Prognostic Meteorological Discussion
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FXCA20 KWBC 041824
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
223 PM EDT MON MAY 04 2015

DISCUSSION FROM MAY 04/12 UTC: IN A SINUSOIDAL WAVE PATTERN...A
TROUGH OVER THE EASTERN GULF/WESTERN CARIBBEAN SEPARATES TWO
RIDGES...WITH ONE OVER MEXICO/WESTERN PORTIONS OF THE DOMAIN AND
THE OTHER OVER THE TROPICAL ATLANTIC/EASTERN CARIBBEAN. THIS
PATTERN IS TO HOLD THROUGH THE MEDIUM RANGE PERIOD.

THE WESTERNMOST RIDGE IS TO DOMINATE THE MID/UPPER LEVEL FLOW
ACROSS THE CENTRAL/SOUTHERN STATES OF MEXICO AND NORTHERN CENTRAL
AMERICA. AT 500 HPA THE RIDGE IS TO ANCHOR ON A CLOSED HIGH TO THE
SOUTH-SOUTHWEST OF COLIMA/MICHOACAN IN SOUTHWEST MEXICO.
PERSISTENT MID/UPPER LEVEL RIDGE PATTERN IS TO INHIBIT ORGANIZED
DEEP CONVECTION ACROSS MOST OF MEXICO. ACTIVITY...IF ANY...IS TO
CONFINE TO THE SIERRA MADRE ORIENTAL...WHERE DIURNAL CONVECTION IS
TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.
ACROSS SOUTHERN HONDURAS-NORTHERN EL SALVADOR AND CENTRAL PORTIONS
OF GUATEMALA DIURNAL CONVECTION IS TO ALSO FAVOR RAINFALL AMOUNTS
OF 00-05MM/DAY AND MAXIMA OF 10MM. OTHER CONVECTION IS TO AFFECT
NORTHEAST HONDURAS AND NICARAGUA WITH ACCUMULATION OF 05-10MM/DAY
AND MAXIMA OF 15-20MM IN SCATTERED CONVECTION. THIS DECREASES TO
00-05MM/DAY AND MAXIMA OF 10MM LATER ON WEDNESDAY.

A MID/UPPER LEVEL TROUGH TO THE EAST EXTENDS SOUTH ACROSS THE
EASTERN GULF OF MEXICO/WESTERN CUBA-NORTHWEST CARIBBEAN TO
SOUTHERN CENTRAL AMERICA. AT 500 HPA THE TROUGH IS TO INITIALLY
ANCHOR ON A CLOSED LOW NEAR HAVANA CUBA. THROUGH TUESDAY EVENING
THE TROUGH WILL LIFT TO THE NORTH-NORTHEAST INTO THE NORTHWEST
BAHAMAS...TO CONTINUE FARTHER NORTH ALONG THE EAST COAST OF
FLORIDA TO SOUTH GEORGIA LATER ON WEDNESDAY/EARLY THURSDAY
MORNING. BEST INFLOW OF SHORT WAVE ENERGY ACROSS CUBA IS EXPECTED
ON DAY 01...WHILE OVER THE BAHAMAS IT IS EXPECTED ON DAY 02. AT
250 HPA COUPLED JETS ARE TO FAVOR BROAD AREA OF DIVERGENCE ALOFT
ACROSS THE NORTHWEST CARIBBEAN/CUBA THROUGH TUESDAY MORNING...AND
THE BAHAMAS DURING THE MIDDAY HOURS ON TUESDAY. AT LOW LEVELS THE
DEEP TROUGH PATTERN ALOFT IS TO INDUCE A FRONTAL WAVE ALONG AN OLD
BAROCLINIC BOUNDARY OVER THE BAHAMAS....WITH LOW TO FORM OVER THE
NORTHWEST BAHAMAS DURING THE AFTERNOON HOURS ON TUESDAY. THROUGH
WEDNESDAY EVENING THE LOW IS TO DEEPEN WHILE LIFTING TO THE
NORTH-NORTHWEST. ACROSS  CUBA THIS IS TO FAVOR RAINFALL AMOUNTS OF
35-70MM/DAY AND MAXIMA OF 150-200MM IN RISK OF ECHO TRAINING
THROUGH TUESDAY MORNING. ON TUESDAY TO WEDNESDAY IT DECREASES TO
10-15MM/DAY WITH MAXIMA OF 20-40MM...WITH SCATTERED DIURNAL
CONVECTION ON WEDNESDAY TO THEN FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM. ACROSS THE CENTRAL-NORTHWEST
BAHAMAS THIS IS TO INITIALLY FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY
AND MAXIMA OF 25-50MM. THIS INCREASES TO 15-30MM/DAY AND MAXIMA OF
40-80MM ON TUESDAY TO WEDNESDAY.

