589  
FXCA20 KWBC 071923  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
222 PM EST WED FEB 07 2018  
 
TROPICAL DISCUSSION FROM FEB 07/12 UTC: AT MID-LEVELS...A ROBUST  
RIDGE CENTERS OVER ANDROS ISLAND/FLORIDA STRAITS AND COVERS MOST  
OF THE GULF OF MEXICO...THE NORTHWESTERN CARIBBEAN AND  
CUBA...JAMAICA AND HISPANIOLA. THE RIDGE WILL MEANDER TO THE  
NORTHEAST AS THE CYCLE PROGRESSES...WHICH WILL SUSTAIN GENERALLY  
FAIR WEATHER CONDITIONS ACROSS THE REGION THROUGH THE CYCLE.  
ALTHOUGH A WEAK SHEAR LINE WILL TRY TO ORGANIZE ON THURSDAY ACROSS  
THE NORTHWESTERN BAHAMAS...ANY ACTIVITY WILL BE LIMITED TO  
ISOLATED AND LIGHT TRADE WIND SHOWERS.  
 
A FRONT IS ARRIVING INTO THE NORTHWESTERN GULF OF MEXICO...AND BY  
WEDNESDAY EVENING IT WILL EXTEND ACROSS THE NORTHEASTERN GULF OF  
MEXICO INTO SOUTHERN TAMAULIPAS. BY THURSDAY EVENING...THE  
BOUNDARY WILL EXTEND ACROSS CENTRAL FLORIDA...INTO THE CENTRAL  
GULF OF MEXICO...WHERE THE GRADIENT WILL START TO WEAKEN.  
PRECIPITATION WITH THIS SYSTEM WILL CLUSTER IN NORTHEASTERN  
MEXICO. INITIALLY...ENHANCEMENT WILL BE PROVIDED BY AN UPPER  
TROUGH APPROACHING FROM THE WEST...AND BY AN UPPER JET LOCATED TO  
THE NORTH WITH ITS ENTRANCE ON CENTRAL TEXAS. THIS WILL FAVOR  
ACCUMULATIONS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ISOLATED  
HIGHER AMOUNTS ARE EXPECTED NORTHERN VERACRUZ/NORTHERN PUEBLA IN  
ASSOCIATION WITH OROGRAPHIC ENHANCEMENT. THIS WILL LEAD TO  
15-20MM/DAY AND MAXIMA OF 25-50MM.  
 
ALSO IN MEXICO...CONVECTION WILL BE ENHANCED IN THE CENTRAL  
PLATEAU/MOUNTAINS UNDER THE INFLUENCE OF THE APPROACHING UPPER  
TROUGH. THIS WILL PROVIDE SUFFICIENT DESTABILIZATION...AS WELL AS  
FAVOR SUFFICIENT MOISTURE ADVECTION TO SUSTAIN PRECIPITATION  
THROUGH SATURDAY. INITIALLY EXPECTING 00-05MM/DAY AND MAXIMA OF  
10MM INCREASING TO 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.  
 
PERIODS WITH ENHANCED CONVECTION ARE ALSO EXPECTED IN THE SOUTHERN  
GULF OF MEXICO/NORTHERN SLOPES OF NORTHERN CENTRAL AMERICA AS A  
MOIST PLUME IS TRANSPORTED INTO THE REGION BY AN EASTERLY WAVE.  
INITIALLY...AMOUNTS WILL BE LIMITED BY ENHANCED LOW-LEVEL  
SHEAR...YET...INTERACTIONS WITH THE MOUNTAIN RANGE WILL LEAD TO  
LOCALIZED ENHANCEMENT ACROSS NORTHERN HONDURAS...SOUTH-CENTRAL  
BELIZE...WHERE EXPECTING 05-10MM/DAY AND ISOLATED MAXIMA OF  
15-20MM THROUGH THURSDAY MORNING. BY THURSDAY-FRIDAY...A MOIST  
POOL OF PRECIPITABLE WATER VALUES EXCEEDING 45MM WILL BUILD IN THE  
GULF OF CAMPECHE. THIS WILL INTERACT BY ENHANCED LOW-LEVEL TROUGH  
PATTERN AND OROGRAPHIC INTERACTIONS TO SUSTAIN DEEP CONVECTION.  
EXPECTING AMOUNTS OF 15-20MM/DAY AND ISOLATED MAXIMA OF 35-70  
CLUSTERING IN THE GULF OF CAMPECHE AND AFFECTING SOUTHERN VERACRUZ  
AND TABASCO. AMOUNTS WILL DECREASE AFTER...AS THE FOCUS FOR  
STRONGEST ACTIVITY RELOCATES TO THE SOUTHERN UNITED STATES AND THE  
TRADES BECOME SOUTHERLIES.  
 
