FXCA20 KWBC 221846 PMDCA TROPICAL DISCUSSION - INTERNATIONAL DESKS NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 246 PM EDT WED MAY 22 2013 DISCUSSION FROM MAY 22/00UTC: SHORT WAVE MID/UPPER TROUGH ACROSS THE BAHAMAS WILL CONTINUE ENHANCING CONVECTION AND ACCUMULATIONS ACROSS THE REGION SOUTHWARD INTO EASTERN CUBA/JAMAICA/HISPANIOLA. THE TROUGH IS FORECAST TO EXIT RAPIDLY WHILE A BROADER TROUGH REORGANIZES TO THE NORTHWEST. EXITING TROUGH WILL LEAD TO A GRADUAL DECREASE IN ACCUMULATIONS. THE TROUGH WILL EXTEND ACROSS THE BAHAMAS INTO HAITI/CENTRAL CARIBBEAN BY 24 HRS...AND TO THE EAST OF THE BAHAMAS BY 48 HRS. ON DAY 01...EXPECTING HEAVIEST ACCUMULATIONS OVER THE NORTHERN AND CENTRAL BAHAMAS WITH AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. OVER SOUTHEASTERN CUBA AND JAMAICA...EXPECTING 05-10MM/DAY AND MAXIMA OF 15-30MM. EXPECTING HIGHER AMOUNTS OVER HISPANIOLA IN INTERACTION WITH EASTERLY WAVE AND DEEP MOIST AIRMASS IN PLACE. EXPECTING ACCUMULATIONS OF 15-30MM/DAY AND MAXIMA OF 40-80MM. BY 36-60 HRS...EXPECTING HEAVIEST AMOUNTS OVER HISPANIOLA WITH ACCUMULATIONS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. OVER JAMAICA...EXPECTING 10-15MM/DAY AND MAXIMA OF 20-35MM. OVER THE BAHAMAS EXPECTING A SHARP DECREASE WITH STILL THE POSSIBILITY FOR ISOLATED HEAVY THUNDERSTORMS AND MAXIMA OF 20-35. DEEP POOL OF PWAT IN THE CARIBBEAN WILL CONTINUE SUSTAINING ACTIVE CONVECTION ACROSS THE CENTRAL LESSER ANTILLES INTO PUERTO RICO. THESE ARE INTERACTING WITH UPPER TROUGH OVER THE CENTRAL CARIBBEAN. OVER PUERTO RICO...EXPECTING MOST ACTIVE TODAY WITH ACCUMULATIONS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. A SURGE IN CONVECTION IS EXPECTED ON DAY 03 ASSOCIATED WITH AN INCREASE IN PWAT AND LOW-LEVEL CONVERGENCE. MODELS DISAGREE IN AMOUNTS WITH THIS NEW SURGE IN CONVECTION. SO FAR EXPECTING ACCUMULATIONS OF 10-15MM/DAY WITH MAXIMA OF 20-40MM. ACROSS THE LESSER ANTILLES...ENHANCED TRADE WIND CONVERGENCE AND PRECIPITABLE WATER WILL SUSTAIN ACTIVE PATTERN OF CONVECTION WITH ACCUMULATIONS OF 05-10MM/DAY AND MAXIMA OF 15-20MM...WITH A SLIGHT INCREASE TOWARDS LATE CYCLE. ACROSS MEXICO...MID-UPPER RIDGE IS TO MEANDER OVER CENTRAL/SOUTHERN MEXICO THROUGH THE CYCLE. THIS WILL LIMIT THE INTENSITY COVERAGE OF DIURNAL CONVECTION. STILL...DIURNAL THUNDERSTORMS ARE EXPECTED ACROSS THE EJE VOLCANICO AND ESPECIALLY THE SIERRA MADRE ORIENTAL WITH ISOLATED ACCUMULATIONS OF 05-10MM/DAY AND ISOLATED MAXIMA OF 15MM. ACROSS NORTHERN CENTRAL AMERICA...DIURNAL CONVECTION IS FINALLY BECOMING MORE ACTIVE. MODELS CONTINUE SHOWING CONVECTIVE INSTABILITY BEING SUFFICIENTLY LARGE TO SUSTAIN MODERATE TO A FEW STRONG DIURNAL THUNDERSTORMS. IN ADDITION...SUBSIDENCE CAP WILL REMAIN WEAK. EXPECTING HEAVIEST ACROSS GUATEMALA TO PRODUCE ACCUMULATIONS OF 15-20MM/DAY AND