Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 210243
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1043 PM AST MON APR 20 2015

.UPDATE...SHOWERS AND THUNDERSTORMS THAT AFFECTED A FEW SPOTS
ACROSS WESTERN AND NORTHERN PR DISSIPATED QUICKLY LATE IN THE
AFTERNOON. A FEW AREAS OF PR HAD SOME MINOR PONDING OF WATER IN
POOR DRAINAGE AREAS.

AFTER THE SHOWERS ENDED...SKIES BECAME PARTLY CLOUDY AND
EVENTUALLY MOSTLY CLEAR. LITTLE TO NO SHOWER ACTIVITY WAS OBSERVED
IN THE EVENING HOURS. LATEST GUIDANCE SUGGESTS THAT THE AVAILABLE
MOISTURE WILL REMAIN FAIRLY CONSTANT OVERNIGHT...WHICH MEANS THAT
SHOWER ACTIVITY SHOULD REMAIN LIMITED. FOR THAT REASON ONLY
ISOLATED TO SCATTERED PASSING SHOWERS ARE IN THE FORECAST IN THE
SHORT TERM...WHICH WAS WHAT WE INHERITED.

FOR TOMORROW AFTERNOON...SHOWERS AND A FEW THUNDERSTORMS ARE
EXPECTED ACROSS THE INTERIOR AND WESTERN SECTIONS OF PR. DUE TO
A SHORTWAVE TROUGH IN THE UPPER LEVELS COMBINED WITH THE LOCAL
EFFECTS.


&&

.AVIATION...MAINLY VFR CONDITIONS EXPECTED THRU THE FCST PERIOD.
HOWEVER...BETWEEN 21/17-21Z TSRA/SHRA IS EXPECTED OVER THE INTERIOR
AND WESTERN SECTIONS OF PR CREATING OBSCD MTN TOPS AND BRIEF MVFR
CONDS...AFFECTING MAINLY TJMZ. LIGHT AND VARIABLE WINDS OVERNIGHT.
THEN AFTER 21/13Z...SFC WINDS FM THE EAST AT 10-15 KTS WITH HIGHER
SEA BREEZE VARIATIONS.


&&

.MARINE...BUOY 41043 TO THE NORTH OF THE LOCAL AREA IS NOW
REPORTING SEAS UNDER 5 FEET. THEREFORE WE EXPECT SEAS MAINLY OF 4
FEET ACROSS THE LOCAL ATLANTIC WATERS WITH OCCASIONAL MOMENTS OF 5
FEET. THE TREND IS FOR SEAS TO CONTINUE MAINLY 2 TO 4 FEET WITH
OCCASIONAL MOMENTS OF 5 FEET FOR THE NEXT FEW DAYS. NORTHEASTERLY
SWELL IS FORECAST TO INVADE THE LOCAL WATERS ON
THURSDAY...INCREASING SEAS TO 6 FEET ACROSS THE LOCAL ATLANTIC
WATERS.


&&

.PREV DISCUSSION... /ISSUED 238 PM AST MON APR 20 2015/

SYNOPSIS...AN UPPER AIR DISTURBANCE WILL MOVE ACROSS THE AREA
TUE. FLAT UPPER LEVEL RIDGE WILL THEN BUILD THROUGH THE END OF THE
WEEK.

DISCUSSION...A SHORTWAVE-TROUGH ALOFT WILL MOVE ACROSS THE AREA
ON TUE AND ALLOW FOR SOME MOISTURE RECOVERY AND AN INCREASE IN
INSTABILITY WITH SHOWERS AND T-STORMS EXPECTED OVER SOUTHWEST PR.
OTHERWISE...THE REST OF THE WEEK WILL BE DOMINATED BY HEIGHT RISES
LEADING TO GRADUAL EROSION OF LOW-LEVEL MOISTURE.

AVIATION...BRIEF MVFR STILL POSSIBLE AT JMZ/JBQ TILL AT LEAST 21Z
AS TSRA/SHRA CONTINUES OVER THE WESTERN INTERIOR IN THE VICINITY OF
JMZ. VFR CONDITIONS ACROSS THE REST OF THE TERMINALS. LOW LEVEL EAST
TO SOUTHEAST WINDS WILL CONTINUE AT 15 KTS OR LESS.

MARINE...SEAS 3-5 FT AND WINDS AROUND 15 KNOTS. A GROUP OF NE
SWELLS IS EXPECTED TO ARRIVE THU NIGHT AT 4 FT AND 14-15 SECS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  77  88  75  88 /  20  20  20  20
STT  76  85  75  85 /  30  30  20  20

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
AM...NONE.
&&

$$

13/25


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