Area Forecast Discussion
Issued by NWS San Juan, PR

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000
FXCA62 TJSJ 270930
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
530 AM AST TUE JAN 27 2015

.SYNOPSIS...MID TO UPPER RIDGE OVER THE EASTERN CARIBBEAN WILL WEAKEN
TONIGHT THROUGH FRIDAY AS TROUGH PATTERN ESTABLISHES ACROSS THE WESTERN
ATLANTIC. PRE-FRONTAL TROUGH/SHEARLINE WILL AFFECT THE LOCAL ISLANDS
THURSDAY AND FRIDAY. POLAR TROUGH WILL LIFT AWAY DURING THE WEEKEND.
MID TO UPPER RIDGE WILL BUILD AGAIN EARLY NEXT WEEK.

&&

.DISCUSSION...SOUTHEASTERLY FLOW ACROSS THE EASTERN CARIBBEAN
REGION HAS PUSHED A BAND OF MOISTURE ACROSS THE LOCAL CARIBBEAN
WATERS AND MONA PASSAGE. AS A RESULT...SCATTERED SHOWERS HAVE BEEN
OBSERVED ACROSS THE CARIBBEAN WATERS AND PORTIONS OF THE SOUTH
COAST PR DURING OVERNIGHT HOURS. THIS AREA OF HIGH MOISTURE CONTENT
WILL LINGER ACROSS THE FORECAST AREA THROUGH THIS AFTERNOON...FAVORING
THE DEVELOPMENT OF NEW SHOWERS ACROSS PORTIONS OF PR/USVI...ESPECIALLY
NW PR THIS AFTERNOON. FOR TONIGHT AND WEDNESDAY...A DRIER AIR MASS
WILL ADVECT OVER THE LOCAL REGION REDUCING THE SHOWER ACTIVITY ACROSS
PR/USVI.

TROUGH PATTERN ACROSS THE WESTERN ATLANTIC WILL FAVOR THE INFLOW
OF MID-UPPER LEVEL ENERGY ACROSS THE FORECAST AREA...FAVORING DEEP
CONVECTION ACROSS THE LOCAL ISLANDS THURSDAY AND FRIDAY. IN ADDITION...
SURFACE TROUGH/SHEAR LINE WILL RELOCATE OVER THE NORTHEAST CARIBBEAN
PROMOTING MOISTURE TRANSPORT OVER PR/USVI LATER THIS WEEK. THE ENHANCE
CONVECTIVE INSTABILITY DURING THURSDAY AND FRIDAY MAY RESULT IN
THUNDERSTORMS ACROSS THE LOCAL AREA. WEATHER CONDITIONS WILL GRADUALLY
IMPROVE DURING THE WEEKEND AND EARLY NEXT WEEK AS TROUGH LIFTS OUT
AND DEEP LAYER RIDGE SLOWLY BUILD IN FROM THE WEST. IF THIS SCENARIO
VERIFIES...A RELATIVELY STABLE PATTERN WILL PREVAIL DURING THE WEEKEND
AND EARLY NEXT WEEK.

&&

.AVIATION...MOSTLY VFR CONDITIONS ARE EXPECTED AT ALL TAF SITES
WITH BRIEF SHOWERS POSSIBLE IN AND AROUND TISX...TIST...TNCM..AND
TKPK. BRIEF MVFR CONDITIONS WILL REMAIN POSSIBLE BETWEEN 27/17Z AND
27/22Z AT TJMZ/TJBQ IN SHRA. SE WINDS AT 10 TO 15 KNOTS WITH SOME
SEA BREEZE VARIATIONS AFT 27/15Z.

&&

.MARINE...SEAS WILL GENERALLY RANGE BETWEEN 2 AND 4 FEET WITH
OCCASIONAL SEAS OF 5 FEET ACROSS THE ATLANTIC WATERS MOST OF THE
WEEK. PULSES OF NW SWELLS OF AROUND 4-5 FEET WILL MOVE ACROSS THE
LOCAL ATLANTIC WATERS AND CARIBBEAN PASSAGES LATE WEDNESDAY/THURSDAY
AND LATE SUNDAY INTO MONDAY. HOWEVER...SEAS ARE FORECAST TO REMAIN
BELOW THE ADVISORY CRITERIA ALL WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  88  73  86  73 /  20  10  40  40
STT  84  75  83  74 /  20  20  30  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...NONE.
&&

$$

71/11





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