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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1816Z Apr 11, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
216 PM EDT FRI APR 11 2014

DISCUSSION FROM APRIL 11/00UTC: A SURFACE FRONT OVER THE WESTERN
ATLANTIC-NORTHWEST CARIBBEAN IS LOSING UPPER LEVEL SUPPORT. UNDER
INFLUENCE OF PREVAILING EASTERLY TRADES...THE TRAILING END OF THIS
FRONT RETROGRESSES ACROSS THE BAHAMAS-CUBA EARLY IN THE
CYCLE...AND THROUGH THE WEEKEND IT IS TO FRONTOLIZE WHILE
RELOCATING NORTH OF THE BAHAMAS. AS IT RETROGRESSES ACROSS THE
BAHAMAS AND CUBA THIS IS TO FAVOR SCATTERED CONVECTION WITH
ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM.

NEXT POLAR TROUGH PULLS ACROSS TEXAS TO THE MISSISSIPPI VALLEY
LATER ON SUNDAY. THE PROGRESSIVE TROUGH WILL SUSTAIN A SURFACE
FRONT ACROSS TEXAS TO NORTHERN COAHUILA EARLY ON MONDAY
MORNING...AND THROUGH THE DAY IT WILL SWING ACROSS
TAMAULIPAS/NUEVO LEON AS A 30-35KT NORTHERLY WIND SURGE ENVELOPS
THE NORTHEAST MEXICO. ACROSS TAMAULIPAS THIS IS TO SUSTAIN
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM...WHILE OVER
VERACRUZ-PUEBLA/HIDALGO THE STRONG NORTHERLIES WILL FAVOR
TOPOGRAPHICALLY INDUCED CONVECTION WITH ACCUMULATION OF
15-20MM/DAY AND MAXIMA OF 25-50MM.

SOUTH OVER THE CARIBBEAN...MID/UPPER LEVEL RIDGE REMAINS DOMINANT
FEATURE...SUSTAINING A TRADE WINDS CAP INVERSION ACROSS MOST OF
THE BASIN/NORTHERN SOUTH AMERICA. STRONG RIDGE PATTERN IS TO
PERSIST THROUGH SATURDAY EVENING/SUNDAY MORNING...MEANWHILE
FAVORING FAIR WEATHER CONDITIONS. IT IS TO THEN GRADUALLY ERODE
FROM THE EAST AS A TUTT LOW NEAR 30N 60W EXTENDS A TROUGH TOWARDS
THE NORTHEAST CARIBBEAN. THROUGH TUESDAY THE TROUGH WILL DEEPEN
ACROSS THE LESSER ANTILLES...WHILE THE RIDGE REALIGNS TO THE WEST
ALONG 72W/73W. AS THE RIDGE ERODES...THE GLOBAL MODEL GUIDANCE
CONTINUES TO SHOW WEAKENING OF THE TRADE WINDS CAP ACROSS THE
NORTHEAST CARIBBEAN ISLES...LIFTING ABOVE 700/650 HPA BY THE EARLY
PART OF NEXT WEEK. DEEPER MOISTURE IS TO THEN POOL ACROSS THE
LEEWARD-VIRGIN ISLES TO PUERTO RICO...WITH MODELS SHOWING PWAT OF
30-35MM IN LIGHT EASTERLY TRADES. THE WEAKER TRADES WILL THEN
ALLOW SEA/LAND BREEZE CYCLE TO DEVELOP...WITH DIURNAL CONVECTION
TO RESULT IN RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.
LOCALLY HIGHER AMOUNTS ARE POSSIBLE OVER HIGH TERRAIN.

THE EVOLVING MID LEVEL RIDGE PATTERN OVER THE BASIN IS TO ALSO
HAVE AN IMPACT ON CONVECTION ACROSS SOUTHERN CENTRAL AMERICA AND
NORTHERN SOUTH AMERICA...WITH MODELS SHOWING DEEPER MOISTURE
POOLING ACROSS VENEZUELA-COLOMBIA AS THE TRADE WINDS CAP WEAKENS.
EARLY IN THE CYCLE CONVECTION IS TO CLUSTER OVER WESTERN
COLOMBIA...WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM. THROUGH SUNDAY THIS INCREASES TO 10-15MM/DAY AND MAXIMA OF
20-40MM. ACROSS NORTHERN COLOMBIA-NORTHWEST VENEZUELA INITIALLY
EXPECTING WIDELY ISOLATED CONVECTION. THROUGH MONDAY MORNING THIS
BECOMES MORE ACTIVE/BETTER ORGANIZED WITH RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-30MM. OVER AMAZONIA IN SOUTHERN
COLOMBIA AND VENEZUELA INITIALLY EXPECTING RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM. THROUGH MONDAY THIS IS TO INCREASE
TO 15-20MM/DAY AND MAXIMA OF 25-50MM.

AN UPPER LEVEL LOW WEST OF THE AZORES EXTENDS A TROUGH TO THE
SOUTHWEST ACROSS THE TROPICAL ATLANTIC TO THE NORTHERN GUIANAS. AS
THE SUBTROPICAL RIDGE PATTERN WEAKENS TO THE WEST...THE TROUGH IS
ALSO FORECAST TO GRADUALLY WEAKEN. THE SUBEQUATORIAL RIDGE IS TO
THEN BUILD FROM THE EAST ACROSS THE TROPICAL ATLANTIC INTO THE
GUIANAS LATER ON SATURDAY/EARLY ON FRIDAY. AS THE UPPER RIDGE
BUILDS ACROSS THE GUIANAS...GLOBAL MODEL GUIDANCE SHOWS A
DIVERGENT PATTERN ALOFT. THIS IS TO THEN VENT DIURNAL CONVECTION.
ACTIVITY IS TO INITIALLY CLUSTER ACROSS FRENCH GUIANA...WITH
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. THROUGH SUNDAY
CONVECTION IS TO BUILD ACROSS SURINAME TO GUYANA...WHERE IT IS TO
FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. THROUGH
MONDAY EVENING THIS IS EXPECTED TO INCREASE TO MAXIMA OF 15-20MM.

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

DAVISON...WPC (USA)
GARCIA...SMN (MEXICO)
FIGUEROA...MARN (EL SALVADOR)