596  
FXCA20 KWBC 091959  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
258 PM EST FRI FEB 09 2018  
 
TROPICAL DISCUSSION FROM FEB 09/12 UTC: MID-LEVEL RIDGE IS  
MEANDERING JUST TO THE NORTHEAST OF THE BAHAMAS...AND IS FORECAST  
TO BUILD AS THE CYCLE PROGRESSES. BY SUNDAY EVENING...THE RIDGE  
WILL EXTEND FROM BERMUDA INTO THE GULF OF HONDURAS AND THE  
PACIFIC/SOUTHERN MEXICO. THIS WILL SUSTAIN GENERALLY FAIR  
CONDITIONS ACROSS THE REGION...INCLUDING THE CAYMAN ISLANDS AND  
JAMAICA. A SLIGHT ENHANCEMENT IN TRADE WIND SHOWERS IS EXPECTED IN  
ASSOCIATION WITH A WEAK AND RAPIDLY PROPAGATING EASTERLY WAVE (SEE  
BELOW). THIS WILL LEAD TO SCATTERED AMOUNTS OF 00-05MM/DAY AND  
ISOLATED MAXIMA OF 10MM IN JAMAICA...CAYMAN ISLANDS AND CENTRAL  
CUBA ON SATURDAY-EARLY SUNDAY. BY SUNDAY-EARLY MONDAY...MOIST  
PLUME REMAINING FROM THIS WAVE WILL LEAD TO MAXIMA OF 10MM IN  
WESTERN CUBA. ALTHOUGH ANOTHER EASTERLY WAVE TRAILS...MOISTURE IS  
MORE LIMITED. REGARDING WIND SPEEDS...AS THE BERMUDA HIGH  
INTENSIFIES...EXPECTING AN INTENSIFICATION OF THE  
TRADES...ESPECIALLY IN THE SOUTHERN BAHAMAS/CUBA AND AREAS TO THE  
SOUTH ON SATURDAY...LASTING AT LEAST THROUGH MONDAY. EXPECTING  
WIND SPEEDS OF 30-35KT...PEAKING BETWEEN 925 AND 850 HPA.  
 
IN MEXICO...AN UPPER TROUGH IS WEAKENING WHILE MEANDERING TO THE  
NORTHEAST. THIS WILL STILL SUSTAIN SCATTERED PRECIPITATION ACROSS  
THE MOUNTAINS/MEXICAN PLATEAU THROUGH EARLY SATURDAY. EXPECTING  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. A NEW TROUGH WILL  
APPROACH ON SUNDAY-MONDAY...YET...THIS NEW TROUGH WILL ARRIVE WITH  
LIMITED MOISTURE. AFTER SATURDAY...ANY CONVECTION IN MEXICO WILL  
BE ISOLATED AND PRODUCE MAXIMA UNDER 10MM/DAY. MOST SCATTERED  
CONVECTION IS EXPECTED ALONG THE EJE VOLCANICO CENTRAL. ALSO IN  
MEXICO...A NEW FRONT WILL ARRIVE ON SUNDAY. BY SUNDAY EVENING IT  
WILL EXTEND ACROSS THE RIO BRAVO INTO SOUTHERN COAHUILA. THIS WILL  
LEAD TO ISOLATED AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM IN  
NORTHEASTERN MEXICO.  
 
