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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1919Z Feb 24, 2015)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
219 PM EST TUE FEB 24 2015

DISCUSSION FROM FEBRUARY 24/00UTC: CONSISTENT WITH PREVIOUS
FORECAST...A 500 HPA HIGH OVER THE YUCATAN PENINSULA IS TO ANCHOR
A MID LEVEL RIDGE ACROSS MEXICO-CARIBBEAN TO NORTHERN SOUTH
AMERICA. STRONG MID LEVEL RIDGE PATTERN IS TO HOLD NEARLY
UNCHANGED OVER THE NEXT DAY...THEN IT IS TO RAPIDLY WEAKEN FROM
THE WEST AS A POLAR TROUGH AMPLIFIES ACROSS THE SOUTHWESTERN USA
TO THE GULF OF MEXICO. LATER ON WEDNESDAY THE HIGH RELOCATES TO
JAMAICA-HAITI...TO THEN SETTLE JUST NORTH OF THE LESSER ANTILLES
LATER ON THURSDAY. ALTHOUGH RIDGE WEAKENS TO THE WEST...CELL OVER
THE CARIBBEAN IS TO GENERALLY PERSIST. INITIALLY...THIS IS TO
FAVOR A STRONG CAP INVERSION ACROSS MEXICO-CENTRAL
AMERICA-GREATER/LESSER ANTILLES...WITH MOISTURE CONFINING TO
ATMOSPHERE BELOW 800 HPA. BUT AS THE RIDGE WEAKENS TO THE WEST THE
CAP INVERSION OVER MEXICO IS EXPECTED TO LIFT...WHILE OVER CENTRAL
AMERICA AND THE ISLANDS OF THE CARIBBEAN THE STRONG CAP INVERSION
IS LIKELY TO PERSIST.

AT LOW LEVELS...A RIDGE EXTENDS WEST ACROSS THE ATLANTIC TO THE
NORTHERN CARIBBEAN. LOW LEVEL RIDGE PATTERN IS FORECAST TO HOLD
OVER THE NEXT FEW DAYS...WITH SOME INTENSIFICATION OVER THE
ATLANTIC-EASTERN CARIBBEAN POSSIBLE LATER ON DAY 03. AS THE RIDGE
BUILDS AND THE GRADIENT TIGHTENS...A TRADE WIND SURGE IS EXPECTED
TO ENTER THE EASTERN CARIBBEAN EARLY ON THURSDAY MORNING...TO
QUICKLY EXPAND ACROSS THE EASTERN TO THE CENTRAL CARIBBEAN. EARLY
IN THE CYCLE THE 900/850 HPA EASTERLY TRADES ARE TO PEAK AT
15-20KT...BUT THROUGH THURSDAY MORNING THEY INCREASE TO 25-35KT.
MEANWHILE...THE PREVAILING EASTERLY WINDS ARE TO FAVOR ADVECTION
OF CLOUD CLUSTERS ACROSS THE TROPICAL ATLANTIC AND THE GENERATION
OF STREAMERS ACROSS THE ISLAND CHAIN. BUT FOR THE MOST PART THESE
ARE TO ONLY FAVOR LIGHT CONVECTION WITH ACCUMULATION OF
00-05MM/DAY AND WIDELY ISOLATED MAXIMA OF 10MM ACROSS THE LESSER
ANTILLES...PUERTO RICO AND PORTIONS OF HISPANIOLA.

