Scientific Forecaster Discussion
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Area forecast discussion...updated
National Weather Service Gray ME
633 PM EDT Mon Oct 14 2019
a cold front moves across the area tonight with a few showers
possible in northern areas. High pressure builds in behind the
front for Tuesday with pleasant weather expected. The next low
pressure system begins affecting our area, with low pressure
strengthening rapidly as it enters the Gulf of Maine Wednesday
night. This will bring a period of heavy rain to northern New
England, with gusty west winds behind the low on Thursday. High
pressure builds in for the weekend.
Near term /until 6 am Tuesday morning/...
630 PM update...
just a few minor changes to the forecast this evening as high
pressure crosses the forecast area tonight. Readings will
eventually drop into the mid to upper 30s north to lower to mid
40s south overnight.
a weak cold front will cross the region late this evening.
Moisture is rather limited with this system however scattered
showers will be possible, mainly over northern areas.
There is very little gradient behind the front at the surface
overnight. It is a challenging forecast in that some patchy fog
may form once again over the interior if winds decouple with
time. Some patchy fog may enter the midcoast region once again
The coldest overnight lows will be over western sections where
cold air advection will allow for 800 mb temperatures to fall below
0c. Lows will range from the mid 30s north and west to the mid
40s further to the south and east.
Short term /6 am Tuesday morning through Tuesday night/...
a weak area of high pressure will crest overhead on Tuesday.
This will allow for sunshine and relatively light winds
throughout the day.
Low pressure begins to move east from the Great Lakes region
Tuesday night. Warm air advection ahead of the system may allow
for an increase in cloudiness over western areas later at night.
Daytime highs will be limited to the 50s in most areas.
This sets the stage for rapid cyclogenesis along the mid
Atlantic coast for the extended portion of the forecast.
Long term /Wednesday through Monday/...
the ensemble and deterministic model solutions are in decent
agreement on the long wave pattern through the upcoming weekend
and the start of the new work week. We begin the period with weak
ridging ahead of an upper low over the Great Lakes. At the
surface...a ridge of high pressure will retreat well offshore
during the day Wednesday as low pressure and a trailing cold
front approach from the Great Lakes. An impulse pivoting around
the upper low will result in secondary low development along the
trailing front over the Delaware-Maryland-Virginia region by Wednesday afternoon.
The deepening low center will ride northeast along the coast to
near /kpsm/ Portsmouth by 12z Thursday. Strengthening onshore
flow and a 70 kt low level jet in advance of this low should
produce a band of heavy rain Wednesday night into Thursday
morning. Steadier and heavier precipitation will taper from
southwest to northeast during the afternoon following the
passage of the surface low. Wrap around moisture and upslope
flow will result in residual clouds and a few upslope rain/snow
showers Thursday night and Friday across the higher terrain. A
ridge of high pressure follows this departing storm system for
Saturday. A weakening and moisture starved cold front will cross
the area Sunday marked by a few clouds and perhaps a mountain
sprinkle. The next disturbance approaches from the Great Lakes
for late Monday into Tuesday.
Aviation /22z Monday through Saturday/...
short term...lower ceiling and patch fog will remain possible
along the midcoast region and across the inland valleys tonight
with locally IFR or LIFR conditions. A few showers may cross
northern areas. Drier Tuesday into Tuesday night as high
pressure builds over the area.
Wed am...LCL IFR psb in am valley stratus and fog.
Wed night - Thu...IFR in rain and fog.
Sfc winds gusting up to 30 kt.
Fri...sct MVFR psb in mtn -shra.
Northwest surface winds gusting up to 25 kt.
short term...winds shift to the west behind a front late tonight
and Tuesday morning. Patchy fog is possible for much of the
night. Winds and seas remain below Small Craft Advisory thresholds through
Wed PM - Thu...gales likely, with gusts approaching storm possible
outside the bays.
rain heavy at times Wednesday night into Thursday may result in
urban and poor drainage flooding. At this time river flooding is
not expected, but will have to watch our typically flashy
rivers in the higher terrain where quantitative precipitation forecast could be higher.