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Area forecast discussion 
National Weather Service Taunton Massachusetts 
411 PM EDT Friday Aug 8 2008 


Synopsis... 
anomalous upper level trough will remain over New England for much 
of the next week. This will bring slightly below normal 
temperatures and bouts of shower and thunderstorm activity at times. 
A threat for a period of heavier rain may develop sometime later 
Sunday into Monday. 


&& 


Near term /until 10 PM this evening/... 
convection increasing in coverage across CT valley and Berkshires at 
3 PM. MLCAPES around 1000 j/kg in this region and instability axis 
extends eastward into north Rhode Island and central Massachusetts so activity may continue to 
increase next 1-2 hours as it moves eastward. 


Severe weather threat will continue this afternoon with large hail the 
primary threat. Laps soundings do show inverted v profile so some 
of the stronger/deeper cores may also have some strong wind. 


Latest mesoanalysis also showing 0-6km shear 30-40 kts across east Massachusetts 
so any storms in this region next 1-2 hours have potential to 
organize into line segments or acquire weak rotation...but shear 
forecast to weaken through the afternoon. 


Expect activity to lift northward by this evening so will have 
highest probability of precipitation this evening northwest zones with probability of precipitation decreasing to the 
south. 


&& 


Short term /10 PM this evening through Saturday night/... 
weak cool front moves offshore later tonight with general drying 
trend and any showers/thunderstorms should be north of region by midnight 
with dry overnight period. 


Sat...looks like a nice day with much less coverage of 
showers/tstms. Digging upper low through northern Great Lakes will 
result in rising heights and 500 mb temperatures warm slightly leading to 
weak instability and marginal middle level lapse rates. We have just 
slight chance probability of precipitation in the grids north of the Mass Pike region during 
the afternoon...but overall looking mostly dry across southern New England. 850 mb 
temperatures +11 to +12 support maxes in upper 70s to lower 80s...but light 
flow will promote local seabreezes in afternoon. 


Sat night...upper low forecast to amplify as it moves through eastern 
lakes with any convection confined to the west of southern New England through 12z 
sun closer to upper vortex. No probability of precipitation in forecast for Sat night. 


&& 


Long term /Sunday through Friday/... 


Sunday and Sunday night... 
an anomalous closed upper level low over the Great Lakes will eject 
shortwave energy into southern New England. While the morning 
should be dry...showers and thunderstorms will develop during the 
afternoon across the interior and make their way towards the coastal 
plain toward evening or at night. Feel areal coverage should be 
fairly extensive so will depict an area of likely probability of precipitation working their 
way from west to east. 500 mb temperatures of around -15c will once 
again create steep middle level lapse rates. In addition...0 to 6 km 
shear values are expected to increase to between 30 and 40 knots 
which is fairly impressive. Low level moisture though is somewhat 
marginal and is the one limiting factor. If we are able to get 
sufficient moisture back...scattered severe thunderstorms are likely 
so this will have to be watched closely. The best chance may be in 
the middle to late afternoon and even into the night with the cold 
temperatures aloft. In addition...there is also some concern for 
locally heavy rainfall leading to more urban street flooding. 
Highs on Sunday should be mainly in the upper 70s with a few 
locations across southeast Massachusetts/Rhode Island reaching into the lower 
80s. Lows Sunday night should mainly be in the upper 50s to lower 
60s. 


Monday... 
12z GFS model appears too fast in lifting out the upper level low 
compared to the other models and the GFS ensembles. 
Therefore...will continue with high chance probability of precipitation for additional 
scattered showers and thunderstorms. Later shifts may have to 
upgrade to likely probability of precipitation if ensembles are on the right track. 
Again...we have some concern for the potential of heavy rain and 
more urban street flooding. Highs should mainly be in the upper 
70s. 


Tuesday... 
at this point it looks like mainly a dry day as we mix out our low 
level moisture on westerly flow. However...its still cold aloft so 
can not rule out a few isolated afternoon or evening showers. 
Therefore...will go with just a 20 pop in the forecast to cover this 
potential. Highs should mainly be in the lower 80s under partly 
sunny skies. 


Wednesday through Friday... 
a low confidence forecast this far into the future. 
However...models agree on another round or two of showers and 
thunderstorms along a cold front. Timing is really tricky this far 
in advance...but best opportunity at this time appears to be the 
second half of Wednesday into Thursday. For now we will go with 
mainly a dry forecast by Friday...but things can change this far out. 


&& 


Aviation /20z Friday through Wednesday/... 
areas of MVFR in scattered showers/thunderstorms through early evening...then MVFR 
or IFR ceilings possibly developing mht/bdl/baf/orh/bos late tonight. 


Sat...local MVFR/IFR ceilings early morning interior 
location...otherwise VFR. Slight chance of a shower mainly north of 
baf-orh-bos in the afternoon. 


Outlook...Sunday through Wednesday... 


Sunday and Monday... 
times of MVFR/IFR conditions in showers and thunderstorms Sunday 
afternoon into Monday. Patchy fog and low clouds are also expected 
at times. 


Tuesday and Wednesday... 
mainly VFR but a few hours of patchy ground fog are possible early 
in the morning. Conditions may deteriorate to MVFR/IFR later on 
Wednesday with the next possible round of showers/thunderstorms. 


&& 


Marine... 
through Sat night...winds and seas below Small Craft Advisory threshold. 


Outlook...Sunday through Wednesday... 


Seas and winds should generally remain below Small Craft Advisory thresholds. 
However...there is a low probability of marginal 25 knot southwest 
wind gusts and 5 foot seas across the southern outer-waters on 
Monday or Monday night. 


Mariners will have to be on the lookout for scattered 
afternoon/evening showers and thunderstorms which could bring 
locally higher winds and seas along with an attendant lightning 
threat. A prolonged period of heavier rains could occur Sunday night 
into Monday. 


&& 


Box watches/warnings/advisories... 
CT...none. 
Massachusetts...none. 
New Hampshire...none. 
Rhode Island...none. 
Marine...none. 


&& 


$$ 
Synopsis...Frank 
near term...kjc 
short term...kjc 
long term...Frank 
aviation...rlg/Frank 
marine...kjc/Frank 

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