Scientific Forecaster Discussion
fxca62 tjsj 171506
Area forecast discussion
National Weather Service San Juan PR
1106 am AST Tue Jan 17 2017
Update...shower activity and cloudiness across the region
diminished by the late morning hours leaving mostly sunny skies
with only a few showers over the offshore Caribbean and Atlantic
waters. Limited showers activity expected during the afternoon
but locally and diurnally induced showers may form and quickly
stream southwest across parts of the interior and southwest
sections of PR. No significant accumulations expected, as mostly
fair weather and stable conditions will prevail across the region
for the next few days. However another round of late evening and
early morning showers will be possible mainly along parts of the
north and east sections of PR and the USVI. No changes made to the
inherited forecast package at this time.
Aviation update...VFR conds will prevail entire prd. Few cumulus/SC
lyrs nr fl025...fl050...mstly clear abv.Low level wnds FM NE 15-20
kts blo fl200...bcmg FM west abv and incr W/ht to Max wnd btw 70-80
kts nr fl400. Few passing shra en Route mainly ovr offshore atl
waters north of islands. Surface wnd FM NE 10-15 kts W/ocnl gusts of 20-25
kts psbl. No sig operational impacts attm.
Marine update...no chg to previous marine discussion. Winds and
seas will continue to gradually diminish and subside through
Wednesday. Small craft advisories will remain in effect for the
offshore waters and local passages. Small craft should exercise
caution else where.
Previous discussion... /issued 520 am AST Tue Jan 17 2017/
Synopsis...high pressure across the western Atlantic will move
east as a intense low pressure system exits the U.S. East Coast
Wednesday into Thursday. A east to east northeast wind flow will
continue to dominates the local region. Winds will diminish
considerably next few days.
Discussion...periods of passing showers prevailed across the
local islands overnight. Showers affected the eastern half of
Puerto Rico with rainfall accumulation less than half inch. An
east to east northeast wind flow will continue to prevail today.
These winds will transport showers across the region from time to
time. Local area will continue to be dominated by a high pressure
system which is located north of the area over the western
Atlantic. This high pressure is expected to weaken next couple of
days as a deep surface low pressure area moves across the western
Atlantic, eroding the high pressure. As a result, winds are
expected to diminish significantly especially after Thursday. No
major changes in the weather pattern is expected next several days
as relatively dry weather conditions are expected to continue
across the local area.
Aviation...mostly VFR conditions are expected across the local
flying area however, a few passing -shra/rain showers expected across taf
sites at times. Winds expected from the east/NE at around 10 kt
increasing at 15 to 20 kt and gusty aft 17/12z.
Marine...seas will continue to gradually subside later today into
Wednesday. Seas up to 7 feet and winds up to 20 knots are expected
to continue through Wednesday morning.
Preliminary point temps/pops...
sju 82 73 81 71 / 30 30 30 10
stt 84 72 82 70 / 30 30 20 20
PR...high rip current risk through late tonight for Culebra-Mayaguez
and vicinity-north Central-Northeast-northwest-San Juan and
Small Craft Advisory until 6 am AST Wednesday for northeast.
Vi...high rip current risk through late tonight for St Croix.
Am...Small Craft Advisory until 6 am AST Wednesday for Anegada
Passage southward to 17n-Atlantic waters of Puerto Rico and
USVI from 10 nm to 19.5n-Mona Passage southward to 17n.
Small Craft Advisory until 6 PM AST this evening for Caribbean
waters of Puerto Rico from 10 nm to 17n.