Scientific Forecaster Discussion
fxus61 kgyx 281908
Area forecast discussion
National Weather Service Gray ME
308 PM EDT sun may 28 2017
weak high pressure over the area will slowly shift east
tonight. The next system over the eastern Great Lakes will lift
north into Quebec tonight and will send a front towards the
region. An area of showers will slowly cross New Hampshire and
western Maine on Memorial Day. Warmer weather returns by the mid
to latter part of the week but with the chance of showers each
Near term /through tonight/...
the center of high pressure has moved off the coast and allowing
a developing onshore southeast flow to develop. This will allow
stratus currently over the southwest coast from psm-pwm to
expand west and north by later tonight as the maritime air mass
slowly moves inland and saturates the lower levels. Over western
areas of inland New Hampshire and ME afternoon clouds developed due to
differential heating to full sun across those areas. These
clouds should generally remain tonight as the approaching weak trough
will help enhance cloud formation by later this evening.
Guidance temps of lows in the upper 40s to lower 50s looks good.
Short term /Monday through Monday night/...
models generally agree on lifting a weakening trof northeast
across the area Monday bringing with it scattered showers and a
moist damp east to southeast onshore flow...although it will be
light. Qpf amounts will be light as the system weakens. Models
generally agree on bringing the main surface low well to the
southeast of Cape Cod and also the heavier precipitation
associated with it. Temps will be very cool Monday with highs
only in the lower to mid 50s. Monday night the system will
slowly exit the area by lingering scattered showers are
expected. Temps will be cool with overnight lows generally in
the mid 40s.
Long term /Tuesday through Sunday/...
500 mb Omega blocking along and north of the US/can border
continues to be the main weather player through this week into
next weekend. Main feature for NW England will be closed low
currently to our west, which will track slowly eastward to the
Maritimes by the weekend, which brings a chance of showers most
days. Models in fair agreement on the larger scale trends, but
confidence on timing of waves that rotate around the closed low
diminishes as we move further out in time.
Initially, ridging in the center of the Omega block will keep
sfc low well to our south, but will also allow southeast onshore flow
to linger into Tuesday, so temps will be cooler Tuesday, with
highs mostly in the upper 50s on the coast to the mid 60
inland. Also expect a fair amount of clouds, and the htreat of
showers, especially mid to late afternoon into Tuesday evening
as wave rotates around the low to our west, and will eventually
drag the occlusion across the County Warning Area late Tue night. Lows will be
in the upper 40s to low 50s.
On Wed, the flow will shift to west-SW and this should allow for
warmer air air to mix down, and keep the sea breezes at Bay
except maybe right at the beaches. Some sun is likely esecially
on the coastal plain in the downslope, and highs should warm
into the 70-75 range in all but the mountains and the mid coast,
which will be in the mid-upper 60s. Another wave will rotate
through Wed afternoon/evening and may see enough sfc warming and
500 mb height falls to produce some thunderstorms and rain in the afternoon.
After this wave clears, flow aloft becomes a little more zonal
on Thu, and this may be the best chance of a dry day with highs
70-75 again on the coastal plain, and mid-upper 60s in the
mtns/foothills. Another wave approaches Friday and brings a
threat for showers back into the forecast. The weekend remains
questionable for showers at this point, but it will likely not
be a washout, as the persistent west flow south of the closed low
should keep things drier, if not necessarily warm.
Aviation /18z Sunday through Friday/...
short term...areas of IFR conditions from kpsm-kpwm will spread
thru Aug and rkd by later tonight...confidence is low on timing.
Further inland VFR conditions will become MVFR tonight and
possibly IFR at times in developing showers from S-north Monday
morning and into the afternoon. Monday night conditions will be
variable MVFR to IFR as a moist maritime air mass sits over the
area with a prolonged light onshore flow.
Long term...Tuesday will start MVFR-IFR, lowest close to the
coast, but should improve a bit in the afternoon. Beyond that
look for VFR Wed-Fri, with tempo reductions in MVFR in rain showers.
Some thunderstorms and rain possible Wed afternoon.
short term...a flow ahead of the next system will have a weak
southeast flow tonight becoming east Monday and through Monday
night. Winds and seas to remain below Small Craft Advisory thresholds thru Mon
Long term...southeast flow Tue shifts to west Wed-Friday, and should
remain blo Small Craft Advisory levels through the period.
the astronomical high tide in Portland is 11.6 feet MLLW at 2:10
am Monday. Winds will be light but onshore through the night
with low seas...but will help keep tides at least a half foot
above the predicted upcoming high tide. Tides currently are
about 8 tenths above their predicted levels so will once again
issue a coastal flood statement to indicated some high water
conditions that may exceed their minimal benchmark levels for
isolated minor flooding at time of the early morning high tide