997 
fxca62 tjsj 110858 
afdsju 


Area forecast discussion 
National Weather Service San Juan PR 
458 am AST Sat Oct 11 2008 


Discussion...scattered to numerous showers and isolated 
thunderstorms were detected overnight mainly across the coastal 
waters. With a northeasterly low level wind flow...some of these 
showers and thunderstorms moved from time to time across the 
northern and eastern sections of Puerto Rico as well as over 
Vieques...Culebra and the U.S. Virgin Islands. The total rainfall 
amounts associated with this activity were generally less one half 
of an inch. For this afternoon the combination of the abundant low 
level moisture across the region provided by a tropical wave across 
the eastern Caribbean...daytime heating...local island effects and 
good upper level dynamic...will promote again the development of 
scattered to numerous showers and isolated thunderstorms across the 
Cordillera Central early in the afternoon and later on across 
southwestern sections of Puerto Rico. 


A very wet weather pattern is still expected for the local islands 
starting late today or tonight and continuing for the next several 
days. An upper level low (tutt) over Puerto Rico this morning with a 
trough extending northeastward across the Atlantic...will continue 
very close to the region until at least Monday. Accordingly to the 
GFS model guidance...this cyclonic flow aloft will weaken by early 
Monday leaving an anticyclonic circulation at the upper level of the 
atmosphere by early next week. 


An active tropical wave and associated area of disturbed weather 
located across the eastern Caribbean this morning...will continue to 
track very slowly to the west northwest today and will begin to 
directly affect the forecast area late tonight and lasting possible for several 
days. Latest GFS guidance develops a low pressure center south of 
Puerto Rico by Monday and moves the low to the north across the 
island Tuesday and Wednesday. This synoptic scenario will change the 
steering currents across the forecast area from unusual directions by the 
middle of the next week. A southwesterly low level wind flow is 
expected by Wednesday. If this synoptic scenario verify...a large 
area of deep tropical moisture will persist across the region for 
the upcoming week. In fact latest model guidance continue to 
indicate the potential for an extended period of active 
weather...possibly through much of next week. The areas most 
affected by these showers will be in the southeast of Puerto 
Rico...but rainfall will spread across the island during the period 
as steering current changes. 


Everyone should remain abreast of the development of this 
potentially dangerous weather situation either by National oceanic and atmospheric administration weather radio 
or local TV or radio station. Favorable conditions for heavy rain 
will last for the whole upcoming week...as these weather features 
(tropical wave and trough) will move as slowly as the wave in the 
previous catastrophic event...which could prolong the flooding for a 
longer period. Stay tuned. 


&& 


Aviation...an approaching tropical wave will bring increased 
cloudiness to the region and spread showers and thunderstorms across 
the local flying area through the early morning hours an into the 
afternoon hours. This will MVFR to brief IFR conditions to 
tkpk...tncm...tist...tisx and tjsj as the shower activity reach the 
coastal areas from time to time. Mostly VFR conditions is forecast 
at the remaining taf site for the rest of the morning hours. During 
the afternoon...isolated thunderstorms can be expected across parts 
of the central and west interior sections of Puerto Rico. This will 
lead to brief MVFR conds by the way 18z-22z in and around tjmz and tjbq. 


&& 


Marine...generally expect winds of 17 knots or less across the 
regional waters through at least Sunday...with seas mostly 6 feet 
or less. However...mariners can expect dangerous lightning and 
higher seas and winds near showers and thunderstorms during the 
next several days. 




&& 


Preliminary point temps/pops... 
sju 87 77 85 77 / 50 70 80 50 
stt 86 78 84 78 / 70 90 90 90 


&& 


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


$$ 


09/72/