Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 161531

Area Forecast Discussion
National Weather Service San Juan PR
1131 AM AST Sat Feb 16 2019

.UPDATE...Mostly sunny and fair weather skies prevailed across the
region during the morning hours with little of no shower activity
noted across the region so far. Fairly light southeast to south
low-level wind flow will give way to local sea breeze variations
in some areas.So far due to lack of significant moisture advection,
see no change to the inherited forecast reasoning and short term
forecast at this time. Mostly isolated showers will remain possible
later this afternoon, but no significant rainfall is expected across
the region. Recent satellite imagery and upper air sounding already
suggests drying trend aloft with base of the upper trough already
crossing eastern Puerto Rico and the Virgin Islands.


.AVIATION UPDATE...VFR durg entire prd. No change to previous AVN
discussion. No sig wx impacts across the local flying area durg


.MARINE UPDATE...No change to previous marine discussion. Recent
data from the surrounding buoys continue to suggest winds between
5-15 kts and seas between 1 to 5 feet near shore and near 6 feet
over the offshore Atlantic due to light chop. Small craft operators
should exercise caution over the offshore Atlantic waters today.


.PREV DISCUSSION... /issued 517 AM AST Sat Feb 16 2019/

SYNOPSIS...Surface high pressure across the east central Atlantic
will continue to promote a moderate southeasterly wind flow today
but winds will shift to an easterly direction on Sunday and
Monday, then east northeast on Tuesday. Mid and upper level trough
will pass through the local area today but ridging will dominate
next week. The available moisture will linger today but will
diminish significantly by Monday.

SHORT TERM...Today through Monday...

Satellite imagery and model guidance suggested the axis of an upper
level trough over the local region. Moisture will gradually increase
under a southeasterly wind flow, but upper level dynamic does not
look favorable for widespread convection across the region. However,
pesky showers should not be ruled out across the U.S. Virgin Islands
and the north, east and south sections of Puerto Rico during the
morning hours followed by afternoon convection across the interior
and western sections. A mid to upper level ridge is forecast to
build aloft promoting a seasonal weather pattern by early next week.

LONG TERM...Tuesday through Sunday...

The long term forecast looks fairly benign with a rather stable
weather pattern. Mid to upper level ridge will dominate and the
available moisture will be below normal, but some patches of
moisture will move through causing brief showers across the USVI
and eastern PR. The forecast soundings show strong cap and very
dry mid levels, which will make it very difficult for locally
induced showers to develop in the afternoon across western PR.
Therefore, given the latest guidance we expect mostly fair weather
in the long term forecast with brief showers at times.

AVIATION...Mainly VFR conditions are expected to prevail through the
forecast period. However, SHRA may develop over Puerto Rico terminal
sites at times. Thunderstorms may develop over the Atlantic Offshore
waters outside of the CWA. SHRA/-SHRA will develop across NW-PR btwn
16/16-22z. Winds will return from the southeast at 10 to 15 kts with
higher gusts and sea breeze variations after 16/13Z.

MARINE...Small craft should exercise caution due to seas up to 6
feet across the Atlantic waters, seas 3 to 5 feet elsewhere.
Moderate southeast winds to persist today, becoming easterly on
Sunday. marine conditions expected to deteriorate by Wednesday of
next week with a northerly swell and fresh east northeast winds.


SJU  87  74  86  74 /  30  50  40  20
STT  83  75  83  73 /  20  50  50  20




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