Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
311 am EST Friday Nov 28 2014
a trough of low pressure over the Gulf of Maine will shift
eastward today. Any snow showers and flurries this morning will
end this afternoon. Cold high pressure will build in from the
west this afternoon and will shift offshore on Saturday. A warm
front will lift north through the region Saturday night. A cold
front will approach from the west Sunday and will cross the region
Sunday night. High pressure will gradually build in from the west
Monday through Tuesday. High pressure will shift offshore Tuesday
night and will be followed by a cold front on Wednesday.
Near term /through today/...
main forecast challenge will be the inverted trough that has
developed over the Gulf of ME and into New England. -Sn/shsn
being reported from central New Hampshire southeast to the seacoast. Continue
to favor the nam12...which is also supported by the
hrrr/rap...although the NAM is doing a better job with quantitative precipitation forecast and
looks to linger it through about 15z...although most precipitation will fall
by 12z. Some accumulating snow possible in central and southern
New Hampshire...and parts of York County ME...maybe an inch in some spots.
Not much quantitative precipitation forecast with this system but ratios are in the 15-20 to 1
range. Once the 700mb trough clears the County Warning Area to the east by
midday...trough breaks down and ridging starts to develop...so
skies become partly to mostly sunny during th afternoon. Highs
will be below normal...ranging from middle-upper 20s to low-middle 30s
south and coast.
Short term /tonight through 6 PM Saturday/...
surface high builds in from the SW tonight and should very good rad
cooling night...especially with snowpack in place. While MOS
guidance generally overdoes rad cooling...a fresh snowpack may
make it more reasonable. Have used a trad blend of models for mins
but have given the mav/met more weight...which bring lows in the
mountains valleys close to zero...and even the warmer southern zones
will see single digits to lower teens for mins.
Saturday looks generally fair with light winds and sunny skies in
the morning...with increasing middle to high clouds in the
afternoon. The listed mixing will lead to another day with high
in the upper 20s to middle 30s.
Long term /Saturday night through Thursday/...
the models are in general agreement on the long wave pattern
through late next week. Several impulses rotating around an upper
low vicinity of Hudson Bay will bring brief shots of Arctic air to
the forecast area. We begin the period with a broad west-southwest
flow aloft and milder temperatures as we wait for the next impulse
to dive southeast into the Great Lakes before racing east into New
England. This impulse will drive an associated cold front through
the region early Monday followed by a brief return of below normal
temperatures for Tuesday. A warm up follows for midweek before the
next impulse drives yet another cold front through the area late
Wednesday. In the dailies...a warm front will cross the area
Sunday followed by a trailing cold front early Monday. High
pressure will cross the region Tuesday. Another cold front will
cross New England late Wednesday followed by high pressure for
Thursday and Friday.
Aviation /08z Friday through Tuesday/...
short term...MVFR conditions due to -sn and low clouds at
kpsm/kcon/kleb/khie will continue into the first part of this
morning...with some periods of IFR in steadier shsn. Improvement
to VFR expect by midday at all terminals. VFR conds then expected
Sat night - Monday...scattered MVFR possible in rain and snow showers.
short term...still seeing seas of 5-6 feet....although this is
mostly due to swell...some wind waves are being generated by NE
jet along the SW ME coast...but seas will continue to subside through
the morning. Otherwise winds/seas remain below Small Craft Advisory criteria.
Sun - Tuesday...small craft winds and seas are likely.
Sun and Tuesday...wind gusts outside the bays could approach gale.
Marine...Small Craft Advisory for hazardous seas until 6 am EST early
this morning for anz150-152-154.