208  
FXCA20 KWBC 291915  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
215 PM EST WED NOV 29 2017  
 
TROPICAL DISCUSSION FROM NOV 29/12 UTC: WEST OVER THE DOMAIN...AT  
500 HPA...A SHORT WAVE RIDGE EXTENDS ACROSS CENTRAL/NORTHERN  
MEXICO WHILE CENTERING ON A CLOSED HIGH NEAR 23N 103W. THROUGH  
FRIDAY EVENING THE RIDGE IS TO AMPLIFY ACROSS THE SOUTHERN STATES  
OF MEXICO TO ENVELOP MOST OF CENTRAL AMERICA/WESTERN CARIBBEAN.  
ALSO AT MID LEVELS...A SHORT WAVE TROUGH TO THE EAST EXTENDS OVER  
THE EASTERN GULF OF MEXICO TO THE YUCATAN. AS THE RIDGE BUILDS TO  
THE WEST THIS IS TO DISPLACE THE TROUGH ACROSS THE YUCATAN TO THE  
WESTERN CARIBBEAN/WESTERN CUBA EARLY ON FRIDAY MORNING. THIS IS TO  
WEAKEN/NEARLY FILL LATER IN THE DAY. AT LOW LEVELS...THE RIDGE  
OVER MEXICO SUSTAINS A LOW LEVEL RIDGE ACROSS THE GULF OF MEXICO.  
THIS FAVORS A NORTHEASTERLY FLOW ACROSS CUBA TO THE WESTERN  
CARIBBEAN. A WANING TROUGH OVER THE WESTERN CARIBBEAN EMBEDS IN  
THIS FLOW. THE PREVAILING NORTHEASTERLY WINDS WILL DRIVE THIS  
FEATURE TO THE SOUTHWEST TO BELIZE-HONDURAS LATER TODAY. THE MID  
LEVEL PERTURBATION OVER THE YUCATAN IS TO INTERACT WITH THE LOW  
LEVEL TROUGH TO ENHANCE CONVECTIVE DEVELOPMENT ACROSS ISLAS DE LA  
BAHIA-NORTHERN HONDURAS AND BELIZE. IN THIS AREA EXPECTING  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 35MM. ON  
FRIDAY-SATURDAY...MOST ACTIVE IS EXPECTED OVER SOUTHERN  
BELIZE-NORTHWEST HONDURAS WITH ACCUMULATION OF 10-15MM/DAY AND  
MAXIMA OF 20-40MM. OVER NORTHEAST HONDURAS/NICARAGUA IT DECREASES  
TO 00-05MM/DAY AND MAXIMA OF 10MM.  
 
THE MID/UPPER LEVEL RIDGE TO THE WEST IS TO ALSO STEER ANOTHER  
SHORT WAVE TROUGH ACROSS FLORIDA TO THE BAHAMAS EARLY IN THE  
CYCLE. ON THURSDAY THIS IS TO MEANDER EAST ACROSS 70W TO NORTHERN  
HISPANIOLA...AND ON FRIDAY IT IS TO PULL ACROSS 60W WHILE TRAILING  
TO PUERTO RICO/VIRGIN ISLES. AS THE MID LEVEL PERTURBATION  
MEANDERS OVER THE WESTERN ATLANTIC IT IS TO INTERACT WITH A  
MEANDERING SURFACE FRONT NORTH OF THE GREATER ANTILLES AND ACROSS  
THE BAHAMAS. LATER TODAY/EARLY THURSDAY MORNING THIS WILL INDUCE A  
FRONTAL LOW TO THE EAST-NORTHEAST OF GRAND BAHAMA. THE LOW IS TO  
SLOWLY DEEPEN AS IT MEANDERS EAST ALONG 25N/26N...NEARING 65W/66W  
LATER ON THURSDAY. THE DEEPENING LOW IS TO THEN DRIVE THE SURFACE  
FRONT SOUTH ACROSS THE CENTRAL BAHAMAS TO WESTERN CUBA LATER ON  
THURSDAY. LATER ON SATURDAY THE FRONT IS TO MEANDER SOUTH JUST  
NORTH OF PUERTO RICO-HISPANIOLA WHILE TRAILING ACROSS THE TURKS  
AND CAICOS TO CUBA. THE DEEPENING LOW IS TO ALSO FAVOR A  
PREFRONTAL SHEAR LINE ACROSS HAITI TO THE CENTRAL CARIBBEAN LATER  
ON THURSDAY. ON FRIDAY IT MOVES ACROSS THE DOMINICAN REPUBLIC TO  
PUERTO RICO...WHILE ON SATURDAY IT IS TO EXTEND ACROSS THE  
NORTHERN LEEWARD ISLANDS. OVER THE NORTHWEST-CENTRAL BAHAMAS AND  
WESTERN CUBA THE MID LEVEL TROUGH/MEANDERING FRONT IS TO TRIGGER  
ISOLATED TO SCATTERED CONVECTION WITH RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15MM. ON THURSDAY...AS A COOL ADVECTIVE  
PATTERN ESTABLISHES ACROSS THE BAHAMAS IT IS TO THEN FAVOR  
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. OVER CUBA  
EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15MM. ON  
FRIDAY-SATURDAY IT DECREASES TO 00-05MM/DAY AND MAXIMA OF 10MM. AS  
THE SHEAR LINE MOVES ACROSS HISPANIOLA ON THURSDAY TO FRIDAY IT  
WILL SUSTAIN RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.  
ACROSS PUERTO RICO-VIRGIN ISLES IT WILL TRIGGER RAINFALL AMOUNTS  
OF 05-10MM/DAY AND MAXIMA OF 15MM ON FRIDAY-SATURDAY. ON THE  
LEEWARD ISLANDS ALSO EXPECTING ACCUMULATION OF 05-10MM/DAY AND  
MAXIMA OF 15MM ON SATURDAY.  
 
