Marine Weather and Tides
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|Sunrise 5:59AM||Sunset 6:45PM||Saturday August 17, 2019 1:19 PM AST (17:19 UTC)||Moonrise 8:24PM||Moonset 7:32AM||Illumination 96%|
7 Day Forecast for Marine Location Near Suï¿½rez, PRHourly EDIT Help
Area Discussion for - San Juan, PR  (on/off)  Help NOTE: mouseover dotted underlined text for definition
|Fxca62 tjsj 171402|
area forecast discussion
national weather service san juan pr
1002 am ast Sat aug 17 2019
No major changes were made to the inherited forecast. An upper
level trough north of the region and its associated surface
trough will result in shower and thunderstorm activity across the
region. So far, passing showers and isolated thunderstorms have
been observed across the local waters and portions of eastern
puerto rico and the u.S. Virgin islands. Afternoon convection is
expected to develop across portions of the interior and western
puerto rico and across the san juan metro area. Isolated activity
will be possible elsewhere. Conditions are expected to improve
tonight as the surface trough moves westward away from the region.
MostlyVFR conditions are expected across all terminals until
17 17z. After that, tempos with MVFR conditions will be possible
across tjsj tjmz tjbq due to showers and thunderstorm development.
Improving weather is expected after sunset across the area. The
tjsj 17 12z sounding showed fl050 winds out of the east at 10 to
Seas of 2 to 4 feet are expected to continue across the local
waters with winds out of the east at 10 to 15 knots. Seas are
expected to mainly remain below 5 feet until Wednesday.
Prev discussion issued 538 am ast Sat aug 17 2019
synopsis... A weak trough will bring scattered showers to the
area today. A tropical wave will bring showers and thunderstorms
Sunday through Tuesday with drying on Wednesday. A weak
disturbance on Thursday and another wave on Saturday morning of
next week will bring some more showers and thunderstorms.
Short term... Today through Monday...
a broad upper level low north of the region and an associated
lower level trough is producing scattered to locally numerous
showers and isolated thunderstorms across the regional waters and
over portions of the islands. These two features in combination
with daytime heating and sea breeze convergence will aid in the
development of afternoon showers and thunderstorms, mainly along
the interior and western sections of pr as well across san juan
and vicinity. Urban and small stream flooding, frequent lightning
and brief gusty winds are possible with this activity. Elsewhere,
brief heavy showers can develop during the afternoon hours.
Moisture drops overnight, as a drier air mass ahead of a tropical
wave moves from the east and limits shower activity across the
region. However, due to the proximity of the upper level low
thunderstorms can not be ruled out across portions of the atlantic
and western waters of pr. By Sunday afternoon, tropical moisture
associated to the tropical wave should gradually increase from the
eastern caribbean waters into the forecast area. As the wave is not
expected to cross the region till later in the day, diurnally
induced afternoon showers and thunderstorms are expected to develop|
in the usual areas and between the usvi and eastern pr waters.
Model guidance suggest that the low to mid levels of the atmosphere
will be saturated due to the wave passage and that the strongest or
best chances for rain and thunderstorms should be across the
caribbean waters and eastern sections of pr and over the usvi
through Monday afternoon and similar or less amounts over the
western half of pr.
Long term... Tuesday through Saturday...
high pressure at upper levels will have nosed in from the east
northeast over the local area by Tuesday. Although lower pressure
will be southeast high pressure will hold to the north through the
end of the period and be the dominant influence over the weather.
Behind the tropical wave that moved through late Sunday and Monday
a band of moisture will flow over the area in east southeast flow
until a 700 mb ridge passes on Tuesday afternoon (20 18z). Then
flow will switch to east northeast at 700 mb and bring some of the
moisture back over the area. This will allow good convection over
puerto rico during the afternoon and evening. This flow will also
be weakly reflected in the surface flow so as to keep temperatures
on the north coast more moderate and generally no higher than the
lower 90s a few miles inland. Conditions on Wednesday and
Thursday become more stable and moisture will fall below 2 inches
of precipitable water on Tuesday night with only minor peaks on
Wednesday night and Thursday evening to bring enhancement to
shower activity. Thunderstorms should be limited, if any, to the
afternoon in western puerto rico Wednesday. Although moisture
will continue low Wednesday through Friday, some disturbances will
trigger scattered showers Thursday afternoon and Friday night
Aviation... MainlyVFR conditions expected through the morning hours
across all terminals. Afternoon shra tsra could cause tempo MVFR to
brief ifr conditions at tjmz tjbq. Brief MVFR conditions are also
possible at tjsj btw 17z-21z. Winds are expected to prevail from the
e-ese at 10-15 kt aft 14z with sea breeze variations.
Marine... Small craft advisory conditions are not expected through
the next 7 days. Brief gusty winds, torrential rains and frequent
lighting will accompany thunderstorms generated by a passing
tropical wave Sunday night through Tuesday night.
Preliminary point temps pops
Sju 89 79 89 78 40 20 40 60
stt 89 80 88 78 50 40 50 70
Sju watches warnings advisories
Short term... Erg
long term... .Cam
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