Area Forecast Discussion

FXCA62 TJSJ 110002

AFDSJU

Area Forecast Discussion

National Weather Service San Juan PR

802 PM AST Sun Dec 10 2017

.UPDATE...Partly cloudy skies across the forecast area with

isolated showers across portions of southwest Puerto Rico. GFS

model brings patches of moisture over the area tomorrow and

Tuesday. This moisture along with easterly trade winds could

cause brief showers across Puerto Rico and the U.S. Virgin islands

tomorrow and Tuesday. The high rip current risk was allowed to

expire at 6 pm due to improving marine conditions.

.AVIATION...VFR conditions will prevail for the reminder of the

TAF period. SHRA and VCTS are possible across TJSJ, TISX AND TIST

by 11/12Z. SFC winds will prevail out of the east at 10 - 15 kts

with an occasional gust possible around 11/16Z.

.MARINE...Seas will start to subside today, but there is still a

small craft advisory for many of the local waters.

.PREV DISCUSSION... /issued 313 PM AST Sun Dec 10 2017/

SHORT TERM...

A cold front will be pushing into the windward passage tonight and

Monday and into Hispaniola by Wednesday. Wednesday night will

represent the farthest progress that the front will make this week.

An approaching long wave trough leaving Florida will push a

weakening ridge over the local area Monday night. The ridge will

stall just east of the area however holding the activity from the

jet and the associated frontal zone well northwest. Moisture will

increase from around 1.1 inch to around 1.4 inches on Wednesday--but

this is still fairly limited.

LONG TERM...

Strong surface high pressure across the northeastern Atlantic will

promote easterly winds to the local islands, although somewhat

light winds on Wednesday and Thursday with patches of moisture

over the area. Then later in the week, another surface high

pressure moves north of the local area, tightening the pressure

gradient and causing breezy conditions for the upcoming weekend.

Given the patches of moisture expected, there many be some brief

showers in the windward side of the islands. The upper levels do

not appear to cause any instability for thunderstorm development.

AVIATION...VFR conditions to continue til 10/22Z except for brief

cigs vcnty TKPK and TJMZ near -SHRA and ovr SE PR. SHRA ending ovr

PR by 11/00Z but chc of SHRA along NE coast of PR and nrn USVI aft

11/06Z. Maximum winds 30-40kt btwn FL400-510 til byd 11/18Z.

MARINE...Winds are diminishing and seas are expected to also

continue falling. Rip current risk should be below high everywhere

by Monday and small craft advisories come down at 2 PM AST today.

.PRELIMINARY POINT TEMPS/POPS...

SJU 77 85 74 85 / 30 30 30 30

STT 78 85 78 84 / 30 30 20 20

.SJU WATCHES/WARNINGS/ADVISORIES...

PR...None.

VI...None.

AM...None.

$$

SHORT TERM...99

LONG TERM....99