Weather

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Area forecast discussion 
National Weather Service Taunton Massachusetts 
425 PM EDT Monday Oct 6 2008 


Synopsis... 
a vigorous short wave disturbance and associated cold front will 
depart the region this evening...followed by cool and dry high 
pressure through midweek. A warming trend will begin late in the week 
and continue into the weekend. It is highly uncertain whether or not 
a low pressure system tracks far enough north to bring US a period of 
rain Friday night and Saturday. 


&& 


Near term /until 6 am Tuesday morning/... 
a vigorous short wave disturbance was located directly over the 
region late this afternoon. This short wave was responsible for 
producing widely scattered showers. A few of these showers 
were producing light to briefly moderate rainfall...with base 
reflectivity values briefly within the 35-40 dbz range. Also just 
received a spotter report of some graupel in Ludlow Massachusetts at 338pm and 
this was also noted at Portland ME at 252pm. Will continue with 
slight chance probability of precipitation across the area until 6pm. 


These showers will dissipate by sunset as the short wave moves 
offshore. A chilly early autumn airmass will be experienced tonight. 
Clouds are also expected to diminish after sunset as well. Clear 
skies and light winds will allow surface temperatures across 
northwestern Massachusetts and southwestern New Hampshire will drop 
into the upper 20s and lower 30s. Thus have issued/upgraded to 
freeze warnings across Cheshire County New Hampshire and Franklin and Hampshire 
counties in Massachusetts. Please refer to the latest npwbox for 
details. The frost advisory might need to be expanded across portions 
of interior eastern Massachusetts between the i95 and i495 
belts...but for now have just included the mention of patchy frost. 


Generally stayed close to MOS temperature guidance. Patchy fog is 
also expected across the interior valleys prior to daybreak. 


&& 


Short term /6 am Tuesday morning through Tuesday night/... 
cool high pressure is expected to build over the region Tuesday and 
Tuesday night. H925 temperatures between +7 and +8 celsius generally 
supports highs in the 60 to 65 degree range Tuesday afternoon. 
Clear skies and diminishing winds will allow sharp radiational 
cooling Tuesday night. Frost advisories and freeze warnings will probably 
be necessary once again for some of the interior valleys and 
outlying sections with lows similar to Monday nights. The exception 
will be across the higher terrain...urban and exposed coastal 
sections where it will be milder. Otherwise expect clear skies and 
dry conditions. 


&& 


Long term /Wednesday through Monday/... 
Wednesday... 
skies should start off mainly sunny in the morning and perhaps into 
middle afternoon. However...an approaching shortwave will lead to an increase 
in high clouds by late in the afternoon. Otherwise...it will be a 
beautiful day as warming middle level temperatures should allow highs 
to recover into the upper 60s to around 70. 


Wednesday night and Thursday... 
a decent middle level shortwave will move through the region Wednesday 
night into the first part of Thursday. Moisture will be 
lacking...but there may be enough forcing and middle level lift for a 
few hours of isolated to scattered showers. Models show the best 
chance for this will be in our western zones as well as north of the 
Massachusetts Pike. GFS model and MOS probability of precipitation appear too low when looking at 
other models as they all have some scattered light quantitative precipitation forecast. For now will 
run with 20 to 30 probability of precipitation from Wednesday night into Thursday 
afternoon. We certainly do not expect a widespread soaking 
rain...but more the potential for a period of scattered showers. As 
for low temperatures...sided closer to warmer met numbers with 
expected increase in cloud cover. Highs on Thursday should recover 
into the upper 60s and lower 70s and we may see some partial 
sunshine by afternoon. 


Friday and Saturday... 
a very low confident and uncertain forecast over this time. The 
operational GFS has had a deep closed upper level low that moves 
into New England Friday night and Saturday. This solution would 
bring a decent period of rain into the region Friday night and 
Saturday. However...the European model (ecmwf)/UKMET show a much weaker system along 
with strong high pressure over New England keeping the action well 
to our south. The Canadian model is somewhat in between and brings 
a period of rain to areas south of the Massachusetts Pike. 


We are leaning towards the drier solutions for now and think the GFS 
is overdone and tracks the system too far north. Nonetheless...will 
have low chance probability of precipitation Friday night into Saturday night in case things 
change as we are still 4 to 5 days out. 


Sunday and Monday... 
mainly dry weather expected over this time. However...a cold front 
could bring a brief passing shower/sprinkle Sunday night and 
Monday. Will carry a 20 pop to cover this potential. Highs could 
reach into the 70 to 75 degree range on Sunday...but mainly 60s are 
expected on Monday behind the cold front. 


&& 


Aviation /20z Monday through Saturday/... 
tonight...VFR. Near MVFR ceilings locally 3500-4000ft until 22z this 
evening with widely scattered showers. A few showers could contain 
brief moderate rain and some graupel. Also scattered ocean effect 
stratocumulus around 2500 feet should develop across the Outer Cape and 
Nantucket after 02z. Brief gusts to 25 knots across the terminals until 
02z this evening. Local IFR conditions in fog patches after 06z 
Keene-kore-kbaf. 


Tuesday. VFR. 


Tuesday night. VFR. Local IFR conditions in ground fog patches 
across The Bogs and river valleys of interior eastern Massachusetts 
and the Connecticut River valley between 06z and 12z. 
Outlook...Wednesday through Saturday... 


Outlook...Wednesday through Saturday... 


Wednesday and Thursday...VFR except for the chance of a few hours of 
patchy ground fog during the late night/early morning hours in the 
typically prone locations. 


Friday and Saturday...it is highly uncertain with considerable model 
disagreement. If a storm tracks far enough north we may see a period 
of MVFR/IFR conditions Friday night and Saturday. If not...VFR 
conditions will continue with high pressure in control. 


&& 


Marine... 
tonight...have issued a Small Craft Advisory for the eastern outer 
waters from Provincetown to Nantucket Island from 00z to 14z Tuesday. 
North wind gusts up to 25 knots possible with seas building up to 5 or 6 feet 
approaching the offshore waters. 


Tuesday...a leftover Small Craft Advisory for hazardous seas across 
the eastern outer waters during the morning. Otherwise winds and 
seas expected to remain below Small Craft Advisory criteria. 


Tuesday night...winds and seas expected to remain below Small Craft 
Advisory criteria. 


Outlook...Wednesday through Saturday... 


Wednesday and Thursday...conditions should remain below Small Craft Advisory 
thresholds. However...decent mixing over the land may result in 
some near shore southwest low 20 knot wind gusts Thursday afternoon. 


Friday and Saturday...a very low confident forecast over this time. 
GFS appears to be overdone so have lowered wna wave height and wind 
forecasts. Nonetheless...we could see Small Craft Advisory conditions for a time if 
the low pressure system makes it as far north as the GFS advertises. 


&& 


Box watches/warnings/advisories... 
CT...frost advisory from 2 am to 8 am EDT Tuesday for ctz002>004. 
Massachusetts...freeze warning from 2 am to 8 am EDT Tuesday for maz002-003- 
008-010. 
Frost advisory from 2 am to 8 am EDT Tuesday for maz004-009- 
011. 
New Hampshire...freeze warning from 2 am to 8 am EDT Tuesday for nhz011. 
Frost advisory from 2 am to 8 am EDT Tuesday for nhz015. 
Rhode Island...none. 
Marine...Small Craft Advisory from 8 PM this evening to 10 am EDT 
Tuesday for anz254. 


&& 


$$ 
Synopsis...Frank 
near term...Strauss 
short term...Strauss 
long term...Frank 
aviation...Frank/Strauss 
marine...Frank/Strauss 

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