659  
FXCA20 KWBC 081931  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
231 PM EST THU FEB 08 2018  
 
TROPICAL DISCUSSION FROM FEB 08/12 UTC: THE PERSISTENCE OF A  
MID-LEVEL RIDGE ACROSS CUBA AND THE BAHAMAS WILL LIMIT RAINFALL  
ACCUMULATIONS THROUGH THE CYCLE. THE RIDGE IS FORECAST TO  
INITIALLY CENTER OVER THE NORTHWESTERN BAHAMAS...TO MEANDER TO 28N  
70W BY SUNDAY. A SURFACE FRONT IS LOCATED WELL TO THE NORTH ACROSS  
CENTRAL FLORIDA AND THE CENTRAL GULF OF MEXICO...YET...THE FRONT  
HAS BECOME STATIONARY AND WILL SHORTLY START RETREATING NORTH  
WHILE WEAKENING. A WEAK SHEAR LINE IS TRYING TO ORGANIZE ACROSS  
THE NORTHWESTERN BAHAMAS ON THURSDAY...YET ANY ACTIVITY WILL BE  
LIMITED TO ISOLATED AND VERY LIGHT TRADE WIND SHOWERS.  
 
IN MEXICO...AN UPPER TROUGH WILL PROPAGATE FROM THE BAJA  
CALIFORNIA REGION ON THURSDAY...TO THE NORTHWEST WHILE BECOMING  
ABSORBED BY A LARGER TROUGH IN THE WESTERN USA. THIS WILL PROVIDE  
SUFFICIENT DESTABILIZATION IN THE MEXICAN HIGHLANDS TO SUSTAIN  
PRECIPITATION THROUGH THE CYCLE. EXPECTING 05-10MM/DAY AND MAXIMA  
OF 15-20MM/DAY ON THURSDAY-FRIDAY. AMOUNTS ARE TO DECREASE TO  
05-10MM/DAY AND MAXIMA OF 15MM ON FRIDAY-SATURDAY. BY  
SATURDAY-SUNDAY...A FURTHER DECREASE IS EXPECTED...TO SUSTAIN  
00-05MM/DAY AND ISOLATED MAXIMA OF 10MM...ESPECIALLY ALONG THE EJE  
VOLCANICO AND THE SIERRA MADRE OCCIDENTAL OF SINALOA. ALSO IN  
MEXICO...THE REMNANTS OF AN EASTERLY WAVE AND ASSOCIATED MOISTURE  
PLUME HAVE REINFORCED THE SURFACE TROUGH PATTERN IN THE GULF OF  
CAMPECHE. MOISTURE...INSTABILITY AND FORCING ARE SUFFICIENT TO  
TRIGGER A FEW HEAVY-RAIN PRODUCING THUNDERSTORMS ON THURSDAY...TO  
PRODUCE ACCUMULATIONS OF 15-20MMM/DAY AND MAXIMA OF 35-70MM. THIS  
IS TO RAPIDLY DECREASE ON FRIDAY...AS THE LOW-LEVEL WINDS BECOME  
SOUTHERLY.  
 
THE STRENGTHENING OF THE LOW-LEVEL RIDGE ACROSS THE ATLANTIC IS  
SUSTAINING A SPEEDING OF THE TRADES ACROSS THE ENTIRE CARIBBEAN.  
THE WINDS WILL REMAIN ACCELERATED THROUGH THE FORECAST CYCLE  
REACHING SPEEDS OF 20-30KT IN SEVERAL LOCATIONS. THE PRESENCE OF  
ENHANCED LOW-LEVEL SHEAR...A SUBSIDENCE CAP...AND VERY DRY MID  
LEVELS ARE LEADING TO GENERALLY FAIR CONDITIONS. HOWEVER...AN  
UPPER TROUGH IN THE ATLANTIC IS LEADING TO SOME DESTABILIZATION OF  
THE ATLANTIC BOUNDARY LAYER...AND AIDING IN THE DEVELOPMENT OF  
WEAK WAVES IN THE TRADES. THESE ARE PROPAGATING RAPIDLY  
WESTWARD...YET LEADING TO A MINOR ENHANCEMENT IN TRADE WIND  
SHOWERS (SEE BELOW). OTHER THAN THIS...ACCUMULATIONS WILL LIMIT TO  
UNDER 10MM/DAY WITH THE EXCEPTION OF THE LESSER ANTILLES...WHERE  
OROGRAPHIC ENHANCEMENT WILL LEAD TO 05-10MM/DAY AND ISOLATED  
MAXIMA OF 15MM THROUGH SATURDAY.  
 
