Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 181124
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
624 AM EST Mon Feb 18 2019

.SYNOPSIS...
Low pressure will track south of Cape Cod early today and bring
light snow to southern and coastal sections. High pressure and
drier air dominates the weather for Tuesday and Wednesday. The
next chance of precipitation occurs Wednesday night into
Thursday as low pressure approaches from the south and west.
More Canadian high pressure builds into the region Friday and
Saturday. Low pressure moves up to the New England coastline
next Sunday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

624 AM...Minor ESTF update to reflect the current mesonet and
radar trends in near term grids.

Prev Disc...
GOES water vapor imagery showed a shortwave impulse vicinity of
the lower Great Lakes. At the surface a 1006 millibar low over
northwest Pennsylvania with a second 1010 millibar low off the
DELMARVA region. NWS Doppler Radar mosaic showed a broken area
of return along and ahead of this feature. For today...the
offshore low will gradually take over and track east-northeast
to the south of Cape Cod by early afternoon. The forecast area
remains on the northern periphery of this system with a tight
south to north gradient in precipitation amounts. Snowfall
amounts will range from 2 to 4 inches near the Massachusetts
border but quickly drop off further north and east with
locations near the international border and near the Penobscot
Valley struggling to see much more than a dusting. In
fact...snow will quickly taper from northwest to southeast this
afternoon as the surface low exits into the maritimes along with
associated shortwave impulse.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Clearing and colder tonight behind the departing disturbance
as high pressure builds east into New England from the northern
plains. Lows will be zero to ten below across the mountains and
zero to ten above for the remainder of the region. Gusty
Northwest winds should produce wind chills in the advisory range
late tonight and Tuesday morning near the international border.
Mostly sunny and cold on Tuesday under the surface high with
high temperatures ranging from the teens across the mountains to
the lower and mid 20s elsewhere.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
The lack of a stable 500 Mb pattern across the nrn hemisphere
continues this winter, and the flow remains progressive, with
more frequent, but generally less significant, systems moving
through. Temps will continue to vary, but nothing ever gets
very cold or very warm thru the long term forecast. Also, this
will continue to lead to changing p-types within each system.

Sfc ridge will slowly track west to east across the CWA Tue
night into Wed, which will lead to mainly fair wx. Should see
decent rad cooling Tue night, and lows will range from 5 to 10
below zero in the colder mtn valleys to 5 to 10 above in srn NH
and along the coast. Most of Tuesday should bee partly to mostly
sunny, with clouds moving in from the SW late in the day. Highs
will be a little milder than Tue, ranging from the low to mid
20s in the mtns, to around 30 in srn NH and on the coast.

The next system will affect the region Wed night into Thu, and
once again models say we miss out on a phase of the nrn and srn
streams, which will occur to our east.   It seems almost
impossible to get phasing west of 70W this winter, and this
system looks no different. This allows the nrn stream sfc low to
hang around long enough to break down the ridge to the N and E
and the cold air will not hold, as E-S flow ahead of the srn
stream low pushes warm air into the CWA. P-type will start as
snow Wed night, most likely after evening commute, and will see
a period of snow overnight, with some warmer air initially
moving aloft in srn NH to produce some sleet, and warm the
boundary layer enough along the coast by Thu morning to change
that to rain as well. Most places look to see a few inches of
snow before the change over, and the Thursday morning commute
will be impacted bu snow or a wintry mix. It`s fast mover, and
current QPF are generally below a half inch, so it should all
be done by around midday Thu, with some clearing in the
afternoon. Highs on Thu will range from the low to mid 30s in
the mtns to around 40 in the south.

Some slightly colder air moves in for Fri/Sat, as sfc high
moves across the CWA, but temps stay pretty close to normal.
Watching another system for late in the weekend, which once
again looks like a snow to rain affair, but at day 7, the
confidence is low.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
Short Term /through Tuesday/...Areas of MVFR developing this
morning in -sn with lcl IFR psb at southern NH TAF sites.
Conditions rapidly improving to VFR btw 19 and 23z today.

Long Term...VFR Tue night and Wed. A period MVFR to IFR
conditions likely Wed night into Thu morning, but should
improvement for Thu night and Fri.

&&

.MARINE...
Short Term /Through Tuesday/...Building winds and seas should
bring SCA conditions to all but Casco Bay by late today with
SCA`s lingering into the day on Tuesday.

Long Term...May need SCA Thu in SE flow, but more likely in NW
Thu night into Fri.

&&

.TIDES/COASTAL FLOODING...
Very high astronomical tides will occur this week, peaking at
11.6 feet mllw midweek. A relatively weak system may be
sufficient to bring a few locations to flood stage from Portland
and points south along the coast during the midday high tide
Thursday.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Wind Chill Advisory from 2 AM to 10 AM EST Tuesday for
     MEZ007>009.
NH...Wind Chill Advisory from 2 AM to 10 AM EST Tuesday for NHZ001.
MARINE...Small Craft Advisory from 4 PM this afternoon to 10 AM EST
     Tuesday for ANZ150>152-154.
     Freezing Spray Advisory from 1 AM to 8 AM EST Tuesday for
     ANZ150-151.

&&

$$

ES


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