Scientific Forecaster Discussion
fxus61 kgyx 192254
Area forecast discussion
National Weather Service Gray ME
654 PM EDT Sat Oct 19 2019
high pressure will build across the region tonight and shift
east on Sunday as the remnants of Nestor pass well to our south.
A weak front moves through Sunday night and high pressure
builds back in for Monday. The next storm system will cross the
region Tuesday into Wednesday.
Near term /until 6 am Sunday morning/...
650 PM update...clear conditions with light to calm winds will
persist this evening. As a result, strong radiational cooling
will take place. Some cirrus will move in later tonight but
should remain on the thin side.
Sfc high pressure wedge shifts across the County Warning Area overnight, and
winds, which are already diminishing, should become nearly calm
almost everywhere after sunset. This should make for a good rad
cooling night, with skies holding mainly clear, save for some
scattered cirrus over the S moving in late. Lows will drop into the
the mid to upper 20s in the north, with some of the sheltered
areas possibly in the low 20s. S of the mtns lows will generally
be in the 30-35 range, perhaps a little warmer in the more urban
areas of srn New Hampshire and along the immediate coast.
Short term /6 am Sunday morning through 6 PM Sunday/...
the high will shift east on Sunday, as the remains of tc Nestor
track east off the mid-Atlantic coast. The day should start
mostly sunny, but cirrus will thicken a bit especially in the
south during the morning. As Nestor passes south, a weak 500 mb
wave will pass to our N, and this will allow for some mid-lvl
interaction between these two systems Sunday afternoon into
evening. Mostly this will be an increase in mid lvl clouds, as
there will some weak deformation in the 850-700 mb lyr. 12z
European model (ecmwf) does show some precip across the srn half of New Hampshire late in
the day, but for now going dry as low lvl air remains quite dry
and precip may struggle to reach the ground. A weak onshore flow
develops, and this will limit highs to the 50s again as well.
Clouds, and any potential rain showers will shift east sun evening, with
clearing overnight, as sfc high pres returns. Expect lows in the
mid 30s to low 40s.
Long term /Sunday night through Saturday/...
overview: Monday begins with high pressure retreating eastward as
a low pressure system approaches from the Great Lakes. This
system will drag its cold front across our region, bringing a
round of showers and rain beginning Tuesday evening and
continuing through much of Wednesday. High pressure builds in
from the southwest Wednesday night and sets up over the far
western Atlantic through Thursday night. Another system may
bring more showers late Friday.
Impacts: no significant impacts anticipated, but the mid-week system
has the potential to produce significant and possibly heavy rainfall.
Details: high pressure will still be in control of New England on
Monday morning as the remnants of Nestor spin well off the mid-
Atlantic coast and well south of New England. Monday looks like
a nice fall day under sunny skies, but the high pressure will
slide off to the east Monday night as a low pressure system
moves through the Great Lakes.
Chances for precipitation will gradually increase Monday night into
Tuesday morning as the system's cold front approaches from the
west. The GFS is faster in bringing in the showers and rain,
doing so Tuesday morning, while the slower Euro holds off any
precipitation even in western New Hampshire until Tuesday
afternoon/evening. Both models agree that Tuesday night will be
the wettest period with the faster GFS bringing the
precipitation to an end earlier on Wednesday than the Euro. Pops
reflect this thinking as well. As far how much precipitation we
may see...quantitative precipitation forecast amounts have come down in the latest guidance,
in the 0.5 to 1 inch range. However, brief periods of heavy
rainfall will still be possible with this system. Also cannot
completely rule out some very light snow accumulations in the
Surface high pressure builds in from the southwest late Wednesday
into Thursday and eventually settles off the mid-Atlantic coast
by Thursday evening. There is some suggestion from the global
models of showers in northern zones on Thursday that quickly
move northeast between the high pressure to our southwest and a
large area of low pressure over Hudson bay; have slight chance
pops in the forecast to account for this. The global models
begin to diverge rather significantly from Thursday night
through the rest of the period so stayed pretty close to the
long-term model consensus in this part of the forecast.
Temperatures look to be rather seasonable throughout the long
term period with some variation of normal to slightly above
normal temperatures expected each day.
Aviation /00z Sunday through Thursday/...
short term...mainly VFR through Sunday night. Could see a short
period of valley fog toward daybreak at khie/kleb.
Long term...VFR conditions are expected at all terminals on
Monday. Conditions will begin to deteriorate early Tuesday as a
cold front approaches from the west, bringing increasing clouds
and then light to moderate showers and rain. Look for MVFR
conditions with brief periods of IFR possible in heavier showers
or rain. Conditions begin to improve on Wednesday into
Thursday, but hie may remain in MVFR through Wednesday night as
clouds hang on in the area.
short term...winds/seas stay below Small Craft Advisory levels thru Sunday
Long term...while winds will generally not be of any concern
outside of some brief periods over the outer waters on Tuesday
and Wednesday, waves are a different story. Waves will build to
6-8 ft in the outer waters by Tuesday afternoon as the likely
remnants of Nestor spin to the south of New England. Waves
should decrease below 5 ft by late Wednesday evening but then
build again above 5 ft late Thursday into Friday morning. The
bays look to remain below Small Craft Advisory criteria throughout the period.