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Area forecast discussion 
National Weather Service Taunton Massachusetts 
557 PM EST Sat Mar 13 2010 


Synopsis... 
a major noreaster stalling near the middle Atlantic coast will lash 
southern New England with periods of heavy wind-swept rains late 
tonight through Monday...then drift out to sea southeast of 
Nantucket Monday night. Strong high pressure from the Great Plains 
follows...probably delivering a spell of nice Spring weather here for 
much of next week from Tuesday Onward. 


&& 


Near term /until 6 am Sunday morning/... 


Have issued a Winter Weather Advisory until midnight tonight for the 
higher elevations of northern Worcester County...southwestern New 
Hampshire...and the east slopes of the Berkshires. This for a mixture 
of snow...rain...and freezing rain. Temperatures around and above 
approx 1200 feet are around or even just below the freezing mark. 
This may allow for some light icing through midnight or so. 
Thereafter...the column should warm up enough for the precipitation 
to go over to mainly plain rain. 


Previous discussion follows... 


Rain will continue to overspread southern New England this evening. 
Winds will also steadily increase. The strongest winds at 4 PM were 
just reaching Long Island New York...and gusting up to 65 miles per hour. Kbox VAD 
wind profile showing east winds up to 45 knots around 2000 feet and 
getting stronger with time. 


Expecting these winds to gradually move north overnight. As such have 
issued a High Wind Warning for the coasts of Massachusetts and Rhode Island...with a Wind 
Advisory for interior southern New England. Some concern for the 
higher terrain of the Worcester Hills and Monadnocks...but not enough 
confidence to go with a warning there. 


Expecting temperatures to remain nearly steady or slowly rise 
tonight. Rain will become heavier overnight as well. Could be some 
sleet mixing in across the higher terrain of central Massachusetts...southern New Hampshire 
and the east slopes of the Berkshires...but not enough to warrant a 
Winter Weather Advisory. 


&& 


Short term /6 am Sunday morning through Sunday night/... 
Sunday... 
the models are in excellent agreement that heavy rain will be 
falling early Sunday morning across much of the region. This a 
result of an easterly low level jet 5 Standard deviations above 
normal resulting in very strong Omega. The NAM model quantitative precipitation forecast looks very 
reasonable and does a good job in showing the shadowing that will 
likely occur in the lower Connecticut River valley...with a 
secondary maximum along the east slopes of the Berkshires/Worcester 
Hills/Monadnocks. The main axis of heavy rain through Sunday 
morning looks to occur across eastern Massachusetts/Rhode Island. 


The strongest low level jet will be lifting northward during 
the morning. Therefore...the focus for the heaviest rain should 
shift into northeast Massachusetts by late morning/early afternoon. The very 
heavy rainfall that falls tonight into Sunday morning will result in 
areas significant urban and poor drainage street flooding. In 
addition...minor to pockets of moderate stream and river flooding 
are also anticipated. 


The easterly low level jet will also result in continued very strong 
wind gusts along the coast early Sunday morning...especially across 
northeast Massachusetts. Still the potential for easterly wind gusts of 45 to 
60 miles per hour during the early to middle morning hours. This combined with 
heavy rain and a very saturated ground will continue to result in 
areas of wind damage. As the low level jet lifts northward later in 
the morning/afternoon the winds should diminish some but it will 
remain windy on the coast. 


As mentioned above the heaviest rain will lift into northeast Massachusetts by 
late morning/early afternoon. There also is some middle level dry air 
that works northward into most of the region. However...weak 
shallow lift will continue to result in widespread light to moderate 
rain during the afternoon hours across most of the region. 
However...moderate to heavy rain will continue to affect northeast Massachusetts 
into the afternoon. 


During the day Sunday...expect the vast majority of the region to 
just see rain. However...a touch of wet snow/sleet may be observed 
along the highest terrain alon the east slopes of the 
Berkshires/Monadnocks. This would be generally at elevations of 
over 1500 feet. 


Sunday night... 
vertically stacked low pressure well south of our region will 
continue result in an onshore flow and widespread rain to the 
region. Will continue with categorical probability of precipitation and again show the 
heaviest precipitation falling across eastern Massachusetts...especially 
northeast Massachusetts. 


