634  
FXCA20 KWBC 111902  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
302 PM EDT WED OCT 11 2017  
 
TROPICAL DISCUSSION FROM OCT 11/12 UTC: UPPER TROUGH IN THE  
CENTRAL UNITED STATES IS SUSTAINING A SURFACE COLD FRONT. THE TAIL  
OF THE FRONT IS WEAKENING ACROSS EXTREME NORTHEASTERN MEXICO.  
HOWEVER...A PRECIPITABLE WATER POOL OF OVER 50MM REMAINS IN  
PLACE...AND EAST-NORTHEASTERLY TRADES WILL CONTINUE INTERACTING  
WITH THE SIERRA MADRE ORIENTAL TO PRODUCE ENHANCED MOISTURE  
CONVERGENCE AND LOCALLY HEAVY RAIN. THROUGH EARLY  
THURSDAY...EXPECTING AMOUNTS OF 20-40MM/DAY AND MAXIMA OF 50-100MM  
IN HIDALGO/NORTHERN VERACRUZ AND NORTHERN PUEBLA. IN  
TAMAULIPAS...EXPECTING COASTAL MAXIMA OF 15-25MM. BY  
THURSDAY-FRIDAY...EXPECTING LARGEST ACCUMULATIONS IN  
VERACRUZ...WHERE TRADE WIND CONVERGENCE WILL LEAD TO 20-40MM/DAY  
AND MAXIMA OF 50-100MM. NORTH ACROSS NORTHERN VERACRUZ INTO  
TAMAULIPAS EXPECTING 10-15MM/DAY AND MAXIMA OF 20-30MM. AMOUNTS  
WILL DECREASE RAPIDLY AFTER. ALSO IN MEXICO...DIURNAL CONVECTION  
ALONG THE SIERRA MADRE OCCIDENTAL AND SIERRA MADRE DEL SUR WILL  
LEAD TO 05-10MM/DAY AND MAXIMA OF 15-25MM. BY  
FRIDAY-SATURDAY...THIS WILL DECREASE TO 05-10MM/DAY AND MAXIMA OF  
15MM TO THE SOUTH OF NAYARIT/JALISCO...AND TO MAXIMA OF 10MM TO  
THE NORTH INTO SONORA.  
 
A TUTT IS RETROGRESSING TO THE SOUTH OF OAXACA-MEXICO ON  
WEDNESDAY...AND IS FORECAST TO MEANDER NEAR THE SOUTH OF  
MICHOACAN/COLIMA ON THURSDAY...TO THEN WEAKEN OFF THE COASTS OF  
JALISCO. THIS TUTT WILL LIMIT ITS EFFECTS ON THE CONVECTION IN  
NORTHERN CENTRAL AMERICA. STILL...INSTABILITY REMAINS IN PLACE TO  
SUSTAIN LOCALLY MODERATE RAINFALL AMOUNTS GRADUALLY DECREASING  
THROUGH THE CYCLE. THROUGH EARLY FRIDAY...EXPECTING ACCUMULATIONS  
OF 10-15MM/DAY AND MAXIMA 20-30MM. THIS IS TO DECREASE TO  
05-10MM/DAY AND MAXIMA OF 15-20MM ON FRIDAY-EARLY SATURDAY. A  
SLIGHT INCREASE IS EXPECTED ON SUNDAY/MONDAY AS A TROPICAL WAVE  
APPROACHES.  
 
ANOTHER REGION OF INTEREST IS THE NORTHERN CARIBBEAN AND THE  
BAHAMAS...AS A STRONG UPPER LOW RETROGRESSES AND INTERACTS WITH A  
TROPICAL WAVE TO ITS SOUTHEAST. BOTH UPPER LOW AND TROPICAL WAVE  
ARE FORECAST TO RETROGRESS IN PHASE THROUGH FRIDAY...YET TO THE  
NORTH OF JAMAICA...ACTIVITY WILL BE MOSTLY ORGANIZED WITH THE  
UPPER LOW...WHILE TO THE SOUTH...CONVECTION WILL GENERALLY FOLLOW  
THE TROPICAL WAVE. THROUGH EARLY THURSDAY...EXPECTING LARGEST  
AMOUNTS IN THE CENTRAL AND NORTHERN BAHAMAS...AND IN NORTH-CENTRAL  
CUBA. HERE...ENHANCED INSTABILITY NEAR THE CENTER OF THE TROUGH  
WILL CONTINUE ENHANCING CONVECTION TO PRODUCE DAILY AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-40MM. ALSO...INTERACTION BETWEEN THE  
APPROACHING TROPICAL WAVE AND VENTILATION IN THE PERIPHERY OF THE  
UPPER TROUGH...WILL ENHANCE ACCUMULATIONS IN JAMAICA TO PRODUCE  
10-15MM/DAY AND ISOLATED MAXIMA OF 20-30MM. IN HISPANIOLA AND  
PUERTO RICO...ENHANCED INSTABILITY WILL LEAD TO 10-15MM/DAY AND  
MAXIMA OF 20-30MM. ISOLATED HIGHER AMOUNTS ARE EXPECTED IN THE  
VIRGIN ISLANDS. BY THURSDAY-FRIDAY...LARGEST AMOUNTS ARE EXPECTED  
IN THE EXTREME NORTHWESTERN BAHAMAS AND IN WESTERN CUBA...WHERE  
EXPECTING 15-20MM/DAY AND MAXIMA OF 25-50MM. A DECREASE IS  
EXPECTED IN JAMAICA AND IN HISPANIOLA AND PUERTO RICO. BY  
FRIDAY-SATURDAY...LARGEST ACCUMULATIONS WILL CLUSTER ACROSS THE  
EXTREME NORTHWESTERN BAHAMAS AND WESTERN CUBA...WHERE EXPECTING  
10-15MM/DAY AND MAXIMA OF 20-30MM. IN JAMAICA...ACTIVITY WILL  
BECOME ENHANCED AGAIN BY THE TRAILING MOIST PLUME BEHIND THE  
TROPICAL WAVE. THIS WILL LEAD TO 10-15MM/DAY AND MAXIMA OF  
20-30MM. IN HISPANIOLA AND SOUTHEASTERN CUBA...DIURNAL CONVECTION  
WILL LEAD TO 05-10MM/DAY AND ISOLATED MAXIMA OF 15-25MM.  
 
