Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 271256
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
856 AM EDT Mon Mar 27 2017

.SYNOPSIS...
Low pressure will track across southern New England later today
before exiting the coast this evening. This disturbance will
produce rain and a light wintry mix across portions of the
interior through late today. A cold front will push through
the region late Tuesday and Tuesday night resulting in upslope
showers and northwesterly flow Wednesday into Thurday. A weak
ridge will build into the region on Thursday and remain through
Friday. The next storm will approach the region on Friday night
bringing widespread precipitation for Friday into Saturday.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...

852 AM...For this ESTF update I dropped the freezing rain
advisory for the Manchester and route 101 corridor as mesonet
shows surface temperatures have warmed several degrees above
freezing. Elsewhere...the various winter weather advisory
headlines remain. The 14z expiration area has been delayed until 15z
as we continue to see temperatures slow to warm above freezing
and some pockets of light freezing rain are likely. I ingested
the current mesonet into near term grids as well for this
update.

Prev Disc...
620 AM...Precip beginning to work in from the west, mostly in
the form of FZRA or RA, at least across NH. For the most part,
temps across NH are within a degree or two of freezing, and will
likely not change much until the sun has been up for a couple
hours, so will hold onto advisories as they are. In ME, seeing
dome UP reports, which may be PL, but again in interior parts of
the coastal plain, except for the eastern zones, temps right
around freezing /although above along the coast from Casco Bay
south/, and similar thinking applies here, that temps will hold
where they are for a few more hours. Further inland in ME
towards the moutnains and foothills, temps are in the upper 20s,
and p-type will be a mixed bag this morning before transition
to freezing rain, or rain by afternoon in some spots.

Previously...Forecast still somewhat problematic as to p-type
today, but it looks like we will see some wintry precip,
especially freezing rain across all but SW coastal zones through
the morning commute. Td depression did lower with first round
of precip overnight, so wet bulb when the second round of precip
come thru will not be as significant, but temps all hovering
right around 32F in all but far nrn and interior ern zones,
where they are in the upper 20s. Only changes to WSW was to end
central NH and interior coastal ME zones at 18Z as temps should
be above freezing by midday. Once precip begins in srn and
coastal Maine, it should begin to mix down warmer temps from
aloft, so in the areas any FZRA should end with a couple hours
of precip onset.

In the NE zones, mixed precip will produce some SN/PL/FZRA
accumulations, but should transition to mostly freezing rain
this afternoon. Here we could see one to tenths of icing thru
the day.

Precip will end from SW to NE during the late afternoon and
early evening. Highs will range from the low 30s in the N to
around 40 in the south.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM TUESDAY/...
For tonight, the sfc low over the gulf of ME shifts eastward and
flow turns to the NNW, which should allow drying aloft and end
the precip. Sfc winds will remain light, so expect some clouds
and some fog to continue. Temps will fall back a few degrees,
but should remain above freezing in many spots outside of the
mountains.

On Tuesday, we will see a low pass to out north and one pass to
our south, and this should pull a cold front across the areas
later in the day, which will bring a chance of showers. It looks
like enough of a SW flow will develop ahead of this front to
mix down warmer air across the entire CWA, with temps rising
into the upper 30s in the north to around 50 in the south.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Typically the long wave pattern serves as a starting point to
drive the forecast. What is notable in this extended period is
the lack of any high amplitude long wave pattern. All of North
American remains under mainly zonal flow with a series of very
quick moving waves pushing through. A few of the waves try to
form a cut off low over the southwest US but overall we see a
very progressive pattern. While the lack of a strong pattern
will keep both the very cold and very warm air at bay putting us
happily near seasonal norms, the quick progression leads to
very low predictability as any small change in the short waves
create a large change the the forecast.

Tuesday night begins with a cold front pushing through with
scattered showers and northwesterly flow following. Upslope
showers will continue through the day on Wednesday.

A ridge builds in for Thursday and into Friday. High
temperatures will be in the 40s with mostly clear skies and calm
winds.

The next low pressure system will develop near Chicago on
Thursday night and move northeastward bringing precipitation
into our area by late Friday. Precipitation will continue
through Friday night and into Saturday. There is still quite a
bit of uncertainty with some options keeping the low center to
our north up the St. Lawrence valley and some allowing it to
redevelop off the coast and moving through the gulf of Maine.
These options mean that precipitation type is still uncertain as
we wait to see which side of the warmer air we are on. For the
moment have stuck with a blend and rain/snow, although some
sleet or freezing drizzle is possible overnight.


Sunday into Monday another ridge builds in returning us to
seasonable temperatures and sunny skies.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
Short Term...Conditions deteriorate to IFR toward daybreak with
FZRA at all but coastal terminals through at least the first
part of this morning. IFR will likely persist through tonight
will some improvement to MVFR on Tue, perhaps some VFR at
KMHT/KCON.

Long Term...
Wednesday will see upslope showers in the mountains resulting in
possible MVFR for HIE through B80. High pressure builds in
Thursday and Friday. Friday night into Saturday low pressure
will move through bringing rain and widespread IFR conditions.

&&

.MARINE...
Short Term...Dropped SCA from CAsco Bay, but otherwise will see
E-NE flow picks up this morning as low passes to our south and
intensifies. Winds diminish this evening, but seas stay up
overnight.

Long Term...
Small Craft conditions are likely Thursday as northwesterly
flow moves over the waters in the wake of the cold frontal
passage.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 5 PM EDT this afternoon for
     MEZ007>009-012>014.
     Freezing Rain Advisory until 2 PM EDT this afternoon for
     MEZ018>022.
     Freezing Rain Advisory until 11 AM EDT this morning for
     MEZ025>028.
NH...Winter Weather Advisory until 5 PM EDT this afternoon for
     NHZ001-002.
     Freezing Rain Advisory until 2 PM EDT this afternoon for
     NHZ003-004-006-009-010.
     Freezing Rain Advisory until 11 AM EDT this morning for NHZ005-
     007-008-011-015.
MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ150>152-154.

&&

$$

ES



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