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Area forecast discussion 
National Weather Service Taunton Massachusetts 
1129 PM EDT Thursday Jul 24 2008 


Synopsis... 
a slow moving cold front will bring heavy rainfall and possible 
flooding to portions of southern New England through this evening. 
A second cold front will approach late this weekend with another 
round of showers and thunderstorms possible. Unsettled weather will 
remain across the region through early next week. 


&& 


Near term /until 6 am Friday morning/... 
moist south flow continues across the eastern half of southern New 
England this evening. Precipitable water values around 1.2 inches in 
the CT River Valley to around 1.9 inches along I-95 in the coastal 
plain. The right entrance region of a 110 knot upper jet is overhead 
helping maintain the lift...along with lingering instability /lifted 
index values remain below zero/. These factors will remain in place 
for a few more hours. Currently expect the back edge of the 
precipitation to finally move off the coast of Cape Cod between 2 and 
4 am. 


A cold front in eastern New York state will then sweep through 
overnight. This will move out the high moisture and also stabilize 
the atmosphere. So we will maintain high probability of precipitation this evening across the 
east with a diminishing trend during the night. Moisture aloft also 
dries overnight...so we would expect some clearing late. 


Until this front actually does move through our region...could still 
see isolated showers pop up. Favored areas this evening would be the 
east slopes of the Berkshires into Cheshire County New Hampshire where the 
terrain will provide and additional triggering mechanism. 


Note...a storm survey was conducted today on the damage that occurred 
across the East Bay portion of Rhode Island and adjacent southeast Massachusetts Wednesday 
afternoon. A public information statement was issued at 505 PM with 
information on an EF1 tornado that occurred in Warren Rhode Island and Swansea 
Massachusetts. Please refer to bospnsbox for more details. 


&& 


Short term /6 am Friday morning through Friday night/... 
we maintained a chance of showers on the cape and islands. Otherwise 
the upper trough pulls out to the northeast with a light dry airmass in 
place. Plenty of sunshine through the day which should promote good 
deep mixing. With 850 mb temperatures of 14c and 10c at 800 mb / 
equivalent to 15c at 850 mb / we would expect maximum temperatures Friday in the 
middle 80s...cooler at the coast. 


Fair dry weather continues Friday night with patchy fog in the light 
flow overnight. 


&& 


Long term /Saturday through Thursday/... 
models continue to show wide spread with the surface features of 
individual model members through a majority of the suite...so not a 
whole lot of confidence with this portion of the forecast. Upper 
level features appear to be more stable...with continuation of the 
long wave troughs on the west and east coasts with the ridge across 
the middle of the country. Excellent extended discussion available 
from HPC long range unit. 


Saturday...lots of questions remain on the timing of the approaching 
front out of the Great Lakes around the cutoff upper low over 
Quebec. At this point...appears that the front may hold off to give 
a partly to mostly sunny day especially over eastern areas. May see 
scattered showers/thunderstorms during the afternoon moving into S New Hampshire/west Massachusetts 
into Worcester County. 


Sunday and Monday...current trend is that the front will crawl 
across the region...with chance-likely showers/thunderstorms through this 
period. Front should push just offshore Monday morning...but chance 
probability of precipitation will continue through most of the day especially along the 
coast closer to the front. 


Tuesday...front stalls S of New England. Clouds may linger...mainly 
over central and southern areas. For now...have removed mention of 
showers from forecast...but tough call especially if any waves form 
on the front. 


Wednesday...appears to be a good day as front sags a bit further S. 
Might see a few showers sneak into south coastal areas late in the 
day and at night. However...still not very confident. 


Thursday...models suggest that a wave may form on the front...which 
may allow the front to lift closer to the region. Have brought 
showers/thunderstorms back in. 


&& 


Aviation /04z Friday through Tuesday/... 
generally MVFR ceilings this evening...with scattered IFR possible 
in heavier showers and isolated thunderstorms. Locally heavy rainfall 
possible. Conditions will in general improve overnight as the rain 
moves off to the east...but clearing and light flow will allow patchy fog 
especially in the western valleys such as around kbaf and kbdl. 


Conditions improve to VFR Friday. Scattered IFR in fog Friday night 
especially in the favored valleys. 


Outlook...Saturday through Tuesday... 


Sat...VFR. Conditions lowering to MVFR-IFR in scattered rain showers/thunderstorms and rain and 
patchy fog from west-east Sat night. 


Sun and Monday...MVFR-IFR am...then MVFR PM scattered shra/tsra. Fog patches 
mainly during the overnight hours. 


Tuesday...MVFR in patchy fog and scattered showers in the morning east portion... 
otherwise VFR. 


&& 


Marine... 
Small Craft Advisory continues along the outer and southern inner 
waters tonight. Seas maximum out tonight south of Marthas Vineyard...then 
diminish during Friday. We maintained the high surf advisory as is in 
Rhode Island and adjacent Massachusetts...with improving conditions Friday. We 
extended the high surf advisory in Marthas Vineyard and Nantucket 
until noon. These islands will be close to lingering 7 foot seas 
during the morning. But even these conditions should improve Friday 
afternoon. 


Outlook...Saturday through Tuesday... 


Saturday...S winds at 10-15 kts with some gusts to 20 knots expected 
with approaching front. Seas will build to around 5 feet on the 
southern outer waters at night. Visibilities reduced in patchy fog...with 
some areas of fog S and east of Nantucket with warm air over the cooler 
waters. 


Sunday and Monday...small craft conditions expected through Sunday 
night on the southern outer waters with seas up to 6 feet possible. 
Expect showers/thunderstorms along with patchy fog over the waters. 


Tuesday...winds shift to west and diminish. Seas also subside below 
5 feet. 


&& 


Hydrology... 
Flood Watch continues for eastern Massachusetts and portions of Rhode 
Island until 2 am. 


The eastward progression of the back edge of the convection has 
slowed down to about 10 miles per hour. This slower progression will keep 
showers and thunderstorms tracking through eastern Massachusetts for the next 
few hours. Radar is indicating that rainfall rates have been reduced to 
0.1 to 0.5 inch per hour...localized higher amounts. Kokx radar 
indicating additional thunderstorms upstream...so could still 
experience periods of heavy rain this evening. 


Monitoring the lower Connecticut River at Hartford and Middletown. 
There is a chance for minor flooding at these two forecast points 
late tomorrow. Historically...July flooding on the lower Connecticut 
is rare. The last time the river went to flood in Hartford during 
the month of July was 35 years ago...in 1973. 


&& 


Box watches/warnings/advisories... 
CT...none. 
Massachusetts...high surf advisory until 8 am EDT Friday for maz020. 
Flood Watch until 2 am EDT Friday for maz006-007-013>021. 
High surf advisory until 12 PM EDT Friday for maz023-024. 
New Hampshire...none. 
Rhode Island...high surf advisory until 8 am EDT Friday for riz006>008. 
Flood Watch until 2 am EDT Friday for riz005-007. 
Marine...Small Craft Advisory until 6 am EDT Friday for anz232-233-250. 
Small Craft Advisory until 6 PM EDT Friday for anz235-237-254- 
255. 


&& 


$$ 
Synopsis...wtb 
near term...wtb/Belk 
short term...wtb 
long term...evt 
aviation...wtb/evt 
marine...wtb/evt 
hydrology...Belk/nmb 

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