As mentioned above we are expecting the vast majority of the region 
to see the precipitation falling in the form of rain. However...the 
thermal profiles do show some cooling Sunday night. 
Therefore...expect the rain to change over to wet snow across the 
higher terrain of the east slopes of the Berkshires and particularly 
the Monadnocks. The thermal profiles are quite marginal and a small 
change can obviously make a big difference. However...the potential 
for a few inches of wet snow exists across the high terrain along 
the east slopes of the Berkshires/Monadnocks with a lower 
probability of a small accumulation in the Worcester Hills. Across 
the highest terrain of the Monadnocks at elevations of 1500 feet or 
greater the potential is there for 6 inches or even a bit more of 
wet snow. Will try to show this graphically in our snow accumulation 
forecast...but will not be issuing a watch since this area covers a 
relatively small area of Cheshire/Hillsborough counties. 
Nonetheless...this is something that certainly will have to be 
watched on later shifts and at least a Winter Weather Advisory may 
eventually be needed. 


&& 


Long term /Monday through Saturday/... 
coastal storm will continue to linger through Sunday. There is multi- 
model and ensemble support for categorical probability of precipitation for most of Monday. 
Therefore...we think Monday will feature occasional showery precipitation 
with bursts of heavier precipitation...mainly in the morning. The 
precipitation will tend to taper off and eventually end from northwest to southeast 
as the afternoon progresses but probably linger into the evening 
across far southeast mass. 


Precipitation type on Monday should mainly be in the form of rain. 
However...the column may become cold enough across the interior high 
terrain for accumulating snowfall...especially the Berks and 
Monadnocks. Wouldn/T be surprised if we/ll eventually need a Winter 
Weather Advisory for snowfall for these locations...and possibly even 
the Worcester Hills. Boundary layer temperatures will be key...as they have 
been for much of this winter. 


Winds will continue to be an issue as well...with persistent onshore 
fetch. Wind advisories may be needed Monday daytime for much of 
eastern New England. 


Rapid clearing takes place Monday night. Much of next week from 
Tuesday Onward looks good...lots of sun and warming temperatures. This will 
give US a good chance to dry out from all the rainfall. 


&& 


Aviation /00z Sunday through Thursday/... 
tonight...high confidence on IFR in wind driven rain. Strong east-NE 
winds 30-40 knots eastern Massachusetts and Rhode Island along with likely low level wind shear. Low 
confidence of ice across east slopes of the Berks. 


Kbos...MVFR ceilings/visibilities lowering to IFR. 


Outlook...Monday through Thursday... 


MVFR/IFR conditions in rain showers /possibly snow orh/ Monday. 
Northeast wind gusts to around 40 knots likely most 
terminals...especially East Coast of mass as well as Rhode Island. Rapid 
improvement to VFR late Monday afternoon and evening from north to S. VFR 
conditions and lighter winds and then expected for much of the 
upcoming week with no major weather systems anticipated. 


&& 


Marine... 
today...seas already building early this morning...up to 10 feet at 
at the southern buoys including southeast of Block Island at 09z. Buzzards 
Bay buoy gusting up to 32 knots. Continued Gale Warning with wind gusts 
up to 40 knots mentioned mainly on the open waters. 


Tonight...expect east-NE gusts up to 45 knots. Seas continue to quickly 
build especially on the eastern waters...forecast up to 20 feet late. 


Sunday and Sunday night... 
storm warnings continue Sunday morning as strong easterly low level 
jet will promote 55 knot wind gusts early in the morning. The 
strongest winds will lift northward Sunday morning...but storm force 
wind gusts may persist across our northern outer-waters into the 
afternoon. 


Otherwise...strong northeast gale force wind gusts are expected to 
continue Sunday night as vertically stacked system spins to our 
south. Have increased the model guidance seas as we expect to see 
at least 25 foot seas across eastern Massachusetts outer-waters through Sunday 
night with a continued excellent fetch. 


Outlook...Monday through Thursday... 


Gales continue through Monday then gradually diminish Monday night 
through Tuesday. Seas will remain dangerous through Monday 
night...especially east of the eastern mass coastline. Winds and 
seas continue to diminish Tuesday through Thursday as higher pressure 
builds in. 


