Weather

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fxus61 kgyx 130729 
afdgyx 


Area forecast discussion 
National Weather Service Gray ME 
329 am EDT Monday Oct 13 2008 


Synopsis... 
a weak back door cold front will drop south and west into the 
forecast area today before washing out. Weak high pressure will 
build over northern New England. A weak cold front will cross the 
region Tuesday night...followed by high pressure Wednesday and 
Wednesday night. A stronger cold front will cross northern New 
England Thursday afternoon and evening. Cold high pressure will 
follow for in the week and next weekend. 


&& 


Near term /until 9 am this morning/... 
latest satellite and radar imagery showed an impulse racing 
southeast across the region. Highest probability of precipitation will continue across 
northern and eastern sections closest to the upper support 
tapering to none probability of precipitation over far southern and western sections. A 
weak boundary extended from north of the lakes east southeast into 
northern Maine and will continue to washout as it drifts to the 
south and west. 


&& 


Short term /9 am this morning through 6 am Tuesday/... 
what's left of the surface boundary makes it's way south and 
west. The upper support exits the area by early afternoon taking 
any lingering showers over northern and eastern sections with it. 
Some drier air builds south and west late in the day with surface 
high pressure over New Brunswick and we may see clouds begin to 
thin out over northeastern areas with a few periods of late day 
sunshine. Otherwise...a mostly cloudy day can be expected with 
highs within a few degrees either side of 60. Some leftover clouds 
tonight with remnants of the baroclinic zone. This should keep 
overnight temperatures rather mild for this time of year with most 
locations bottoming out in the 40s. 


&& 


Long term /Tuesday through Sunday/... 
the northern stream will become more active as the unusually strong 
middle level ridge breaks down early in the period. By the end of the 
period...short waves in the middle levels could deliver the coldest 
air of the season late this week into next weekend. 


A middle level short wave ejected out of the intermountain closed middle 
level system will ride over the collapsing middle level ridge Tuesday 
into Tuesday night. As it does...it will push a cold front into 
the St Lawrence River valley Tuesday afternoon. The airmass ahead 
of the front is fairly moist for the middle of October...with the 
best warm air advection north and west of the region through 
Tuesday evening. 


At this point...Tuesday should remain dry with showers probably no 
crossing the border until after dark. With some sunshine in the 
late morning and early afternoon...a blend of MOS numbers was used 
for highs. The surface gradient could support gusty south winds 
near the coast in the afternoon. 


The short wave crosses northern Maine Tuesday night. It should push 
the surface front through the region between 0600 UTC and 1200 UTC 
Wednesday. There should be enough moisture for showers in the higher 
terrain and possibly central Maine with the front. Further south 
and west...held the mention out for now as the best support in the 
middle levels is to the north and east. 


There is some indication of stratus possible near the coast in 
southwest flow late Tuesday night. Did not hit this too hard 
yet...but later shifts may have to account for this. The southwest 
flow ahead of the front...along with its late arrival...suggest 
that the GFS MOS numbers are probably too low Tuesday night. A 
blend of MOS numbers was used for lows (as there was a fairly 
large gap between the Eta model and GFS MOS numbers). 


The middle level support exits Wednesday morning. Outside of the 
potential for upslope clouds Wednesday morning...Wednesday should 
feature sunshine and a gusty west wind. A blend of MOS numbers was 
used for highs Wednesday. The next frontal passage should occur 
Thursday afternoon and evening. Not much of a return flow ahead of 
the front...so showers should be limited to the northern zones. 
Behind this...the coldest air of the season should arrives...possibly 
in pieces. Though not mentioned in the text forecasts yet...there 
could be upslope snow showers in the mountains Friday and Friday 
night in the cold air advection. 


Not much in the way of change to the forecast after this...as the 
GFS and European model (ecmwf) show some differences on how much the middle level 
system closes with the cold air. This will have some bearing on 
whether a surface low developing near the baroclinic zone gets 
close enough for a brush late in the week or next weekend. 


&& 


Aviation /07z Monday through 11z Tuesday/... 
short term...expect VFR conditions. Except for scattered MVFR in 
showers and ceilings north and east of kaug this morning. 


Long term /12z Tuesday through Friday/... 
VFR conditions are expected through Tuesday evening. There could 
be some pockets of MVFR conditions in scattered showers late 
Tuesday night ahead of a cold front. There is also some indication 
of IFR/LIFR conditions in stratus near the coast in the southwest 
flow for kpwm and possibly kaug late Tuesday night. Not sure about 
this yet...but the wind direction could favor stratus coming ashore 
for a few hours ahead of the cold front. 


There may be some MVFR conditions with the passage of a cold front 
Thursday afternoon and evening. After this...mainly VFR conditions 
are expected. 


&& 


Marine... 
short term /today and tonight/...quiet on the waters with weak 
back door front washing out as it drops south and west today. 


Long term /Tuesday through Friday...winds will increase from the 
south and then southwest west ahead of a cold front Tuesday 
afternoon and evening. At this point...the gradient...nor the 
height of the mixed layer...appear to support small craft winds. 
Seas may briefly approach 5 feet on the outer ocean waters Tuesday 
evening...but overall seas should remain below small craft levels. 


Mixing in cold air advection could result in gusts to 20 knots 
Wednesday. Winds may approach small craft levels behind a stronger 
cold front Thursday evening and Friday morning. However...there is 
some model disagreement on how much mixing will occur...so winds 
were kept below 25 knots for now. 


&& 


Gyx watches/warnings/advisories... 
ME...none. 
New Hampshire...none. 
Marine...none. 


&& 


$$ 

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