####018005978#### FXCA20 KWBC 141852 PMDCA TROPICAL DISCUSSION - INTERNATIONAL DESKS NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 251 PM EDT TUE MAY 14 2024 FORECAST BULLETIN 14 MAY 2024 AT 1845 UTC: THE OVERALL SYNOPTIC PATTERN FAVORS ISOLATED TO NO SHOWER ACTIVITY ACROSS THE CARIBBEAN FOR THE NEXT FEW DAYS...WITH MAINLY LOCAL AND DIURNAL EFFECTS ALLOWING RAINFALL DEVELOPMENT OVER THE ISLANDS IN THE CARIBBEAN. ABOVE NORMAL PRECIPITABLE WATER ACROSS SOUTHERN TO EASTERN MEXICO WILL HELP IN THE DEVELOPMENT OF SHOWER ACTIVITY ACROSS THE AREA...BUT THE ACTIVITY WILL BE CYCLICAL ACCORDING TO THE MODEL GUIDANCE...MEANING THAT THE MODELS SUGGEST A DIURNAL AND LOCAL EFFECT ALSO BEING THE MAIN REASON FOR SHOWER DEVELOPMENT...GENERALLY IN THE LATE AFTERNOON INTO THE EVENING HOURS EACH DAY. THAT BEING SAID...THE MAIN STORY WITH REGARDS TO SIGNIFICANT RAINFALL WILL BE ALONG THE ITCZ/MONSOON TROUGH AND HOW IT WILL AFFECT NORTHERN SOUTH AMERICA AND SOUTHERN CENTRAL AMERICA. THE LATEST SATELLITE IMAGERY AS WELL AS THE LATEST MODEL GUIDANCE SUGGEST THAT THE MORE PERSISTENT SHOWER ACTIVITY WILL BE ALONG THE ITCZ AND IN AREAS OF VERY DEEP MOISTURE ACROSS NORTHERN SOUTH AMERICA AND CENTRAL AMERICA. SEVERAL EASTERLY WAVES AND SFC TROUGHS WILL ENHANCE THE AMOUNTS OF RAIN ACROSS NORTHERN SOUTH AMERICA...WHILE IN THE PACIFIC SIDE...THE ITCZ/MONSOON TROUGH...WILL HAVE A STRONG SOUTHERLY COMPONENT...CAUSING THE CONVERGENCE ZONE TO BE OVER PANAMA...COSTA RICA...AND NEARBY COUNTRIES. THIS CONVERGENCE ZONE WITH THE DEEP MOISTURE OVER THE AREA WILL CAUSE PERSISTENT AND SIGNIFICANT SHOWER ACTIVITY OVER THE NEXT FEW DAYS. AT THE SURFACE ACROSS THE REGION...THERE IS A LOW PRESSURE ACROSS THE NORTHWESTERN ATLANTIC...WITH A COLD FRONT EXTENDING SOUTH INTO THE TROPICAL ATLANTIC...NEAR 25N TO THE NORTHEAST OF THE GREATER ANTILLES. THERE IS ALSO A STRONG SFC HIGH PRESSURE ACROSS THE NORTH CENTRAL ATLANTIC. THIS SETUP WOULD CAUSE EASTERLY WINDS ACROSS THE CARIBBEAN...THOUGH BECOMING SOUTHEAST ACROSS THE WESTERN CARIBBEAN IN TO THE GULF OF MEXICO AS WELL AS OVER THE BAHAMAS. A COUPLE OF SFC LOW PRESSURE ACROSS THE EAST CENTRAL TO SOUTHEAST USA WILL MOVE EAST OVER THE NEXT FEW DAYS...HAVING AN ASSOCIATED WARM FRONT ACROSS THE WESTERN ATLANTIC AND A COLD FRONT MOVING IN TO THE GULF OF MEXICO AND A STATIONARY FRONT ACROSS NORTHEASTERN MEXICO BY WEDNESDAY. THE MID-LEVELS ARE LESS EXCITING ACROSS THE TROPICAL REGION...WITH A MID LEVEL RIDGE ACROSS THE CENTRAL CARIBBEAN INTO THE BAHAMAS AND A TROUGH WITH AXIS ACROSS THE WESTERN TROPICAL ATLANTIC NORTH OF THE NORTHEASTERN CARIBBEAN. AS THE TROUGH AND RIDGE MOVE EAST OVER THE NEXT COUPLE OF DAYS...A BROAD MID LEVEL TROUGH WILL THEN MOVE INTO THE NORTHERN SECTIONS OF THE GULF OF MEXICO AND INTO THE NORTHERN BAHAMAS BY THURSDAY. THE UPPER LEVELS SEEM TO BE IN PHASE WITH THE MID LEVELS...ALSO