687 
fxca62 tjsj 181959 
afdsju 


Area forecast discussion 
National Weather Service San Juan PR 
359 PM AST Friday Jul 18 2008 


Synopsis... active tropical wave along 70 west with area of low 
pressure over central Caribbean south of Hispaniola continues to 
move west around 15 kts. Drier airmass on wake of wave to settle 
across northeast Caribbean through Saturday night. A weaker 
tropical wave east of the Lesser Antilles around 49 west is 
expected to bring an increase in moisture across USVI/PR on 
Sunday. 


Discussion... 
convection this afternoon was limited to the northwest west 
interior and west part of north central due to strong heating and 
some residual moisture in wake of strong tropical wave south of 
Hispaniola. Heaviest rainfall through middle afternoon was between 
Camuy and Quebradillas. NAM model was forecasting strong 
convection for this afternoon an it verified very well for the 
northwest part of the island. Drier air has settled across the 
east half of PR and USVI therefore mostly dry weather in store for 
tonight with just isolated light showers. 


Tomorrow looks like another dry day per GFS. NAM keeps normal 
afternoon convection along the west and northwest...otherwise no 
additional weather. Forecast will continue with generally dry 
weather through Saturday night and then by Sunday increasing moisture 
as next tropical wave moves in. Wave looks weak at present and the 
prospects for rainfall should be for enhanced afternoon 
convection Sunday as upper trough TUTT moves westward too. 


Aviation...VFR conditions are expected to prevail over the 
northeast Caribbean Airport from san eastward to tncm and 
tkpk. Only isolated light showers expected. Isolated evening 
thunderstorm near tjbq could prouce MVFR until 02z. 


Marine...seas along the southern extreme of our coastal zones 
will improve slightly this evening...and be just below Small Craft Advisory 
criteria starting overnight. 


&& 


Preliminary point temps/pops... 
sju 78 89 78 88 / 20 20 20 40 
stt 79 89 78 90 / 20 40 50 50 


&& 


Sju watches/warnings/advisories... 
PR...none. 
Vi...none. 
&& 


$$ 


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