IN NORTHWESTERN SOUTH AMERICA...CONVECTION IS OCCURRING ALONG THE  
PACIFIC BASINS OF ECUADOR AND SOUTHERN COLOMBIA...ALTHOUGH A CAP  
IS LIMITING THE DEVELOPMENT OF THUNDERSTORMS. MODELS AGREE ON AN  
INCREASE IN PRECIPITABLE WATER AND ONSHORE LOW-LEVEL WINDS FROM  
FRIDAY THROUGH SUNDAY. THIS WILL LEAD TO AN INCREASE IN  
ACCUMULATIONS FROM 05-10MM/DAY AND ISOLATED MAXIMA OF 15MM IN  
SOUTHERN COLOMBIA...GRADUALLY INCREASING TO 05-10MM/DAY AND MAXIMA  
OF 15-25MM. FAIR CONDITIONS WILL CONTINUE IN EASTERN  
COLOMBIA/ECUADOR UNDER THE INFLUENCE OF THE LOW-LEVEL JET IN THE  
LLANOS. THIS IS TO PERSIST THROUGH THE CYCLE.  
TO THE EAST...QUIET PATTERN IN THE GUIANAS IS TRANSITIONING TO A  
WETTER ONE AS A MOIST POOL ARRIVES FROM THE TROPICAL ATLANTIC.  
STRONG CONVECTION IS OCCURRING OFF THE AMAZON DELTA/AMAPA...AND A  
MOISTURE POOL OF PRECIPITABLE WATER VALUES EXCEEDING 60MM HAS  
BUILT. AS THE MOIST PLUME ENTERS THE GUIANAS GRADUALLY THROUGH THE  
CYCLE...EXPECTING A NOTICEABLE INCREASE IN PRECIPITATION. THROUGH  
EARLY FRIDAY...  
A FEW HEAVY-RAIN PRODUCING THUNDERSTORMS IN EASTERN FRENCH GUIANA  
WILL SUSTAIN SUSTAIN 20-40MM/DAY AND ISOLATED MAXIMA OF 50-100MM.  
BY FRIDAY-SATURDAY...AS MOIST PLUME CRAWLS WESTWARD...EXPECTING  
ACCUMULATIONS TO BE LIMITED BY ENHANCED LOW-LEVEL SHEAR...AND BY A  
DECREASE IN UPPER DIVERGENCE. THIS WILL SUSTAIN AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-35MM OVER FRENCH GUIANA...WHILE  
EXPECTING 05-10MM/DAY AND MAXIMA OF 15-25MM IN SURINAME. BY  
SATURDAYSUNDAY...ACTIVITY WILL CLUSTER IN FRENCH GUIANA AND  
NORTHERN GUYANA...WHERE EXPECTING SIMILAR RAINFALL AMOUNTS.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
51W 55W 58W 62W 66W 71W 75W 79W EW 22N  
58W 61W 66W 71W 76W 81W 86W 90W EW 21N  
97W 102W 105W 108W 111W EXITS EW 15N  
 
AN EASTERLY WAVE HAS FORMED IN THE ATLANTIC AND IS INITIALIZED AT  
51W. THIS WAVE WILL ENTER THE BASIN ON FRIDAY...WHERE IT WILL  
CONTINUE SUSTAINING AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM  
ACROSS THE LESSER ANTILLES. BY SATURDAY-SUNDAY...IT WILL ENHANCE  
ACTIVITY IN THE DOMINICAN REPUBLIC TO SUSTAIN ISOLATED MAXIMA OF  
15-20MM.  
 
ANOTHER EASTERLY WAVE IS INITIALIZED JUST TO THE EAST OF THE  
LEEWARD ISLANDS AT 58W. THIS WAVE WILL ENTER THE ARC OF THE  
ANTILLES LATER ON THURSDAY...TO SUSTAIN MAXIMA OF 15MM THROUGH  
EARLY FRIDAY. BY FRIDAY-SATURDAY...AS THE MOIST PLUME CROSSES  
HISPANIOLA...IT WILL SUSTAIN ISOLATE MAXIMA OF 15-25MM. BY  
SATURDAY SUNDAY...IT WILL ENHANCE THE COVERAGE OF TRADE WIND  
SHOWERS ACROSS JAMAICA...THE CAYMAN ISLANDS...AND CENTRAL  
CUBA...TO SUSTAIN MAXIMA GENERALLY UNDER 10MM/DAY.  
 
AN EASTERLY WAVE INITIALIZED AT 97W HAS EXITED INTO THE PACIFIC  
AND IS NO LONGER AFFECTING THE CONTINENT. TRAILING MOISTURE  
PLUM...HOWEVER...WILL SUSTAIN STRONG CONVECTION IN THE GULF OF  
CAMPECHE ON THURSDAY TO SUSTAIN MAXIMA OF 35-70MM...AND MUCH  
WEAKER CONVECTION IN CENTRAL GUATEMALA/SOUTHERN BELIZE...WHERE  
EXPECTING MAXIMA OF 15MM.  
 
GORDON...NMS (BELIZE)  
NIXON...BDM (THE BAHAMAS)  
GALVEZ...WPC (USA)  
 

 
 
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