455 
FXCA62 TJSJ 280208
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1008 PM AST SAT JUL 27 2013

.UPDATE...NO SIGNIFICANT CHANGES WERE MADE TO THE PREVIOUS
FORECAST WITH THE EXCEPTION OF THE WIND FORECAST. THE REMNANTS OF
WHAT WAS TROPICAL STORM DORIAN WILL PASS JUST TO OUR NORTH AS A
TROPICAL WAVE ACCORDING TO THE NATIONAL HURRICANE CENTER AND ALSO
MODEL GUIDANCE. THE 18Z GFS RUN HAS THE PRECIPITABLE WATER
DECREASING LATE TONIGHT AND INTO SUNDAY AFTERNOON...INCREASING
SLIGHTLY LATE SUNDAY FOR A BRIEF PERIOD AS THE REMNANTS OF DORIAN PASS
TO OUR NORTH. ON MONDAY INTO TUESDAY THOUGH...THE GFS MODEL TAKES
PRECIPITABLE WATER DOWN TO UNDER 1.2 INCHES. 850MB THETA-E IS EXPECTED
TO DECREASE ON SUNDAY AND DECREASE EVEN MORE ON MONDAY.
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ARE LIKELY ON SUNDAY
AFTERNOON ACROSS THE INTERIOR AND WESTERN PR WHILE THE REST OF THE
AREA OBSERVES ISOLATED TO SCATTERED SHOWERS. ON MONDAY...LOWER
THETA-E AND OVERALL LOWER MOISTURE SHOULD KEEP THE LOCAL AREA
RELATIVELY DRY.

&&

.AVIATION...VFR CONDS WILL CONTINUE ALL SITES XCP AFT 28/16Z IN WRN 
PR AND NW OF EL YUNQUE. EXPECT SHRA/TSRA AND MOUNTAIN OBSCURATIONS 
TO DEVELOP AFT 28/16Z AND MVFR TJMZ AND TJBQ DURG PASSAGE OF HEAVY 
SHRA. LLVL WINDS ESE 5 TO 15 KT.

&&

.MARINE...SEAS OF UP TO 6 FEET EXPECTED THROUGH SUNDAY. GUIDANCE
SUGGESTS THAT SEAS UP TO 7 FEET ARE POSSIBLE ON MONDAY.


&&

.PREV DISCUSSION... /ISSUED 249 PM AST SAT JUL 27 2013/ 

SYNOPSIS...TUTT ACROSS THE SOUTHWEST ATLANTIC INTO THE EAST CENTRAL
CARIBBEAN WILL WEAKEN OVER THE WEEKEND...AS HIGH MOVES IN FROM THE
TROPICAL ATLANTIC INTO THE EASTERN CARIBBEAN. A SECOND TUTT IS
EXPECTED TO DEVELOP ACROSS THE CENTRAL ATLANTIC EARLY NEXT WORK
WEEK. SURFACE HIGH ACROSS THE NORTH CENTRAL ATLANTIC WILL CONTINUE
TO PROMOTE A MODERATE TO FRESH TRADE WIND FLOW ACROSS THE LOCAL
ISLANDS. TROPICAL STORM DORIAN IS FORECAST TO PASS NORTH OF THE
LOCAL ISLANDS LATE SUNDAY NIGHT THROUGH MONDAY AS A TROPICAL
DEPRESSION.

DISCUSSION...SKIES WERE PARTLY TO MOSTLY CLOUDY OVER THE LOCAL
ISLANDS DURING THE DAY TODAY. SHOWERS WITH THUNDERSTORMS DEVELOPED
OVER NORTHWEST PUERTO RICO THIS AFTERNOON. WINDS WERE FROM THE
EAST TO EAST SOUTHEAST AT 5 TO 15 MPH WITH SOME HIGHER GUSTS AND
SEA BREEZE VARIATIONS. TEMPERATURES WERE IN THE UPPER 80S IN
COASTAL AREAS.

BASED ON THE LATEST FORECAST FROM THE NATIONAL HURRICANE CENTER... 
TROPICAL STORM DORIAN IS EXPECTED TO PASS NORTH OF THE LOCAL ISLANDS 
LATE SUNDAY NIGHT THROUGH MONDAY AS A TROPICAL DEPRESSION. MODEL
GUIDANCE CONTINUED TO INDICATE THAT MOST OF ITS ASSOCIATED MOISTURE
SHOULD REMAIN NORTH OF THE REGION.

SHOWER COVERAGE AND THUNDERSTORM INTENSITY SHOULD DECREASE SUNDAY 
INTO EARLY NEXT WORK WEEK AS TUTT MOVES WEST WHILE WEAKENING...
AND HIGH ALOFT ESTABLISHES OVER THE EASTERN CARIBBEAN. IN ADDITION...
AS THIS PATTERN EVOLVES..A DRIER AIR MASS WILL MOVE IN FROM THE
EAST. WRF AND GFS SUGGESTED PWAT VALUES BELOW 2 INCHES OVER THE
NEXT FEW DAYS. UNDER THE PREVAILING WIND FLOW...THIS WILL RESULT
IN PASSING SHOWERS ACROSS EASTERN PUERTO RICO AND U.S. VIRGIN
ISLANDS DURING THE MORNING HOURS...FOLLOWED BY AFTERNOON CONVECTION...
DRIVEN BY LOCAL EFFECT AND DIURNAL HEATING...ACROSS WESTERN PUERTO
RICO EACH DAY. AT THIS TIME...A MOISTURE SURGE IS EXPECTED TO
APPROACH THE LOCAL ISLANDS TUESDAY EVENING...AND MAY INCREASE
OVERNIGHT SHOWER ACTIVITY ACROSS THE LOCAL ISLANDS.

AVIATION...XPT VFR THRU SUNDAY XCP IN ISOLD MVFR IN SHRA/TSRA BOTH 
AFT WI OBSCD MTNS. WINDS BLO FL150 ESE 15-20 KT BCMG E TONITE THEN 
WEAKENING SUNDAY.

MARINE...LATEST GUIDANCE CONTINUED TO INDICATE SEAS UP TO 7 FEET
ACROSS THE OFFSHORE WATERS ON MONDAY...AS REMNANTS OF TS DORIAN
MOVE NORTH OF THE AREA. SURFACE HIGH ACROSS THE NORTH CENTRAL
ATLANTIC WILL CONTINUE TO PROMOTE A MODERATE TO FRESH TRADE WIND
FLOW ACROSS THE LOCAL ISLANDS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  87  77  89 /  20  30  20  20 
STT  78  89  78  88 /  20  20  30  30 

&&

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

$$

12/25