Weather

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Area forecast discussion 
National Weather Service Taunton Massachusetts 
1009 am EDT Monday Oct 6 2008 


Synopsis... 
a vigorous upper level disturbance and associated cold front will 
cross the region today...followed by cooler and drier air late in 
the day. High pressure and dry weather will return Tuesday through 
Thursday. Unsettled weather may return late in the week into next 
weekend. 


&& 


Near term /until 6 PM this evening/... 
a vigorous short wave disturbance will cross southern New England 
today. Latest radar loop indicates showers crossing northwestern 
Massachusetts and eastern New York state. Radar reflectivity returns 
of 30 to 35 dbz noted across Franklin County. So raised probability of precipitation to high 
chance to low likely across the east slopes of the Berkshires and 
the Monadnocks. 


Cross sections indicate moisture is lacking below 850 millibars...but 
given steepening low level lapse rates this afternoon...and cold 
temperatures aloft with the approaching short wave...have added low 
chance probability of precipitation across the remainder of the region today. However showers 
are expected to be brief. Generally followed the latest NAM solution. 


&& 


Short term /6 PM this evening through 6 am Tuesday/... 
high pressure and drier air will arrive tonight. This will result in 
clear skies and diminishing winds. This will set the stage for for 
widespread frost...if winds diminish enough. 06/00z models indicate 
850 mb temperatures approaching -1c...making tonight one of the 
coldest so far this autumn. 


Mav and met MOS guidance temperatures look very reasonable. 


Have posted a frost warning for much of western Massachusetts...northeast 
CT...and central Hillsborough County New Hampshire late tonight. Most confident 
across western Massachusetts and central Hillsborough County...but it is a very 
close thing across the outlying areas of northeast CT...especially 
toward the foothills of the Berkshires. 


Did not include Franklin County Massachusetts and Cheshire County New Hampshire as these 
County have already experienced a widespread frost. However...these 
two counties may require a freeze warning tonight. Confidence is not 
very high yet that at least half of this area will see freezing 
temperatures. So will let next shift take a closer look. 


&& 


Long term /Tuesday through Sunday/... 
medium range models remain in pretty good agreement through 
Thursday. Beyond that...each model solution seemed to handle upper 
air features rather differently...though some general agreement seen 
in some of the members. Big question for the eastern Seaboard will 
be whether an inverted trough sets up...then low pressure runs along 
it bringing in precipitation for the weekend. At this point...have leaned 
toward the GFS op run and ensembles...though not a whole lot of 
confidence at this point. 


Tuesday through Thursday...high pressure out of eastern Canada works 
slowly S across New England to the middle Atlantic coast. This will bring 
dry and cool weather for Tuesday and Wednesday. As the high shifts 
off the coast...winds shift to west-SW which will bring a moderating 
trend. Appears the high shifts east into the western Atlantic...which will 
hold off the precipitation from an approaching cold front. May start to see 
low chance of showers moving into the region after midnight. 


Friday and Saturday...models trying to bring the front into the 
region but timing is in question. Some models also try to weaken the 
front as it pushes east while the western Atlantic ridge hangs tough. 
Kept in low chance probability of precipitation for Friday as the front stalls over the 
region. Low pressure may develop over the middle Atlantic coast...then try to 
ride up the front for Friday night and Saturday. Kept in high chance 
probability of precipitation for Saturday as the front weakens to an inverted trough. Will 
be rather muggy with highs in the middle-upper 60s. Not a whole lot of 
confidence with this solution...however. 


Sunday...low confidence forecast continues. Appears that a weak high 
may build over northern New England...but a lot of questions as to 
whether the inverted trough remains close enough to the coast to 
keep scattered showers going. At this point...lowered probability of precipitation to slight 
chance with partly sunny but cool weather. This may break up...with 
dry cold front possibly sweeping through late Sunday or Sunday night. 


&& 


Aviation /14z Monday through Friday/... 
VFR conditions today and tonight. The exception will be patchy IFR in 
low clouds and fog this morning across southeast Massachusetts...Rhode Island and extreme 
northeast CT. 


Outlook...Tuesday night through Friday... 


Tuesday through Thursday...VFR. Patchy nighttime fog possible with local MVFR 
visibilities. 


Thursday night and Friday...VFR-MVFR ceilings/visibilities in scattered showers. Low 
risk of IFR. 


&& 


Marine... 
north winds expected to increase this afternoon. Wind gusts may 
approach 25 knots across the eastern waters towards evening and 
overnight. A Small Craft Advisory may be necessary late in the 
day...but will hold off on headlines for now and let the next shift 
take a closer look. 


Outlook...Tuesday through Friday... 


Tuesday...northwest wind will gust to 20 knots mainly on the outer 
waters...but will diminish by late in the day. Seas will remain at 
around 5 feet on the outer waters...but will subside at night. 


Wednesday...winds and seas will remain below small craft criteria 
with high pressure overhead. 


Thursday...winds shift to SW by early Thursday and will 
increase...though will remain below small craft criteria. Seas will 
build up to 4 feet on the southern outer waters. 


Friday...SW winds will approach small craft criteria mainly on the 
waters east and south of Cape Cod. Seas may build up to 5 feet on the 
waters S and east of Nantucket. Visibilities may lower to below 3 nm in 
scattered showers and patchy fog. 


&& 


Box watches/warnings/advisories... 
CT...frost advisory from 2 am to 9 am EDT Tuesday for ctz002>004. 
Massachusetts...frost advisory from 2 am to 9 am EDT Tuesday for maz004- 
008>011. 
New Hampshire...frost advisory from 2 am to 9 am EDT Tuesday for nhz015. 
Rhode Island...none. 
Marine...none. 


&& 


$$ 
Synopsis...evt 
near term...Strauss 
short term...Belk 
long term...evt 
aviation...Belk/evt 
marine...Belk/evt 

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