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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1159Z Feb 16, 2018)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
659 AM EST FRI FEB 16 2018

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM FEB 16/06
UTC: THE PRESENCE OF A PERSISTENT UPPER TROUGH PATTERN OVER THE
ATLANTIC CONTINUES DESTABILIZING THE BOUNDARY LAYER AND ENHANCING
THE VERTICAL DEVELOPMENT OF TRADE WIND SHOWERS MOSTLY DUE TO THE
PRESENCE OF COLD AIR IN THE MID-LEVELS OF THE ATMOSPHERE. MOISTURE
IS LIMITED...BUT THE SHALLOW MOISTURE POOLS THAT ARE BUILDING IN
REGIONS OF TRADE WIND CONVERGENCE ARE SUFFICIENT TO TRIGGER
MODERATE TRADE WIND SHOWERS.

MODELS ARE SHOWING THAT THE UPPER TROUGH PATTERN IN THE ATLANTIC
IS TO PERSIST...AND WILL BE REINFORCED BY ANOTHER TROUGH DIGGING
FROM THE NORTH ON FRIDAY AND SATURDAY. AT LOW LEVELS...THE TRADE
WINDS REMAIN STRONG AS THEIR SPEEDS RANGE FROM 15-25KT FROM THE
EAST/NORTHEAST OR FROM 80-90 DEGREES. THESE ARE FORECAST TO
INCREASE LATE ON SUNDAY TO SPEEDS OF 20-30KT...IN ASSOCIATION WITH
THE STRENGTHENING OF A MID- AND LOW-LEVEL RIDGE TO THE NORTH.
ALTHOUGH THE ENHANCED UPPER CONVERGENT PATTERN AND SUBSIDENCE IN
THE ISLANDS SHOULD LIMIT VERTICAL DEVELOPMENT...OROGRAPHIC FORCING
RELATED TO THE STRENGTHENING OF THE TRADES WILL BALANCE THE
DECREASE IN PRECIPITATION AND RELOCATE THE REGIONS WITH LARGEST
ACCUMULATIONS. STILL...RAINFALL ACCUMULATIONS SHOULD REMAIN UNDER
0.5 INCHES/DAY. ISOLATED LARGER AMOUNTS ARE EXPECTED IN NORTHERN
AND EASTERN PUERTO RICO IN REGIONS OF ENHANCED OROGRAPHIC
CONVERGENCE AND WHERE THE MOST ROBUST TRADE WIND SHOWERS OCCUR.

GORDON...NMS (BELIZE)
NIXON...BDM (THE BAHAMAS)
GALVEZ...WPC (USA)