Tropical Storm Warning 1011, NWS JSJ

Area Forecast Discussion
National Weather Service San Juan PR
512 AM AST Thu Sep 7 2017

.Synopsis...Hurricane Irma will continue to push away from the area
today with some lingering outer rain bands on the eastern side of
the system still affecting portions of Puerto Rico and the USVI.
These rain bands should come to an end by tonight as Irma pushes
further away from the area.  However, Hurricane Jose could bring
outer rain bands to the area this weekend as it tracks well to the
northeast of the islands.  Lingering moisture over the area next
week in the wake of Jose will keep a risk of rain in the forecast
each day.

.Short Term...Today through Saturday...

Outer rain bands on the eastern periphery of Hurricane Irma will
persist over Puerto and the USVI today through tomorrow.  This is
most evident by a band of higher atmospheric moisture content
represented by moderately high precipitable water values of 2.2 to
2.3 inches lingering over the region through tomorrow.  These bands
could produce some locally heavy rainfall on the southern side of
Puerto Rico due to the southerly flow of 10 to 15 knots persisting
through tomorrow.  This heavy rainfall could produce localized flash
flooding, and the Flash Flood Watch is in effect for all of the
islands including in the USVI through tomorrow.  A brief break in
the rain activity may occur Friday night as a drier slot of air
passes over the area, but increasing moisture and some outer rain
bands associated with Hurricane Jose could begin to affect the USVI
and Puerto Rico by Saturday afternoon as the storm approaches the
northern Leeward Islands.

Long Term...Sunday through Thursday

Hurricane Jose is expected to track well to the northeast of the
islands on Sunday and the deeper pool of moisture and outer
rainbands associated with Jose should also begin to shift away from
the area. The remainder of next week will see a broad upper level
ridge of high pressure extend across the forecast area and then
remain in place through Thursday.  A band of some more moist air as
noted by precipitable water values of 2.1 to 2.2 inches on Monday
and Tuesday could bring a few more higher elevation showers and
thunderstorms to the area each day. By Wednesday and Thursday, a
surge of drier air is expected to move in from the east and push
precipitable water values down below 2 inches.  More isolated
showers and storms are expected to develop each day due to this
drier airmass settling in.

.Aviation...Expect to see a general east-southeast wind around 15
knots in place at all of the terminals today. After 00z tonight,
winds should fall to around 10 knots as the pressure gradient
decreases across the region. Lingering rain showers and MVFR
visibilities and ceilings will persist at TJPS, TJMZ, and TJBQ
through around 12-14z, but should improve into VFR range for the
day as the more persistent bands of showers push further to the
west and offshore. The remainder of the terminals should see
prevailing VFR conditions through the forecast period.

.Marine...As Hurricane Irma departs the area and winds decrease over
the waters to between 5 and 10 knots from the east-southeast by
tonight seas will also begin to drop off.  Expect to see seas fall
from 8 to 12 feet over the northern waters back to 5 to 8 feet by
tomorrow.  Seas should further drop to 3 to 5 feet over the northern
waters by next week.  The southern waters should see seas of 4 to 6
feet today fall to 2 to 4 feet over the weekend and next week.  Due
to the high seas in place over the northern waters, a Small Craft
Advisory is in effect for all of the coastal waters except for
the nearshore Caribbean waters south of Puerto Rico through this
afternoon. A High Surf Advisory is also in effect for the
northwest and west shores of Puerto Rico through this morning due
to the high seas and large crashing waves persisting along the
coast. These conditions should improve by the afternoon.

.PRELIMINARY POINT TEMPS/POPS...
SJU  89  78  91  80 /  80  30  50  40
STT  87  76  87  80 /  70  60  60  50

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Flash Flood Watch through Friday afternoon for Central Interior-
     Culebra-Eastern Interior-Mayaguez and Vicinity-North
     Central-Northeast-Northwest-Ponce and Vicinity-San Juan and
     Vicinity-Southeast-Southwest-Vieques-Western Interior.

     High Surf Advisory until noon AST today for Mayaguez and
     Vicinity-Northwest-Western Interior.

     Small Craft Advisory until 6 PM AST this evening for Southwest.

VI...Flash Flood Watch through Friday afternoon for St Croix-
     St.Thomas...St. John...and Adjacent Islands.

     Small Craft Advisory until 6 PM AST this evening for
     St.Thomas...St. John...and Adjacent Islands.

AM...Flash Flood Watch through Friday afternoon for Coastal Waters OF
     Southwestern Puerto Rico out 10 NM-Coastal Waters of
     Northern USVI and Culebra out 10 NM-Coastal Waters of
     Southern Puerto Rico out 10 NM-Coastal Waters of Southern
     USVI Vieques and Eastern Puerto Rico out 10 NM.

     Small Craft Advisory until 6 PM AST this evening for Anegada
     Passage Southward to 17N-Atlantic Waters of Puerto Rico and
     USVI from 10 NM to 19.5N-Caribbean Waters of Puerto Rico
     from 10 NM to 17N-Coastal Waters OF Northwestern Puerto
     Rico out 10 NM-Coastal Waters OF Southwestern Puerto Rico
     out 10 NM-Coastal Waters of Northern Puerto Rico out 10 NM-
     Coastal Waters of Northern USVI and Culebra out 10 NM-
     Coastal Waters of Southern USVI Vieques and Eastern Puerto
     Rico out 10 NM-Mona Passage Southward to 17N.

&&

SHORT TERM...Grigsby
LONG TERM....Grigsby