Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 231600 AAD

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1200 PM EDT Fri Jun 23 2017

Tropical moisture from the remnants of Tropical Storm Cindy...
and an approaching frontal system will result in showers and
thunderstorms today and tonight. A series of surface troughs or
weak cold fronts will cross the area this weekend into early
next week bringing us the chance of showers from time to
time...especially in central and northern areas.


1157 AM Update...Forecast in good shape with minor adjustments
to lessen area of shower activity as it continues to lift north
this hour. Upstream water vapor imagery doesn/t hold much
promise for significant forcing through the afternoon...although
weak isentropic upglide and increasingly unstable airmass should
allow isolated to scattered showers/storms to continue to fire.
Clearing trend is beginning and noted this hour that KFIT has
already hit 90...with this heat poised to reach into my southern
zones over the next few hours.

946 AM Update...Continue to refine PoPs based on latest local
and regional radar mosaic. The rain has not been terribly
heavy...but it has been persistent. Have also had to drop near
term temperatures a good bit given ongoing cloud cover. Breaks
to our south and west suggest that we/ll be able to make up for
lost time later this morning...with only minor adjustments to
afternoon highs at this point. No other significant changes at
this time.

810 AM Update...Updated PoPs to reflect widespread rainfall over
the northern half of the forecast area...and thus boosted rain
chances to categorical in these areas. Expect this to gradually
lift north as the mid level flow backs during the day...but
north of a LEB-IZG-RKD line...expect shras through the morning.
No other changes attm.

715 AM Update...
No wholesale changes to the forecast at this time. Showers...
some heavy in nature...are already spreading across the forecast
area this morning. Expect this to continue based on CAM guidance
and current radar. These showers have the potential for very
high rainfall rates and overall high QPF given plenty of
tropical moisture in the region thanks to Cindy...however the
exact location of heavy rainfall is not possible to
discern. Adjusted a few parameters including temperatures and
dewpoints as well as PoPs.

Previous discussion...
Clouds are increasing ahead of an approaching low pressure
system with southerly flow increasing at the surface. Currently
winds are calm but these will increase during the heat of the
day with dew points reaching the 60s and temperatures reaching
the 70s and 80s. Portions of southern NH and southwest Maine
will see upper 80s ahead of a surface front which will arrive
late in the day. Precipitation will increase over the higher
terrain initially as forcing for ascent arrives and this will
spread south and east with time. Thunderstorms are expected with
locally heavy rainfall which will tap into moisture from Cindy.
Storms will generally be garden variety with substantial
forcing arriving so late. Any areas that do get ample insolation
may see stronger storms.


Showers continue through the evening and overnight hours with
the threat for torrential downpours diminishing after midnight.
Drier air does not entrain into the region until Saturday so
overnight lows will be on the warm side and in the 60s and even
lower 70s. Highs warm into the 70s and 80s Saturday.


Cold front will push offshore by Saturday night, but the broader
upper trough will remain over the area for the next several
days. This will bring a relatively persistent weather pattern
featuring temperatures near normal (highs in the 70s, lows in
the 50s to near 60), a light offshore westerly wind, and
diurnally-induced showers and occasional thunderstorms each
afternoon, diminishing in the evenings. There may be a few
stronger waves which rotate through the trough providing a
better focus for precipitation, but for the most part
precipitation chances are based on afternoon heating beneath the
cool trough aloft generating instability and daily scattered
showers. Given the light flow pattern, expect a sea breeze most
days which will keep the coast a little cooler and limit the
precipitation chances there.

The axis of the upper trough moves through the region Tuesday
into Tuesday night, with a subsident northwest flow behind the
trough on Wednesday. This may enhance the shower activity on
Tuesday and then cut it off for Wednesday. Surface high pressure
over the Southeastern USA shifts east toward the East Coast
later in the week, allowing some warmer air to begin spilling
into New England late in the week.


Short Term...VFR conditions should dominate all locations
through the morning...but by afternoon...expect increasing
shower and thunderstorm coverage to result in some occasional
MVFR/IFR restrictions...esp at HIE/LEB/AUG. Also...marine layer
will likely work into RKD with IFR CIGS/MVFR VSBYS.
Shower/thunderstorm coverage will decrease Friday night...but
with moist airmass still in place...expect a good amount of haze
and fog...with locally dense fog possible depending on how much
rain we realize. Southerly winds will gust to 20 kts today.

Long Term...A dry west to northwest flow out of Canada will keep
conditions VFR this weekend and much of next week. There will be
a chance of afternoon showers and possibly a few thunderstorms
each day, with the best chance being in the interior.


Short Term...SCA continues for increasing SW winds Friday
afternoon into early Saturday morning. Winds will likely peak
Saturday evening.

Long Term...Cold front moves into the Gulf of Maine Saturday
night with a light offshore flow behind it. Winds will be fairly
light through the coming week in the absence of any strong
pressure systems, with the daily flow being dominated by the sea


Astronomical high tides will continue through the weekend with
the possibility of minor flooding particularly with the tide
tonight /11:11 pm EDT at Portland/...and potentially again
Saturday night.


MARINE...Small Craft Advisory until 8 AM EDT Saturday for ANZ150-152-


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