214  
FXCA20 KWBC 051921  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
221 PM EST MON FEB 05 2018  
 
TROPICAL DISCUSSION FROM FEB 05/12 UTC: AT UPPER LEVELS...THE  
SUBEQUATORIAL RIDGE EXTENDS ACROSS NORTHERN SOUTH AMERICA INTO  
MOST OF THE CARIBBEAN. THE RIDGE IS FORECAST TO CONTINUE COVERING  
MOST OF THE CARIBBEAN TO THE EAST OF A LINE FROM THE GULF OF  
HONDURAS-CENTRAL BAHAMAS THROUGH THE CYCLE. AT MID-LEVELS...A  
RIDGE EXTENDS FROM NORTHERN CENTRAL AMERICA/SOUTHERN GULF OF  
MEXICO EAST INTO HISPANIOLA AND PUERTO RICO...WHERE IT IS FORECAST  
TO LINGER THROUGH WEDNESDAY...TO THEN ORGANIZE ON A CLOSED HIGH  
OVER WESTERN CUBA. SOUNDING DATA ANALYSIS SHOWS THAT A STRONG CAP  
IS STILL PREVAILING ACROSS THE NORTHERN CARIBBEAN...WHERE ACTIVITY  
IS GENERALLY LIMITED TO ISOLATED LIGHT TRADE WIND SHOWERS. IN THE  
SOUTHERN CARIBBEAN AND THE TROPICAL ATLANTIC THE TRADE WIND CAP IS  
WEAKER...YET THE LACK OF SATURATION ABOVE THE BOUNDARY-LAYER WILL  
CONTINUE LIMITING PRECIPITATION VIA THE TURBULENT MIXING OF DRY  
AIR. AS THE AFOREMENTIONED MID AND UPPER RIDGES PERSIST AND  
MEANDER SLIGHTLY NORTHWARD...THE UPPER TROUGHS IN THE WESTERLIES  
ARE FORECAST TO AVOID DIGGING INTO THE BASIN. THIS WILL LIMIT THE  
SOUTHWARD PROGRESSION OF ASSOCIATED SURFACE FRONTS TO AREAS TO THE  
NORTH OF THE FLORIDA STRAIT/NORTHWESTERN BAHAMAS...WHILE FAIR  
CONDITIONS PREVAIL ELSEWHERE.  
 
ON MONDAY...A POLAR TROUGH THAT HAS EXITED THE EASTERN COAST OF  
THE UNITED STATES IS SUSTAINING A SURFACE COLD FRONT ACROSS THE  
SOUTHERN FLORIDA PENINSULA/NORTHERN BAHAMAS. AS THE TROUGH EXITS  
TO THE NORTHEAST...THE FRONT WILL PROPAGATE VERY LITTLE SOUTHWARD  
ON MONDAY...TO START WEAKENING ON TUESDAY. BY MONDAY EVENING THE  
FRONT WILL EXTEND ACROSS THE NORTHWESTERN BAHAMAS INTO EXTREME  
SOUTHERN FLORIDA WHILE BECOMING STATIONARY. BY TUESDAY  
EVENING...THE ILL-DEFINED BOUNDARY WILL STILL EXTEND ACROSS THE  
NORTHWESTERN BAHAMAS INTO SOUTH FLORIDA...WHILE RAPIDLY LOSING  
DEFINITION. THE FRONT WILL ENHANCE SHOWERS ACROSS THE NORTHWESTERN  
BAHAMAS TO PRODUCE LIGHT ACCUMULATIONS ON MONDAY AND  
TUESDAY...WITH FORECAST RAINFALL AMOUNTS OF 00-05MM/DAY AND  
ISOLATED MAXIMA OF 10MM.  
 
THE NEXT COLD FRONT TO ENTER THE BASIN IS FORECAST TO ARRIVE INTO  
THE EXTREME NORTHWESTERN GULF OF MEXICO BY WEDNESDAY  
EVENING...WHEN THE WESTERN TAIL OF THE FRONT WILL EXTEND INTO  
NORTHERN TAMAULIPAS IN MEXICO. BY THURSDAY EVENING...THE BOUNDARY  
WILL EXTEND ACROSS CENTRAL FLORIDA...CENTRAL TAMAULIPAS IN MEXICO.  
A SHEAR LINE WILL ORGANIZE BY THIS PERIOD TO EXTEND ACROSS THE  
NORTHWEST BAHAMAS INTO EXTREME NORTHWESTERN CUBA AND THE  
NORTHEASTERN YUCATAN PENINSULA. INITIALLY...RAINFALL WILL CLUSTER  
IN NORTHEASTERN MEXICO. BY WEDNESDAY-THURSDAY...LARGEST  
ACCUMULATIONS WILL BE TRIGGERED BY ENHANCED BY OROGRAPHIC UPLIFT  
IN NORTHERN VERACRUZ/PUEBLA...TO SUSTAIN 10-15MM/DAY AND MAXIMA OF  
20-40MM. FURTHER NORTH ACROSS TAMAULIPAS AND NUEVO LEON EXPECTING  
05-10MM/DAY AND MAXIMA OF 15MM. AMOUNTS IN ASSOCIATION WITH THE  
FRONT WILL DECREASE AFTER. REGARDING THE SHEAR LINE...EXPECTING  
ALSO LIGHT ACCUMULATIONS WHILE THE REGION REMAINS UNDER THE  
INFLUENCE OF THE MID-LEVEL RIDGE.  
 
