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Tropical Discussion
 
(Latest Discussion - Issued 1813Z Mar 31, 2015)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
213 PM EDT TUE MAR 31 2015

DISCUSSION FROM MARCH 31/12 UTC: MID LEVEL TROUGH OVER THE WESTERN
ATLANTIC/NORTHERN CARIBBEAN SPLITS THE SUBTROPICAL RIDGE IN TWO
CELLS...WITH ONE DOMINATING MEXICO-CENTRAL AMERICA AND THE OTHER
THE EASTERN CARIBBEAN. THE ONE OVER MEXICO IS TO ANCHOR ON A
CLOSED HIGH THAT IS TO MEANDER OVER SOUTHWEST STATES OF MEXICO.
ASSOCIATED RIDGE AXIS IS TO SLOWLY BUILD NORTH ACROSS MEXICO AND
EAST ACROSS THE YUCATAN/NORTHERN CENTRAL AMERICA TO THE WESTERN
CARIBBEAN. THE MID LEVEL RIDGE PATTERN IS FORECAST TO STRENGTHEN
ITS FOOTHOLD THROUGH THURSDAY EVENING. AS THE RIDGE
BUILDS...EXPECTING THE GRADUAL EROSION OF AVAILABLE MOISTURE AND
DECREASE IN CONVECTION ACROSS CENTRAL-SOUTHERN MEXICO AND NORTHERN
CENTRAL AMERICA. BEST MOISTURE CONVERGENCE...MEANWHILE... IS
EXPECTED ACROSS BELIZE-QUINTANA ROO IN THE YUCATAN-NORTHERN
GUATEMALA AND NORTH COAST OF HONDURAS. EARLY IN THE CYCLE EXPECT
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM IN SCATTERED
CONVECTION. THROUGH WEDNESDAY THIS DECREASES TO 00-05MM/DAY AND
MAXIMA OF 10MM. OTHER CONVECTION TO THE NORTH IS TO AFFECT THE
NORTHWEST STATES OF MEXICO EARLY IN THE CYCLE...WHEN SHORT WAVE
TROUGH IN THE SOUTHERN STREAM LIFTS OVER THE RIDGE...TO TRIGGER
SCATTERED CONVECTION WITH ACCUMULATION OF 00-05MM/DAY AND MAXIMA
OF 10MM.

THE MID LEVEL RIDGE TO THE EAST EXTENDS ACROSS THE EASTERN
CARIBBEAN ISLES INTO THE TROPICAL ATLANTIC. UNDER PRESSURE...IT IS
TO SLOWLY MOVE EAST ACROSS THE ISLAND CHAIN INTO THE TROPICAL
ATLANTIC/NORTHERN GUIANAS EARLY IN THE CYCLE...WHERE IT IS TO
REMAIN THROUGH THE END OF THE WEEK. AS IT PULLS AWAY...CAP
INVERSION ACROSS PUERTO RICO-ISLAND CHAIN IS FORECAST TO WEAKEN.
THIS WILL ALLOW FOR DEEPER MOISTURE TO POOL ACROSS THE NORTHEAST
CARIBBEAN ISLES...WITH PWAT EXPECTED TO INCREASE TO 35-40MM LATER
ON WEDNESDAY TO THURSDAY. ACROSS THE GUIANAS THE OPPOSITE IS
TRUE...WITH RELOCATING MID LEVEL RIDGE TO STRENGTHEN THE CAP
INVERSION AND FAVOR GRADUAL EROSION OF AVAILABLE MOISTURE. A RAPID
DRYING TREND IS EXPECTED THROUGH WEDNESDAY MORNING.

