Prognostic Meteorological Discussion
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FXCA20 KWBC 051821
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
221 PM EDT TUE MAY 05 2015

DISCUSSION FROM MAY 05/12 UTC: MID UPPER LEVEL TROUGH OVER THE
EASTERN GULF/CENTRAL CARIBBEAN SPLITS THE SUBTROPICAL RIDGE IN TWO
CELLS...WITH ONE OVER MEXICO AND THE OTHER OVER THE TROPICAL
ATLANTIC/EASTERN CARIBBEAN. THIS PATTERN IS FORECAST TO HOLD
THROUGH THE MEDIUM RANGE PERIOD.

RIDGE TO THE WEST ANCHORS ON A CLOSED HIGH TO THE SOUTH-SOUTHWEST
OF COLIMA/MICHOACAN MEXICO. THE ASSOCIATED RIDGE IS TO ENVELOP THE
CENTRAL/SOUTHERN STATES OF MEXICO-THE YUCATAN PENINSULA AND
PORTIONS OF GUATEMALA. THE PERSISTENT MID/UPPER LEVEL RIDGE
PATTERN IS TO INHIBIT ORGANIZED DEEP CONVECTION ACROSS MOST OF
MEXICO. ISOLATED DEEP CONVECTION...HOWEVER...IS TO GENERALLY LIMIT
TO CENTRAL MEXICO...TO AFFECT MEXICO-MEXICO DF/PUEBLA AND PORTIONS
OF VERACRUZ. IN THIS AREA DIURNAL CONVECTION IS TO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND ISOLATED MAXIMA OF 15-20MM. OTHER
CONVECTION IS TO AFFECT NORTHEAST HONDURAS AND NICARAGUA WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15MM IN SCATTERED
CONVECTION. THIS DECREASES TO 00-05MM/DAY AND MAXIMA OF 10MM LATER
ON WEDNESDAY THROUGH THURSDAY.

THE MID/UPPER LEVEL TROUGH TO THE EAST EXTENDS SOUTH ACROSS THE
EASTERN GULF OF MEXICO/WESTERN CUBA-NORTHWEST CARIBBEAN TO
SOUTHERN CENTRAL AMERICA. A STRONG CYCLONIC MAXIMA EMBEDS IN THIS
AXIS...TO LIFT FROM SOUTH FLORIDA EARLY IN THE CYCLE TO OFF THE
SOUTHEAST COAST LATER ON WEDNESDAY/EARLY THURSDAY MORNING. AT LOW
LEVELS THIS SUSTAINS AN INVERTED TROUGH ACROSS CENTRAL/WESTERN
CUBA TO THE NORTHWEST BAHAMAS. THROUGH THIS EVENING MODELS
CONSISTENTLY SHOW A LOW FORMING ALONG THIS AXIS OVER THE NORTHEAST
BAHAMAS. THIS IS TO THEN RELOCATED NORTH OF THE ISLANDS LATER ON
WEDNESDAY. AS IT LIFTS...THE MID LEVEL VORTEX IS TO INITIALLY
FOCUS SHORT WAVE ENERGY ACROSS CENTRAL PORTIONS OF CUBA...WHERE IT
IS TO ENHANCE DIURNAL CONVECTION TO RESULT IN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 30-60MM. THIS THEN DECREASES TO
10-15MM/DAY AND MAXIMA OF 20-45MM ON WEDNESDAY...WHILE ON THURSDAY
MAXIMA PEAKS AT 15-20MM. OVER THE CENTRAL-NORTHWEST BAHAMAS THE
TROUGH ALOFT AND SURFACE LOW ARE TO FAVOR ORGANIZED DEEP
CONVECTION WITH RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA OF
50-100MM WITH RISK OF ECHO TRAINING THROUGH THIS EVENING...AND
05-10MM/DAY AND MAXIMA OF 15-20MM ON WEDNESDAY TO THURSDAY.  OVER
THE SOUTHEAST BAHAMAS/TURKS IT IS TO SUSTAIN ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-30MM THROUGH WEDNESDAY MORNING.

AS THE MID/UPPER LEVEL TROUGH MEANDERS OVER THE CARIBBEAN...IT IS
TO FAVOR SCATTERED CONVECTION OVER THE CAYMAN ISLES EARLY IN THE
CYCLE...WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-30MM/DAY
THROUGH WEDNESDAY MORNING. THIS DECREASES TO 05-10MM DAY AND
MAXIMA OF 15-20MM ON WEDNESDAY TO THURSDAY MORNING. AS IT MEANDERS
OVER THE SOUTHERN CARIBBEAN...THE TROUGH ALOFT IS TO ENHANCE
DIURNAL CONVECTION ACROSS PANAMA-COSTA RICA TO SOUTHERN
NICARAGUA...WHERE LONG WAVE TROUGH PATTERN IS TO FAVOR RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. A SLIGHT DECREASE IS
POSSIBLE ON THURSDAY. THE TROUGH ALOFT IS TO ALSO ENHANCE
CONVECTION OVER 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/DAY. OVER THE CAUCA/CAUCA VALLEY
TO THE SOUTHWEST AND THE EASTERN PLAINS EXPECTING RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15MM. ACROSS THE EASTERN PLAINS THIS
INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-35MM LATER ON THURSDAY.

THE MID/UPPER LEVEL RIDGE TO THE EAST ANCHORS AT 500 HPA ON A
CLOSED HIGH OVER THE TROPICAL ATLANTIC NEAR 20N 57W...WITH AXIS
WEST ACROSS THE ISLAND CHAIN TO THE EASTERN CARIBBEAN. THIS FAVORS
A BROAD AREA OF SUBSIDENCE... WITH SHALLOW MOISTURE CONFINING TO
ATMOSPHERE BELOW 800/850 HPA. 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 LATER ON WEDNESDAY-FRIDAY. THIS IS TO DELAY
ONSET OF SEA BREEZE CONVERGENCE...AND IS LIKELY TO REDUCE CHANCES
OF MEASURABLE RAINFALL AMOUNTS. BROAD LOW LEVEL RIDGE OVER THE
TROPICAL ATLANTIC SUSTAINS A TIGHT GRADIENT...WITH A TRADE WIND
SURGE NOTED TO THE SOUTH OF 15N AND ACROSS 55W/56W. 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...WITH
GENERALLY FAIR CONDITIONS FORECAST TO PREVAIL ACROSS THE ISLAND
CHAIN.

MID/LOW LEVEL RIDGE PATTERN IS TO CONTINUE INFLUENCING 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 ON THE EASTERN PORTIONS OF FRENCH GUIANA AND TO
THE SOUTH OF 03N INTO EQUATORIAL SOUTH AMERICA...WITH RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM IN SCATTERED
CONVECTION. THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-25MM ON
WEDNESDAY TO THURSDAY EVENING.

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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