&& 


Hydrology... 
the models continue in excellent agreement in showing widespread 
rainfall totals between 3 and 6 inches across much of the region 
through Monday. This is not only supported by the operational 
models but also backed up by the GFS/sref ensembles which gives US 
very high confidence. This a result of a strong easterly low level 
jet 5 Standard deviations above normal which is bringing copious 
moisture and strong lift into the region. The models also agree 
that the highest totals will be across the northeast Massachusetts region where 
the low level jet impinges on the region the longest. In 
addition...secondary maximums will likely occur along the east 
slopes of the Berkshires/Worcester Hills/Monadnocks as a result of 
the easterly upslope flow. Local minimums will occur in the lower 
Connecticut River valley as a result of shadowing. 


All in all...a widespread 3 to 6 inches of rain will fall with the 
heaviest tonight into Sunday morning. However...the rain will 
continue to right into Monday afternoon. This will result in 
significant urban and poor drainage street flooding. In 
addition...minor to moderate river flooding will likely occur at 
several locations as a result of the heavy rain. 


&& 


Tides/coastal flooding... 
will go ahead and convert the coastal Flood Watch to a warning 
across most of eastern Massachusetts. We expect widespread minor with pockets 
of moderate coastal flooding at the time of high tide late Sunday 
morning/early afternoon. The mrpsse is already underdone by 1 foot 
early this afternoon. Therefore...we expect a 2 to 2.5 foot storm 
surge at the time of high tide late Sunday morning/early afternoon 
along with winds still gusting to 45 miles per hour along the coast. This 
combined with 25 foot seas just offshore will lead to widespread 
minor to pockets of moderate coastal flooding. Will also go ahead and 
issue a coastal flood statement for Cape Cod/Nantucket for the 
potential of minor coastal flooding late Sunday morning. 


Will continue the coastal Flood Watch late Sunday night for the 
eastern Massachusetts coast and also extend it to Cape Cod/Nantucket for the 
late Sunday night high tide cycle. High seas and another 2 to 2.5 
foot storm surge will bring more widespread minor with pockets of 
moderate coastal flooding. 


Same story for Monday...east-northeast gales will continue to pile water up 
along the beach. Areas of moderate coastal flooding on the East Coast 
of mass will be possible. 


In addition...significant beach erosion is expected right through 
Monday. 


&& 


Climate... 
daily records for 3/14/10 
bos 1.93 1958 
pvd 1.28 1980 and previous 
orh 1.39 1986 
bdl 1.35 1986 


If Boston receives 3 inches in 1 day...this will be the first time 
since may 2006. The average for Boston is ... an easy feat. 
We will see how this divides through midnight this coming night. 


&& 


Box watches/warnings/advisories... 
CT...Wind Advisory until 8 am EDT Sunday for ctz002>004. 
Flood Watch through Monday morning for ctz002>004. 
Massachusetts...Flood Watch through Monday morning for maz002>021-026. 
Winter Weather Advisory until midnight EST tonight for maz002- 
004-008-009-026. 
Wind Advisory until 8 am EDT Sunday for maz002>005-008>013-026. 
High Wind Warning until 8 am EDT Sunday for maz022>024. 
High Wind Warning until 8 am EDT Sunday for maz006-007-014>021. 
Coastal Flood Warning from 10 am to 3 PM EDT Sunday for maz007- 
015-016-019. 
Coastal Flood Watch from Sunday evening through late Sunday 
night for maz007-015-016-019-022-024. 
New Hampshire...Flood Watch through Monday morning for nhz011-012-015. 
Winter Weather Advisory until midnight EST tonight for nhz011- 
015. 
Wind Advisory until 8 am EDT Sunday for nhz011-012-015. 
Rhode Island...Wind Advisory until 8 am EDT Sunday for riz001>004. 
High Wind Warning until 8 am EDT Sunday for riz008. 
Flood Watch through Monday morning for riz001>008. 
High Wind Warning until 8 am EDT Sunday for riz005>007. 
Marine...Storm Warning until 8 am EDT Sunday for anz232>237-255-256. 
Storm Warning from 11 PM EST this evening to 3 PM EDT Sunday 
for anz230-231-250-251. 
Storm Warning until 3 PM EDT Sunday for anz254. 


&& 


$$ 
Synopsis...ekster 
near term...ekster/Belk 
short term...Frank 
long term...ekster 
aviation...Belk/ekster/Frank 
marine...Belk/ekster/Frank 
hydrology...Frank 
tides/coastal flooding...Frank/ekster 

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