BROAD MID/UPPER LEVEL TROUGH IS TO THEN REMAIN ACROSS THE WESTERN
ATLANTIC TO THE NORTHERN CARIBBEAN. AS IT HOLDS...SHORT WAVE
PERTURBATIONS ARE TO REVOLVE AROUND THIS AXIS. THESE ARE TO STREAM
ACROSS THE CARIBBEAN BASIN/GREATER ANTILLES...WITH A FAIRLY STRONG
SHORT WAVE TROUGH TO MOVE ACROSS THE CENTRAL CARIBBEAN EARLY IN
THE CYCLE...AND THROUGH THURSDAY IT IS TO LIFT ACROSS PUERTO
RICO-NORTHEAST CARIBBEAN ISLES. LATER IN THE WEEK...AS THE MID
LEVEL RIDGE BUILDS TO THE WEST...TROUGH OVER THE WESTERN ATLANTIC
IS TO BECOME BETTER ORGANIZED. AT 250 HPA THE TROUGH ALOFT IS TO
STEER A SUBTROPICAL JET MAXIMA ACROSS THE WESTERN ATLANTIC. AS IT
MIGRATES NORTH OF THE GREATER ANTILLES...THIS IS TO SUSTAIN AN
UPPER CONVERGENT PATTERN LATER ON THURSDAY EVENING/FRIDAY MORNING.
BUT THROUGH SATURDAY ENVIRONMENTAL CONDITIONS BECOME MORE
FAVORABLE AS DIVERGENCE ON THE JETS ENTRANCE REGION ENVELOPS THE
NORTHERN CARIBBEAN ISLES. MEANDERING MID/UPPER LEVEL TROUGH IS TO
ENHANCE CONVECTION ACROSS EASTERN CUBA-JAMAICA THROUGH WEDNESDAY
MORNING...WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-30MM/DAY. THIS THEN DECREASES TO 05-10MM/DAY AND MAXIMA OF 15MM
ON WEDNESDAY THROUGH FRIDAY. OVER HISPANIOLA...
MEANWHILE...EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-30MM THROUGH WEDNESDAY MORNING. THEN EXPECT ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-20MM IN SCATTERED CONVECTION. ON
FRIDAY TO SATURDAY...DEEPENING MID LEVEL TROUGH WILL THEN SUSTAIN
AN INCREASE WITH RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-45MM. OVER PUERTO RICO AND THE VIRGIN/LEEWARD ISLES EXPECTING
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM THROUGH
WEDNESDAY EVENING. ON THURSDAY...AS SHORT WAVE TROUGH PULLS ACROSS
THE NORTHEAST CARIBBEAN...EXPECTING AN INCREASE IN ACTIVITY WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM. LOCALLY HIGHER
AMOUNTS ARE HIGHLY LIKELY AS TROUGH ALOFT FAVORABLY INTERACTS WITH
SEA BREEZE CONVERGENCE. AT LOW LEVELS...BROAD POLAR RIDGE MOVES TO
THE WESTERN ATLANTIC THROUGH THURSDAY EVENING...DRIVING A
PREFRONTAL SHEAR LINE ACROSS THE NORTHEAST CARIBBEAN ISLANDS WHILE
ALSO FAVORING A COOL ADVECTIVE PATTERN. THIS IS TO BRIEFLY INDUCE
AN INCREASE IN CONVECTION ACROSS THE VI AND LEEWARD ISLANDS DURING
THE DAY ON THURSDAY WHEN WE EXPECT ACCUMULATION OF 05-10MM/DAY AND
MAXIMA OF 15MM.

AMPLIFYING MID/UPPER LEVEL TROUGH AND WEAKENING OF THE SUBTROPICAL
RIDGE ACROSS THE CARIBBEAN BASIN IS TO FAVOR AN INCREASE IN
CONVECTION ACROSS COLOMBIA AND NORTHWEST/SOUTHERN PORTIONS OF
VENEZUELA. THROUGH WEDNESDAY AFTERNOON ITCZ MOISTURE IS TO SURGE
ALONG THE COAST/ANDEAN REGION OF COLOMBIA TO SUSTAIN AN INCREASE
IN CONVECTION. IN THIS AREA EXPECTING RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM THROUGH WEDNESDAY MORNING. THIS
INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-45MM ON WEDNESDAY
THROUGH FRIDAY. OVER NORTHWEST VENEZUELA INTO NORTHERN COLOMBIA
ACTIVITY IS TO ALSO INTENSIFY LATER ON THURSDAY/EARLY FRIDAY.
INITIALLY EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM. THROUGH FRIDAY THIS INCREASES TO 05-10MM/DAY AND MAXIMA OF
15-30MM. OVER AMAZONIA IN SOUTHERN VENEZUELA-COLOMBIA EXPECTING
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM IN SCATTERED
DEEP CONVECTION.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
NONE

CRAIG...TTMS (TRINIDAD AND TOBAGO)
DAVISON...WPC (USA)