Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Gray ME
1034 am EDT Sat Mar 25 2017
a cold front shifts south of the region today and stalls there,
producing some rain and snow over southern New Hampshire.
High pressure builds in tonight from the north and will shift
east on Sunday. A warm front will approach from the southwest on
Sunday and cross the region Sunday night, providing a round of
mixed wintry precipitation Sunday night into Monday. Low
pressure moves north of the region on Tuesday and drags a cold
front through on Wednesday. High pressure will build in from
the west for the end of the week.
Near term /until 6 PM this evening/...
1030 am update...
latest radar imagery continues to show precipitation heading
towards southern New Hampshire and far southwest Maine from
western New England. Have continued high pops along the New Hampshire/Massachusetts
border for the next several hours. Thereafter, high pressure
shunts any precipitation well to our south.
Made small adjustments to temperatures and dew points based on
current conditions. It will be chilly but temperatures will be closer
to normal today than the very cold conditions yesterday.
Elevation will play a role in any snow, with the hilltowns
picking up an inch of snow and possibly more above 1000 feet.
have updated the forecast based on early morning
temperatures. Although the wind shift with the cold front has
moved through to southern New England, the cold air is really
only being felt across the state of Maine where temperatures
have actually fallen below freezing. Elsewhere temperatures have
remained above freezing tonight.
a cold front is sliding southward early this morning, and has
made its way to near the Massachusetts line already. This will
bring a light northerly wind today with some drier air.
Meanwhile, a mid level shortwave trough will squirt eastward
over the top of a Sharp Ridge over the eastern Great Lakes and
move through southern New England during the day today. This
will provide another round of precipitation, primarily to
southern New Hampshire. As precipitation arrives, once again
expect temperatures to cool and precipitation to quickly become
snow. Some light accumulation is possible, but temperatures are
expected to be near or above freezing which should prevent
significant accumulation. If all of the forecast quantitative precipitation forecast accumulates
as snowfall, then it is possible that up to 2 inches could
accumulate, but again we expect it to begin as rain and
temperatures to be near or above the critical melting point
which will limit accumulations to under an inch after the change
over. Further to the north and east across the eastern part of
the forecast area, temperatures will warm into the low to mid
40s this afternoon and stay dry.
Short term /6 PM this evening through 6 PM Sunday/...
high pressure shifts over the area tonight which will allow
winds to go calm with good radiational cooling conditions. How
low we go will depend on the amount of low level moisture. It
looks like at least northern areas will have enough dry air in
place to allow temperatures to drop into the single digits,
while southern New Hampshire and coastal Maine may only drop
into the 20s.
As the high shifts east on Sunday it will set up an easterly low
level flow across New England. This type of flow promotes cold
air damming to the east of the mountains. With cold
temperatures expected to start the morning, the damming should
keep the temperature from warming all that much across eastern
New Hampshire and coastal/interior Maine. By Sunday afternoon,
the onshore low level flow may bring enough moisture to produce
some light drizzle or freezing drizzle, mainly over eastern New
Hampshire and southwest Maine. The temperature is expected to be
fairly close to the critical 32 degree mark, so will need to be
alert for the potential for light icing to occur. Models would
like to warm temperatures above freezing Sunday afternoon, but
with a cold air dammed flow that may not happen. Have lowered
forecast temperatures below model guidance to account for this.
Long term /Sunday night through Friday/...
at 500 mb, coldest core of air sits north of Labrador through
the weekend, with troughing shifting eastward across far
northern Maine tonight and Sunday. Several weak waves will move
through zonal flow behind this system from Sunday through
Wednesday, before a larger trough closes off east of the
Maritimes at then end of the week. The good news is that the
coldest air retreats poleward, and the bad news is we have to ht freezing rain expected Sunday night into Monday morning,
especially away from the coast.
short term...light winds are expected over the waters as high
pressure crosses the region through Sunday.
Long term...weak low pressure developing over the waters Monday
should keep winds below Small Craft Advisory levels, but as the low shifts east
Tue-Wed, will see northwest flow pick up and may need Small Craft Advisory Tue night and