Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
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FXUS61 KGYX 171344
Area Forecast Discussion
National Weather Service Gray ME
944 AM EDT Fri Mar 17 2017
High pressure will build in from the west today providing dry
but cool weather. High pressure will slide off shore Saturday as
low pressure develops south of New England. This system will
pass out to sea south of New England on Saturday night, but a
few snow showers are possible. Warmer and dry weather are in
store for Sunday through Monday. A cold front will cross the
region Monday night followed by a secondary cold front Tuesday
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --945 am update: Very quiet day with skies mostly sunny attm. Made
some adjusments to sky cover to go with clear conditions thru
the rest of the day across most areas. In the mountains some
clouds expected to develop early this afternoon due to
differential heating and very weak approaching upper s/wv. In
put latest msonet data for next few hours and no other changes
Update...Minor changes to reflect latest observational trends.
Previous discussion...Upper low continues to keep the region in
cool...cyclonic flow. Lingering low level moisture is leading
to some upslope clouds and patches drifting over the mtns and
downstream to the coast. Can not rule out some snow
showers...especially NW of the mtns. Where it has cleared
out...temps have been able to get into the single digits. Cloudy
areas remain in the upper teens and 20s.
Gradually the low level moisture dries out today...with clouds
being more likely to the E and closer to the upper low. As high
pressure tries to nose into the area...mixing will be on the
shallow side. So despite mid level temps warming a few degrees
we may not be able to realize those temps. That may be enough to
continue the sub-freezing streak going on across the area.
-- End Changed Discussion --
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
Surface ridging tonight should allow for clear and calm
conditions. I undercut guidance temps as a result...and with
fresh snow on the ground some well below normal temps are
Sat upper trof digs S of New England. Flow becomes onshore S of
PWM. With mid level temps around -10C and water temps around 3
or 4C...enough differential exists for some ocean effect snow
showers. I have introduced some slight chance PoP for Srn
NH...as these could bring a very light snowfall late Sat despite
low pressure being well to our S.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
The models are in decent agreement on the longwave pattern
through late next week. We begin the period with a closed low over
the northeast CONUS. This upper low will lift out early in the
period with ridging and milder weather to follow for the start of
the new work week. Unfortunately...digging shortwave energy will
quickly carve out another upper trough over eastern Canada and the
northeast CONUS for much of the second half of the work week. By
Friday and the start of next weekend...warmer air arrives as the
upper trough lifts out. The upshot of this pattern on sensible
weather will be a veritable roller coaster in temperature this
period. Temperatures rebound to normal of slightly above normal
values early in the period...only to see a return to well below
normal temperatures for the second half of the new work week. In
the dailies...the upper low and an associated surface low will
pass close by to our south and east Saturday night and Sunday.
Areas along the Massachusetts border as well as extreme southwest
coastal Maine could get brushed by the northern periphery of the
precipitation shield with this storm system. At this point...it
looks like any accumulation there would be a dusting to an inch.
Elsewhere...we should see little if any precipitation. A ridge of
high pressure and slightly milder air will follow for Monday.
Tuesday will be the mildest day of the work week before a series
of cold frontal passages reintroduce much colder air into the area
for the second half of the work week. High pressure will build
east and crest across the region on Thursday before retreating
offshore by Friday.
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
Short Term...Widespread VFR conditions expected thru Sat.
Cyclonic flow continues over the mtns...and some scattered MVFR
CIGs are possible as the low level moisture slowly dries up.
Then late in the day Sat...onshore flow may brings some MVFR in
ocean effect SHSN to Srn NH...mainly PSM and MHT.
Sun...Sct MVFR psb vcnty KPSM in -shsn.
NE sfc wnd gusting to 25 kt at cstl TAF sites.
Tue...Sct MVFR in mtn -shsn.
Short Term...Winds and seas continue to diminish as low pressure
pulls away from the area. SCA for hazardous seas is no longer in
effect as seas have dropped below 5 ft across the coastal
Sun......Gales are likely.
Mon...A Small Craft is psb outside the bays.
Tue...Gales are likely, with a Small Craft for the bays.