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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1831Z Mar 23, 2015)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 PM EDT MON MAR 23 2015

DISCUSSION FROM MARCH 23/00 UTC:  UPPER TROUGH IN THE SOUTHERN
STREAM IS RAPIDLY EXITING NORTHEASTERN MEXICO INTO THE CENTRAL
GULF OF MEXICO. THIS TROUGH WILL EXTEND ACROSS NORTHERN
FLORIDA-CENTRAL GULF BY MONDAY EVENING...TO RAPIDLY EXIT EAST AND
POSITION ALONG 60W BY TUESDAY EVENING. THE SYSTEM IS SUSTAINING A
SURFACE FRONT FORECAST TO EXTEND ALONG THE NORTHERN
BAHAMAS-SOUTHEASTERN GULF OF MEXICO INTO THE GULF OF
CAMPECHE-SOUTHERN VERACRUZ BY MONDAY EVENING...TO RAPIDLY LOSE
DEFINITION WHILE ILL-DEFINED BOUNDARY MEANDERS ACROSS THE NORTHERN
BAHAMAS-EXTREME NORTHWESTERN CUBA-NORTHERN YUCATAN-GULF OF
CAMPECHE BY TUESDAY EVENING. FRONT WILL SUSTAIN SOME SCATTERED
CONVECTION ACROSS SOUTHEASTERN MEXICO AS NORTHERLY WINDS ENHANCE
OROGRAPHIC UPLIFT. THROUGH EARLY WEDNESDAY EXPECTING ACCUMULATIONS
OF 05-10MM/DAY AND MAXIMA OF 15-30MM/DAY ACROSS CENTRAL/EASTERN
MEXICO AND VERACRUZ/OAXACA. THE FRONT WILL ALSO PRODUCE
PRECIPITATION AS IT MOVES ACROSS THE NORTHERN BAHAMAS THROUGH
EARLY TUESDAY. MODELS ARE SHOWING INSTABILITY WITH GDI VALUES
EXCEEDING 40 AND ENHANCED UPPER DIVERGENCE AHEAD OF MAIN TROUGH
AXIS. THIS WILL LEAD TO SCATTERED THUNDERSTORMS WITH AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-25MM MAXIMA WILL DECREASE TO 10MM/DAY
BY TUESDAY INTO EARLY WEDNESDAY IN LINGERING LIGHT RAIN SHOWERS
ALONG WEAKENING FRONT. SCATTERED ACTIVITY IS ALSO EXPECTED ACROSS
CUBA TO PRODUCE ISOLATED MAXIMA OF 10MM/DAY.

NEXT SIGNIFICANT TROUGH MOVING INTO THE REGION WILL POSITION OVER
THE WESTERN GREAT PLAINS OF THE UNITED STATES BY THURSDAY. THIS
TROUGH WILL LEAD TO THE DEVELOPMENT OF A POLAR HIGH AND ASSOCIATED
FRONTAL INCURSION AND NORTES EVENT IN THE WESTERN GULF OF MEXICO.
THE FRONT WILL ENTER CENTRAL TAMAULIPAS BY THURSDAY EVENING
LEADING TO ANOTHER ROUND OF MODERATE SHOWERS. EXPECTING MAXIMUM
ACCUMULATIONS ALONG EASTERN SLOPES INCREASING TO OVER 20-40 MM/DAY
BY THURSDAY INTO EARLY FRIDAY.

OTHER REGION OF INTEREST ACROSS MEXICO IS THE SIERRA MADRE
ORIENTAL BETWEEN TLAXCALA/NORTHERN VERACRUZ INTO PUEBLA/OAXACA.
INSTABILITY ASSOCIATED WITH THE DIURNAL HEATING IS BECOMING
SUFFICIENTLY LARGE TO TRIGGER SHORT-LIVED SCATTERED AFTERNOON
THUNDERSTORMS IN A QUASI DAILY BASIS. THESE WILL LEAD TO
ACCUMULATIONS OF 05-10MM/DAY AND MAXIMA OF 15-30MM/DAY.

MID-UPPER RIDGE IS DOMINATING MOST OF THE CARIBBEAN BASIN
SUSTAINING SEASONAL SUBSIDENCE INVERSION OVER THE REGION. THIS IS
LIMITING ACTIVITY TO SHALLOW CONVECTION WITH ACCUMULATIONS OFTEN
BELOW 15MM/DAY. LOCALLY ENHANCED ACTIVITY IS EXPECTED ACROSS
NORTHERN HISPANIOLA LATE ON MONDAY INTO EARLY TUESDAY...AS SURFACE
TROUGH ENHANCES LOW-LEVEL CONVERGENCE AND ASCENT. EXPECTING MAXIMA
TO INCREASE TO 15MM/DAY. OTHER REGION OF INTEREST WILL BE THE
CENTRAL LESSER ANTILLES ON TUESDAY INTO EARLY WEDNESDAY...WHEN AN
EASTERLY WAVE WILL CROSS THE REGION (SEE BELOW). EXPECTING AN
INCREASE IN THE COVERAGE AND INTENSITY OF SHOWERS TO PRODUCE
ACCUMULATIONS OF 05-10MM/DAY AND MAXIMA OF 15-20MM LASTING INTO
EARLY THURSDAY.

ACROSS NORTHERN SOUTH AMERICA...SEASONALLY QUIET PATTERN HAS
RETURNED AS MID-LEVEL RIDGE HAS SET FOOTHOLD OF THE SOUTHERN
CARIBBEAN ONCE AGAIN. THE SOUTHEASTERN CARIBBEAN/VENEZUELA ARE
ALSO IN THE CONVERGENT/DRY SIDE OF A MID-LEVEL TROUGH THAT EXTENDS
INTO GUYANA-RORAIMA. THE UPPER TROUGH IS ALSO UNDULATING THE ITCZ
OFF THE COASTS OF AMAPA/FRENCH GUIANA...LEADING TO AN INCREASE IN
PRECIPITABLE WATER. THIS REGION OF DEEP-LAYER MOISTURE WILL
GRADUALLY MAKE IT INLAND AS UPPER TROUGH LOSES DEFINITION AND THE
UPPER CONVERGENT PATTERN STARTS RECEDING. AS THIS
HAPPENS...EXPECTING ACTIVITY TO INCREASE IN FRENCH GUIANA AND
EVENTUALLY SURINAME...WITH AMOUNTS AS HIGH AS 15-20MM/DAY AND
MAXIMA OF 25-50MM/DAY ACROSS FRENCH GUIANA ON WEDNESDAY INTO
THURSDAY.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
55W      56W    58W    60W    62W    64W    66W   DISSIPATES EW

EASTERLY WAVE INITIALIZED AT 55W WILL ENHANCE ACCUMULATIONS
ESPECIALLY ACROSS THE CENTRAL LESSER ANTILLES LATE ON TUESDAY INTO
EARLY THURSDAY. THIS WILL LEAD TO ACCUMULATIONS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM...DECREASING AFTERWARDS.

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