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FXCA20 KWBC 171645
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1244 PM EDT WED JUL 17 2024
FORECAST BULLETIN 17 JUL 2024 AT 1630 UTC: A SURFACE HIGH PRESSURE
ACROSS THE CENTRAL ATLANTIC CONTINUES TO DOMINATE THE ATLANTIC
BASIN...AND THE LATEST GUIDANCE SUGGESTS IT WILL CONTINUE AT LEAST
THROUGH THE REST OF THE WEEK. THERE IS A WEAK SFC LOW DEVELOPING
ACROSS THE SOUTHWESTERN CARIBBEAN...CLOSE TO PANAMA AND
COLOMBIA...WHICH WILL CAUSE MOISTURE FROM THE MONSOON TROUGH TO
POOL OVER THE WATERS ADJACENT TO SOUTHERN CENTRAL AMERICA AND
NORTHWESTERN SOUTH AMERICA OVER THE NEXT FEW DAYS. THE CENTRAL TO
EASTERN TROPICAL ATLANTIC IS FAIRLY QUIET AS A LARGE PLUME OF
SAHARAN DUST AND DRY AIR IS PRESENT OVER MOST OF THE TROPICAL
ATLANTIC...WITH THE EXCEPTION OF AREAS ALONG THE ITCZ / MONSOON
TROUGH. TROPICAL WAVES OVER THE REGION WILL CAUSE LOCALLY HIGHER
AREAS OF MOISTURE...WHICH WILL HELP INCREASE THE CHANCES OF
SHOWERS AS THEY APPROACH LAND AREAS. THERE IS AN UPPER LOW ACROSS
THE WESTERN TROPICAL ATLANTIC...EAST OF THE BAHAMAS...AND ANOTHER
OVER EASTERN TEXAS. THESE UPPER LOWS WOULD CAUSE RISING MOTION
JUST NORTH OF THE CARIBBEAN AND OVER NORTHEASTERN MEXICO
RESPECTIVELY...WHICH MAY PLAY A ROLE IN A MARGINAL RISK OF SQUALLY
WEATHER OVER THE BAHAMAS ON THURSDAY. AN UPPER TROUGH OVER THE
CENTRAL CARIBBEAN IS EXPECTED TO WEAKEN OVER THE NEXT FEW
DAYS...AND ITS LIMITED IMPACT COULD CAUSE MODEST AMOUNTS OF
SHOWERS OVER CENTRAL AMERICA.
IN TERMS OF RAINFALL ACCUMULATIONS...SOME SECTIONS OF NORTHERN
SOUTH AMERICA WOULD HAVE SIGNIFICANT RAINFALL...THOUGH DIFFERENT
SECTIONS EACH DAY THROUGH THE END OF THE WORKWEEK. THESE LOCAL
MAXIMUM RAINFALL COULD BE ATTRIBUTED TO THE INTERACTION BETWEEN
TROPICAL WAVES WITH THE LOCAL TERRAIN EFFECTS AND AVAILABLE
MOISTURE. THE MID AND UPPER LEVEL DYNAMICS ARE NOT PARTICULARLY
FAVORABLE FOR PROLONGED RISING MOTION OR VENTILATION. THAT
SAID...THE AFOREMENTIONED LOW PRESSURE NEAR PANAMA WILL BRING
PERSISTENT MOISTURE FROM THE MONSOON TROUGH INTO THE PANAMA AND
WESTERN COLOMBIA OVER THE NEXT FEW DAYS. THE RAINFALL FORECAST FOR
WESTERN COLOMBIA SUGGESTS DAILY ACCUMULATIONS IN THE ORDER OF
10-15MM/DAY WITH MAX VALUES RANGING FROM 20 TO 35MM TODAY AND
THURSDAY. FRIDAY INTO SATURDAY COULD BE A BIT DRIER WITH MAX
VALUES OF 25MM OR LESS. FOR THE REST OF NORTHERN SOUTH
AMERICA...THE AVAILABLE MOISTURE AND THE INTERACTION WITH THE
TROPICAL WAVES AND LOCAL TERRAIN COULD CAUSE PERIODS OF
SIGNIFICANT RAINFALL...THOUGH THE HEAVIEST RAIN IS EXPECTED OVER
PORTIONS OF VENEZUELA...GUYANA AND NORTHERN COLOMBIA. TODAY AND
TOMORROW...RAINFALL MAXIMA ACROSS ISOLATED SECTIONS OF THE
AFOREMENTIONED AREAS COULD BE AS MUCH AS 30-80MM...BUT THIS IS A
COMPROMISE BETWEEN THE GLOBAL MODELS AND THE CURRENT OBSERVED
CONDITIONS. THE GFS MODEL CONTINUES TO BE BULLISH WITH THE
RAINFALL AMOUNTS. AND GIVEN THE CURRENT SATELLITE IMAGERY...WE
ONCE AGAIN DECIDED TO LEAN TOWARDS THE GFS...BUT WITH SLIGHTLY
LOWER AMOUNTS. BASED ON THE LATEST GUIDANCE...FRIDAY TO SATURDAY
APPEARS TO BE HE DRIEST DAY OVER THE NEXT THREE DAYS...WITH THE
HIGHEST MAX VALUE BEING 45MM OR LESS.
