TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
652 AM EDT MON AUG 01 2011

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. AT UPPER
LEVELS...THE SUBEQUATORIAL RIDGE NOW EXTENDS FROM THE TROPICAL
ATLANTIC WESTWARD ACROSS THE ISLAND CHAIN TO THE EASTERN
CARIBBEAN. AT LOW LEVELS...A TROPICAL WAVE/BROAD AREA OF LOW
PRESSURE LIES TO THE EAST OF THE ISLAND CHAIN. THE NHC CONTINUES
TO MONITOR THIS AREA FOR POSSIBILITY OF TROPICAL CYCLOGENESIS.
THIS FEATURE IS GOING TO BE THE FORECAST CHALLENGE...AS IT IS
LIKELY TO SUSTAIN ORGANIZED CONVECTION ACROSS THE EASTERN
CARIBBEAN ISLES.

ALOFT...THE MODELS SHOW SUBEQUATORIAL RIDGE BECOMING WELL
ESTABLISHED THROUGH THURSDAY MORNING...TO ANCHOR AT 250 HPA ON A
CLOSED HIGH JUST SOUTH OF PUERTO RICO. LATER IN THE WEEK IT WILL
THEN MERGE WITH THE SUBTROPICAL RIDGE AS THE LATTER BUILDS ACROSS
THE EASTERN USA TO THE WESTERN ATLANTIC. AS THE RIDGE
PERSISTS/BECOME BETTER ESTABLISHED...IT WILL CONTINUE VENTING DEEP
CONVECTION IN ASSOCIATION WITH SYSTEM ENTERING THE ISLAND CHAIN.
CONVECTIVE ACTIVITY IS TO START ACROSS THE VIRGIN ISLANDS TOMORROW
AFTERNOON...AND MAINLAND PUERTO RICO DURING THE LATE
EVENING/MORNING HOURS. THE GLOBAL GUIDANCE SHOWS MAXIMA OF FOUR TO
SIX INCHES WITH THIS SYSTEM...WITH REGIONAL NAM PEAKING AT EIGHT
TO TEN INCHES. LOOKS LIKE MOST INTENSE IS GOING TO BE ACROSS THE
VIRGIN ISLES-EASTERN/SOUTHERN PUERTO RICO.

DEPENDING ON HOW QUICKLY IT ORGANIZES...THIS SYSTEM MIGHT END UP
ESTABLISHING A MOIST INFLOW AS IT TAPS INTO THE ATLANTIC ITCZ. THE
MOIST FLUX COULD LAST INTO THURSDAY MORNING...IF NOT LONGER. SO WE
COULD BE FACING 48-60 HRS OF ORGANIZED ACTIVITY. THIS IS GOING TO
BE HEAVY RAINS OVER AN AREA THAT IS SATURATED FROM PREVIOUS
EVENTS. IT IS NOT GOING TO TAKE MUCH TO GENERATE LARGE SCALE
FLOODING.

NEELY...BDM (THE BAHAMAS)
DAVISON...NCEP (USA)