114 
FXCA62 TJSJ 261859
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
259 PM AST TUE MAR 26 2013

.SYNOPSIS...SURFACE HIGH PRESSURE RIDGE REGRESSING FURTHER EAST ACROSS
THE CENTRAL ATLANTIC WILL MAINTAIN LIGHT TO MODERATE EAST SOUTHEAST
WINDS ACROSS THE REGION THROUGH WEDNESDAY. THEREAFTER AND INTO THE
WEEKEND...A WEAKENING COLD FRONT NOW ACROSS THE WEST AND SOUTHWEST
ATLANTIC...WILL APPROACH THE AREA FROM THE NORTHWEST AND INDUCE AN
EAST NORTHEAST WIND FLOW. THIS IN TURN WILL TIGHTEN THE LOCAL PRESSURE
GRADIENT AND INCREASE THE PREVAILING TRADE WIND FLOW INTO THE WEEKEND.
BY THAT TIME...EXPECT THE DISSIPATING FRONTAL BOUNDARY/SHEAR LINE
TO STALL WEST AND JUST NORTH OF THE AREA. THIS WILL HELP CREATE A
MOIST LOW TO MID LEVEL CONVERGENT ZONE ACROSS THE REGION. IN THE
UPPER LEVELS... HIGH PRESSURE RIDGE WILL REMAIN IN PLACE AT LEAST
UNTIL WEDNESDAY THEN GRADUALLY ERODE DURING THE LATTER PART OF THE
WEEK INTO THE WEEKEND...AS A BROAD POLAR TROUGH MOVES EASTWARDS
ACROSS WEST AND CENTRAL ATLANTIC.

&&

.DISCUSSION...OVERALL DRY AND RELATIVELY STABLE ENVIRONMENT WILL 
PREVAIL ACROSS THE LOCAL AREA TODAY THROUGH WEDNESDAY. THEREFORE
ONLY ISOLATED SHORT LIVED CONVECTION IS EXPECTED ACROSS SOME OF
THE ISLANDS. EXPECT A GRADUAL CHANGE IN THIS OVERALL SCENARIO BY
THURSDAY AND INTO THE UPCOMING WEEKEND...AS THE AFOREMENTIONED
COLD FRONT APPROACHES THE AREA FROM THE NORTHWEST. THIS WILL BRING
A BRAND OF FRONTAL MOISTURE TO THE REGION WHILE A PREFRONTAL TROUGH
SETS UP THURSDAY INTO SATURDAY. THIS PATTERN WILL RESULT IN AN INCREASE
IN LAYERED PRECIPITABLE WATER AND THUS A BETTER CHANCE FOR LOCAL CONVECTION
ACROSS THE ISLANDS AND SURROUNDING WATERS. SO FAR BASED ON THE LATEST
MODEL GUIDANCE...LATE THURSDAY THROUGH SATURDAY APPEARS TO BE THE
MOST ACTIVE PERIOD...WITH BEST POTENTIAL FOR CONVECTIVE ACTIVITY
ON FRIDAY AND POSSIBLY SATURDAY. FOR THE REST OF THE WEEKEND...MOISTURE
WILL LINGER ACROSS THE REGION AS THE NORTHEAST WIND FLOW BECOMES
MORE EASTERLY INTO THE EARLY PART OF NEXT WEEK.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES FOR THE 
PERIOD WITH NO SIGNIFICANT WEATHER HAZARD EXPECTED. SOME AFTERNOON 
CONVECTION IS POSSIBLE OVER NW PUERTO RICO LATER THIS AFT. SERLY 
WINDS AROUND 10-20KT DOMINATING THIS AFT.

&&

.MARINE...OVERALL TRANQUIL SEAS WILL CONTINUE OVERNIGHT THROUGH 
WEDNESDAY. BY WEDNESDAY NIGHT A NNW SWELL WILL APPROACH THE REGIONAL
WATERS...AND BRING A SLIGHT INCREASE IN THE LOCAL SEAS. AT THIS
TIME HOWEVER...WAVE HEIGHT ARE EXPECTED TO REMAIN BELOW 7 FEET.
LOCAL TRADE WINDS WILL SHIFT BACK TO THE NORTHEAST BY THURSDAY AND
CONTINUE THROUGH THE END OF THE WEEK AS HIGH PRESSURE RIDGE WILL
BUILD ACROSS THE SOUTHWEST ATLANTIC.

&&

.CLIMATE...SO FAR THE MAXIMUM HIGH TEMPERATURE OF 92 DEGREES TODAY
HAS TIED THE DAILY RECORD SET AT THE LUIS MUNOZ MARIN AIRPORT SAN
JUAN/P.R. IN 1984.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  73  85  73  85 /  10  20  20  20 
STT  74  85  74  84 /  20  20  20  20 

&&

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

$$

15/09