THE TRADES ARE SPEEDING IN THE CARIBBEAN...AND WILL REMAIN  
ACCELERATED THROUGH THE FORECAST CYCLE. THE ENHANCED LOW-LEVEL  
SHEAR...SUBSIDENCE CAP...AND VERY DRY MID LEVELS ARE LEADING TO  
GENERALLY FAIR CONDITIONS. THIS WILL LEAD TO MAXIMA GENERALLY  
UNDER 10MM/DAY...WITH THE EXCEPTION OF THE ARC OF THE LESSER  
ANTILLES...WHERE OROGRAPHIC FORCING WILL SUSTAIN ISOLATED MAXIMA  
OF 15MM. ALSO...THE GENERATION OF STREAMERS WILL PRODUCE LOCAL  
ENHANCEMENT. THIS WILL BE THE CASE IN PUERTO RICO AND THE EASTERN  
DOMINICAN REPUBLIC ON FRIDAY-SATURDAY...WHERE ACCUMULATIONS WILL  
BE ALSO ENHANCED BY A SHALLOW MOIST PLUME. IN THESE REGIONS  
EXPECTING 05-10MM/DAY AND ISOLATED MAXIMA OF 15-20MM. SLIGHTLY  
HIGHER AMOUNTS ARE POSSIBLE IN HISPANIOLA...WHERE OROGRAPHIC  
FORCING WILL BE LARGER. ALSO...A WEAK AND RAPIDLY PROPAGATING  
TROUGH IN THE TRADES WILL PROVIDE MINOR ENHANCEMENT OF TRADE WIND  
CONVECTION IN EASTERN HONDURAS/NICARAGUA AND EASTERN COSTA RICA ON  
FRIDAY...TO SUSTAIN 05-10MM/DAY AND MAXIMA OF 15MM.  
 
IN NORTHWESTERN SOUTH AMERICA...CONVECTION IS CLUSTERING TO  
WESTERN COLOMBIA AND ECUADOR...WHERE ENHANCEMENT IS OCCURRING BY  
WESTERLY WINDS AT LOW-LEVELS AND ITCZ CONVERGENCE. SINCE THE  
LOW-LEVEL MOISTURE CONVERGENCE IS FORECAST TO DECREASE THROUGH THE  
CYCLE...SO WILL ACCUMULATIONS. IN COLOMBIA...THE DECREASE WILL  
MOSTLY REFLECT IN A DECREASE IN THE COVERAGE OF DIURNAL  
CONVECTION. THIS WILL CHANGE FROM SCATTERED SHOWERS/ISOLATED  
THUNDERSTORMS IN MOST OF CENTRAL/WESTERN COLOMBIA ON  
WEDNESDAY...TO ISOLATED ACTIVITY CLUSTERING IN EXTREME  
SOUTHWESTERN COLOMBIA BY FRIDAY-SATURDAY. IN ECUADOR...ACTIVITY  
WILL PERSIST ON A DAILY BASIS TO PRODUCE 05-10MM/DAY AND MAXIMA OF  
15MM. VERY ISOLATED HIGHER AMOUNTS ARE POSSIBLE ALONG THE WESTERN  
SLOPES OF THE ANDES.  
 
TO THE EAST...QUIET PATTERN IN THE GUIANAS IS TRANSITIONING TO A  
WETTER ONE AS A MOIST POOL ARRIVES FROM THE TROPICAL ATLANTIC.  
THIS WILL LEAD TO A FEW HEAVY-RAIN PRODUCING THUNDERSTORMS IN  
EASTERN FRENCH GUIANA DEVELOPING ON THURSDAY TO SUSTAIN  
15-30MM/DAY AND ISOLATED MAXIMA OF 40-80MM. BY  
FRIDAY-SATURDAY...AS MOIST PLUME CRAWLS WESTWARD...EXPECTING  
ACCUMULATIONS TO BE LIMITED BY ENHANCED LOW-LEVEL SHEAR. THIS WILL  
SUSTAIN AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM EXTENDING  
FROM FRENCH GUIANA INTO CENTRAL AND NORTHERN PORTIONS OF GUYANA.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
88W 93W 97W 102W 105W EXITS EW 19N  
 
AN EASTERLY WAVE INITIALIZED AT 88W AND TO THE SOUTH OF 19N...IS  
RAPIDLY PROPAGATING WESTWARD AND CROSSING NORTHERN CENTRAL AMERICA  
ON WEDNESDAY. ALTHOUGH THE WAVE WILL EXIT INTO THE PACIFIC TO  
RAPIDLY PROPAGATE WESTWARD ON WEDNESDAY...THE MOISTURE POOL  
LINGERING IN THE CARIBBEAN BASIN WILL SUSTAIN A FEW SHOWERS AND  
THUNDERSTORMS IN NORTHERN HONDURAS/BELIZE ON WEDNESDAY...WITH  
ISOLATED MAXIMA OF 15-20MM/DAY...AND MORE ORGANIZED CONVECTION IN  
THE GULF OF CAMPECHE ON THURSDAY-FRIDAY...WHERE EXPECTING ISOLATED  
MAXIMA OF 35-70MM IN THE STRONGEST THUNDERSTORMS.  
 
GORDON...NMS (BELIZE)  
NIXON...BDM (THE BAHAMAS)  
GALVEZ...WPC (USA)  
 

 
 
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