770
FXCA20 KWBC 132020
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
319 PM EST MON JAN 13 2025
FORECAST BULLETIN 13 JANUARY 2025 AT 20 UTC
A VERY DISORGANIZED MJO UPPER DIVERGENT SIGNAL IS EXITING THE
ATLANTIC BASIN. A WEAK UPPER DIVERGENT KELVIN WAVE IS FORECAST TO
CROSS THE CARIBBEAN THROUGH THE FORECAST CYCLE... BUT THE
INFLUENCE OF AN EXTENSIVE AND ROBUST MID-LEVEL RIDGE WILL LIMIT
THE POTENTIAL IMPACTS OF THIS KELVIN. THE RIDGE IS ANTICIPATED TO
MAINTAIN ITS CURRENT ZONAL-LIKE STRUCTURE THROUGH THE LATE WEEK...
WHILE STARTING TO GRADUALLY WEAKEN ON WEDNESDAY AFTERNOON.
A SERIES OF BOUNDARIES WILL TRAVERSE THE CARIBBEAN BASIN DURING
THE NEXT THREE DAYS. THE FIRST BOUNDARY IS A COLD FRONT THAT IS
EXPECTED TO BE ACROSS THE GULF OF MEXICO BASIN WITH A STATIONARY
FRONT EXTENDING INTO SOUTH VERACRUZ/ WEST TABASCO THIS EVENING. BY
TUESDAY EVENING... THE COLD FRONT WILL EXTEND ACROSS THE CENTRAL
BAHAMAS AND INTO THE GULF OF MEXICO BASIN. THIS FRONT WILL MERGE
WITH ANOTHER COLD FRONT DEVELOPING TO THE NORTHEAST OF THE BAHAMAS
ON WEDNESDAY. BY WEDNESDAY EVENING... THE COLD FRONT WILL EXTEND
ACROSS THE SOUTHERN BAHAMAS...WHILE IN AREAS WEST THE BOUNDARY IS
ANALYZED AS A STATIONARY FRONT ACROSS NORTHERN CUBA INTO THE
CENTRAL GULF OF MEXICO. IT IS IMPORTANT TO MENTION THAT THERE ARE
SIGNIFICANT MODEL DIFFERENCES IN THE POSITION OF THE FRONT THROUGH
THE FORECAST CYCLE. WE DECIDED TO LEAN TOWARDS THE ECWMF DUE TO
ITS CONSISTENCY WITH OTHER GLOBAL MODELS. THIS COLD FRONT WILL
HAVE MINIMAL PRECIPITATION IMPACTS IN THE REGION DUE TO A
MID-TO-UPPER LEVEL POTENT RIDGE DOMINATING IN THE REGION.
HOWEVER... IN SOUTHEAST MEXICO... AS THE STATIONARY BOUNDARY LOSES
ITS STRUCTURE THROUGH TUESDAY AFTERNOON... NORTHERLY FLOW IS
EXPECTED TO ENHANCE OROGRAPHIC EFFECTS IN SOUTH VERACRUZ/ WEST
TABASCO... AND DECREASE BY WEDNESDAY. EXPECT A RAINFALL MAXIMA OF
15 - 30 MM/DAY FOR TODAY AND TUESDAY.