FAIR WEATHER EXTENDS ACROSS MOST OF THE CARIBBEAN UNDER THE DRYING  
AND STABILIZING INFLUENCE OF THE MID-LEVEL RIDGES. YET...AS THE  
500 HPA RIDGE ORGANIZES ON A CLOSED HIGH IN CUBA BY  
WEDNESDAY...EXPECTING A SLIGHT COOLING OF THE MID-LEVELS TO  
DEVELOP IN AREAS TO THE EAST OF THE RIDGE IN ASSOCIATION WITH THE  
ADVECTION OF A COOLER AIR MASS FROM THE NORTH. THIS WILL SUSTAIN A  
GRADUAL DESTABILIZATION OF THE BOUNDARY LAYER IN THE EASTERN  
CARIBBEAN...WHICH WILL RESULT IN A GRADUAL INCREASE IN THE  
COVERAGE AND INTENSITY OF TRADE WIND SHOWERS BY MID-WEEK.  
INITIALLY...EXPECTING ISOLATED SHOWERS TO PRODUCE 00-05MM/DAY AND  
MAXIMA OF 10MM MOSTLY IN EASTERN SLOPES. THIS WILL INCREASE TO  
05-10MM/DAY AND MAXIMA OF 15MM...ESPECIALLY ACROSS THE LESSER  
ANTILLES AND PUERTO RICO/VI BY WEDNESDAY-THURSDAY. ALSO...AN  
EASTERLY WAVE HAS ORGANIZED AND IS RAPIDLY PROPAGATING ACROSS THE  
SOUTHERN CARIBBEAN. THE WAVE ENHANCE PRECIPITATION IN CENTRAL  
AMERICA AND MEXICO FROM TUESDAY-FRIDAY (SEE BELOW).  
 
THE PACIFIC ITCZ IS LOSING ORGANIZATION...YET IT CONTINUES  
ENTERING THE COAST ACROSS EXTREME NORTHERN ECUADOR/SOUTHERN  
COLOMBIA. THIS IS DUE TO THE INFLUENCE OF A NORTHERLY LOW-LEVEL  
JET IN PANAMA. THE NORTHERLIES ARE FORECAST TO WEAKEN THROUGH THE  
CYCLE...TO RESULT IN A DECREASE IN LOW-LEVEL CONVERGENCE AND  
RAINFALL AMOUNTS THROUGH THE CYCLE. INITIALLY...EXPECTING  
10-15MM/DAY AND ISOLATED MAXIMA OF 20-40MM FROM NORTHWESTERN  
ECUADOR NORTH INTO THE SOUTHERN CHOCO AND VALLE DEL CAUCA.  
ACCUMULATIONS WILL DECREASE TO 05-10MM/DAY AND MAXIMA OF 15-25MM  
BY TUESDAY-WEDNESDAY...AND TO MAXIMA OF 15MM BY  
WEDNESDAY-THURSDAY. TO THE EAST...THE ATLANTIC ITCZ LIES TO THE  
SOUTH OF THE AMAZON DELTA. THIS IS SUSTAINING CURRENTLY FAIR  
CONDITIONS IN THE GUIANAS. A POCKET OF MOISTURE IN THE TRADES IS  
ARRIVING INTO TRINIDAD AND TOBAGO...NORTHEASTERN VENEZUELA AND  
NORTHERN GUYANA ON MONDAY. THIS WILL SUSTAIN A SLIGHT INCREASE IN  
THE ACCUMULATIONS PROVIDED BY TRADE WIND SHOWERS...TO PRODUCE  
05-10MM/DAY AND MAXIMA OF 15MM ON A DAILY BASIS. MUCH DRIER  
CONDITIONS ARE EXPECTED IN THE SOUTHERN GUIANAS.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
67W 73W 78W 83W 88W 93W 98W 102W EW 17N  
 
AN EASTERLY WAVE IS INITIALIZED AT 67W AND TO THE SOUTH OF 17N.  
THIS WAVE IS MOVING RAPIDLY ACROSS THE SOUTHERN CARIBBEAN WITH  
LITTLE EFFECTS IN RAINFALL ACCUMULATIONS. THE WAVE WILL BECOME  
MORE SIGNIFICANT ONCE IT ENTERS CENTRAL AMERICA...AS IT REACHES  
THE CARIBBEAN COASTS OF COSTA RICA...NICARAGUA...AND HONDURAS ON  
TUESDAY-EARLY WEDNESDAY. EXPECTING RAINFALL ACCUMULATIONS  
INCREASING TO 05-10MM/DAY AND MAXIMA OF 15-20MM.  
SIMULTANEOUSLY...EXPECTING MAXIMA OF 15MM IN THE CARIBBEAN ISLANDS  
OF SAN ANDRES AND NUEVA PROVIDENCIA. BY  
WEDNESDAY-THURSDAY...EXPECTING SIMILAR ACCUMULATIONS FROM NORTHERN  
HONDURAS WEST INTO COASTAL BELIZE. BY THURSDAY-FRIDAY...MODELS ARE  
SUGGESTING LARGER AMOUNTS DEVELOPING IN THE GULF OF CAMPECHE AS  
THE WAVE ENTERS THE REGION. IT IS STILL EARLY TO DETERMINE A  
RANGE...YET MAXIMA WILL LIKELY EXCEED 25MM IN THE STRONGEST  
THUNDERSTORMS.  
 
GORDON...NMS (BELIZE)  
NIXON...BDM (THE BAHAMAS)  
DAVISON/GALVEZ...WPC (USA)  
 

 
 
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