SUCCESSIVE MID LEVEL PERTURBATIONS ARE THEN FORECAST TO STREAM
ACROSS THE SOUTHWEST USA TO NORTHERN MEXICO...WITH A FAIRLY STRONG
VORTEX EXPECTED LATER ON WEDNESDAY. BUT AS THE RIDGE HOLDS TO THE
EAST...THESE ARE TO THEN LIFT TO THE NORTHEAST ACROSS THE NORTHERN
GULF/SOUTHERN USA. AT LOW LEVELS...AN ELONGATED FRONT IS TO
STRETCH ACROSS FLORIDA PENINSULA-GULF OF MEXICO TO NORTHEAST
MEXICO/SOUTH TEXAS. AS MID LEVEL PERTURBATIONS INTERACT WITH THIS
BOUNDARY...A SURFACE LOW IS TO DEVELOP ACROSS THE NORTHERN GULF
LATER ON WEDNESDAY. THE LOW IS FORECAST TO DEEPEN AS IT MIGRATES
TO THE EAST-NORTHEAST...TIGHTENING THE GRADIENT WHILE DRIVING THE
FRONT SOUTH TO NORTHERN VERACRUZ MEXICO LATER ON WEDNESDAY.
THROUGH THURSDAY THE FRONT IS TO SURGE ACROSS THE FLORIDA
PENINSULA...WHILE TRAILING ACROSS THE SOUTHERN GULF OF MEXICO TO
OAXACA/SOUTHERN VERACRUZ. THROUGH FRIDAY AFTERNOON THE FRONT IS TO
MEANDER OVER THE NORTHWEST BAHAMAS-FLORIDA KEYS TO THE SOUTHERN
STATES OF MEXICO. AS IT SURGES ACROSS THE SOUTHERN STATES OF
MEXICO THIS IS TO TRIGGER SCATTERED CONVECTION WITH RAINFALL
AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. THROUGH THURSDAY
EVENING EXPECTING AN INCREASE ACROSS VERACRUZ-OAXACA WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM...TO SPREAD EAST
AND SOUTH ACROSS CHIAPAS/CAMPECHE TO THE YUCATAN LATER ON FRIDAY.

THE GUIANAS REMAIN UNDER THE INFLUENCE OF TWO TROUGHS...A NORTHERN
HEMISPHERE SHORT WAVE TROUGH OVER THE TROPICAL ATLANTIC AND A TUTT
LOW OVER BRASIL. THE NORTHERN HEMISPHERE LOW/TROUGH IS TO MEANDER
OVER THE NORTHERN GUIANAS THROUGH TUESDAY EVENING...THEN STARTS TO
WEAKEN WHILE LIFTING TO THE EAST-NORTHEAST. THE TUTT LOW TO THE
SOUTH...MEANWHILE...IS TO CENTER NEAR 09S 55W LATER ON
TUESDAY...WHILE EXTENDING A TROUGH TO THE SOUTHERN
GUIANAS/AMAZONIA IN VENEZUELA. THIS IS TO THEN WEAKEN TO AN OPEN
TROUGH OVER BRASIL LATER ON WEDNESDAY. AS THE TROUGHS
INTERACT...THESE ARE TO SUSTAIN AN ITCZ MOIST SURGE ACROSS THE
NORTHERN GUIANAS...WITH HIGH PWAT CONTENT MOISTURE TO RAPIDLY
ADVECT ACROSS THE GUIANAS THROUGH WEDNESDAY. ACROSS FRENCH GUIANA
TO NORTHEAST SURINAME THIS IS TO FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM. THIS DECREASES TO 05-10MM/DAY
AND MAXIMA OF 15-20MM THROUGH THURSDAY EVENING. ACROSS SURINAME TO
GUYANA IT IS TO INITIALLY FAVOR LIGHT RAINFALL AMOUNTS...BUT THIS
IS TO RAPIDLY INCREASE EARLY ON THURSDAY MORNING WHEN WE EXPECT
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-40MM.
FURTHERMORE...THE TUTT LOW TO THE SOUTH IS TO SUSTAIN ORGANIZED
DEEP CONVECTION ALONG THE NEAR EQUATORIAL TROUGH OVER NORTHERN
PARA-AMAZONAS-RORAIMA IN BRASIL TO AMAZONIA IN SOUTHERN VENEZUELA
AND COLOMBIA...WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF
20-45MM.

OVER WESTERN COLOMBIA...MEANWHILE...WEAK CELL OF THE PANAMANIAN
LOW TO THE WEST IS TO ENHANCE MOISTURE CONVERGENCE ALONG THE WEST
COAST AND THE ANDEAN REGION. AS THE MID LEVEL RIDGE PATTERN OVER
THE CARIBBEAN EVOLVES... ENVIRONMENTAL CONDITIONS ARE TO IMPROVE
AND BECOME MORE CONDUCIVE TO DEEP CONVECTION. THROUGH WEDNESDAY
AFTERNOON EXPECTING CONVECTION TO INCREASE FROM 05-10MM/DAY AND
MAXIMA OF 15MM...TO 05-10MM/DAY AND MAXIMA OF 15-20MM. THIS IS TO
INITIALLY CONFINE TO THE WEST COAST...BUT THROUGH THE CYCLE BUILDS
EASTWARD ACROSS THE ANDES.

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

CRAIG...TTMS (TRINIDAD AND TOBAGO)
NANDA...MDS (SURINAME)
DAVISON...WPC (USA)