Weather

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Area forecast discussion 
National Weather Service Taunton Massachusetts 
349 PM EDT Thursday Aug 28 2008 


Synopsis... 
high pressure dominates our weather through the end of this week. A 
cold front will cross southern New England Saturday night. This 
should be followed by high pressure from Canada providing dry and 
warming weather through midweek. 


&& 


Near term /until 6 PM this evening/... 
minor adjustment regarding hourly temperatures...dewpoints and sky cover. 
Otherwise little additional change necessary at this time. 


Previous discussion... 
high thin clouds have pushed across most of southern New England. The 
rain associated with the remnants of Fay remains well to our 
southwest...over western New York/PA into the Middle Atlantic States. A high 
pressure ridge remains across New England...and will continue to 
provide dry weather through today. 


Winds will shift to NE-east as the high starts to push NE into Maine... 
but the ridge axis will remain over New England. So...expect dry 
weather with wispy high clouds through the day. Highs will be a tad 
warmer than yesterday...still mainly in the 70s with a couple of 80 
degree readings. 


&& 


Short term /6 PM this evening through Friday night/... 
tonight...high pressure ridge continues across New England...though will 
start to push east overnight. With onshore flow...overnight lows will 
not be quite as low as last couple of days along with slowly 
increasing humidity. Some models do try to bring in low clouds along 
the coast with onshore flow...along with cutoff low S of Nova 
Scotia. Have mentioned possibility in a couple of coastal Airport 
locations. Overnight lows will mainly be in the 50s. 


Friday...the ridge finally breaks down during the day. Models 
continue to keep precipitation west of the region. A front begins to approach 
out of the eastern Great Lakes as winds begin to shift to se-S. 
Clouds will thicken during the day especially along the coast...but 
it should remain dry. Highs will once again be in the 70s...though a 
few degrees cooler than today due to the cloud cover. 


&& 


Long term /Saturday through Thursday/... 
the 12z GFS and 00z European model (ecmwf) look similar in handling the pattern over 
the USA this period. Main features are a weak cold front moving 
through New England Saturday and moving offshore early Saturday 
night...and building upper high pressure over the eastern USA 
thereafter. 


The cold frontal passage on Saturday looks like a marginal event. Jet level 
support trails the front late Saturday night. Middle level winds are 
forecast around 30 knots and low level winds at 15 knots. The best 
dynamical support based on the 12z runs would be in northern and 
western sections...but 4 more model runs between now and then the 
timing could shift enough to move this favored area. Precipitable 
water values are expected to climb to 1.7 inches which might support 
a few heavy showers. For now we will maintain low end chance probability of precipitation 
for Saturday afternoon and early night. 


Closed upper low over the Maritimes will keep a cool northwest flow 
over New England Sunday with -12c aloft over Maine and New Hampshire...and 
probably into eastern mass as well. This would support some diurnal 
cumulus development midday...then diminishing as the low moves east. 


Otherwise the upper pattern digs a trough over the western USA and 
builds a ridge over the east. This means generally dry weather for US 
Sunday through at least Wednesday. 850 mb temperatures start around 11c 
Sunday and increase to 18c Wednesday...suggesting highs around 80f 
Sunday warming through the 80s through midweek. If 850 temperatures actually 
linger near 18c Wednesday...then highs near 90f would be possible. 
For now we will go above guidence but keep it in the 80s. 


On Thursday a cold front approaches through the eastern Great 
Lakes. Low pressure lingers off the Maritimes. The GFS keeps US 
between systems...warm and dry...while the 00z European model (ecmwf) drifts the 
ocean storm west and brings a chance of showers to eastern 
sections. Inclination is to keep the weather dry Thursday. Could be a 
chance of showers Thursday night especially in northern sections...with 
the approaching cold front. 


&& 


Aviation /20z Thursday through Tuesday/... 
today...VFR. 


Tonight...VFR. Local MVFR visibilities in patchy fog after midnight. 


Friday...local MVFR visibilities in patchy early morning...improving by 
14z. Otherwise VFR. Expect ceilings at or above 12kft. 


Outlook...Saturday through Tuesday... 
generally VFR through the period. Patchy MVFR/IFR in showers/thunderstorms 
Saturday afternoon and night with cold front passage. Northwest 
surface flow Sunday through Tuesday. 


&& 


Marine... 
today and tonight...expect NE winds at 15 knots or less with highest 
wind on the far east waters. Seas will be up to 4 feet. NE swells from 
stationary low pressure S of Nova Scotia could bring seas up to 5 feet on 
the far outer waters. 


Friday...NE winds will shift to east as ridge shifts into Maine and the 
Maritimes. Seas will remain at 4 feet or less. 


Outlook...Saturday through Tuesday... 
light winds and seas through most of the period. A cold front moving 
across the waters Saturday night may bring scattered showers and 
thunderstorms. Low pressure lingering south of Nova Scotia may send 
4 to 5 foot swells to the waters east of Cape Cod and Nantucket 
Monday. 


&& 


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


&& 


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