Area Forecast Discussion
Issued by NWS San Juan, PR

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144
FXCA62 TJSJ 230011
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
Issued by National Weather Service MIAMI FL
811 PM AST Fri Sep 22 2017

.AVIATION...
South to southeast flow will continue to favor showers and scattered
thunderstorms tonight over Puerto Rico along with considerable
mid to high level clouds. Highest chance for rain will be in the
high terrain and upslope regime over southern and western Puerto
Rico. The US Virgin Islands is experiencing a drier airmass with
conditions improving.

&&

.PREV DISCUSSION... /issued Issued by National Weather Service MIAMI FL/

SHORT TERM...
Deep tropical moisture coupled with a south to southeast flow will
keep precipitable water values well over 2 inches through the
weekend. This will allow for any showers and thunderstorms that do
develop to have the potential for heavy rainfall.

Any additional rainfall that Puerto Rico receives will continue to
aggravate the ongoing flooding on many of the rivers. Also, there
is standing water away from the rivers, in many locations, as
well. Mudslides have occurred across the island and will likely
continue if additional rainfall is received. Thus, in coordination
with the office in San Juan, we will keep the Flash Flood Watch
up across all of Puerto Rico through 8 am. But, the Flash Flood
Watch outside of Puerto Rico will be allowed to expire.

Reiterating, it is difficult to ascertain conditions in the area
as nearly all communications links are down. However, some gauges
continue to report. Some river and stream levels are slowly
falling but still remain in flood.

Heat Index values will begin to rise at or above 100 for the
weekend. This will make recovery efforts difficult and overall
living unpleasant as electricity remains out across the island.

LONG TERM...
The pattern will change Tuesday into Tuesday night. Flow will
become easterly and precipitable water values will drop to around
1.75 inches. This will bring relatively drier conditions to the
forecast area.

AVIATION...
South to southeast flow will continue to favor showers and scattered
thunderstorms today over Puerto Rico along with considerable mid to
high level clouds. Highest chance for rain will be in the high
terrain and upslope regime over southern Puerto Rico. The US Virgin
Islands is experiencing a drier airmass with conditions improving.

MARINE...
Small Craft Advisory will remain in effect over the coastal waters
to the northwest of Puerto Rico because seas will be around 7 feet
in this area. Elsewhere, small craft exercise caution will be
headlined as conditions have improved to below SCA criteria. Showers
and thunderstorms with heavy rain, locally higher winds and
waves, and reduced visibilities will be possible the rest of today
through the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  82  85  81  87 /   0   0   0   0
STT  83  83  82  83 /   0   0   0   0

&&

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

VI...None.
AM...Flash Flood Watch through Saturday morning for Coastal Waters OF
     Southwestern Puerto Rico out 10 NM-Coastal Waters of
     Southern Puerto Rico out 10 NM.

     Small Craft Advisory until 8 AM AST Saturday for Atlantic Waters
     of Puerto Rico and USVI from 10 NM to 19.5N.

&&

$$

AVIATION...AH



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