainfall can`t ruled out.
Latest satellites images and surface analysis depicted a tropical across 40 West this afternoon. Model guidance suggests that moisture associated with this wave will likely reach the local region on Tuesday. Another pulse of Saharan Dust will encompass the region with the passage of the wave.
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.AVIATION... Isolated to scattered SHRA expected across Eastern PR, USVI and the Leeward islands taf sites tonight and early Sunday morning. Mostly VFR conditions expected across the rest of the local flying area. SHRA developing over western and interior PR could create brief MVFR conditions and mtn obscurations after 24/17 through at least 24/22Z, impacting mainly TJMZ and the vicinity of TJPS/TJBQ. Easterly low level winds will diminish tonight 10-15 knots increasing at 10-20 knots with sea breeze variations and higher gusts after 24/14z.
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.MARINE...Seas up to 5 feet and winds up to 20 knots are forecast across the local waters. Mariners are urged to exercise caution across parts of the waters due to winds, however...no Small Craft Advisories are anticipated over the next few days.
Area Forecast Discussion National Weather Service San Juan PR 511 AM AST SUN JUL 24 2016
.SYNOPSIS...An upper level trough/TUTT west of Puerto Rico is enhancing the instability across Puerto Rico and the U.S. Virgin Islands. Another surge of moisture associated with a tropical wave is expected on Tuesday. Drier and more stable pattern will return to the islands by midweek. Then...Another TUTT will be positioned over the region between Thursday and Friday bringing once again unstable conditions.
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.DISCUSSION...Satellite Precipitable Water Analysis shows an area of deep moisture associated with an induced trough over the Northeast Caribbean Region. This high moisture content will combine with the instability aloft to support scattered to numerous showers across the local waters and portions of the islands today. Although... most of the showers will remain over the local waters this morning... some showers will move inland over the eastern third of Puerto Rico the rest of the morning. Stronger showers and isolated thunderstorms are expected over portions of the Cordillera Central and parts of the North and West Puerto Rico this afternoon. The U.S. Virgin Islands will experience scattered showers at times.
Slightly drier pattern is anticipated on Monday as the TUTT moves over the Central and Wrst Caribbean. However...scattered showers remain in the forecast...especially across western Puerto Rico during the afternoon hours. Operational models indicate deep moisture associated with a tropical wave reaching the local region on Tuesday. This will result in another round of showers and thunderstorms across the local area. Generally stable pattern is forecast by midweek as a drier air mass with Saharan Dust will reach the local islands.
Unstable conditions will likely return to the islands at the end of the work week as another upper trough/TUTT will move over the islands. Therefore...expect another round of showers and thunderstorms.
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.AVIATION...Mainly VFR conditions are expected to prevail, however, passing trade wind showers could reach the Leeward, USVI and eastern PR terminals thru the fcst period. Streamers are expected to develop by mid to late morning across the USVI, resulting in periods of -RA at times and SCT cigs between FL025-FL070. SHRA/TSRA will develop over the interior and western PR with areas of mtn obscurations between 16Z-22z, resulting in TEMPO MVFR conditions at TJBQ/TJMZ. Also, SHRA can affect at times TJSJ during the afternoon hours. Low level winds prevail E-ESE at 10-20 knots with sea breeze variations after 14Z.
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.MARINE...Typical seas are forecast across the local waters. Mariners can expect seas of 3-5 feet and winds around 10-20 knots over the next several days. Small craft operators should exercise due to winds up to 20 knots across the coastal waters of Northern Puerto Rico. However...no Small Craft Advisories are anticipated over the next 5-7 days.
Area Forecast Discussion National Weather Service San Juan PR 129 PM AST SUN JUL 24 2016
.SYNOPSIS...An inverted upper trough just to the west of Puerto Rico will continue to enhance moisture transport across Puerto Rico and the U.S. Virgin Islands tonight. Another surge of moisture associated with a weak tropical wave is expected to reach the region on Tuesday. Drier air will move across the region by midweek. Accordingly to model guidance, a more vigorous tropical wave will reach the region by the upcoming weekend.
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.DISCUSSION...Under the influence of an inverted upper trough, isolated to scattered passing showers affected the USVI, Vieques, Culebra, Eastern PR and the surrounding coastal waters this morning and early this afternoon. This activity is expected to combine with strong daytime heating and local orographic effects to induce the development of scattered showers and isolated thunderstorms across north, western and interior sections of Puerto Rico this afternoon. The upper low is expected to move farther to the west on Monday resulting in a slight improve in the weather conditions.
