Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Gray ME
1003 am EST Friday Dec 19 2014
weak high pressure moves across the region today into Saturday. As
the highs builds over northern Maine Sunday and Sunday night...the
flow will turn onshore and may produce some light ocean effect
snow. Due to onshore flow. Weak low pressure passes south of the
region on Tuesday...with more significant low tracking to our
west Wednesday and Thursday...which could bring windy conditions
and the potential for heavy rain around Christmas evening.
Near term /through tonight/...
update...no major changes to the current forecast. Model guidance
continues to poorly handle the low level stratocu deck banked
around the mountains and spilling around either side. Persistence will
be the rule for sky cover today. Some clearing is noted north of the
border...but it will take several hours before encroaching into
the County warning forecast area.
not a whole lot going on in the near term...however the cloud
forecast has proven tricky. Downsloping with northwest flow is
causing clearing southeast of the mountains...while elsewhere the
stratus is going to have a tough time going anywhere as it gets
trapped beneath the inversion with ridge moving in. Combine that
with low sun angle...and areas away from the downsloping will most
likely remain cloudy through the day until drier air finally
pushes in from the north this evening.
Short term /Saturday/...
skies will clear out Friday night and temperatures will drop as we
should radiate nicely. Still the coldest spots should only be in
the single digits across the north while with the lack of snow
cover across the southern half of the County warning forecast area should prevent
temperatures from getting too Cold. Saturday is shaping up to be a
fairly nice day with a weak surface trough staying to our south
and this should keep any light rain or drizzle activity off shore
Long term /Saturday night through Thursday/...
we will see a return to downstream blocking...in both northern and southern
stream...over the Atlantic by middle-late week...which will basically
keep the cold air to our north and west...but will allow for significant
storm system to track to our west as well and likely bring windy
conds with the potential for heavy rain Wednesday and Wednesday night.
To start out...surface high begins to build over northern ME...with
equatorward side of the high producing onshore flow across the
Gulf of ME. Models continue to spit out a few hundredths of quantitative precipitation forecast
over seacoast New Hampshire and Merrimack valley region...as well as easterly
upslope areas as far inland as the Monadnocks...mainly Sunday into
Sunday evening. For now calling these flurries /or sprinkles even
right on the coast/...but could turn out to be more of occnl very
light precipitation with little...if any...accums. Elsewhere..look for
partly - mostly cloudy skies with highs in the north to middle-upper 30s
on the coast and Merrimack valley.
Monday looks mostly dry..but M/cdy...as weak low passes to our S.
By Tuesday...will see 500mb closed low over the northern plains and
Midwest go through several cycles of deepening and filling as energy
continues to dive into it...eventually lifting NE into Quebec Thursday
into Friday. Will first see a little light precipitation late Tuesday into Tuesday
evening...as weak surface low moves to our northwest...but main event will
be Wednesday into Thursday as surface low over Ohio Valley bombs out as it tracks
northward into the Great Lakes. Models try to produce surface low to the
east over middle-Atlantic region...but any low that does develop
looks to track to our west as it gets pulled back toward to the
stacking main system over the Great Lakes. This will keep the cold
air away...and bring a mainly rain event to the region with the
bulk of the precipitation falling Wednesday into Wednesday night. Cannot rule out the
potential for some heavier snows at higher elevations in the
mountains...but it looks like mainly rain for the vast majority of the
County Warning Area. Also...will be windy as low level warm air advection jet develops east of the
triple point Wednesday afternoon and evening. Highs Wednesday could approach
50 in some spots as the warm air works in.
Look for drier and cooler air to work in from the SW behind the
system with precipitation ending and partial clearing. Just the threat
of rain/snow showers in gusty west flow with highs still above normal in
the middle 30s to middle 40s.
Aviation /15z Friday through Tuesday/...
short term...areas of MVFR ceilings will continue mainly in the CT
River Valley and mountains into Friday afternoon and then low
clouds should lift as drier air moves in from the north Friday
evening. VFR conditions prevail at all terminals for the
remainder of the period.
Long term...mainly VFR Sat night through Tuesday...although some very
light snow could produce MVFR to IFR conds at kpsm and maybe kmht
short term...there may be a few wind gust up to 25 knots by
daybreak...but winds should continue to ease as high pressure
moves in so decided to cancel Small Craft Advisory. No flags are expected for the
remainder of the period as light winds are expected with high
Long term...waters remain generally quiet Sat night through Tuesday.
High potential for gales Wednesday night into Thursday.