567  
FXCA20 KWBC 161811  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
110 PM EST FRI FEB 16 2018  
 
TROPICAL DISCUSSION FROM FEB 16/12 UTC: UNDER THE INFLUENCE OF AN  
UPPER TROUGH IN THE PACIFIC...EXPECTING RAINFALL TO CONTINUE IN  
EXTREME NORTHWESTERN MEXICO THROUGH EARLY SATURDAY. INTERMITTENT  
WILL LEAD TO 05-10MM/DAY AND MAXIMA OF 15-20MM IN THE NORTHERN  
MOUNTAINS OF SONORA. ELSEWHERE IN NORTHERN BAJA CALIFORNIA AND  
NORTHERN SONORA EXPECTING MAXIMA UNDER 10MM/DAY. A DRYING TREND  
FOLLOWS...YET...LIGHT RAIN SHOWERS ARE EXPECTED ON A DAILY BASIS  
IN THE CENTRAL MOUNTAINS OF MEXICO.  
 
TO THE EAST... THE ROBUST RIDGE THAT EXTENDS FROM THE PACIFIC  
COAST OF MEXICO/GULF OF MEXICO TO ABOUT 30N AND 60W. ALTHOUGH AN  
ASSOCIATED CLOSED HIGH WILL MEANDER THROUGH THE CYCLE...THE  
INFLUENCE OF THE RIDGE WILL PERSIST ACROSS THE REGION...EXTENDING  
SOUTH INTO THE CENTRAL CARIBBEAN. TO THE SOUTH OF THE RIDGE...A  
TROUGH AXIS IS FORECAST TO LINGER EARLY IN THE CYCLE EXTENDING  
FROM THE TROPICAL ATLANTIC INTO THE SOUTHEASTERN CARIBBEAN. MODELS  
CONTINUE SHOWING AN UPPER TROUGH DIGGING FROM THE NORTH ATLANTIC  
BY FRIDAY-SATURDAY. THIS WILL PUSH THE CURRENT TROUGH AXIS  
SOUTHWARD INTO NORTHERN SOUTH AMERICA BY EARLY SATURDAY. THE TRADE  
WIND CAP IS STRENGTHENING ACROSS THE CARIBBEAN...YET...THE MOST  
IMPORTANT FACTOR LIMITING RAINFALL ACCUMULATIONS IS THE LARGE  
AMOUNT OF DRY AIR ABOVE THE BOUNDARY LAYER. THIS WILL CONTINUE  
SUSTAINING MAXIMA GENERALLY UNDER 10MM. EXCEPTIONS ARE  
PANAMA/COSTA RICA/SOUTH EASTERN NICARAGUA...WHERE TRADE WIND  
CONVERGENCE WILL SUSTAIN 05-10MM/DAY AND ISOLATED MAXIMA OF  
15-25MM. A DECREASE IS EXPECTED IN NICARAGUA ON SUNDAY. NOTE THAT  
THE MID-LEVEL RIDGE IS FORECAST TO STRENGTHEN ON SUNDAY THROUGH  
TUESDAY...WHICH WILL STRENGTHEN THE LOW-LEVEL RIDGE AND INDUCE AN  
INTENSIFICATION OF THE TRADES BY EARLY NEXT WEEK...ESPECIALLY  
ALONG THE NORTHEASTERN CARIBBEAN...INCLUDING THE SOUTHERN  
BAHAMAS...HISPANIOLA...EASTERN CUBA.  
 
IN THE GULF OF HONDURAS...AN INCREASE IN PRECIPITATION IS EXPECTED  
FROM SUNDAY THROUGH TUESDAY. THIS WILL BE UNDER THE INFLUENCE OF A  
ZONALLY-ORIENTED MID-LEVEL TROUGH DEVELOPING IN THE REGION. THIS  
WILL BE SUFFICIENTLY WELL DEFINED TO INTERACT WITH THE LOW-LEVELS  
AND AID WITH THE BUILDING OF A MOISTURE POOL AND A TROUGH IN THE  
TRADES. EXPECTING AN ENHANCEMENT IN RAINFALL AMOUNTS...AIDED BY  
TRADE WIND CONVERGENCE IN NORTHEASTERN HONDURAS AND SOUTHERN  
BELIZE/CENTRAL GUATEMALA. AMOUNTS WILL INCREASE ON SATURDAY-SUNDAY  
TO SUSTAIN 05-10MM/DAY AND MAXIMA OF 15-20MM. A FURTHER INCREASE  
IS EXPECTED ON SUNDAY-MONDAY TO MAXIMA OF 15-25MM...TO LAST AT  
LEAST THROUGH TUESDAY.  
 
IN SOUTH AMERICA...ELEVATED CAP CONTINUES EXTENDING ACROSS ECUADOR  
AND COLOMBIA. MOISTURE POOL HAS BUILT SUFFICIENTLY TO SUSTAIN AN  
INCREASE IN RAINFALL ACCUMULATIONS. THE WESTERLY WINDS LOOK RATHER  
WEAK THROUGH THE CYCLE...WHICH IS LOWERING THE CHANCE FOR HEAVY  
RAINFALL. YET...STILL EXPECTING ACCUMULATIONS IN THE ORDER OF  
10-15MM/DAY AND MAXIMA OF 20-30MM...WHEREAS IN ECUADOR...ACTIVITY  
WILL PEAK ON SATURDAY TO PRODUCE ISOLATED MAXIMA OF 25-50MM. EAST  
OF THE ANDES...A DRYING TREND IS EXPECTED UNDER THE INFLUENCE OF  
THE STRENGTHENING LOW-LEVEL JET OF VENEZUELA AND COLOMBIA. THIS  
WILL PUSH THE MOISTURE CONVERGENCE TO PERU/BRASIL BY SUNDAY/MONDAY.  
 
ALSO IN NORTHERN SOUTH AMERICA...A DRYING TREND WILL DEVELOP  
STARTING SATURDAY. THIS IS UNDER THE INFLUENCE OF THE CONVERGENT  
SIDE OF A MID-LEVEL TROUGH MEANDERING IN FROM THE NORTH. OVER  
GUYANA AND SURINAME THIS WILL LEAD TO RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-25MM ON FRIDAY-SATURDAY. AMOUNTS ARE  
TO DECREASE TO MAXIMA OF 15-20MM ON SATURDAY-SUNDAY AND A FURTHER  
DECREASE IS EXPECTED ON SUNDAY-MONDAY RESULTING IN DAILY  
ACCUMULATIONS OF 00-05MM/DAY AND MAXIMA OF 10MM. AN EXCEPTION IS  
EASTERN FRENCH GUIANA WHERE ACTIVE CONVECTION WILL PERSIST. IN  
THIS AREA EXPECTING ACCUMULATIONS OF 15-20MM/DAY AND MAXIMA OF  
25-50MM THROUGH SATURDAY-SUNDAY WITH A DECREASE TO 10-15MM/DAY AND  
MAXIMA OF 20-30MM ON SUNDAY-MONDAY.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
NONE  
 
GORDON...NMS (BELIZE)  
NIXON...BDM (THE BAHAMAS)  
GALVEZ...WPC (USA)  
 

 
 
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