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 30-35KT BETWEEN 850-925HPA. THESE WILL MIX DOWN  
TO THE SURFACE DURING PERIODS OF STRONG VERTICAL MIXING...TO  
SUSTAIN WIND GUSTS OF 15-20KT. IN THE ATLANTIC...AN EXTENSIVE  
UPPER TROUGH CONTINUES DESTABILIZING THE BOUNDARY LAYER. THE  
LIMITING FACTOR FOR DEEP CONVECTION IS THE LACK OF MOISTURE IN THE  
MID-LEVELS. YET...THE SUBSIDENCE CAP HAS WEAKENED AND RISEN TO THE  
MID-LEVELS. THE UPPER TROUGH IS INDUCING WEAK PERTURBATIONS IN THE  
TRADES...WHICH ARE STREAMING INTO THE CARIBBEAN AS WEAK EASTERLY  
WAVES. YET...THESE WILL PROVIDE MINOR ENHANCEMENT IN THE COVERAGE  
AND INTENSITY OF TRADE WIND SHOWERS. ALTHOUGH MOST ACTIVITY WILL  
BE ISOLATED AND PRODUCE AMOUNTS UNDER 10MM/DAY...A FEW EXCEPTIONS  
WILL BE REGIONS OF OROGRAPHIC ENHANCEMENT SUCH AS THE LESSER  
ANTILLES...EASTERN PUERTO RICO...AND EASTERN HISPANIOLA (SEE BELOW  
UNDER TROPICAL/EASTERLY WAVES). MODELS ARE SUGGESTING AN INCREASE  
IN ACCUMULATIONS BY EARLY NEXT WEEK ACROSS THE CENTRAL ANTILLES.  
THIS WILL DEVELOP DUE TO DESTABILIZATION BY THE INFLUENCE OF A  
STRENGTHENING TROUGH AXIS FROM AN UPPER TROUGH IN THE ATLANTIC.  
THIS WILL LIKELY TRIGGER ISOLATED MAXIMA OF 15-20MM/DAY IN THE  
CENTRAL LESSER ANTILLES.  
 
IN NORTHWESTERN SOUTH AMERICA...CONVECTION WILL START TO INCREASE  
IN THE PACIFIC BASINS OF ECUADOR AND SOUTHERN COLOMBIA. THIS IS IN  
ASSOCIATION WITH ITCZ CONVERGENCE AND A GRADUAL INCREASE IN  
PRECIPITABLE WATER AND MOISTURE CONVERGENCE. AMOUNTS WILL INCREASE  
FROM 05-10MM/DAY AND MAXIMA OF 15-25MM IN CENTRAL/SOUTHERN ECUADOR  
AND MAXIMA OF 15MM IN COLOMBIA ON FRIDAY...TO GENERALIZED AMOUNTS  
OF 10-15MM/DAY AND MAXIMA OF 20-35MM BY SUNDAY. A SLIGHT INCREASE  
IS EXPECTED ON MONDAY.  
 
TO THE EAST...PRECIPITATION IS INCREASING IN THE GUIANAS AS  
MOISTURE PLUME ARRIVES FROM THE ATLANTIC. FURTHERMORE...AS UPPER  
TROUGH DIGS ACROSS THE NORTHEASTERN CARIBBEAN/TROPICAL  
ATLANTIC...MODELS ARE CONFIDENT ON AN UPPER JET DEVELOPING BETWEEN  
12N-15N...FROM THE LESSER ANTILLES EAST INTO THE CAPE VERDE  
ISLANDS. AS THE JET STRENGTHENS INTO EARLY NEXT WEEK...EXPECTING A  
DECREASE IN THE SURFACE PRESSURES ACROSS NORTHEASTERN SOUTH  
AMERICA. THIS WILL GRADUALLY DRAW DEEP-LAYER MOISTURE NORTHWARD  
FROM THE EQUATORIAL ATLANTIC. THROUGH EARLY SATURDAY...EXPECTING  
05-10MM/DAY AND MAXIMA OF 15-25MM FROM CENTRAL GUYANA EASTWARD. BY  
SATURDAY AND ON...EXPECTING 10-15MM/DAY AND MAXIMA OF 20-35MM  
DEVELOPING IN COASTAL REGIONS.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
58W 62W 66W 71W 75W 78W 81W 84W EW 22N  
66W 71W 76W 81W 86W DISSIPATES EW 20N  
 
AN EASTERLY WAVE IS INITIALIZED AT 58W. 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 AT 66W. THIS WAVE HAS A MORE  
ROBUST MOIST PLUME...AND WILL SUSTAIN ISOLATED MAXIMA OF 15-25MM  
AS IT CROSSES HISPANIOLA ON FRIDAY. 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...TO THEN RAPIDLY LOSE DEFINITION.  
 
GORDON...NMS (BELIZE)  
NIXON...BDM (THE BAHAMAS)  
GALVEZ...WPC (USA)  
 

 
 
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