TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
334 PM EDT WED JUL 24 2024

FORECAST BULLETIN 24 JUL 2024 AT 1930 UTC: THE RELATIVELY DENSE
SAHARAN DUST LAYER (SAL) THAT WAS AFFECTING PORTIONS OF THE
WESTERN CARIBBEAN HAS NOW MOVED WEST NORTHWEST...AND IS MOSTLY
AFFECTING NOW THE GULF OF MEXICO AS WELL AS PORTIONS OF EASTERN
COASTAL AND SOUTHERN MEXICO. CLEANER AIR HAS MOVED INTO THE
CARIBBEAN REGION...BUT ANOTHER RELATIVELY DENSE SAL MOVING THROUGH
THE TROPICAL ATLANTIC WILL MOVE INTO THE EASTERN CARIBBEAN BY
TONIGHT. IN TERMS OF AVAILABLE MOISTURE...NORMAL TO BELOW NORMAL
MOISTURE IS BEING OBSERVED ACROSS THE CARIBBEAN...WITH THE DRIEST
PATCH OF MOISTURE EXPECTED OVER CENTRAL AMERICA TODAY...ESPECIALLY
OVER HONDURAS WEST INTO CHIAPAS IN MEXICO AND THE YUCATAN
PENINSULA...ESSENTIALLY IN AREAS WITH SOME LINGERING SAHARAN DUST.
HIGHER THAN NORMAL MOISTURE IS NOW BEING OBSERVED ACROSS THE
CARIBBEAN WATERS...SOUTHERN CENTRAL AMERICA AND NORTHERN SOUTH
AMERICA. CENTRAL TO NORTHERN MEXICO AS WELL AS PORTIONS OF THE
GREATER ANTILLES ALSO HAVE ABOVE NORMAL MOISTURE. THAT BEING
SAID...THE DENSE SAL MOVING INTO THE CARIBBEAN WILL CAUSE DRIER
AIR TO MOVE IN...AND BY SUNDAY...MOST OF THE EASTERN TO CENTRAL
CARIBBEAN WILL HAVE BELOW NORMAL MOISTURE AS WELL AS SOME SAHARAN
DUST.

ACCORDING TO THE NATIONAL HURRICANE CENTER...THERE IS NO CYCLONE
ACTIVITY EXPECTED OVER THE NEXT 7 DAYS ACROSS THE ATLANTIC BASIN.
HOWEVER...THERE ARE A COUPLE OF DISTURBANCES IN THE EAST PACIFIC
THAT THE NATIONAL HURRICANE CENTER IS MONITORING FOR POSSIBLE
TROPICAL CYCLONE FORMATION. ONE OF THEM HAS A LOW CHANCE OF
FORMATION...BUT THE OTHER...KNOWN AS EP93 HAS A MEDIUM...OR 50
PERCENT CHANCE OF TROPICAL CYCLONE FORMATION IN 48 HOURS AND ALSO
IN 7 DAYS. REGARDLESS OF DEVELOPMENT...BOTH OF THESE DISTURBANCES
ARE FORECAST TO CONTINUE MOVING WEST AND INTO OPEN WATERS. 

AT THE SURFACE...A STRONG HIGH PRESSURE CONTINUES TO DOMINATE THE
ATLANTIC...CAUSING EASTERLY TO SOUTHEASTERLY WINDS ACROSS THE
ATLANTIC...CARIBBEAN AND THE GULF OF MEXICO. THERE IS ALSO A SFC
LOW OVER SOUTHEASTERN TEXAS...WHICH IS CONTRIBUTING TO THE
SOUTHEASTERLY TO SOUTHERLY WINDS OVER THE WESTERN GULF OF MEXICO.
A SFC LOW OVER THE SOUTHERN CARIBBEAN...JUST NORTH OF PANAMA IS
CAUSING A TIGHTENING OF THE PRESSURE GRADIENT ACROSS THE CARIBBEAN
SEA AND THEREFORE LOCALLY STRONGER WINDS OVER THE CARIBBEAN
WATERS. THIS SFC LOW WILL MEANDER OVER THE SOUTHERN CARIBBEAN FOR
THE NEXT FEW DAYS...NOT ONLY CAUSING PERSISTENT LOCALLY STRONGER
WINDS OVER THE CARIBBEAN...BUT ALSO CAUSING MOISTURE CONVERGENCE
OVER COSTA RICA AND PANAMA...ESPECIALLY ON FRIDAY INTO SATURDAY
WHEN ANOTHER SFC LOW MOVES ACROSS THE EASTERN PACIFIC AND CAUSES
PLENTY OF MOISTURE CONVERGENCE OVER COSTA RICA AND WESTERN PANAMA.

THE UPPER LEVELS ARE PROVIDING SOME SUPPORT FOR CONVECTION ACROSS
THE WESTERN GULF OF MEXICO AND INTO PORTIONS OF MEXICO. THIS IS
DUE TO AN UPPER TROUGH OVER CENTRAL US INTO NORTHERN MEXICO
COMBINING WITH DEEP MOISTURE OVER THE AREA.  THERE IS ANOTHER
UPPER LOW...THIS ONE ACROSS THE WESTERN TROPICAL ATLANTIC JUST
EAST OF THE BAHAMAS...WHICH WILL CAUSE ENOUGH INSTABILITY TO
PROMOTE THE DEVELOPMENT OF SQUALLY WEATHER ACROSS THE SOUTHERN
BAHAMAS...TURKS AND CAICOS AND INTO CUBA...BUT THE AIR IS
RELATIVELY DRY OVER THAT AREA...AND THEREFORE THE COVERAGE AREA
WITH HIGH AMOUNTS OF RAIN IS EXPECTED TO BE LIMITED. ACCORDING TO
THE LATEST GUIDANCE...PORTIONS OF EASTERN CUBA COULD OBSERVE OVER
45-50MM FROM FRIDAY INTO SATURDAY WITH THE STRONGEST STORMS.