ACROSS MEXICO...THE WIDESPREAD COVERAGE OF RAIN IS EXPECTED TO
CONTINUE FOR THE REST OF THE WORKWEEK. AN AREA OF MOISTURE
CONVERGENCE ALONG THE SIERRA MADRE AND ADJACENT AREAS WILL HELP
PROMOTE PERSISTENT LIGHT TO MODERATE SHOWERS OVER THE AREA. A SFC
HIGH PRESSURE TO THE WEST OF NORTHERN MEXICO...WITH A WEAK LOW
PRESSURE WEST OF CENTRAL MEXICO WILL PUSH ONSHORE FLOW INTO THE
WEST COAST OF THE COUNTRY. THIS WESTERLY FLOW WILL COMBINE WITH A
PREDOMINANTLY EASTERLY WIND FLOW FROM THE GULF...CAUSING THE
PERSISTENT MOISTURE CONVERGENCE. DAILY RAIN VALUES BETWEEN 05-15MM
WITH LOCALIZED MAXIMA BETWEEN 20-45MM CAN BE EXPECTED ACROSS MANY
SECTORS OF MEXICO THROUGH THE END OF THE WORKWEEK. HOWEVER...A
LARGE AREA...MOSTLY COVERING JALISCO AND NEARBY STATES ARE
FORECAST UP TO 50MM ON FRIDAY INTO SATURDAY.
THE FORECAST RAINFALL AMOUNTS ACROSS THE CARIBBEAN ISLANDS AND
MOST OF CENTRAL AMERICA IS RELATIVELY MODEST RELATIVELY SPEAKING.
ACROSS THE CARIBBEAN...THERE IS A LARGE PLUME OF SAHARAN DUST
MOVING IN...WHICH IN PART WILL CAUSE LIMITED SHOWER ACTIVITY OVER
THE CARIBBEAN ISLANDS AS THE SAHARAN DUST PROPAGATES WESTWARD.
THAT BEING SAID...THE FORECAST RAINFALL FOR THE CARIBBEAN AND
CENTRAL AMERICA FOR TODAY AND THURSDAY INTO EARLY FRIDAY IS
BETWEEN 05-10MM WITH MAXIMA OF 35MM OR LESS...IF IT RAINS...AS
MANY AREAS OF CENTRAL AMERICA AND THE CARIBBEAN ISLANDS ARE
FORECAST LITTLE TO NO RAIN. FRIDAY INTO SATURDAY IS A BIT MORE
ACTIVE FOR CENTRAL AMERICA...ESPECIALLY IN AND AROUND EL
SALVADOR...WHERE 15 TO 20MM WITH MAXIMA UP TO 80MM IS POSSIBLE.
THE CARIBBEAN WILL CONTINUE OBSERVING A RELATIVELY DENSE
CONCENTRATION OF SAHARAN DUST INTO THE WEEKEND...AND THEREFORE THE
RAINFALL AMOUNTS MAY BE MODEST ACROSS THE CARIBBEAN ON FRIDAY INTO
SATURDAY.
ALAMO...(WPC)
FERNANDER...(BDM)
CLARKE...(CINWS)
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