HAVING A TROUGH WITH AXIS ACROSS THE TROPICAL ATLANTIC INTO THE EASTERN CARIBBEAN...AND A RIDGE OVER THE CENTRAL CARIBBEAN NORTH IN TO THE BAHAMAS AND THE WESTERN TROPICAL ATLANTIC. THAT SAID...THERE IS AN UPPER JET ACROSS THE SOUTHEAST USA WITH A BROAD UPPER TROUGH...WHICH WILL MOVE EAST AND CAUSE THE UPPER TROUGH TO HAVE ITS AXIS ACROSS THE WESTERN TROPICAL ATLANTIC BY WEDNESDAY EVENING. THIS FEATURE MAY BE IMPORTANT AS THE GR02T ALGORITHM SUGGESTS A MARGINAL RISK FOR SVR WX ACROSS THE EXTREME NORTHERN BAHAMAS TONIGHT INTO WEDNESDAY MORNING AS THE UPPER TROUGH MOVES IN...CAUSING STRONG DIVERGENCE ALOFT. AS MENTIONED ABOVE...THE MAIN CONVECTION AND SHOWER DEVELOPMENT IS EXPECTED ALONG THE ITCZ. HOWEVER...ACROSS SOUTHERN CENTRAL AMERICA...THE CONVERGENCE OF THE ITCZ WILL MOVE NORTH AND INTO COSTA RICA AND PANAMA...TO PRODUCE PERSISTENT SHOWER ACTIVITY OVER THE AREA EVERY DAY FOR THE REST OF THE WORKWEEK. WITH THE HIGHEST RAINFALL ACCUMULATIONS...NEAR 60MM OVER THE PACIFIC COASTAL SIDE OF PANAMA AND COSTA RICA TODAY INTO WEDNESDAY MORNING...WHILE THE HIGHER ELEVATIONS OF THOSE COUNTRIES MAY OBSERVE MAX VALUES BETWEEN 60 AND 80MM ON WEDNESDAY AND THURSDAY DURING THE DAY. THE CHANCES OF RAIN INCREASE FOR NICARAGUA...SOUTHERN GUATEMALA AND EL SALVADOR ON WEDNESDAY AND THURSDAY AS MOISTURE INCREASES...THOUGH THE RAINFALL AMOUNTS WILL BE GENERALLY UNDER 25MM. ACROSS MEXICO...THE ONSHORE WIND FLOW ACROSS SOUTHERN AND EASTERN MEXICO WILL COINCIDE WITH AN ABOVE NORMAL AMOUNT OF PRECIPITABLE WATER. THE MID AND UPPER LEVELS ARE RELATIVELY BENIGN...WITH HIGH PRESSURE IN THE MID LEVELS AND ZONAL FLOW IN THE UPPER LEVELS...WHICH WILL TRANSLATE TO DAILY RAINFALL ACROSS PORTIONS OF SOUTHERN AND EASTERN MEXICO HEAVILY INFLUENCED BY DIURNAL EFFECTS. FOR THAT REASON THE LATEST GUIDANCE INSISTS IN RAINFALL DURING THE AFTERNOON INTO THE VERY EARLY MORNING. THE DAILY RAINFALL MAX WILL BE UP TO 35MM TODAY AND WEDNESDAY ACROSS ISOLATED AREAS...WHILE THURSDAY INTO FRIDAY LOOKS A BIT DRIER. THERE IS AN UPPER LEVEL JET ACROSS NORTHERN MEXICO...BUT IT IS VERY DRY ACROSS THAT AREA AND THE MODEL GUIDANCE DOES NOT SUGGEST RAINFALL OVER THOSE SECTORS. ONE LAST THING TO NOTE...THE NATIONAL HURRICANE CENTER IS MONITORING AN AREA OF POSSIBLE TROPICAL CYCLONE DEVELOPMENT ACROSS THE EASTERN PACIFIC...TO THE SOUTH OF SOUTHERN MEXICO. AT THIS TIME THERE IS CONSIDERABLE UNCERTAINTY...BUT THE OUTLOOK BY THE HURRICANE CENTER SAYS THAT AN AREA OF LOW PRESSURE IS FORECAST TO FORM ALONG A TROUGH SEVERAL HUNDRED MILES TO THE SOUTH OF THE GULF OF TEHUANTEPEC...AND THAT SOME GRADUAL DEVELOPMENT IS POSSIBLE AS THE LOW MOVES TO THE WEST-NORTHWEST AS IT REMAINS SOUTH OF THE COAST OF MEXICO THROUGH EARLY NEXT WEEK. WE WILL CONTINUE TO MONITOR THIS AREA AND WILL FOLLOW THE OUTLOOKS AND LATEST FORECASTS FROM THE NATIONAL HURRICANE CENTER. ALAMO...WPC (USA) $$