MAXIMA OF 30-60MM. OVER NORTHERN EL SALVADOR/HONDURAS/NORTHWESTERN NICARAGUA EXPECTING 10-15MM/DAY AND MAXIMA OF 20-35MM. ON DAYS 02-03 EXPECTING ACCUMULATIONS TO DECREASE TO 10-15MM/DAY AND ISOLATED MAXIMA OF 20-40MM/DAY IN DIURNAL CONVECTION. ISOLATED HIGHER AMOUNTS ARE ALWAYS POSSIBLE IN INTERACTION WITH OROGRAPHY. ACTIVE CONVECTION WILL PERSIST OVER SOUTHERN CENTRAL AMERICA IN ASSOCIATION WITH DEEP AND LARGE MOISTURE POOL ACROSS SOUTHERN CARIBBEAN/EASTERN PACIFIC AND AN ITCZ TO THE NORTH OF ITS CLIMATOLOGICAL POSITION. THIS WILL SUSTAIN NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS COSTA RICA AND PANAMA THROUGH THE CYCLE. EXPECTING AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM/DAY THROUGH 60 HRS AND A SLIGHT DECREASE ON DAY 02. AS BEST MOISTURE POOL MOVES WESTWARD...EXPECTING AN INCREASE OVER COSTA RICA/PACIFIC COAST OF NICARAGUA/GULF OF FONSECA TO PRODUCE ACCUMULATIONS OF 15-20MM/DAY AND MAXIMA OF 35-70MM. OVER NORTHERN SOUTH AMERICA...ACTIVE CONVECTION WILL PERSIST ACROSS NORTHERN COLOMBIA/NORTHWESTERN VENEZUELA EARLY IN THE CYCLE...IN ASSOCIATION WITH AN EASTERLY WAVE AND DEEP MOISTURE POOL. AMOUNTS WILL START DECREASING TOWARDS MID/LATE CYCLE AS DRIER AIR MASS MOVES INTO THE REGION. IN TERMS OF ACCUMULATIONS...EXPECTING HEAVIEST THROUGH 36 HRS ACROSS NORTHERN COLOMBIA/NORTHWESTERN VENEZUELA WITH AMOUNTS OF 15-30MM/DAY AND MAXIMA OF 35-70MM WITH A DECREASING TREND AFTERWARDS. FURTHER EAST...SUBSIDENCE INVERSION ASSOCIATED WITH MID-LEVEL RIDGE WILL ESTABLISH A TRANSIENT QUIET PATTERN ACROSS NORTHEASTERN VENEZUELA INTO THE NORTHERN GUIANAS. DRY AND STABLE AIRMASS WILL GRADUALLY MAKE IT WESTWARD LEADING TO A DECREASE IN ACCUMULATIONS OVER VENEZUELA THROUGH THE CYCLE. AN ARRIVING TROPICAL WAVE AND ASSOCIATED MOISTURE SURGE WILL PRODUCE AN INCREASE OVER THE GUIANAS BY LATE CYCLE. EXPECTING AMOUNTS INCREASING TO 05-10MM/DAY AND MAXIMA OF 15-20MM. TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC INITIAL 24 36 48 60 72 84 TYPE 40W 43W 46W 49W 52W 55W 58W TW 74W 76W 79W 82W 85W 87W 89W EW TROPICAL WAVE ALONG 40W IS TO ENTER FRENCH GUIANA LATE ON DAY 02...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM/DAY. AN EASTERLY WAVE ALONG 74W IS TO INTERACT WITH THE NEAR EQUATORIAL TROUGH OVER NORTHWEST VENEZUELA/NORTHERN COLOMBIA TO SUSTAIN RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA OF 35-70MM/DAY. ACROSS PANAMA/COSTA RICA IT IS TO THEN SUSTAIN RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM/DAY...INCREASING TO MAXIMA OF 35-70MM/DAY ONCE IT GETS OVER COSTA RICA. LOCALLY HEAVY AMOUNTS ARE ALSO EXPECTED IN NICARAGUA. WAVE WILL INTERACT WITH REGION OF ENHANCED TRADE WIND MOISTURE CONVERGENCE AND ENHANCE ACCUMULATIONS ACROSS JAMAICA AS WELL. BLENMAN...BMS (BARBADOS) MCKENZIE...BDM (BAHAMAS) DAVISON/GALVEZ...WPC (USA) $$