TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
324 PM EDT FRI JUL 19 2024

FORECAST BULLETIN 19 JUL 2024 AT 1900 UTC: A SURFACE HIGH PRESSURE
WILL CONTINUE OVER THE ATLANTIC AT LEAST INTO THE WEEKEND. A WEAK
SFC LOW ACROSS THE SOUTHWESTERN CARIBBEAN...WILL SLOWLY MOVE WEST
AND INTO NICARAGUA BY SATURDAY. MOST OF THE TROPICAL ATLANTIC
CONTINUES TO BE FAIRLY QUIET AS A LARGE PLUME OF SAHARAN DUST IS
PRESENT OVER THE AREA. THERE ARE A FEW TROPICAL WAVES IN THE
ATLANTIC BASIN. THESE TROPICAL WAVES ARE CAUSING LOCALLY HIGHER
AREAS OF MOISTURE...WHICH WILL HELP INCREASE THE CHANCES OF
SHOWERS AS THEY APPROACH LAND AREAS EVEN WITH THE SAHARAN DUST
SURROUNDING IT. IN THE MID LEVELS...THERE IS A HIGH PRESSURE
ACROSS THE CENTRAL ATLANTIC...EXPANDING INTO THE GULF OF MEXICO
AND INTO THE EASTERN CARIBBEAN. THERE ARE ALSO WEAK MID LEVEL LOWS
ACROSS THE MONSOON TROUGH IN THE EAST PACIFIC.

IN TERMS OF RAINFALL ACCUMULATIONS...THE LOCAL MAXIMUM RAINFALL
OVER NORTHERN SOUTH AMERICA COULD BE ATTRIBUTED TO THE INTERACTION
BETWEEN THE DEEP AVAILABLE MOISTURE WITH THE LOCAL TERRAIN
EFFECTS. THE MID AND UPPER LEVEL DYNAMICS ARE NOT CONDUCIVE FOR
ENHANCED AND PROLONGED CONVECTION. THE AREA IN NORTHERN SOUTH
AMERICA WITH THE MOST SIGNIFICANT RAINFALL IS EXPECTED TO BE
ACROSS CENTRAL TO EASTERN VENEZUELA INTO WESTERN GUYANA...LIKELY
DUE TO THE MOISTURE INTERACTING WITH THE LOCAL MOUNTAINOUS
TERRAIN. THE LATEST MODEL GUIDANCE IS SUGGESTING DAILY MAX TOTALS
OF 25-50MM OVER EASTERN VENEZUELA AND THE WESTERN SECTION OF
GUYANA. WESTERN COLOMBIA COULD HAVE AS MUCH AS 35MM TODAY AND
SATURDAY INTO SUNDAY...BUT THE SUNDAY INTO WEDNESDAY COULD HAVE
MAX RAINFALL TOTAL CLOSER TO 25MM.

CENTRAL AMERICA COULD HAVE SOME AREAS WITH AN ENHANCED
PRECIPITATION THIS WEEKEND. THIS WILL BE DUE TO THE SFC LOW
PRESSURE MOVING WEST AND BRINGING MOISTURE TO PORTIONS OF CENTRAL
AMERICA INTO NICARAGUA. THERE IS ALSO A TROPICAL WAVE MOVING WEST
ACROSS CENTRAL AMERICA THIS WEEKEND. AT THIS TIME...THE DIFFERENT
GLOBAL MODELS INDICATE THAT OVER THE NEXT 3 DAYS...THE RAINFALL
TOTAL COULD ACCUMULATE AS MUCH AS 75 TO 100MM OVER SEVERAL SECTORS
OF CENTRAL AMERICA...THOUGH THE GFS MODEL IS VERY BULLISH IN THE
RAINFALL AMOUNTS...SUGGESTING OVER 100MM ACROSS ISOLATED
AREAS...BUT OTHER GLOBAL MODELS ARE SUGGESTING MAXIMA OF AROUND
60MM. GIVEN THE RECENT MODEL PERFORMANCE AND INITIALIZATION...THE
GFS CONTINUES TO BE PREFERRED...BUT OUR FORECAST MAX RAIN IS NOT
AS BULLISH AS THE GFS MODEL SUGGEST.

ACROSS MEXICO...THE WIDESPREAD COVERAGE OF RAIN CONTINUES TO BE
EXPECTED THROUGH THE WEEKEND. BOTH THE GFS AND ECMWF MODELS
CONTINUE TO INDICATE THAT OVER THE NEXT 72 HOURS...ONLY A SMALL
PORTION OF THE COUNTRY WOULD RECEIVE NO RAIN. BASED ON THE 19/00Z
GUIDANCE...THE BAJA PENINSULA AND PORTIONS OF THE TEXAS/MEXICO
BORDER WOULD HAVE LITTLE TO NO RAIN OVER THE 3-DAY PERIOD. BUT
ESSENTIALLY THE REST OF THE COUNTRY CONTINUES TO BE FORECAST TO
RECEIVE SOME RAIN EACH DAY...AND A GOOD PORTION OF IT MAY RECEIVE
SIGNIFICANT RAIN. ESPECIALLY ACROSS SINALOA AND DURANGO...TO THE
SOUTHEAST TO OAXACA AND VERACRUZ...WHICH COULD RECEIVE A 3-DAY
TOTAL OF AROUND 30-75MM ACCORDING TO THE GLOBAL MODELS. THIS IS
DUE TO PERSISTENT MOISTURE CONVERGENCE ALONG THE SIERRA MADRE AND
ADJACENT AREAS...WHICH WILL HELP PROMOTE PERSISTENT LIGHT TO
MODERATE SHOWERS OVER THE AREA.

THE FORECAST RAINFALL AMOUNTS ACROSS THE CARIBBEAN ISLANDS ONCE
AGAIN IS RELATIVELY MODEST FOR THIS WEEKEND. THE GFS MODEL IS ONCE
AGAIN AN OUTLIER AND IS SUGGESTING AS MUCH AS 70MM OF RAIN ACROSS
THE EASTERN THIRD OF PR ON TODAY INTO SATURDAY...WHILE THE OTHER
MODELS SUGGEST CLOSER TO 30MM. GIVEN THE AMOUNT OF SAHARAN DUST
OVER THE CARIBBEAN AND THE LACK OF MID TO UPPER LEVEL
DYNAMICS...THE GFS SOLUTION SEEMS A BIT TOO BULLISH...AND
THEREFORE OUR FORECAST FOR PR AND HISPANIOLA IS A BIT LOWER THAN
THE GFS. THEREFORE...AT THIS TIME WE ARE FAVORING THE REST OF THE
MODEL CONSENSUS AND SUGGEST MODEST RAIN...WITH UP TO 45MM TODAY
INTO SATURDAY...THEN AROUND 20-35MM OF RAIN THEREAFTER INTO MONDAY
MORNING. THE REST OF THE EASTERN CARIBBEAN ISLANDS ARE FORECAST
VERY MODEST AMOUNTS OF RAIN...WITH DAILY RAINFALL MAXIMA GENERALLY
UNDER 25MM.


ALAMO...(WPC)
FERNANDER...(BDM)