FARTHER EAST...AT MID LEVELS...A WANING CELL OF THE SUBEQUATORIAL  
RIDGE EXTENDS OVER THE EASTERN CARIBBEAN/LESSER ANTILLES. UNDER  
PRESSURE FROM THE SHORT WAVE TROUGH STREAMING ACROSS THE WESTERN  
ATLANTIC THE RIDGE IS EXPECTED TO WEAKEN. ALTHOUGH IT  
WEAKENS...OVER PUERTO RICO-HISPANIOLA AND THE VIRGIN ISLES A TRADE  
WINDS CAP IS TO PERSISTS DURING THE NEXT FEW DAYS...WHILE OVER THE  
WINDWARD/FRENCH ISLES IT RELAXES ITS FOOTHOLD BY MIDDAY ON  
THURSDAY. AT LOW LEVELS...A DEEP LAYER EASTERLY FLOW DOMINATES THE  
EASTERN-CENTRAL CARIBBEAN. AS THE FRONTAL LOW DEEPENS TO THE NORTH  
OF THE ISLANDS ON THURSDAY-FRIDAY...IT IS TO INDUCE AN INVERTED  
TROUGH ACROSS THE EASTERN CARIBBEAN...TO EXTEND SOUTH TO NORTH  
BETWEEN CENTRAL VENEZUELA AND PUERTO RICO. IN RESPONSE TO THIS  
FEATURE...THE LOW LEVEL WINDS OVER THE EASTERN CARIBBEAN ARE TO  
VEER TO THE SOUTHEAST. THIS WILL THEN DRAW A PLUME OF TROPICAL  
MOISTURE NORTH ACROSS THE WINDWARD ISLES TO THE EASTERN CARIBBEAN.  
THIS IS TO ADVECT NORTH TO PUERTO RICO-SAINT CROIX LATER DURING  
THE WEEKEND. MEANWHILE... ACROSS TRINIDAD-TOBAGO AND NORTHEAST  
VENEZUELA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF  
20-40MM. ON THURSDAY AFTERNOON SHALLOW CONVECTION WILL SPREAD  
NORTH ACROSS BARBADOS AND THE WINDWARD/FRENCH ISLANDS...TO SUSTAIN  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS  
JAMAICA...MEANWHILE... EXPECTING RAINFALL AMOUNTS OF 00-05MM/DAY  
AND MAXIMA OF 10MM.  
 
OVER PANAMA-COSTA RICA...BRISK NORTHEASTERLY TRADES ARE TO ENHANCE  
LOW LEVEL MOISTURE CONVERGENCE ALONG THE ITCZ...TO SUSTAIN  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM. ON  
THURSDAY-FRIDAY IT DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-20MM.  
OVER COLOMBIA...AN ILL ORGANIZED CELL OF THE PANAMANIAN LOW/TROUGH  
FAVORS A MOIST WESTERLY FLOW THAT IS CONVERGING ALONG THE WESTERN  
PLAINS. IN THIS AREA EXPECTING SCATTERED DEEP CONVECTION TO  
TRIGGER RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM.  
THROUGH SATURDAY THIS DECREASES 10-15MM/DAY AND MAXIMA OF 20-30MM.  
ON THE ANDEAN REGION-EASTERN PLAINS OF COLOMBIA DIURNAL CONVECTION  
IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.  
OVER VENEZUELA MOST ACTIVE IS EXPECTED ACROSS AMAZONIA TO THE  
SOUTH. IN THIS AREA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND  
MAXIMA OF 15MM.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE  
SOF  
58W 61W 63W 65W 67W 69W 72W 74W TUTT-INDCD  
13N  
72W 73W 74W DISSIPATES TUTT-INDCD  
28N  
 
A TUTT INDUCED EASTERLY WAVE IS INITIALIZED ALONG 58W AND TO THE  
SOUTH OF 13N. THIS IS BECOMING NEGATIVELY TILTED...WITH MOST  
ACTIVE CONVECTION FORMING TO THE WEST OF THE WAVE AXIS. THIS IS TO  
AFFECT TRINIDAD/TOBAGO-ORINOCO DELTA REGION EARLY IN THE  
CYCLE...TO SUSTAIN RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF  
25-50MM. ACROSS NORTHEAST VENEZUELA THIS IS TO FAVOR ADDITIONAL  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM ON  
THURSDAY...WHILE ACROSS AMAZONIA TO THE SOUTH INTO EASTERN  
COLOMBIA IT IS TO TRIGGER RAINFALL AMOUNTS OF 05-10MM/DAY AND  
MAXIMA OF 15-20MM.  
 
A WANING EASTERLY WAVE ALONG 72W AND SOUTH OF 28N IS TO SUSTAIN  
SCATTERED CONVECTION ACROSS THE TURKS AND CAISOS/SOUTHEAST  
BAHAMAS-EASTERN CUBA EARLY IN THE CYCLE...WITH RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-20MM. WAVE IS TO DISSIPATE LATER ON  
THURSDAY.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page