Area Forecast Discussion
Issued by NWS San Juan, PR
FXCA62 TJSJ 250151
Area Forecast Discussion
National Weather Service San Juan PR
951 PM AST Mon Oct 24 2016
After the end of the afternoon showers and thunderstorms, mostly
clear skies were observed. Although, showers are not affecting
the west coast of Puerto Rico, the river sensor at Guanajibo
River, continues to indicate it is at flood stage, however no
significant flooding was reported by emergency managers. The
Doppler radar detected most of the shower activity across the
local waters. However Culebra, the northern sections of Puerto
Rico and the U.S. Virgin Islands were affected by moderate to
brief heavy showers tonight. For the rest of tonight and tomorrow,
surface trough and moisture will linger across the region with
prevailing winds mainly from the northeast. Therefore, expect
periods of early morning showers focused mainly across the
northeastern slopes of eastern Puerto Rico. This will be followed
by afternoon convection over parts of the central mountain range
and southwest Puerto Rico. Some of the afternoon showers and
thunderstorms may lead to periods of locally heavy rainfall with
minor urban and small stream flooding.
Prevailing VFR at all Terminals but VCSH fcst to cont til 25/14z.
Isold TSRA en route btw ern PR and USVI as well as N of TJSJ ovr
coastal waters. Few Tops FL200-FL300. SCT-BKN FL020... FL050...
FL100. L/lvl winds fm NE will cont to steer cld lyrs with embedded
passing SHRA inland ovr N coastal sections of islands, with ocnl
Mtn top obscr due to low scud clds and SHRA til 25/14z. Aft
25/16z...SHRA/TSRA psbl ovr and downwind of Ctrl Mtn range of PR.
Brief MVFR expected at TJMZ/TJPS til 25/22z. SFC wnds fm NE at
5-15 kt. Sea breeze variations 25/14z-25/23z.
Tranquil marine conditions will continue to prevail with seas up
to 4 feet and winds 10 knots or less except in the Atlantic
Offshore waters and passages where winds will be 10 to 15 knots
and seas up to 5 feet.
.PREV DISCUSSION... /issued 139 PM AST Mon Oct 24 2016/
SYNOPSIS...Upper level ridge will weaken rapidly Tonight and
Tuesday as a broad polar moves across the eastern United States
Seaboard and the Northwest Atlantic. This upper level pattern
will hold through the next few days. Upper level ridge will build
again over the northeast Caribbean by Thursday. A pre-frontal
trough just over the region will maintain abundant moisture across
the local islands for the next several days.
DISCUSSION...A pre-frontal trough across the region will maintain
a moist an unstable weather pattern across the local islands until
at least Wednesday. Doppler weather radar detected scattered
showers and isolated thunderstorms across central interior and
western sections of Puerto Rico early in the afternoon. This
activity is expected to increase late this afternoon and lasting
until the early evening hours. Soils are saturated due to the
previous days rainfall and therefore Urban and Small Stream
flooding are possible this afternoon and evening across central
interior and western Puerto Rico.
Model guidance suggests that the frontal boundary remnants will
remain north of the region for the next few days. This moisture
will maintain a moist and unstable weather environment favorable
for the development of shower and thunderstorm activity across the
region. Showers and thunderstorms are therefore expected Tuesday
and Wednesday across portions of the local islands. A weak
tropical wave, near 60 West this afternoon will continue to move
westward, reaching the local islands Thursday and Friday and
maintaining a wet weather pattern across the area until the ends
of the work week.
AVIATION...Brief MVFR with mountain obscurations expected at
TJMZ/TJPS until at least 24/23Z. After 24/23Z mostly VFR
conditions will prevail across the local flying area with
vicinity SHRA across the Leewards, USVI and TJSJ taf sites. After
25/16Z SHRA/TSRA will develop again around Cordillera Central and
downstream from El Yunque. Winds NE at 5-15 kt up through FL200.
Sea breeze variations aft 14z.
MARINE...Tranquil marine conditions are expected to continue
through mid this week with seas below 5 feet and winds around 15
knots. Today`s rip currents risk is low across the local beaches.
.PRELIMINARY POINT TEMPS/POPS...
SJU 78 88 78 88 / 40 50 50 30
STT 78 87 78 87 / 40 50 50 30