TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
714 AM EDT WED JUN 19 2013

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. TUTT LOW
NORTH OF THE ISLANDS EXTENDS A TROUGH TO THE EASTERN CARIBBEAN.
THIS AXIS HAS STARTED ITS WESTWARD MIGRATION AS A CELL OF THE
SUBEQUATORIAL RIDGE BUILDS FROM THE EAST. AS A RESULT...FORECAST
AREA TRANSITIONING FROM MID/UPPER CONVERGENCE TO DIVERGENCE...WITH
ENVIRONMENTAL CONDITIONS BECOMING FAVORABLE FOR DEEP CONVECTION. A
TROPICAL WAVE IN THE EASTERLY TRADES IS NOW IN PHASE WITH THE TUTT
ALOFT...WITH CONVECTIVE ACTIVITY FLARING UP EARLY THIS MORNING
ACROSS THE LEEWARD ISLANDS. CONVECTIVE CELLS ARE ALSO BUILDING
WEST AHEAD OF THIS WAVE ACROSS THE VIRGIN ISLES TO PUERTO RICO.

AS THE SUBEQUATORIAL RIDGE INTENSIFIES...THE TUTT WILL RELOCATE
ACROSS HISPANIOLA-CENTRAL CARIBBEAN EARLY IN THE CYCLE. THROUGH
FRIDAY AFTERNOON THE RIDGE IS TO GRADUALLY BECOME THE DOMINANT
FEATURE WHILE TROUGH BEGINS TO PULL. AS A RESULT...DIVERGENT
PATTERN ALOFT IS GOING TO BE RELATIVELY BRIEF/SHORT LASTING...WITH
STRONG CAP TO GRADUALLY ESTABLISH THROUGH THE DAY ON THURSDAY TO
EARLY FRIDAY. THIS IS TO THEN SUSTAIN A RAPID EROSION OF AVAILABLE
WATER FOLLOWING THE WAVE PASSAGE.

BEST MOISTURE CONVERGENCE IS EXPECTED ACROSS THE VIRGIN
ISLES-EASTERN PUERTO RICO DURING THE MORNING TO EARLY AFTERNOON
HOURS...WITH PWAT TO PEAK AROUND 50MM. BUT LATER IN THE DAY IT
WILL START TO DROP AT A FAIRLY FAST PACE. AS A RESULT...EXPECTING
MOST ACTIVE CONVECTION WITH APPROACHING WAVE TO DEVELOP ACROSS THE
USVI TO EASTERN PORTIONS OF PUERTO RICO...WITH RAINFALL AMOUNTS TO
PEAK AT 20-45MM. LATE AFTERNOON/EVENING ACTIVITY IS THEN EXPECTED
ACROSS THE CARIBBEAN WATERS OF PUERTO RICO AND POSSIBLY SOUTH
COAST OF THE ISLAND. AS A DRYER AIR MASS ENVELOPS THE FORECAST
AREA...FAIR WEATHER CONDITIONS ARE TO THEN FOLLOW.

MCKENZIE...BDM (BAHAMAS)
ROBINSON...MSJ (JAMAICA)
DAVISON...WPC (USA)