299 
fxus61 kcar 181525 
afdcar 


Area forecast discussion 
National Weather Service Caribou ME 
1125 am EDT Friday Jul 18 2008 


Synopsis... 
low pressure will move along a stationary front located through 
central Maine producing showers and thunderstorms across the 
region today through Saturday afternoon. Low pressure will move east of 
the region Saturday afternoon as high pressure builds in from the 
northwest. Another low pressure will approach the region late 
Sunday into early next week with another round of showers and 
possible thunderstorms. 
&& 


Near term /through tonight/... 
have adjusted probability of precipitation based on latest radar trends. Also...removed 
thunderstorms from zones 1>2 and the enhanced thunderstorm wording from zones 3>6 
since abundant cloud cover and approaching rainfall should keep 
this area too stable for any enhanced convection. 


Main challenge this term will be the potential for severe weather later 
this afternoon into the evening and flooding potential. This is 
addressed below. 


Decided on a blend of the NAM and sref as the latest radar and 
satellite imagery matches up well. Therefore first batch of precipitation moving 
across the northern tier of the County Warning Area is in response to shortwave moving east. 


Another round of showers and scattered thunderstorms are in the forecast later 
this morning and continuing through early tonight as mesoscale convective vortex/surface low 
pressure tracks from Ontario through northern Maine. Continued to follow the 
daycrew/S lead on the probability of precipitation west/categorical across the northern tier and 
then tapering probability of precipitation back as one heads further S. Northern areas look to 
stay stable west/the help of morning rafl and clouds. Some elevated 
convection is expected. Organized convection looks best S of a 
Caribou to Chamberlain Lake line. Storm Prediction Center has entire County Warning Area in slight 
risk for severe thunderstorms. Looks like strong winds the main threat as wbzs 
running above 11.5k feet. Mu convective available potential energy prognosticated to hit 1000-1500 j/kg this 
afternoon. Strong shear is noted especially west/in 0-3km of 35+ kts. Kis 
running into the middle 30s and swi above 300. The thing that could 
inhibit organized severe are the meager lapse rates from 700-500 mbs 
which continue to advertised below 6.0 c/km. 


Another concern is the potential for heavy rafl west/the potential for 
flooding as strong low level jet of 45+ kts is poised to be running over 
Theta-E ridge that will be in place mainly across cntl and 
interior downeast. Precipitable waters  above 1.8 inches and high kis could very well 
aid in very heavy rafl into the nighttime hours. Surface low/mesoscale convective vortex slowly 
moves into New Brunswick by early Saturday morning west/rafl 
beginning to wind down. 


Quantitative precipitation forecast grids are a blend of the HPC and the sref which points to northern 
areas picking up and an inch or more of rafl before winding down. 
Would not be surprised to see reports come in above 2 inches in 
hvier thunderstorms. 


Daycrews temperatures were accepted west/some minor tweaking across cntl and 
interior downeast areas to raise maxes today/ 
&& 


Short term /Saturday through Saturday night/... 
models in fairly good agreement with low pressure moving east of 
the state early Saturday with showers coming to an end across 
mainly northern sections. As low moves east, it will drag a cold 
front through the state during the day on Saturday. Front may be 
the focus of showers and thunderstorms as it moves through 
central and downeast sections Saturday afternoon. Limiting factor 
will be upper air support as shortwave trough will be exiting the 
region by midday with increasing stable lapse rates in the middle 
levels. High pressure will build across the region Saturday night 
into Sunday with improving conditions. 
&& 


Long term /Sunday through Thursday/... 
loaded the gmos for the long term. Unsettled pattern for next week 
as another low pressure moves across the state on Monday with 
showers and possible thunderstorms. Then both GFS and European model (ecmwf) 
gradually develop deep upper trough across the region by the end 
of the week keeping conditions on the cool and wet side for most 
of the week. 
&& 


Aviation /15z Friday through Tuesday/... 
rain will overspread kbgr terminal after 1530z with isolated thunderstorm 
possible. Expect conditions to deteriorate to MVFR and possible 
IFR in any heavy rainfall through 18z. Elsewhere VFR expected this afternoon 
then MVFR conds developing in rain mainly after 18z. 


Primarily VFR except IFR/MVFR in any showers or thunderstorms Saturday 
through Tuesday. 
&& 


Marine... 
near term: no headlines. Main concern is the fog that has visibilities 
below 1 nm. Carried fog right into tonight west/visibility running 1 nm or 
less. Southeast swell still evident at this time and continued the mention of the 
swell into tonight. Brought seas up to 3-5 feet today to account for 
the swell. 


Short term: weak cold front will cross the waters Saturday 
evening followed by weak high pressure for Sunday. Winds and seas 
to remain below Small Craft Advisory criteria Saturday and Sunday. Used a blend of 
the NAM and GFS for winds and went a foot or two below the wnawave 
for seas. 
&& 


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


&& 


$$ 


Near term...duda/Hewitt 
short term...Foster 
long term...Foster 
aviation...duda/Hewitt 
marine...duda/Hewitt/Foster