Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
622 am EDT Sat Sep 20 2014
high pressure will shift offshore today. A warm front tracks
northeast across the area tonight. A cold front will quickly
follow from the west late Sunday into Monday...and will provide a
round of showers and maybe even an isolated thunderstorm. A second
cold front will cross the area Tuesday followed by high pressure
for the remainder of the week.
Near term /until 6 PM this evening/...
615 am...quick update...mainly for temperatures...as they are quite
variable this morning on the coastal plain...ranging from near 30
in some sheltered locations /ksfm is 28 while nearby mesonet at North
Berwick is 44 and Springvale is 41/. Also made some sky
adjustments as some as stratocu is working across New Hampshire...and will
make for cloudy start in western and northern New Hampshire...as well as far western
ME...although models do show that these clouds do mix out laterthis
Previously...as surface high shifts offshore today...will see SW flow
start to push in warmer air. Expect several wave of cirrus through
the day...but should not be enough to prevent some sun from coming
through. SW winds push up to 10 to 15 miles per hour...maybe a few gusts
along the coast this afternoon...with highs in the 60s...and a few
spots reaching 70 in interior southern New Hampshire and SW ME.
Short term /6 PM this evening through 6 PM Sunday/...
will see more in the way of clouds move in this evening...and
although the lack of sun will limit the mixing of the S-SW
winds...should still see 5-10 miles per hour wind in a lot of spots. This
will allow for moist air to ride in and keep the mins from falling
too much. Lows in the 50s will seem balmy after the last few
nights. SW boundary layer flow will remain fairly strong...and this
combined with the increasing low level moisture will likely develop
some coastal stratus and fog. Given a persistent surface flow stratus
seems a good bet...and not expecting a dense fog.
There is a weak and broad low sitting off the Florida coast this
morning...and models want to pick it up in the 500mb flow and drag
it NE...moving offshore. There is nothing very dynamic about
it...and it looks to keep far enough east to keep most of its precipitation
offshore. Only concern is that if may produce weak area of
frontogenesis on its northwest side as it moves through Sun morning...as
some of the models are hinting at. Have put some 20ish probability of precipitation in the
forecast Sun morning to cover this for now...and see what later
model runs come up with.
Think Sunday will start out fairly cloudy between clouds in the north
form warm air advection and low stratus...however...will see some ridging move in
at all levels behind that weak offshore low....and before the
front comes in...so should see at least some partly sunny skies
late morning into at least part of the afternoon. Highs will get
into the 70s most places...except for the immediate middle-coast
where the onshore flow will keep temperatures in the middle-upper 60s. By
middle-late afternoon could see some rain showers or even a few thunderstorms and rain
developing in northern and western zones as the front approaches. There
will be instability as dew points rise into the low-middle 60s...but a
trigger will be hard to find until the surface front actually moves
through...but that will not be until sun evening.
Long term /Sunday night through Friday/...
the models are in general agreement on the long wave pattern
through late next week. A trough arrives from the Great Lakes
early in the period. By Wednesday...the upper trough lifts out and
is followed by building heights and an upper ridge over the
eastern two-thirds of the Continental U.S.. we begin the period with a cold
front crossing the area Sunday night/early Monday accompanied by a
few showers...with a chance for lingering showers behind the
front across the higher terrain on Monday. Another cold front
crosses the area on Tuesday with the coolest air of the upcoming
week to arrive for the midweek period. Rising heights and an
expansive area of high pressure bring steadily moderating
temperatures and dry weather for the tail end of the work week
into next weekend.
Aviation /10z Saturday through Wednesday/...
short term...mainly VFR through today...although could see a an hour
or two of fog at kleb or khie this am. Coastal fog/stratus move in
this evening...and will bring the coastal terminals and kaug to
IFR or Lower Middle-late evening...with MVFR ceilings and some light fog
possible at inland locations. Improvement to VFR is expected by
probably not until midday Sunday.
Monday am...areas of MVFR in showers.
Tuesday...scattered MVFR possible in showers.
short term...SW flow will increase today and could peak with a few
gusts to 25 knots around sunset...but the winds are expected to
diminish as pressure gradient slackens. However..the persistent SW
could pushes seas up to around 5 feet...especially late tonight and
Monday - Tuesday...small craft winds and seas are possible.