ABOVE NORMAL MOISTURE OVER MEXICO WILL COMBINE WITH THE
AFOREMENTIONED UPPER TROUGH ACROSS NORTHERN MEXICO TO CAUSE
PERSISTENT SHOWER ACTIVITY OVER MANY SECTORS OF CENTRAL INTO
NORTHEASTERN MEXICO TODAY. THEN THE HEAVIEST RAINFALL ON THURSDAY
AND FRIDAY WILL BE MORE CONCENTRATED ACROSS THE CENTRAL PORTIONS
OF MEXICO. EVEN THOUGH THE SIERRA MADRE OCCIDENTAL IN MEXICO IS ON
THE CONVERGENT SIDE OF THE UPPER TROUGH...THE LOW LEVEL WIND FLOW
WILL BE FROM THE EASTERN PACIFIC INTO THE SIERRA MADRE
OCCIDENTAL...WHICH WILL PROVIDE MOISTURE TO MOVE INLAND AND SHOWER
ACTIVITY IS EXPECTED TO DEVELOP DUE TO OROGRAPHIC
LIFTING...ESPECIALLY ON FRIDAY INTO EARLY SATURDAY.
THEREFORE...THE COMBINATION OF FACTORS WILL CAUSE MANY SECTORS IN
MEXICO TO OBSERVE RAINFALL OVER THE NEXT FEW DAYS...BUT THE
CENTRAL PORTIONS ARE FORECAST TO HAVE THE MORE SIGNIFICANT RAIN
FROM TODAY INTO THE WEEKEND.

ACROSS CENTRAL AMERICA...THE LOCATIONS WITH MOST PRECIPITATION ARE
EXPECTED TO BE AREAS IN AND AROUND COSTA RICA AND PANAMA...DUE TO
THE AFOREMENTIONED SFC LOW PRESSURE AND PERSISTENT DEEP MOISTURE
OVER THE AREA. ONE DAY TO PAY ATTENTION TO IS FRIDAY INTO
SATURDAY...THE GFS MODEL IS VERY BULLISH WITH ITS RAINFALL
FORECAST...SUGGESTING UP TO 125MM AND A RISK OF MCS OVER WESTERN
PANAMA INTO COSTA RICA. THE ECMWF IS NOT AS BULLISH WITH THE
AMOUNTS...BUT CONSIDERING THE DEEP MOISTURE CONVERGENCE AND THE
LOCAL TOPOGRAPHY AND THE DIVERGENCE IN THE UPPER LEVELS...HAVING
ISOLATED AREAS OF OVER 100MM WOULD NOT BE OUT OF THE REALM OF
POSSIBILITIES. THE CARIBBEAN COAST OF NICARAGUA AND HONDURAS WILL
HAVE SIGNIFICANT AMOUNTS OF RAIN TODAY AS WELL AS THURSDAY...WITH
MAX VALUES NEAR 20-45MM AS THE SFC LOW MOVES CLOSER TO NICARAGUA.
THEN EVEN HIGHER AMOUNTS ON FRIDAY INTO EARLY SATURDAY ACROSS
NICARAGUA.

NORTH CENTRAL COLOMBIA WILL HAVE LOCALIZED AMOUNTS OF RAIN NEAR
50MM TODAY...WHILE CENTRAL TO NORTHWEST COLOMBIA WILL HAVE UP TO
50MM ON THURSDAY. FRIDAY INTO SATURDAY...A PASSING TROPICAL WAVE
AND A SFC TROUGH WILL COMBINE TO CAUSE POSSIBLE MAX RAINFALL
VALUES OF 40-75MM OVER COLOMBIA. ACROSS OTHER PORTIONS OF NORTHERN
SOUTH AMERICA...ANOTHER SECTOR TO OBSERVE IS THE CENTRAL TO
EASTERN SECTIONS OF VENEZUELA. THE MID TO UPPER LEVELS ARE NOT
CAUSING CONDUCIVE FOR ENHANCED CONVECTIVE SUPPORT...BUT THE LOW
LEVEL WINDS AND DEEP MOISTURE WILL COMBINE WITH THE OROGRAPHIC
LIFTING OVER THE AREA TO CAUSE DAILY SHOWERS AND THUNDERSTORMS. 
ACROSS THE CARIBBEAN ISLANDS AND INTO THE BAHAMAS...MODEST AMOUNTS
OF RAIN ARE EXPECTED OVER THE NEXT FEW DAYS GIVEN THE RELATIVELY
DRY AIR. THE GLOBAL MODEL GUIDANCE IS SUGGESTING MAX VALUES OF
ABOUT 50MM OVER ISOLATED AREAS FOR A 3-DAY TOTAL PRECIPITATION.
HOWEVER...ISOLATED AREAS OVER HISPANIOLA...CUBA AND SOUTHERN
BAHAMAS COULD OBSERVE OVER 60MM IN THE 3-DAY PERIOD DUE TO THE
POSSIBLE STRONG CONVECTION EXPECTED OVER THE AREA...ESPECIALLY
EASTERN CUBA.



ALAMO...(WPC)
FERNANDER...(BDM)
CLARKE...(CINWS)