Latest satellites images and surface analysis depicted a tropical wave along 50 West this afternoon. Model guidance suggests that moisture associated with this wave will likely reach the local region on Tuesday. Another pulse of Saharan Dust is expected to encompass the region with the passage of the wave. Accordingly to model guidance, a more vigorous tropical wave will reach the region by the upcoming weekend.
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.AVIATION...Mainly VFR conditions will prevail with vicinity SHRA across the Leeward, USVI and eastern PR terminals thru the fcst period. Streamers are expected to persist across the USVI until 20Z, resulting in periods of SHRA at times and SCT cigs between FL025-FL070. SHRA/TSRA are expected to develop over the northern, interior and western PR with areas of mtn obscurations between 16Z-22Z, resulting in TEMPO MVFR conditions at TJBQ/TJMZ. SHRA can also affect TJSJ during the rest of afternoon hours. Low level winds prevail E-ESE at 10-20 knots
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.MARINE...Mariners can expect seas of 3-5 feet and winds around 10-20 knots over the next several days. Small craft operators should exercise due to winds up to 20 knots across the coastal waters of Northern Puerto Rico. However...no Small Craft Advisories are anticipated over the next 5-7 days.
Area Forecast Discussion National Weather Service San Juan PR 526 AM AST MON JUL 25 2016
.SYNOPSIS...Mid level ridge over the western Atlantic will shift westward over the next few days. Deep moisture associated with a tropical wave is forecast to reach the local region on Tuesday. Upper level trough/TUTT will dig southwestward and relocate over the region between Thursday and Friday. Another tropical wave expected late in the weekend.
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.DISCUSSION...Satellite loops indicated bands of moisture embedded in the trade wind flow approaching the Northeast Caribbean Region. This moisture advection over the local area have resulted in showers affecting the regional waters and the windward areas. Additional showers will move inland over portions of the U.S. Virgin Islands and eastern Puerto Rico the rest of the morning. Stronger showers and isolated thunderstorms are expected to develop over portions of the West Interior and parts of the Northwest Puerto Rico this afternoon. The U.S. Virgin Islands will experience isolated to scattered showers at times.
Operational models indicate deep moisture associated with a tropical wave reaching the local region on Tuesday. This will result in another round of showers and thunderstorms across the local area. Moisture and instability will diminish on Wednesday...reducing the shower coverage across forecast area.
Unstable conditions will likely return to the islands at the end of the work week as a upper trough/TUTT will move over the islands. Then...another tropical wave is forecast to reach the local region during the weekend. Therefore...moist and unstable pattern will be likely the second part of the week.
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.AVIATION...Mostly VFR conditions are expected to prevail with passing -SHRA across the Leeward, USVI and E PR flying area. SHRA/TSRA expected over western PR with areas of mtn obscurations between 16Z-22z, resulting in brief periods of MVFR conds at TJBQ/TJMZ. Low level winds prevail E-ESE at 10-20 knots with sea breeze variations after 14Z.
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.MARINE...Mariners can expect seas of 3-5 feet and winds around 10-20 knots over the next several days. Small craft operators should exercise due to winds up to 20 knots across the coastal waters of Northern Puerto Rico. Winds and seas may increase significantly during the weekend as a stronger tropical wave moves across the local waters.
Area Forecast Discussion National Weather Service San Juan PR 205 PM AST MON JUL 25 2016
.SYNOPSIS...Tropical wave will move across the area Tuesday. SAL will encompass the region Wednesday and Thursday. Next tropical wave is expected on Sunday.
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.DISCUSSION...Mostly sunny skies prevailed across Puerto Rico and the U.S. Virgin Islands this morning. Some light passing showers affected the local islands..but were brief. This afternoon...some showers with thunderstorms developed over the western interior and northwest sections of Puerto Rico. This activity was locally induced and should dissipated near sunset.
For tomorrow...a Tropical wave is expected to affect the local area...increasing the changes for shower and thunderstorm activity across the region. After the passage of this wave...an area of Saharan air layer is expected to move across the region...which will suppress the shower development across the region. It is not until Sunday...better chances for showers and thunderstorms are expected as an active tropical wave moves across the region.
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.AVIATION...VFR conditions expected during most of the period. -SHRA expected across the Leeward, USVI and E PR flying area from time to time during the afternoon. Brief periods of MVFR are likely across western PR, due to SHRA/TSRA between 25/19Z-22z. E-ESE surface winds at 15 to 20 kt with sea breeze variations and higher gusts in/near shra/tsra. Winds are expected to drop at 5 to 15 knots overnight, although higher gusts can be expected in SHRA.
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.MARINE...Seas up to 5 feet and winds up to 20 knots are expected. Small Craft should exercise caution mainly across the atlantic waters.
