406
FXCA20 KWBC 221848
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
147 PM EST WED JAN 22 2025
FORECAST BULLETIN 22 JANUARY 2025 AT 18:30 UTC
MEDIUM RANGE DISCUSSION: THE UPPER CONVERGENT MJO SIGNAL CONTINUES
STRENGTHENING OVER THE CARIBBEAN BASIN. THIS WILL CONTINUE TO
LIMIT AREAS OF HEAVY PRECIPITATION WITH THE EXCEPTION OF REGIONS
WHERE TRADE WIND CONVERGENCE PLAY A ROLE IN HIGILIGHTING
ACCUMULATIONS.
ARCTIC BLAST: A SYSTEM OFF INTEREST CONTINUES TO BE A STRONG COLD
FRONT THAT EXTENDS FROM THE CENTRAL NORTH ATLANTIC ACROSS THE
NORTHWEST BAHAMAS AND INTO THE GULF OF HONDURAS. BY WEDNESDAY
EVENING EXPECT THE BOUNDARY IS FORECAST TO BECOME STATIONARY WHILE
EXTENDING ACROSS NEW PROVIDENCE/ANDROS ISLAND...WEST
CUBA...CENTRAL GULF OF HONDURAS INTO ISLAS DE LA BAHIA AND
NORTH-CENTRAL HONDURAS. BY THURSDAY EVENING EXPECT THE BOUNDARY
ACROSS GRAND BAHAMA...FLORIDA STRAIT...WEST CUBA AND INTO QUINTANA
ROO/SOUTHERN BELIZE. A NEW POLAR HIGH IS FORECAST TO STRENGTHEN
ACROSS THE SOUTHEAST USA LATE ON THURSDAY...TO STRENGTHEN ONCE
AGAIN NORTHERLY WINDS ACROSS THE GULF OF MEXICO AND THE GULF OF
HONDURAS. THIS WILL TRANSPORT THE BOUNDARY TO THE SOUTHEAST INTO
CENTRAL CUBA/CAYMAN ISLANDS BY FRIDAY EVENING...WHERE IT WILL
DISSIPATE. THE NORTHERLY WINDS WILL ALSO REORGANIZE THE REST OF
THE FRONT. BY FRIDAY EVENING EXPECT THE BOUNDARY ACROSS THE
NORTHWEST BAHAMAS...WEST CUBA INTO THE NORTHERN YUCATAN PENINSULA.
THE LARGEST RAINFALL AMOUNTS WITH THIS BOUNDARY ARE EXPECTED IN
WESTERN PORTIONS OF THE BASIN GIVEN HIGHER AMOUNTS OF AVAILABLE
MOISTURE AND A WEAKNESS IN THE MID-LEVEL RIDGE. THROUGH EARLY
THURSDAY EXPECT 20 - 40MM/DAY AND MAXIMA OF 75 - 125MM IN NORTHENR
HONDURAS AND ISLAS DE LA BAHIA. BY THURSDAY THE RETREATING FRONT
WILL POSE A RISK OF ECHO TRAINING IN SOUTHERN QUINTANA ROO AND
NORTHERN BELIZE...WHERE EXPECT MAXIMA OF 25 - 50MM THROUGH EARLY
FRIDAY. BY FRIDAY THROUGH EARLY SATURDAY EXPECT ENHANCED LOW-LEVEL
CONFLUENCE AND CONVERGENCE DEVELOPING ALONG THE EASTERN YUCATAN
PENINSULA INTO COASTAL BELIZE AND NORTHWEST HONDURAS/EAST
GUATEMALA...AHEAD OF THE NORTHERN FRONT...TO FAVOR 20 - 40MM/DAY
AND MAXIMA OF 50 - 100MM.
CARIBBEAN: MOST OF THE CARIBBEAN WILL BE UNDER THE INFLUENCE OF
THE MID-LEVEL RIDGE...WHICH IS FORECAST TO CENTER NEAR 25N 50W
THROUGH THE FORECAST CYCLE...WHILE EXTENDING A STABLE LAYER INTO
THE CENTRAL AND EASTERN CARIBBEAN. MORE THAN STABILITY
ITSELF...THE PRESENCE OF VERY DRY MID-LEVELS WILL FAVOR DRY AIR
ENTRAINMENT PROCESSES TO LIMIT CLOUD COVER AND PRECIPITATION
AMOUNTS. IN THE LOW-LEVELS...ACCELERATED TRADES WILL
CONTINUE...WHICH WILL CONTINUE TO LIMIT RESIDENCE TIMES OF ANY
CONVECTION AND REDUCE CLOUD STRUCTURES BY ENHANCED VERTICAL WIND
SHEAR. MODERATE PRECIPITATION AMOUNTS ARE EXPECTED TO BE VERY
LOCALIZED AND CLUSTER TO REGIONS OF ENHANCED OROGRAPHIC UPLIFT IN
EASTERN SLOPES OF SHARP TERRAIN. THIS WILL FAVOR VERY ISOLATED
MAXIMA OF 15 - 20MM/DAY IN EASTERN SLOPES OF THE CENTRAL LESSER
ANTILES. MODERATE AMOUNTS ARE EXPECTED IN PORTIONS OF COSTA RICA
AND EASTERN NICARAGUA WHERE MAXIMA IN THE 20 - 35MM/DAY RANGE IS
EXPECTED. NOTE THAT VERY ISOLATED HIGHER AMOUNTS ARE LIKELY IN
REGIONS OF ENHANCED OROGRAPHIC UPLIFT.
IN NORTHERN SOUTH AMERICA THE REGION OF INTEREST ARE THE GUIANAS.
THE ATLANTIC ITCZ IS RETURNING NORTHWARD AND IS INTERACTING WITH
AN UPPER TROUGH IN THE TROPICAL NORTH ATLANTIC. THIS IS BUILDING
LARGE VALUES OF PRECIPITABLE WATER/AVAILABLE MOISTURE ALONG THE
ITCZ AND AREAS DOWNWIND IN THE SOUTH AMERICAN COAST. THE FORECAST
STRENGTHENING OF THE LOW-LEVEL WINDS IN THE TROPICAL ATLANTIC WILL
SETUP AN ENVIRONMENT FAVORABLE FOR ECHO TRAINING ALONG THE ITCZ.
THIS WILL FAVOR AMOUNTS OF 20 - 40MM/DAY AND MAXIMA OF 50 - 100MM
PRIMARILY IN FRENCH GUIANA AND SURINAME ON THURSDAY THROUGH EARLY
FRIDAY. BY FRIDAY INTO EARLY SATURDAY EXPECT MAXIMA OF 40 - 80MM
IN THIS FRENCH GUIANA DND NORTHERN SURINAME...WHILE IN GUYANA
EXPECT MAXIMA OF 25 - 50MM. TO THE WEST...ACTIVITY IN THE PACIFIC
BASIN OF NORTHERN SOUTH AMERICA IS EXPECTED TO CONTINUE BEING VERY
ISOLATED AND LIMITING TO CENTRAL/SOUTHERN COLOMBIA AND COASTAL
ECUADOR. AN INCREASE IN ONSHORE FLOW AND PRECIPITABLE WATER ON
FRIDAY WILL LIKELY FAVOR AN INCREASE IN ACCUMULATION TO MAXIMA OF
20 - 35MM IN THE ECUADORIAN COAST AND WESTERN SLOPES.
GALVEZ...(WPC)
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