IN NORTHERN SOUTH AMERICA...CONVECTION IS ACTIVATING IN THE AMAZON  
BASIN. FURTHERMORE...THE ITCZ IS STARTING TO MEANDER GRADUALLY TO  
THE SOUTH. THIS WILL LEAD TO A TRANSIENT INCREASE IN ACCUMULATIONS  
IN THE GUIANAS. THROUGH EARLY THURSDAY...EXPECTING 05-10MM/DAY AND  
MAXIMA OF 15-20MM. AS A TROPICAL WAVE APPROACHES EXPECTING FURTHER  
ENHANCEMENT ON THURSDAY...WHEN EXPECTING ACCUMULATIONS OF  
10-15MM/DAY AND MAXIMA OF 20-35MM. BY FRIDAY-SATURDAY EXPECTING  
SIMILAR AMOUNTS. IN THE AMAZON BASIN...EXPECTING SCATTERED DIURNAL  
CONVECTION ON A DAILY BASIS...WITH AMOUNTS INCREASING FROM  
05-10MM/DAY AND MAXIMA OF 15-25MM ON WEDNESDAY-THURSDAY...TO  
10-15MM/DAY AND MAXIMA OF 20-35MM AFTER. IN NORTHERN  
COLOMBIA...DIURNAL CONVECTION WILL LEAD TO 10-15MM/DAY AND MAXIMA  
OF 20-30MM THROUGH EARLY FRIDAY. AS THE TROPICAL WAVE EXITS INTO  
CENTRAL AMERICA...BY FRIDAY-SATURDAY EXPECTING 10-15MM/DAY AND  
MAXIMA OF 20-35MM CLUSTERING IN EXTREME WESTERN COLOMBIA AND MOST  
OF PANAMA/SOUTHERN COSTA RICA. EXPECTING A DECREASE TO THE EAST  
ACROSS CENTRAL COLOMBIA.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
47W 50W 53W 55W 58W 60W 63W 65W TW 16N  
71W 74W 76W 79W 81W 83W 85W 87W TW 16N  
 
A TROPICAL WAVE INITIALIZED AT 41W ARRIVES IN THE BASIN DURING  
LATE THURSDAY-FRIDAY...TO ENHANCE CONVECTION IN WESTERN SURINAME  
AND GUYANA...PRODUCING MAXIMA OF 20-30MM/DAY. ON  
FRIDAY-SATURDAY...EXPECTING SIMILAR AMOUNTS IN GUYANA AND  
NORTHEASTERN VENEZUELA.  
 
A TROPICAL WAVE...INITIALIZED AT 71W IS ILL-DEFINED...BUT  
PROPAGATING ACROSS HISPANIOLA AND COLOMBIA...WHERE EXPECTING  
10-15MM/DAY AND MAXIMA OF 20-30MM. SIMILAR AMOUNTS ARE EXPECTED IN  
JAMAICA. BY THURSDAY-FRIDAY...THE WAVE WILL LEAD TO MAXIMA OF  
15-20MM/DAY IN PANAMA AND JAMAICA. TRAILING MOISTURE PLUME BEHIND  
THE WAVE WILL ENHANCE ACCUMULATIONS IN JAMAICA ON FRIDAY...TO  
PRODUCE 10-15MM/DAY AND MAXIMA OF 20-30MM. AS IT CROSSES PANAMA  
AND COSTA RICA ON FRIDAY...EXPECTING AN INCREASE TO 10-15MM/DAY  
AND MAXIMA OF 20-35MM IN THESE REGIONS.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
GALVEZ...WPC (USA)  

 
 
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