Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KGYX 170536 AAC
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
136 AM EDT Mon Oct 17 2016
A weak cold front will sweep across the region tonight preceded by
a few rain showers. The front will stall to our south on Monday.
Monday should turn out mild and dry before the stalled front
returns north with another round of showers for Monday night. Even
warmer air will move into southern sections Tuesday, and then all
areas Wednesday with an isolated shower possible. Unsettled
weather is expected for the end of the week with somewhat cooler
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
950 PM Update...Just some minor timing adjustments on PoPs for the
next few hours based on latest reflectivity trends, otherwise very
little change to the going forecast. Band of showers should move
through by 06z for the most part, with mainly western zones seeing
light measurable rain.
630 PM Update...Just a few minor changes to the forecast for the
rest of the evening based on latest trends in observational data
and latest mesoscale model data. Highest PoPs continue to be in
the mountains overnight where forcing for ascent will be the
greatest. They will tend to weaken as they head to the coast, with
only a few hundreths expected on the coastal plain at best. Have
also added patchy fog late.
At 18z...a 994 millibar low was centered east of Hudson Bay with a
trailing cold front through the eastern Great Lakes. NWS doppler
radar mosaic showed a band of scattered to broken convection along
and ahead of this boundary. For tonight...shortwave impulse noted
on GOES water vapor imagery over north Great Lakes will race
eastward across Ontario and Quebec Provinces tonight. This is
impulse will serve to drive the surface cold front southward
across the forecast area along accompanied by clouds and showers.
With the exception of upslope areas in the mountains...clearing
will occur from northwest to southeast across the area late
tonight with patchy stratus and fog developing. It`ll be notably
milder then the past few nights with lows in the upper 40s to
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
On Monday...the cold front will run out of gas and stall just to
our south. Lingering clouds across the mountains will scatter out
as surface high pressure builds by to our north across Quebec
province. Highs will range from the 60s to the lower and mid 70s
elsewhere in initially light offshore flow. By Monday
evening...clouds will once again be on the increase as the stalled surface
front begins to return north as a warm front in response to an
approaching shortwave over the Great Lakes. Shower activity will
gradually increase for the overnight period in response to best
forcing. Lows will be mainly in the lower and mid 50s...with upper
40s along the international border area.
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Chance of high impact weather: Minimal.
The broad ridging at 500 mb over the ern half of the CONUS holds
through most of the week, and despite some smaller scale waves in
the flow, it will continue to being in some very warm air aloft.
More persistent and deeper troughing moves in for next weekend, as
blocking sets up to our NE. Models differ on the extent of the
blocking and subsequent deeping of the trough and intrusion of the
cold air, but the trend will be cooler, and perhaps wetter, over
the weekend into early next week.
Tuesday will start off fairly cloudy with a threat showers across
most of the CWA in the morning as WAA moves across the region. The
sfc warm front will lag behind the upper front as initially E-SE
will promote the cooler more stable air thru much of the day in
the eastern zones. Where the front does push through, and the sun
breaks out in the warm sector, it will be quite warm with highs in
the 70s. At this point this looks to be the the srn third of NH,
the CT valley and perhaps into far SW ME. North of the front
highs will be stuck in the mid 50s to mid 60s, with clouds
lingering thru most of the day. Should see enough of a push to the
sfc front that it eventually breaks the inversion across all but
far NE zone late Tue and Tue night with overnight on the balmy
side for mid October, in the mid 50s to low 60s. Cold front will
push through late Tue night into early Wed, and the htreat of
another round of showers is possible Tue night.
As is often the case, especially in cases like this where air
above the surface doesn`t change all that much, it will be warmer
across all those areas that stayed N of the warm from on Tuesday
and Wed highs will range from the mid-upper 60s in the mtns to midto
upper 70s in srn NH and SW ME.
Sfc high builds in beneath ridging aloft Wed night and Thu, with
milder temps, but a little cooler with more clouds and flow
turning from to south. By Friday models deepen trough to our west
and move it through New England FRiday and Saturday before
stalling just to our NE. Best chance for precip will be centered
around Fri and Fri night when good southerly flow ahead of the
front and potential offshore low come together and good produce a
period of rain, Otherwise any precip just looks showery at this
point, and unlikely to occur in all periods that have chc pops,
but just to uncertain to narrow down at this point.
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --Short Term /through Tuesday/...
Summary: A cold front will settle south of the region today with
improving flying conditions after showers and some fog through
daybreak. This front will return Monday night and Tuesday bringing
additional chances for showers and deteriorating flying conditions.
Restrictions: Showers now departing the terminals...with perhaps a
few vicinity RKD over the next couple of hours. Expect MVFR cigs to
hold through daybreak HIE...with patchy fog south of this bringing
LIFR/IFR conditions CON/AUG/LEB...and possibly MHT. VFR takes over
early Monday morning and continues through the evening. Monday
night...showers work back in from the west /for northern areas/
...with likely a new round of restrictions HIE/LEB...with fog again
possible south of this. Low clouds may cause restrictions to persist
over our Maine terminals through much of Tuesday as surface warm
front will likely get stuck to the south and west of this.
Winds: Light west/southwesterly through daybreak will become 5-
10kts from the northwest today /outside of afternoon sea breezes/.
Monday night and Tuesday...a shift to more easterly flow is
expected...but wind speeds remaining below 10kts.
LLWS: None through Monday night. LLWS possible over Maine
terminals Tuesday atop stout llevel inversion associated with
northeastward lifting warm front.
Thunder: Very slight chance of an embedded thunderstorm northern
areas Monday night as an area of showers pushes from west to east
across the area.
Long Term...Could see another brief round of flight restrictions
Tue night as a cold front moves through. VFR expected Wed into
Thu, with possible flight restrictions Thu night and Friday.
-- End Changed Discussion --
Short Term /through Monday night/...Winds and seas will be near
small craft for much of tonight as a cold front crosses the
waters. Thereafter...winds and seas are expected to remain below
sca threshold the remainder of the period.
Long Term...Winds/seas approach SCA late Tuesday and Tuesday night
in SW flow ahead of cold front, and could see borderline conds for
a few hours in this timeframe. Otherwise winds/seas below SCA
through the end of the week.
We`re currently in the period of high astronomical tides.
High tides of note are referenced to the Portland Harbor tide gage
where flood stage is 12 ft mllw. It won`t take much onshore wind
or wave action to cause issues along the coast and the situation will
be watched closely through late this week.
1217 PM Mon 11.7 ft mllw
1251 AM Tue 11.0 ft mllw
108 PM Tue 11.7 ft mllw
200 PM Wed 11.5 ft mllw
256 PM Thu 11.1 ft mllw
-- Changed Discussion --ME...None.
MARINE...Small Craft Advisory until 6 AM EDT early this morning for
-- End Changed Discussion --