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Area forecast discussion 
National Weather Service Taunton Massachusetts 
1016 am EDT sun Jul 6 2008 


Synopsis... 
a Bermuda high pressure system will bring increasingly warm and 
humid air into southern New England through Wednesday. Temperatures may 
exceed 90 on Tuesday and Wednesday across much of the region with high humidity 
levels. In addition...isolated to scattered strong afternoon and 
evening thunderstorms are expected at times through the middle of the 
week until drier and somewhat cooler air arrives by Thursday or Friday. 


&& 


Near term /until 6 PM this evening/... 
clouds and fog still slow to erode due to shield of middle/high clouds 
above...but breaks have been noted across SW New Hampshire and northern Massachusetts where 
most sunshine is expected this afternoon. Light S/southeast flow should keep 
clouds locked in fairly well closer to S coast. 


Area of convection from southern New Jersey to well southeast of Long Island does 
not look like it will impact Nantucket or S coast through afternoon... 
as it runs up into more stable airmass. Across interior...we may see 
isolated showers/storms develop where we have a bit more instability 
/cape only up to 750/ and weak convergence from upper trough moving 
through. 03z srefs pinpoint areas from Berkshires into northern CT 
and central Massachusetts late this afternoon...as does 12z NAM to a lesser 
degree. We will have slight chance probability of precipitation in much of interior as a 
result...though we certainly do not expect to see a lot of activity 
develop. 


&& 


Short term /6 PM this evening through 6 am Monday/... 
for tonight...main concern will be development of dense fog near S 
coast as S flow continues with higher dewpoints. We may need to hit 
fog harder in later forecasts. 


Any leftover scattered showers/thunderstorms will taper off across inland 
areas...but may linger along the immediate S coast and islands. 
Appears weak waves may work into those areas with the broad SW flow. 
Will also notice dewpoints increasing overnight as tropical airmass 
takes over. 


Will be a warm and muggy night as some locations may not see temperatures 
drop below 70...a typical Summers night. 


&& 


Long term /Monday through Saturday/... 
Monday... 
any leftover precipitation along the southeast New England coast 
should exit the region by early morning. Otherwise...fog patches 
burn off by middle morning and a southwest flow of air will result in a 
very warm and humid day. Partly sunny skies with 850 mb temperatures 
around +16c should yield highs the upper 80s away from the marine 
influence of the South Coast/cape/islands. It will also feel quite 
humid as surface dewpoints will be climbing into the lower 70s. 


Scattered thunderstorms are forecast to develop during the afternoon 
mainly along and northwest of a Boston to Providence line and 
particularly across the interior. It will be quite unstable with 
convective available potential energy in the 1000-2000 j/kg range. However...no real trigger 
evident...so am expecting convection to be scattered based on local 
pockets of heating...with the any storms being fed by the outflow 
boundaries from surrounding storms. Cannot rule out a localized 
severe storm but wind fields are relatively weak. 


Monday night... 
scattered showers/thunderstorms should come to an end during the 
evening with the loss of daytime heating. We should see areas of 
fog develop with high dewpoints...particularly in locations that see 
precipitation. Lows should again only fall into the upper 60s and 
lower 70s. 


Tuesday... 
a hot and humid day is on tap for southern New England. Warming middle 
level temperatures should support highs mainly in the lower 90s away 
from the South Coast/cape/islands. Surface dewpoints in the lower 70s 
or just above 70 will make it feel quite uncomfortable outside with 
heat index values possibly in the middle to upper 90s. Southwest to west 
winds will reach 30-35 kts aloft and some gusts to 20-30 miles per hour are 
possible at the surface in the afternoon and early evening. 


Despite warmer temperatures at both 700 mb and 500 mb...the 
atmosphere will not be completely capped. The 18z and 00z GFS runs 
have consistently shown a band of high relative humidity...and implied convection... 
streaming eastward from the Midwest and arriving in western Massachusetts and 
western CT around 00z Wednesday. With the high heat and humidity in 
place...think we will pop scattered but strong thunderstorms late in 
the day as this arrives. It may weaken as it heads toward the coast 
later Tuesday evening. 