THE SECOND BOUNDARY OF INTEREST IS AN ELONGATED COLD FRONT
CURRENTLY EXTENDING FROM NEAR THE AZORES ISLANDS INTO THE SOUTHERN
BAHAMAS. BY THIS EVENING... IT WILL BEGIN TO DECAY ACROSS THE
SOUTHERN BAHAMAS. THROUGH THE REST OF THE FORECAST CYCLE... THE
DECAYING BOUNDARY WILL BE ANALYZED AS A FRONT SHEAR LINE AND IS
FORECAST TO EXTEND ACROSS BARBUDA/ ST KITTS AND NEVIS ON BOTH
TUESDAY AND WEDNESDAY. ANOTHER PRE-EXISTING SHEAR LINE IS
CURRENTLY EXTENDING ACROSS CENTRAL LESSER ANTILLES INTO THE ABC
ISLANDS. STARTING THIS EVENING THROUGH WEDNESDAY EVENING... THE
SHEAR LINE WILL EXTEND ACROSS SAINT LUCIA/ MARTINIQUE AND JUST
NORTH OF CURACAO WHILE MOVING VERY LITTLE... AND IS EXPECTED TO
BEGIN DECAYING BY WEDNESDAY EVENING. THE DAY OF GREATEST RAINFALL
IMPACT WILL BE TUESDAY AND WEDNESDAY. A LONG FETCH OF MOISTURE
FROM THE CENTRAL ATLANTIC WILL EXTEND ACROSS MARTINIQUE INTO THE
ABC ISLANDS... YIELDING TO A RAINFALL MAXIMA OF 15 - 30MM ON
TUESDAY IN THE LAKE OF MARACAIBO AND A RAINFALL MAXIMA OF 15 -
25MM/DAY THE ABC ISLANDS FOR TUESDAY AND WEDNESDAY. MEANWHILE...
THE LESSER ANTILLES SHOULD OBSERVE ITS GREATEST RAINFALL MAXIMA ON
WEDNESDAY MORNING THROUGH THURSDAY MORNING WITH A TOTAL OF 15 -
25MM.
IN COSTA RICA AND PANAMA... AN UPPER TROUGH DEVELOPING OVER
COLOMBIA ON TUESDAY EVENING WILL MIGRATE INTO THE GULF OF PANAMA
THROUGH WEDNESDAY EVENING. THIS TROUGH WILL PROVIDE VENTILATION TO
THE REGION. ADDITIONALLY... A SERIES OF MOISTURE PLUMES ARRIVING
FROM THE CARIBBEAN WILL BE IMPACTING THE REGION ... WHICH ARE
BEING ENHANCED BY THE MID-TO-UPPER LEVEL RIDGE IN THE NORTH
CARIBBEAN AND THE DEVELOPMENT OF THE CARIBBEAN LOW LEVEL JET.
THESE PROCESSES WILL ENHANCE THE POTENTIAL FOR MOISTURE
CONVERGENCE AND OROGRAPHIC EFFECTS. EXPECT ACCUMULATIONS
INCREASING... PARTICULARLY IN NORTHWEST PANAMA... TO REACH MAXIMA
OF 20 - 40MM BY WEDNESDAY THROUGH EARLY THURSDAY.
IN SOUTH AMERICA... IN COLOMBIA... THE PANAMANIAN TROUGH AND ITCZ
CONTINUE TO BE THE MAIN DRIVERS FOR CONVECTION. HOWEVER... EXPECT
A DECREASE IN AVAILABLE MOISTURE IN THE REGION. IN COASTAL
ECUADOR... A COMBINATION OF WARMER SSTS AND LOCAL INCREASE IN
AVAILABLE MOISTURE WILL ENHANCE PRECIPITATION CHANCES... TO FAVOR
A RAINFALL MAXIMA OF 20 - 35MM POSSIBLE ON TUESDAY AND WEDNESDAY.
ELSEWHERE... THE NOCTURNAL JET OF COLOMBIA AND VENEZUELA BEGINS TO
DOMINATE IN THE WEST AMAZON BASIN...TO EXTEND INTO NORTHERN PERU
STARTING LATE ON WEDNESDAY. THIS... COUPLED WITH AN INCREASE IN
LOW LEVEL NORTHEASTERLY WINDS FROM THE CENTRAL ATLANTIC... WILL
YIELD TO A DRYING TREND IN THE NORTH OF SOUTH AMERICA DUE TO DRY
AIR ADVECTION AND INCREASED LOW-LEVEL WIND SHEAR.
TINOCO...(WPC)
GALVEZ...(WPC)
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