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fxus61 kbox 061409 
afdbox 


Area forecast discussion 
National Weather Service Taunton Massachusetts 
1009 am EDT Monday Jul 6 2009 


Synopsis... 
low pressure from north of the Great Lakes approaches late today 
and moves over New England Tuesday...producing scattered showers and 
possible thunder Tuesday and Wednesday. High pressure brings drier 
and warmer weather late in the week. A cold front will move through 
New England Saturday night or Sunday. 


&& 


Near term /until 6 PM this evening/... 
middle level low remains north of the lakes today with main focus for 
convection likely remaining north and west of southern New England. However...low probability 
of a few storms spilling into northwest zones later this afternoon. 


500 mb temperatures -14 to -16c across north zones but low level moisture will 
be a limiting factor with dewpoints in the low/middle 50s. Modified een 
sounding for 79/55 yields MLCAPES below 500 j/kg so any convection 
will be isolated to widely scattered. Will continue low chance probability of precipitation for SW New Hampshire and 
northwest Massachusetts with slight chance to mht-baf. 0-6km shear near 40 knots so an isolated 
storm could produce marginally severe hail and wind...but limited 
instability does not support organized severe. 


&& 


Short term /6 PM this evening through 6 PM Tuesday/... 
tonight...leftover scattered showers or thunderstorms possible 
across the far interior. Otherwise a seasonably mild night expected 
with light southwesterly flow advecting higher dewpoint air. Some 
patchy fog is expected to develop. 


Tuesday...a cold front will aproach from the west. Showers and 
thunderstorms are expected to become more numerous by afternoon as 
the cold pool sinks southeast. 500 mb temperatures cool to -16 to -18c late in 
the day. In addition moisture convergence is expected to increase 
along the frontal boundary as it slowly crosses the forecast area 
from west to east. Noting dewpoints rising into the lower 60s in 
southern New England with dewpoints dropping into the 40s and 50s 
west of the County Warning Area. In addition a 100 knots h25 jet streak 
will be centered over the region with the left front exit region 
nearby. 


Main focus area for convection should occur across western New 
England by midday spreading east. Southwesterly flow should help 
boost temperatures well into the 70s across portions of the interior 
with surface dewpoints in the lower to middle 60s. This would yield 
surface based convective available potential energy of around 1000 j/kg. The potential exists for 
severe weather but will not use enhanced wording in the zone forecast product at this 
time. Will await future model guidance to refine the severe 
potential and highlight concerns in the hazardous weather outlook. 


&& 


Long term /Tuesday night through Sunday/... 
lingering convection early Tuesday night. The NAM keeps indices up 
through the night with ml cape 500-1000 j...totals around 50...Li -2 
to -3. GFS stabilizes overnight with totals dropping back to around 45 
while the Li drops back to 0-1. It is possible convection could 
linger through the night...for now we will diminish probability of precipitation after midnight. 


Wednesday...second verse but not quite like the first. Stability 
indices bottom out again as upper low and cold pool hover over New 
England. Coldest temperatures aloft are forecat over northern mass/southern 
New Hampshire while most unstable indices are over eastern mass. We will 
contiune to indicate chance probability of precipitation for showers and toss in isolated 
thunder. Wet bulb zero is forecast at 8000-8500 feet. Am not 
mentioning hail at this time...but it is on my mind. 


High pressure builds in Thursday...but some question as to how fast 
the surface low moves off. If slow to move off then we may have an 
east/northeast flow into eastern Massachusetts which would at least 
hold down daytime temperatures and may hold in cloud cover longer than we/d 
like. For now we will keep 50-70 percent sky cover for Thursday morning 
and engage in some positive thinking for the afternonn with mostly 
clear skies. 


Friday looks dry as high pressure moves over the region. 


Cold front approaches for the weekend. Timing is a question with the 
European model (ecmwf) slower and the GFS faster. We prefer the slower European model (ecmwf) solution 
in general. A forecast update at 5 am incorporates changes from this 
solution. 


&& 


Aviation /14z Monday through Friday/... 
today and tonight...VFR. Isolated to widely scattered rain showers/thunderstorms and rain kbaf-kmht and 
points northwest 21z-03z. Patchy fog may bring local MVFR visibilities after 06z. 


Tuesday...VFR becoming widespread MVFR with local IFR conditions. 
Patchy morning fog. MVFR visibilities and ceilings in numerous showers and 
thunderstorms developing after 16z. Some thunderstorms may bring 
strong winds and hail particularly west of i95. 


Outlook /Tuesday night through Friday/... 


Tuesday night and Wednesday...VFR early with scattered MVFR in 
showers and thunderstorms. Areas of IFR in fog overnight and early Wednesday. 


Thursday...VFR. Potential for east winds at the Massachusetts coast 
which may bring in IFR ceilings and fog. 


Friday...VFR. 


&& 


Marine... 
today through Tuesday...winds and seas expected to remain below 
Small Craft Advisory criteria through Tuesday. A cold front 
approaching late Tuesday will bring showers and thunderstorms. Some 
thunderstorms may bring strong winds and hail. 


Outlook /Tuesday night through Friday/... 


Winds and seas are expected to remain below Small Craft Advisory levels 
during the period. 


&& 


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


&& 


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