National Weather Service San Juan PR
151 PM AST Mon Nov 7 2016
.SYNOPSIS...A shear line over the area will weaken as the frontal
boundary to the northeast continues east. Good moisture levels
will continue to decline ever so slightly during the next 10 days,
allowing showers and thunderstorms to persist--mainly in the
afternoons over the interior.
At mid and upper levels...A long wave trough will pass over the
area on Tuesday night. High pressure will then ridge into the area
and dominate the Caribbean yielding northwest flow over the local
area. Mid level moisture will diminish beginning Tuesday night
At lower levels...A weak trough will persist over the local area
until Friday when a weak easterly wave will move through. By the
weekend easterly trade winds will resume and high pressure will
ridge over the area by mid week next week.
&&
.DISCUSSION...The area was mostly cloudy early this morning and
showers and thunderstorms persisted over the caribbean waters
associated with a shearline extending out of a strong low in the
western Atlantic. The shear line will make a little easterly
progress but ultimately dissipates and reforms well northwest of
the local area in 48 to 72 hours. Moisture remains rich and this
will continue showers and thunderstorms over the local waters and
during the afternoons and evenings over Puerto Rico. Some showers
will also affect the U.S. Virgin Islands. Currently the GFS
depicts a dry band moving in from the southeast across Saint Croix
Tuesday night and over Puerto Rico on Wednesday. Nevertheless some
shower activity is still expected Wednesday with lesser coverage
and accumulations.
Currently showers are forming and dissipating fairly rapidly in
slow moving bands. This will bring urban and small stream flooding
to both northeast and northwestern Puerto Rico. Showers will reach
the northern Virgin Islands later this evening, but may stall
before moving into Saint Croix owing to the advance of drier air
from the southeast as forecast by the GFS and observed in the
MIMIC product.
Other than the trough moving through at lower levels Friday
morning, few significant features are noted, other than the
persistent boundary that remains north and northwest of the area
separating the moist tropical air from the modified polar air. New
fronts enter the area and reinforce the boundary without
significant progress of the boundary toward Puerto Rico and the
U.S. Virgin Islands.
&&
.AVIATION...Brief MVFR due low cig and SHRA/Isold TSRA ovr and vcty
TJBQ/TJSJ/TJNR/TJPS til 07/22z. SCT-BKN cld lyrs nr FL020...FL040...
FL100 across the entire flying area with BKN-OVC cigs en route btw
PR and Nrn Leewards. Isold max tops FL350-FL400 W/TSRA. Winds blo
FL200 fm S-SE at 5-15 kts bcmg westerly and incr w/ht abv to MAX
WND 50-60 kts nr FL350. Sfc wnd mainly lgt/vrb except for sea
breeze variations.
&&
.MARINE...Tranquil seas in the Atlantic will be invaded by medium
period swell from the low currently in the western Atlantic and
will bring 7 to 8 foot seas, a high risk of rip currents and surf
up to 8 or 9 feet. Seas will return to 5 feet or less by Friday.
Small craft advisories are expected by Wednesday 9 November.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 77 86 77 89 / 40 20 20 20
STT 77 86 77 87 / 40 30 20 20