Weather

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Area forecast discussion 
National Weather Service Caribou ME 
533 PM EDT Sat Oct 11 2008 


Synopsis... 
skies are expected to clear in all areas by later this evening as 
strong high pressure builds in from the north. Clouds will 
increase in the north again Sunday as a cold front approaches... 
with showers Sunday night. High pressure from Quebec will provide 
for fair and seasonable conditions on Monday. Clouds...however will 
increase again Monday night with a chance of showers late as a 
warm front approaches the region. Tuesday will be partly cloudy 
and warmer. 
&& 


Near term /through Sunday/... 
upper vortex diving southeast across the northern tier of the County Warning Area per 
latest satellite WV imagery. European model (ecmwf) had this feature pegged on Friday and 
its latest run continues its continuity of bringing it across the 
northern tier of the County Warning Area this evening. 12z gfs40 has caught on to 
this feature as well. 


Therefore...boosted the probability of precipitation up to 20% for isolated showers across 
the northern zone mez002,005 & 006 into the evening in response to 
the vortex. Some positive vorticity advection noted that is helping to generate some light 
rain shower action at this time per latest radar mosaic. Action will quickly 
die out after 00z as vortex moves into New Brunswick. 


Some adjustment was done to sky grids as well to boost up northern 
areas to mostly cloudy for the evening and then clouds should 
dissipate for a time before the next batch arrives later 
tonight. 


Strong high pressure will build in from the northwest tonight. This 
system is expected to crest over southern New England during the day 
Sunday. A cold front to the north and northeast of the forecast area 
is expected to approach the region later Sunday. This system will 
spread clouds into northern portions of the state late Sunday. Have 
initialized the sky grids with a blend of the nam12 and gfs40. 
Minimal pop are also expect by late Sunday also do to the weak front 
approaching from the north. Pop grids have also been created with a 
model blend. For temperature...dew point and winds have initialized 
with gmos. Will make some manual adjustments to lower min 
temperatures and increase winds speed slightly today. 
&& 


Short term /Sunday night through Tuesday/... 
typical of fast west-northwest flow regime aloft patterns...the short term for 
this after forecast update will feature several S/wvs. The first Sun night 
will bring a chance of showers ahead of a back door type cold front. 
This front should clear most of the showers S of the forecast area by Monday morning as 
it moves offshore of the Maine coast. After a brief break Monday 
featuring near to just above normal hi temperatures...return flow at all 
levels from the surface to 500 mb will bring warm advcn along with 
increasing clouds ahead of the warm front. Cannot rule out showers 
late Monday night...msly over northern portions of the forecast area. We used a belnd of 
models for the pop distribution late Monday night...with the NAM 
appearing to be to strong with warm frontal probability of precipitation and the European model (ecmwf) 
to dry at this time. 


Most models indicate the potential of significant surface to 850 mb 
warming by Tuesday after under at least partly sunny skies. We raised hi 
temperatures into the 60s everywhere Tuesday after...but 18z to 21z temperatures of 
+14 to +18 degree c suggest the potential of hi temperatures in the 
70s...especially over east central and downeast areas. Will wait on 
subsequent model runs to confirm the arrival of the warm sector 
by midday Tuesday before go this bullish on hi temperatures Tuesday. Lastly... 
we went with a European model (ecmwf)/GFS blend for the arrival of any showers ahead 
of an approaching cold front for late Tuesday after. The 12z opnl GFS 
appears at least 6 hours to fast with this shower band...bringing it 
into northern portions of the forecast area by 18z...compared to other slower models 
and the previous opnl GFS run. 
&& 


Long term /Tuesday night through Saturday/... 
a cold front will rapidly exit Maine early Wednesday morning. High 
pressure will briefly build before another shortwave arrives 
Thursday morning. This feature appears poised to mainly affect the 
northern and western portions of the region with light 
rainshowers throughout Thursday. Strong cold air advection occurs behind 
this system during later Thursday into Saturday. By Saturday, there's some 
potential for snow flurries at higher elevations followed by a 
chilly Saturday night. Temperatures could drop to near 20f in 
mountain valleys of northwest Maine as high pressure settles over Maine. 
Gmos temperatures appear a bit high for Friday and Saturday. && 


Aviation /18z Saturday through Thursday/... 
msly VFR conditions expeceted through Thursday...with brief MVFR clgs 
possible in any showers Sun night...late Monday night and again late Tuesday 
into Tuesday evening. 
&& 


Marine... 
near term: have initialized the wind grids with an equal blend of 
the nam12 and gfs40. This combination has been working well so 
will not make any changes. For waves have used NAM version of swam 
model. Only change was to make some minor adjustments to intra- 
coastal wave heights. 


Short term: no hdlns anticipated...although waves do increase into 
the 2 to 4 feet range by Tuesday night across the outer waters. Used the 
same blend of winds as in the near term...and kept close to ww3 
with WV heights reduced some near the immediate coast. 
&& 


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


&& 


$$ 


Near term...mignone/Hewitt 
short term...vjn 
long term...mwalker 
aviation...mignone 
marine...mignone/vjn