025  
FXCA20 KWBC 171806  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
205 PM EDT MON JUN 17 2024  
 
FORECAST BULLETIN 17 JUN 2024 AT 1800 UTC:  
 
THE MAIN STORY CONTINUES TO BE THE CENTRAL AMERICAN GYRE (CAG)  
THAT DEVELOPED...CAUSING EXCESSIVE AMOUNTS OF RAIN ACROSS CENTRAL  
AMERICA INTO PORTIONS OF SOUTHERN AND EASTERN MEXICO. IT IS ALSO  
WORTH MENTIONING...THAT AS OF THIS WRITING...THE NATIONAL  
HURRICANE CENTER HAS DETERMINED THAT A LOW PRESSURE FORMING OVER  
THE BAY OF CAMPECHE HAS A 70 PERCENT CHANCE OF TROPICAL CYCLONE  
FORMATION IN 48 HOURS. AN AIR FORCE RESERVE HURRICANE HUNTER  
AIRCRAFT IS SCHEDULED TO INVESTIGATE THE SYSTEM LATER TODAY.  
HOWEVER...REGARDLESS OF THE DEVELOPMENT OF THIS SYSTEM...PORTIONS  
OF CENTRAL AMERICA AND MEXICO WILL RECEIVE EXCESSIVE AND VERY  
HAZARDOUS AMOUNTS OF RAIN THIS WEEK. ANOTHER FEATURE WORTH  
MENTIONING IS THE TUTT LOCATED OVER THE WEST CENTRAL TROPICAL  
ATLANTIC...WHICH IS SLOWLY MOVING WEST AND EXPECTED TO BE OVER THE  
NORTHWESTERN CARIBBEAN TO THE SOUTHEASTERN GULF OF MEXICO BY LATE  
WEDNESDAY INTO THURSDAY. THIS TUTT WILL PROVIDE INSTABILITY ACROSS  
THE CARIBBEAN ISLANDS AND THE BAHAMAS...CAUSING A MARGINAL TO  
SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE GREATER  
ANTILLES INTO THE BAHAMAS ON TUESDAY AND WEDNESDAY.  
 
STARTING WITH THE CAG...WHICH WILL PRODUCE EXCESSIVE AMOUNTS OF  
RAIN ACROSS PORTIONS OF CENTRAL AMERICA THIS WEEK...EVEN BEYOND  
OUR 3-DAY PERIOD. THE LATEST MODEL GUIDANCE SUGGESTED THAT THE  
72-HR RAINFALL TOTAL WILL RANGE BETWEEN 8 AND 10 INCHES  
(200-250MM) ON THE PACIFIC SIDE OF CENTRAL AMERICA...FROM THE  
GOLFO DE FONSECA TO CHIAPAS OF MEXICO. OTHER SIGNIFICANT AMOUNTS  
OF RAIN ARE FORECAST OVER OTHER PORTIONS OF MEXICO...SUCH AS  
CHIAPAS...CAMPECHE...AND INTO THE NORTHEAST YUCATAN PENINSULA...AS  
WELL AS NORTHEASTERN MEXICO IN AND AROUND TAMAULIPAS...WHERE 72-HR  
MAX TOTALS OF 100-150MM ARE SUGGESTED BY THE MODEL GUIDANCE. THE  
PERSISTENT ONSHORE FLOW INTO THE PACIFIC CENTRAL AMERICAN  
COAST...WITH THE ABOVE NORMAL MOISTURE...WILL PROVIDE A PERSISTENT  
PATTERN FOR SHOWER DEVELOPMENT FOR THE AFOREMENTIONED AREAS.  
 
THE CARIBBEAN REGION WILL BE UP AND DOWN EARLY THIS WEEK AS THERE  
IS SOME SAHARAN DUST THAT COULD APPROACH THE LESSER ANTILLES THIS  
AFTERNOON INTO TUESDAY. THIS PLUME OF SAHARAN DUST WILL SLOWLY  
MOVE WEST...AND IT IS EXPECTED TO GET TO HISPANIOLA BY LATE  
WEDNESDAY INTO THURSDAY. FOR THAT REASON...THE UPPER TROUGH WILL  
HELP DEVELOP THUNDERSTORMS ON TUESDAY ACROSS THE EASTERN GREATER  
ANTILLES ON TUESDAY INTO EARLY WEDNESDAY. THE UPPER TROUGH WILL  
MOVE WEST AND PROVIDE INSTABILITY FOR STRONG THUNDERSTORM  
DEVELOPMENT OVER PORTIONS HAITI INTO CUBA ON WEDNESDAY INTO  
THURSDAY. AS THE SAHARAN DUST IS EXPECTED TO MOVE OVER PUERTO RICO  
AND EASTERN HISPANIOLA ON WEDNESDAY INTO THURSDAY...THE  
THUNDERSTORM ACTIVITY IS EXPECTED TO BECOME MORE ISOLATED...BUT  
SOME OF THEM COULD BE STRONG FOR BRIEF PERIODS. THE OVERALL  
EXPECTED RAINFALL OVER THE CARIBBEAN IS UNDER 50MM FOR THE 3-DAY  
PERIOD...BUT ISOLATED SECTIONS COULD OBSERVE HIGHER AMOUNTS...SUCH  
AS THE POSSIBLE STRONG THUNDERSTORMS THAT DO DEVELOP OVER  
HISPANIOLA...WHICH CAUSE ISOLATED AMOUNTS TO 50MM ACROSS PORTIONS  
OF HAITI ON TUESDAY INTO WEDNESDAY.  
 
NORTHERN SOUTH AMERICA WILL HAVE A SERIES OF SFC TROUGHS IN THE  
AREA EARLY THIS WEEK. THE 72-HR RAINFALL ACCUMULATION COULD HAVE  
ISOLATED MAX VALUES OF 50-100MM ACROSS PORTIONS OF  
VENEZUELA...COLOMBIA...AND ECUADOR. BUT OVERALL...MOST OF THE  
RAINFALL EXPECTED OVER NORTHERN SOUTH AMERICA WILL BE  
CONVECTIVE...AS THE DIURNAL HEATING INTERACTS WITH THE AVAILABLE  
MOISTURE...AND WILL BE ENHANCED BY THE TROUGHS IN THE AREA. EACH  
DAY WILL HAVE MAX TOTALS OF 25-45MM IN DIFFERENT SECTIONS.  
 
IN SUMMARY...THE LATEST GUIDANCE CONTINUES TO SUGGEST THAT THE  
POSITIONING OF THE MONSOON TROUGH IN THE PACIFIC...COMBINED WITH  
THE CAG...WILL CONTINUE TO CAUSE A VERY MOIST ONSHORE FLOW INTO  
CENTRAL AMERICA FOR THE NEXT SEVERAL DAYS. THIS WILL CAUSE A VERY  
HAZARDOUS MULTI-DAY WET SPELL FOR PORTIONS OF CENTRAL AMERICA INTO  
MEXICO. THE CARIBBEAN WILL HAVE SOME MOMENTS WITH STRONG  
THUNDERSTORMS...PARTICULARLY ON TUESDAY AND WEDNESDAY...BUT MAY BE  
LIMITED ACROSS THE NORTHEASTERN CARIBBEAN AS SAHARAN DUST MOVES  
IN. NORTHERN SOUTH AMERICA WILL ALSO HAVE MOMENTS OF SHOWERS AND  
THUNDERSTORMS AS THE SFC TROUGHS COMBINE WITH THE DIURNAL HEATING  
AND AVAILABLE MOISTURE.  
 
ALAMO (WPC)  
CLARKE (CINWS)  
FERNANDER (BDM)  
 
 
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