AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
313 PM AST WED MAY 11 2011

.SYNOPSIS...A DEEP LAYER LOW ACROSS THE NORTHWESTERN ATLANTIC WILL
CONTINUE TO PROMOTE UNSTABLE WEATHER CONDITIONS OVER THE LOCAL AREA
AT LEAST THROUGH THE NEXT FEW DAYS. THIS FEATURE IS TO MEANDER OVER
THE NORTH ATLANTIC THROUGHOUT THE END OF THE WEEK BEFORE START TO
PULL NORTHEAST...AS A RIDGE OF HIGH PRESSURE MOVES OVER THE NW
ATLANTIC. WEATHER CONDITIONS WILL SLIGHTLY IMPROVE DURING THE
WEEKEND WHEN A CONVERGENCE PATTERN ALOFT ESTABLISHES OVER THE
NORTHEASTERN CARIBBEAN.

&&

.DISCUSSION...SHOWERS HAVE BEGUN TO DEVELOP ACROSS PARTS OF THE
ISLANDS IN THE LAST FEW HOURS. MOST OF THE SHOWERS ARE AFFECTING
THE INTERIOR AND EASTERN SECTIONS OF PUERTO RICO AS WELL AS THE
COASTAL WATERS NORTHEAST OF SAINT JOHN. THESE SHOWERS ARE MOVING
TOWARD THE ENE AT AROUND 5 TO 10 MPH. ADDITIONAL SHOWERS AND
THUNDERSTORMS WILL DEVELOP DURING THE NEXT COUPLE OF HOURS ACROSS
THE FORECAST AREA. THE COMBINATION OF A BROAD DEEP LAYER LOW OVER
THE NW ATLANTIC AND A INDUCED TROUGH/SHEAR LINE CONFLUENT OVER
PUERTO RICO AND THE USVI IS SUSTAINING A MOISTURE SURGE ACROSS THE
NORTHEASTERN CARIBBEAN. IN ADDITION...THE SUBTROPICAL JET MAXIMA
IS LOCATED JUST NORTHEAST OF THE ISLANDS FAVORING A GENERALLY
DIVERGENT PATTERN ALOFT ACROSS THE LOCAL REGION. WITH THIS HIGH
MOISTURE CONTENT AND FAVORABLE DYNAMICS ALOFT...UNSETTLED WEATHER
PATTERN IS EXPECTED TO CONTINUE ACROSS THE ISLANDS AT LEAST THROUGH
THE END OF THE WORK WEEK. OPERATIONAL MODELS REMAIN RATHER CONSISTENT
IN DEPICTING GOOD CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH AT
LEAST THE NEXT 24-36 HOURS...AS THE UNSTABLE CONDITIONS PREVAIL
AND A SERIES OF SHORTWAVES STREAMS ACROSS THE ISLANDS. DUE TO THE
SOIL ACROSS MUCH OF THE CENTRAL AND NORTHERN SECTIONS OF PUERTO
RICO REMAIN FAIRLY SATURATED AND RIVERS AND STREAMS REMAIN AT HIGH
LEVELS IN SOME AREAS...ADDITIONAL RAINFALL WILL CAUSE SOME OF THE
RIVERS AND STREAM TO QUICKLY RISE. THEREFORE THE POTENTIAL FOR
URBAN AND SMALL STREAM FLOODING AS WELL AS MUDSLIDES IN AREAS OF
STEEP TERRAIN WILL CONTINUE THROUGH AT LEAST FRIDAY. HOWEVER...
SOME IMPROVEMENT IS POSSIBLE OVER THE WEEKEND AS A HIGH PRESSURE
RIDGE BUILDS ACROSS THE NW ATLANTIC PROMOTING A CONVERGENCE PATTERN
ALOFT.

&&

.AVIATION...MOSTLY VFR CONDITIONS WILL PREVAIL ACROSS MOST TAF
SITES. HOWEVER AT LEAST UNTIL 11/23Z PERIODS OF MVFR CONDS WILL BE
POSSIBLE IN ISOLD SHRA OR TSRA...MAINLY OVR OR VCNTY OF TJSJ...TIST
AND TISX...AS WELL AS TNCM AND TKPK. MTN TOP OBSCURATION ALSO PSBL
WITH PASSING SHRA/ISOLD TSTM OVER THE E AND W INTERIOR SECTIONS OF
PR.

&&

.MARINE...BROAD TROUGH OVER THE NW WESTERN ATLANTIC IS GENERATING
A NORTH SWELLS OF 6 FEET THAT WILL REACH THE LOCAL ATLANTIC WATERS
TOMORROW EVENING INTO FRIDAY. MEANWHILE...LIGHT TO MODERATE WINDS
WILL RESULT IN TRANQUIL SEAS OF GENERALLY 4 FEET OR LESS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  74  84  74  85 /  20  70  30  40
STT  75  84  74  82 /  40  70  30  40

&&

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

$$