681 
fxus61 kcar 181935 
afdcar 


Area forecast discussion 
National Weather Service Caribou ME 
335 PM EDT Friday Jul 18 2008 


Synopsis... 
low pressure will move east of the region tonight. Another low 
will approach from the west Saturday and move east Sunday. 
&& 


Near term /until 7 PM this evening/... 
the remnant convective complex that moved across the forecast area 
earlier today helped to stabilize the air across the Caribou 
warning area today. Convection has been confined to our southwest 
where airmass is much more unstable. Expect lingering showers 
across the region through the rest of the afternoon with any 
isolated thunderstorms confined to western and interior downeast areas. 
&& 


Short term /7 PM this evening through Monday/... 
models in the short term are somewhat in dis-array with there 
varios solutions. The 12z NAM...in particular...seemed to be an 
outlier with its near 1000 mb low over northern portions of our forecast area Sat 18z 
compared to the weak mean sea level surface pressure shown by the other models... 
particularly the 12z GFS. With this in mind...this aft's update in 
the short rnge was based entirely on the 12z opnl GFS run...which 
was closer to the 00z GFS ens mean. In short...the 12z GFS run 
brings the showers msly over central and downeast areas to an end by 
midday Sat...allowing the northern two thirds of the region to 
experience partly sunny skies by Sat after...after Erly morning pchy fog. 


Weak S/waves in zonal flow aloft along with modest cape values of around 
500 j/kg may result in after/Erly evening isolated showers/thunderstorms Sat. Sat night 
and sun with partly to mcldy skies and dry conditions north and central 
while downeast areas remain cloudy...with scattered showers/after thunderstorms. Cape 
values of near 1000 j/kg sun after suggest a little more convective 
potential with thunderstorms...but not enough for severe storms yet at this time. 


Clouds and higher shower chances will gradually move nwrd Sun night into 
Monday...withe northern most extent somewhat uncertain at this time. For now... 
will bring likely probability of precipitation as far north as central Maine and chance probability of precipitation into north 
Maine by Monday after...which is further north tha suggested by 12z opnl 
GFS run...but in line with the GFS ens mean. 
&& 


Long term /Monday night through Friday/... 
a frontal system moves off the southeastern coast Monday night 
leaving a chance of rain early Tuesday downeast. An upper level 
trough over Quebec will bring the risk of showers or isolated 
thunderstorms Tuesday and Wednesday, especially during the afternoon 
and evening. The upper level trough moves eastward towards the 
Maritimes Wednesday night and the chance of showers decreases for 
Thursday. 
&& 


Aviation /19z Friday through Wednesday/... 
expect mainly VFR conditions except some MVFR/IFR is possible in any 
showers and patchy fog tonight into Erly Sat morning. VFR is msly 
anticipated Sat through sun...xcpt MVFR/IFR again in patchy fog late 
Sat night. MVFR/IFR conditions are possible Sun night into Monday msly 
for downeast sites while northern taf sites hold on to VFR. MVFR/IFR 
conditions forecast area wide Monday night Ino Tuesday morning should improve to VFR for 
Tuesday after into Wednesday. 
&& 


Marine... 
near term: no hdlns. 


Short term: no hdlns...with ww3 sea heights kept just below Small Craft Advisory levels 
for Monday and Monday night based on long srly wind bias over cold SSTs of our 
waters. Fog could be a problem attms beginning late tonight and continuing 
into Sat night as moist tropical air with dewpoints greater than 
SSTs crosses our waters. 
&& 


Car watches/warnings/advisories... 
ME...none. 
Marine...none. 


&& 


$$ 


Near term...duda 
short term...vjn 
long term...mwalker 
aviation...duda 
marine...duda/vjn