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Tropical Discussion
 
(Latest Discussion - Issued 1710Z Apr 12, 2021)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
110 PM EDT MON APR 12 2021

TROPICAL DISCUSSION FROM APR 12/17 UTC: SOUTH OVER THE DOMAIN...AT
250 HPA...A CELL OF THE SUBEQUATORIAL RIDGE IS THE DOMINANT
FEATURE AS IT EXTENDS WEST ACROSS NORTHERN SOUTH AMERICA/SOUTHERN
CARIBBEAN TO CENTRAL AMERICA. POLAR TROUGH EXITING THE EASTERN USA
EARLY IN THE CYCLE IS TO PRESS AGAINST THIS AXIS...WITH A BROAD
POLAR TROUGH TO AMPLIFY OVER THE WESTERN ATLANTIC TO THE NORTHERN
CARIBBEAN ON TUESDAY-WEDNESDAY. A 70KT-110KT SUBTROPICAL JET
MAXIMA ROUNDING THE BASE OF THE TROUGH IS TO THEN SEPARATE THIS
AXIS FROM THE RIDGE TO THE SOUTH WHILE SIMULTANEOUSLY STRADDLING
THE NORTHERN CARIBBEAN ISLANDS. AT LOW LEVELS...A WANING FRONT
TRAILS ACROSS THE CENTRAL ATLANTIC TO THE LEEWARD ISLANDS...WHILE
A BETTER ORGANIZED FRONT IS TO STREAM ACROSS THE NORTHWEST
BAHAMAS-WESTERN CUBA LATER TODAY. ON TUESDAY...REINFORCED BY A
SECONDARY FRONT...THE LATTER SURGES ACROSS THE BAHAMAS/TURKS AND
ACROSS CUBA TO THE NORTHWEST CARIBBEAN...MEANWHILE FAVORING A
PREFRONTAL TROUGH OVER THE EASTERN CARIBBEAN/PUERTO RICO. ON
WEDNESDAY THE FRONT MOVES SOUTH INTO THE NORTHEAST CARIBBEAN WHILE
TRAILING ACROSS THE NORTHERN LEEWARD ISLANDS...WITH A PREFRONTAL
SHEAR LINE FORMING AHEAD OF THIS BOUNDARY LATER IN THE DAY. AS THE
FRONT ENTERS THE NORTHERN BAHAMAS-CUBA IT IS TO SUSTAIN LIGHT
CONVECTION...WITH ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM.
ON TUESDAY FOCUS SHIFTS TO EASTERN CUBA-JAMAICA...WITH
ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM...WHILE OVER
NORTHERN HISPANIOLA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15MM. ACROSS PUERTO RICO...AS ENHANCED BY THE UPPER
LEVEL JET MAXIMA AND THE PREFRONTAL TROUGH...THIS WILL RESULT IN
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. OVER THE
LEEWARD ISLANDS...MEANWHILE...ONLY EXPECTING RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM.

THE UPPER LEVEL CELL OF THE SUBEQUATORIAL RIDGE...AS IT MEANDERS
ACROSS NORTHERN SOUTH AMERICA INTO CENTRAL AMERICA...IS TO VENT
DIURNAL CONVECTION OVER THE CONTINENT. OVER WESTERN COLOMBIA...AT
LOW LEVELS...THE PANAMANIAN TROUGH WILL SUSTAIN A MOIST
WEST-NORTHWESTERLY FLOW ACROSS THE ANDES. AS THE MOISTURE
CONVERGES ON THE WESTERN SLOPES OF THE ANDES THIS WILL HELP
SUSTAIN AN ACTIVE PATTERN...WITH RAINFALL AMOUNTS OF 15-20MM/DAY
AND MAXIMA OF 25-50MM. ON WEDNESDAY-THURSDAY MOST ACTIVE SHIFTS TO
THE CAUCA/CAUCA VALLEY TO THE SOUTHWEST...WITH ACCUMULATION OF
15-20MM/DAY AND MAXIMA OF 30-60MM...WHILE OVER THE EJE
CAFETERO/NORTHWEST COLOMBIA EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM. OVER NORTHERN VENEZUELA TO
NORTHERN COLOMBIA EXPECTING MODERATE RAINFALL AMOUNTS WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-30MM. THROUGH
WEDNESDAY...HOWEVER...THE DAILY MAXIMA DECREASES TO 15-20MM.
HIGHER AMOUNTS ARE EXPECTED TO THE SOUTH OVER EASTERN
COLOMBIA-AMAZONIA IN SOUTHERN VENEZUELA AND RORAIMA IN
BRASIL...WITH RAINFALL AMOUNTS INCREASING FROM 10-15MM/DAY AND
MAXIMA OF 20-40MM EARLY IN THE CYCLE TO 15-20MM/DAY AND MAXIMA OF
25-50MM ON TUESDAY TO WEDNESDAY...WEAKENING TO 10-15MM/DAY AND
MAXIMA OF 20-30MM ON WEDNESDAY-THURSDAY.

OVER CENTRAL AMERICA...THE RIDGE ALOFT IS TO ALSO VENT DIURNAL
CONVECTION CLUSTERING ALONG THE CONTINENTAL DIVIDE. ACROSS PANAMA
AND COSTA RICA THIS WILL RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-20MM OVER THE NEXT FEW DAYS. OVER GUATEMALA-EL
SALVADOR/SOUTHERN HONDURAS THIS WILL GRADUALLY INCREASE FROM
00-05MM/DAY AND MAXIMA OF 10MM DURING THE DAY TODAY TO 05-10MM/DAY
AND MAXIMA OF 15-30MM ON WEDNESDAY...WITH SOME OF THE HIGHER
RESOLUTION MODELS SHOWING POTENTIAL FOR LOCALLY HIGHER RAINFALL
AMOUNTS.

THE INFLUENCE OF THE UPPER LEVEL RIDGE LIMITS TO NORTHERN SOUTH
AMERICA AND CENTRAL AMERICA...WHILE MEXICO IS TUTT OVER THE
EASTERN PACIFIC IS TO PREVAIL. AT 250 HPA THE TUTT WILL EXTEND TO
THE SOUTH-SOUTHEAST FROM COLIMA/NAYARIT TO THE ITCZ TO THE SOUTH.
ACROSS CENTRAL MEXICO THE TROUGH ALOFT IS TO ENHANCE AIR MASS
RELATED CONVECTION...TO RESULT IN RAINFALL AMOUNTS OF 00-05MM/DAY
AND MAXIMA OF 10MM IN LATE AFTERNOON CONVECTION.

TROPICAL WAVES/TUTT INDUCED PERTURBATIONS/TRADE WIND SURGES
NONE SIGNIFICANT

DAVISON...WPC (USA)