Re: Caribbean - Central America Weather
Posted: Tue Jul 26, 2016 5:11 am
by cycloneye
Area Forecast Discussion National Weather Service San Juan PR 549 AM AST TUE JUL 26 2016
.SYNOPSIS...Tropical wave will continue to move across the forecast area Today. Surface high pressure will continue across the Atlantic waters. A drier mid level air mass with Saharan dust will move over the islands on Wednesday and linger through Thursday. An upper level trough will develop late Wednesday into Thursday to the northeast of the islands and move westward quickly, enhancing showers and thunderstorms on Thursday afternoon across the mountain ranges of PR. Next tropical wave is expected on Friday followed by another one on Sunday.
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.DISCUSSION...Scattered to numerous showers and thunderstorms affected the Atlantic and Caribbean waters during the overnight hours. A couple of thunderstorms affected the northeastern quadrant of Puerto Rico with frequent lightning observed just between Culebra and Fajardo. The doppler radar estimated between 0.75 to near 1 inch of rain from Rio Grande to Trujillo Alto. These showers and thunderstorms will continue through the day as the tropical wave exits the local area in the evening hours. For this afternoon, thunderstorm development is expected mainly over the interior and NW quadrant of PR. Urban and small stream flooding is expected due to already saturated soils across these areas.
For Wednesday, dry mid level air with SAL will limit shower development over the islands. A TUTT low is forecast to develop to the northeast of the area and move quickly over Hispaniola to enhance showers and thunderstorms on Thursday afternoon. Moisture will increase once again on Friday as a weak tropical wave/easterly perturbation moves over the islands. Saharan dust is expected once again on Saturday and on Sunday another wave is forecast to enter the eastern Caribbean.
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.AVIATION...SHRA and TSRA associated with a tropical wave will affect the flying area today. However...VFR conds will prevail across most of the TAF sites, except in and around TJMZ and TJBQ where mountain obscurations and brief MVFR conds are likely between 17Z-22Z. Low level winds prevail E at 10-20 kts with sea breeze variations and gusty winds near the TSRA.
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.MARINE...Seas are expected to remain below small craft advisory criteria for the next several days. However, seas up to 6 feet and east winds up to 20 knots are expected Today. Therefore, small crafts should exercise caution across the Atlantic and Caribbean waters. Thunderstorms are expected to continue through this evening across the local waters. Periods of torrential rainfall, frequent lightning and gusty winds are expected. Also, isolated waterspouts can`t be ruled out.
Area Forecast Discussion National Weather Service San Juan PR 142 PM AST TUE JUL 26 2016
.SYNOPSIS... A tropical wave will exit the local area this evening. Followed by a dry air mass with Saharan Dust Particles on Wednesday and Thursday. Then another easterly tropical wave is forecast to move across the islands on Friday. The model guidance are forecasting a strong easterly wave around Sunday. At the surface, a broad surface high pressure across the northeast Atlantic will continue to produce a moderate east wind flow across the region for the next several days. At the upper levels, a TUTT low will build over the region Thursday into Friday.
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.DISCUSSION... Most of the showers and thunderstorms that affected the eastern half of Puerto Rico and the U.S. Virgin Islands during the morning hours dissipated or moved over the Atlantic waters. However, still expecting more showers and thunderstorms to develop along the interior and northwestern portions of Puerto Rico this afternoon. As a result the potential for urban and small stream flooding, frequent lightning and gusty winds still possible across these sections.
Satellite imagery and model guidance suggested the arrival of a dry air mass with Saharan dust particles as this wave moves away from the CWA. As a result, limit shower/thunderstorm activity is expected on Wednesday. A TUTT low is forecast to build over the region by Thursday and Friday. This upper level feature is expected to enhance the potential for showers and thunderstorms. Another tropical wave is forecast to enter the Eastern Caribbean, increasing the tropical moisture across the local islands. Saharan dust is expected once again on Saturday and on Sunday another wave is forecast to enter the eastern Caribbean.
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.AVIATION...VFR conds will prevail across most of the TAF sites, except in and around TJMZ and TJBQ where mountain obscurations and brief MVFR conds are likely between 18Z-22Z. Low level winds prevail E at 10-20 kts with sea breeze variations and gusty winds near the TSRA.
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.MARINE... Small crafts should exercise caution across the Atlantic and Caribbean waters due to seas up to 6 feet across the region. The potential for thunderstorms still expected over the western half of the local waters, as the tropical wave move away this evening. Periods of torrential rainfall, frequent lightning and gusty winds are expected. Also, isolated waterspouts can`t be ruled out.