DEEP TROUGH PATTERN ALOFT IS TO ALSO TRIGGER CONVECTION ACROSS THE
CAYMAN ISLANDS EARLY IN THE CYCLE...TO FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-30MM. THROUGH WEDNESDAY THIS
DECREASES TO 00-05MM/DAY AND MAXIMA OF 10MM. ACROSS JAMAICA
CONDITIONS BECOME MORE FAVORABLE AND CONDUCIVE TO DEEP CONVECTION
ON TUESDAY TO WEDNESDAY...WHEN WE EXPECT RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM. OTHER CONVECTION TO THE SOUTH IS
EXPECTED ACROSS PANAMA-COSTA RICA TO SOUTHERN NICARAGUA...WHERE
LONG WAVE TROUGH PATTERN IS TO FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-30MM THROUGH TUESDAY MORNING...AND
05-10MM/DAY WITH MAXIMA OF 15-20MM THEREAFTER. OTHER ENHANCEMENT
IS EXPECTED ACROSS NORTHWEST PORTIONS OF COLOMBIA...WHERE DEEP
TROUGH ALOFT IS TO VENT DIURNAL CONVECTION TO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-30MM. OVER THE CAUCA/CAUCA
VALLEY TO THE SOUTHWEST AND THE EASTERN PLAINS EXPECTING RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM.

MID/UPPER LEVEL RIDGE TO THE EAST ANCHORS ON A 500 HPA HIGH OVER
THE TROPICAL ATLANTIC...WITH AXIS WEST ACROSS THE ISLAND CHAIN TO
THE EASTERN CARIBBEAN. THIS FAVORS A BROAD AREA OF
SUBSIDENCE...CAPPING MOISTURE TO LOW LEVELS OF THE ATMOSPHERE
WHILE INHIBITING VERTICAL DEVELOPMENT. UNDER INFLUENCE OF DEEP
TROUGH PATTERN TO THE WEST HIGH LEVEL MOISTURE IS TO LIFT ALONG
THE FRINGES OF THE RIDGE INTO HISPANIOLA AND PUERTO
RICO...FAVORING A DENSE CI/CS SHIELD EARLY ON WEDNESDAY-THURSDAY
THAT IS TO DISRUPT THE DIURNAL HEAT CYCLE. ANY CONVECTION OVER
THESE ISLANDS IS EXPECTED OVER THE NEXT TWO DAYS...WITH LIGHT
RAINFALL AMOUNTS IN BRIEF/PASSING TRADE WIND SHOWERS. ALONG THE
ISLAND CHAIN DRY AND FAIR CONDITIONS ARE TO GENERALLY PREVAIL OVER
THE NEXT FEW DAYS. BROAD LOW LEVEL RIDGE OVER THE TROPICAL
ATLANTIC SUSTAINS A TIGHT GRADIENT...WITH A TRADE WIND SURGE NOTED
TO THE SOUTH OF 15N. A DENSE SAL EVENT ACCOMPANIES THE SURGING
EASTERLY TRADES. THIS IS TO REACH THE ISLAND CHAIN EARLY ON
WEDNESDAY MORNING AND THEN RAPIDLY SPREAD INTO THE EASTERN
CARIBBEAN. THIS IS TO HELP SUSTAIN THE DRY AND DUSTY CONDITIONS
AFFECTING THE EASTERN CARIBBEAN ISLES.

MID/LOW LEVEL RIDGE PATTERN IS TO ALSO INFLUENCE WEATHER
CONDITIONS ACROSS THE NORTHERN GUIANAS TO EASTERN/CENTRAL
VENEZUELA. THESE ARE TO REMAIN ON THE CONVERGENT SIDE OF THE
RIDGE...WHICH IS TO CONTINUE INHIBITING ORGANIZED CONVECTION. MOST
ACTIVE IS EXPECTED TO THE SOUTH OF 03N INTO EQUATORIAL SOUTH
AMERICA...WHERE WE EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM IN SCATTERED CONVECTION. LOCALLY HIGHER AMOUNTS
ARE EXPECTED OVER SOUTHERN GUYANA ON TUESDAY.

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

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





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