Wednesday... 
little change to previous forecast reasoning. An approaching cold 
front and 850 mb temperatures warming to around +18c should yield 
another hot and humid afternoon. Continued above guidance values for 
temperatures...especially considering the downslope flow. Have 
highs from 90 and 95 away from the South Coast/cape/islands. Heat 
index values will reach the 95 to 100 degree range as high dewpoints 
will remain in place. It will still be on the breezy side but not 
quite as strong as Tuesday. 


Main concern will be for strong to possibly severe thunderstorms 
during the afternoon and evening as the cold front drops into the 
region. With decent wind fields aloft...could see damaging straight 
line winds as the main threat. 


Thursday and Friday... 
drier air follows behind the front. Kept some low chance probability of precipitation 
Thursday morning mainly along and southeast of I-95. One fly in this 
ointment is that showers/thunderstorms could refire in the afternoon 
if the front has not completely cleared our region as expected. Highs 
should be mainly in the 80s over this time and humidity levels should 
not be as oppressive as drier air works into the region. 


A sunny and dry day is forecast for Friday with seasonable highs in the 
80s and lower humidity. 


Saturday...high pressure moves off to the east but am still expecting 
sunshine and warm temperatures. 


Next chance of rain would be with an approaching front Sunday night 
and Monday next week...per GFS...but that is a long way off. 


&& 


Aviation /14z Sunday through Thursday/... 
MVFR throughout most of region into afternoon...but interior 
terminals should improve to VFR as cloud deck slowly lifts. Potential 
for isolated thunderstorms kbdl/kbaf/korh after 20z. Activity S of New 
England should remain well offshore. 


Tonight...any scattered showers/thunderstorms will end by around 03z. Otherwise 
expect patches of MVFR-IFR ceilings/visibilities in fog. LIFR expected 
kfmh/khya/kack. 


Outlook...Monday through Thursday... 


Monday through Wednesday...we are mainly looking at VFR 
conditions from the late morning through the early evening hours 
during this time. However...rounds of scattered 
showers/thunderstorms will result in time of MVFR/IFR conditions. 
In addition...MVFR/IFR conditions expected overnight as areas of low 
clouds and fog patches develop in the very humid airmass. 


Thursday...VFR except for a chance of MVFR ceiling/visibility in rain shower/thunderstorm cape 
and islands in the morning. 


&& 


Marine... 
this afternoon...light S/southeast winds with seas 1 to 3 feet. Fog will 
slowly lift through early afternoon...and showers/storms well S of 
New England will pass southeast of Nantucket. 


Tonight...winds will shift to SW at 10 knots or less. Wave models are 
suggesting that the seas will pick up to 4 feet on the southern 
waters...likely due to increasing SW fetch around the large western 
Atlantic high. At this point...expect to remain below small craft 
criteria. Will also see patchy fog redevelop. 


Outlook...Monday through Thursday... 


Persistent south to southwest flow through the middle of the week 
will allow for Small Craft Advisory seas in the Monday through Wednesday time frame across our 
southern outer-waters. In addition...wind gusts to near Small Craft Advisory 
conditions are expected Monday...with gusts to 30 knots forecast late 
Tuesday into Tuesday night...then again gusts to Small Craft Advisory criteria possible Wednesday. 
Areas of dense fog will affect the waters at times during the 
overnight and early morning hours as very high dewpoint air moves 
over the relatively cool ocean waters. 


If the cold front moves through without slowing down...then 
visibilities will improve early Thursday as lower dewpoint air gradually 
filters in. 


&& 


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


&& 


$$ 
Synopsis...gaf 
near term...jwd - 1015 am 
short term...evt 
long term...gaf 
aviation...jwd - 1015 am 
marine...jwd - 1015 am 

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