Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
241 am EST Wednesday Nov 25 2015
high pressure overhead will shift offshore today as a broad upper
level ridge builds over New England. This will bring above average
temperatures through the end of the week. The high will hold
offshore through Friday...with the next chance for rain Friday
afternoon and night as a cold front traverses the region. Fair and
colder weather will return in the wake of the front Saturday into
early next week. The next chance of precipitation does not appear
to come until midweek.
Near term /through today/...
large bank of low cloud cover continues to slowly erode this
morning. This was keeping temperatures in check for much of the forecast
area...but now clear skies and little wind should allow readings
to fall pretty quickly before dawn. Most areas should make another
run at the teens to low 20s.
High pressure in control otherwise...with dry weather but not much in the
way of mixing. Temperatures will be seasonable before return flow starts
up late in the day.
Short term /tonight through Thursday/...
SW flow continues to build overnight. Initially surface ridge axis
will remain at least over eastern areas...and we could see a quick
drop in temperatures after sunset. Eventually warm air advection wins out...and temperatures
should slowly respond by creeping up through the night. Stuck with
a non-diurnal trend during this period.
Warm air advection continues Thursday...but mixing remains on the shallow side.
Despite that...mixing down temperatures from 975 mb still yields readings
in the low to middle 50s across southern zones...and 40s in the north. A nice
mild day for Holiday plans. The warm air advection plus increasing moisture on SW
flow will lead to the possibility for clouds increasing during the
day Thursday. Sref products hinting at this being most likely southeast of the
Long term /Thursday night through Tuesday/...
broad deep-layer southwesterly flow will be in place Thursday
night and Friday out ahead of an approaching cold front.
Therefore...relatively warm temperatures are expected Thursday
night and Friday. The cold front will continue to drop
southeastward late Friday and cross the region Friday night. Rain
showers may begin to affect northernmost zones late Friday
afternoon. However...the bulk of the region shouldn/T see any wet
weather until Friday night. The highest probability of precipitation Friday night will be
across the interior. Toward the coastal plain and southern
zones...we have only gone with chance probability of precipitation at this time since the
forcing with the front weakens with time and moisture source seems
to get cut off. Either way...any shower activity looks to exit
early Saturday morning. High pressure moves in during the day on
Saturday as well as Sunday and will result in cooler and drier
weather. High pressure will likely hold into early next week with
continued fair weather. Will be watching for the next chance of
rain midweek as low pressure ejects out of the Great Lakes. Right
now...it looks mostly wet versus white.
Aviation /07z Wednesday through Sunday/...
short term /through 12z Wednesday/...VFR conditions expected through
tonight. Increasing SW flow Thursday will transport warmer and more
moist air northward. This will lead to clouds developing through the
day...which may lead to areas of MVFR ceilings.
Long term...VFR conditions are expected Thursday night and Friday
as high pressure holds over the region. MVFR conditions are
expected Friday night for much of the region as showers move into
the area with a cold front. VFR conditions are expected to resume
by early Saturday morning as the front pushes offshore...with VFR
conditions expected to continue into early next week.
short term /through Thursday/...SW flow is expected to increase
into Thursday. Seas will gradually build above 5 feet...with wind gusts
near 25 kts possible by late Thursday.
Long term...small craft conditions are expected...especially on
the ocean waters...Thursday night into Saturday as southwesterly
flow ahead of a cold front strengthens. The front should move
across the waters by Saturday morning with subsiding conditions
expected Saturday night into early next week.
astronomical tides will be near the peak for the month over the
next few days. On Friday the high tide in Portland around 11 am is
11.5 feet. While this is close to the 12 feet flood stage... the
southwest wind is expected to prevent a surge of water along the
coastline. Most likely areas to see any sort of surge would be
along the midcoast where the southwest wind has more of an onshore
component though any impacts should be very minor.