Area forecast discussion
National Weather Service Gray ME
1007 PM EDT Sat may 18 2013
Synopsis...
high pressure will move off the coast tonight. A warm front
approaches from the southwest late Sunday and Sunday
night...bringing a round of showers with it. On and off again
showers can be expected early to middle next week as a series of
disturbances track eastward across New England.
&&
Near term /until 6 am Sunday morning/...
10 PM update...patch of stratus has developed over SW ME and southeast
New Hampshire. The question is how far this spreads overnight. Mesoscale models
all in agreement that the stratus does spread...but they cover
different areas. For now...think that it will likly spread north and east
along the first cut of upslope just inland from the coast...and
have brought broken-overcast into this area overnight. Otherwise...just a
few tweaks to temperatures and probability of precipitation.
740 PM update...rain showers will mostly diminish with sunset... a few
sprinkles remain [possible through the evening...especially over the
terrain of Franklin/Somerset counties as weak surface and low level
boundary hangs in place. Also...will have to watch for low stratus
and fog developing on the coastal plain tonight. Models suggesting
it and a patch has developed over coastal York County S into
Portsmouth. With dew points over the water around 50...and only in the
upper 30s to low 40s not far inland...and weak southeast flow...could see
it developing later this evening.
Previously...a dry and cool northwest flow will continue into
tonight. The widely scattered afternoon insblty clouds and sprinkles will come to
an end after sunset followed by p/c conds. Overnight mins will range
from the middle 30s in the mountains to middle 40s along the coastal plain.
&&
Short term /6 am Sunday morning through Sunday night/...
the forecast gets somewhat interesting Sunday and Sunday night.
Models widely differ with pops, timing, and location of minor
S/wves and also quantitative precipitation forecast. Will assume the GFS is overplaying convection
moving through the dirty ridge and also the areal coverage of showers
Sunday and Sunday night. Will prefer the solution closer to the
drier NAM and also lower probability of precipitation so made adjustments accordingly.
Used a blend of the mav/met MOS guidance for temperatures.
&&
Long term /Monday through Saturday/...
global models agree that a front will stall over or just north of
the area through Thursday. Models do differ on the exact location
and timing of weak short waves moving along the front. This will
affect timing of precipitation as well as wind direction. For now have
used the European model (ecmwf). This results in the threat of showers and embedded
thunderstorms through the period. Looks like the highest probability of precipitation will
be over the mountains Monday into Tuesday with a better threat of
showers over the south Tuesday into Tuesday night. The onshore
flow may produce areas of fog and drizzle along the coast. A more
organized low will move along the front on Thursday into Thursday
night. Once this low moves past the area expect dry and cool
conditions for next weekend.
&&
Aviation /02z Sunday through Thursday/...
short term...2340z update...conds for low stratus and some fog are
coming together this evening...and have added to most of the
terminals. Some has already developed in kpsm and along the SW ME
coast. Where this St/fog develops tonight...there is some question
as to whether the coastal terminals can improve to VFR on
Sunday...given weak southeast flow persisting through the day. Current
thinking is there will be some improvement...but whether ceilings get
to VFR is uncertain. All terminals will see a chance of IFR ceiling/visibility
in isolated to scattered -shra late Sunday afternoon and Sunday night.
Long term...
MVFR to IFR conditions will be wide spread due to a stalled front
and areas of low pressure moving along the front. An onshore flow
could promote fog along coastal areas.
&&
Marine...
short term...a light southeast onshore flow continues tonight and increases
somewhat on Sunday and Sunday night as the pressure gradient
slowly increases. The onshore flow will remain below Small Craft Advisory conds
through Sunday night.
Long term...
wind directions will be variable due to the location of a stalled
front. Expect them to turn onshore by middle week. Areas of fog may
form. Winds and seas to remain below Small Craft Advisory levels through
Wednesday...they will approach Small Craft Advisory levels Thursday and Thursday
night as low pressure approaches.
&&
Fire weather...
the fire weather danger will be fairly low for the next several
days as green up continues across the region. Winds will be light
into Sunday morning...then winds increase on Sunday but off the ocean which
will result in higher relative humidity values pushing inland. Isolated showers
will increase in coverage late Sunday. There will be a better chance
of showers during the work week which will be accompanied by
fairly high relative humidity values.
&&
Gyx watches/warnings/advisories...
ME...none.
New Hampshire...none.
Marine...none.
&&
$$
Synopsis...
near term...cempa
short term...
long term...
aviation...
marine...
fire weather...
