Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
706 PM EDT Wednesday Mar 12 2014
low pressure will rapidly intensify as it moves off the New
England coast overnight. This system will continue northeast
through the Maritimes on Thursday. A ridge of high pressure will
pass to the south Friday morning. Low pressure approaches from the
northern plains on Friday. A cold front will cross the region
Saturday night. High pressure will gradually build in from the
west Sunday through Tuesday.
Near term /until 6 am Thursday morning/...
700 PM...tricky forecast as rain falls along the coast with a
sharp liquid/frozen transition from central New Hampshire into
western and central Maine. At 22z...a 983 millibar low was vicnity
of the Delaware-Maryland-Virginia and will race rapidly northeast across the Gulf of
Maine later tonight. As winds become more northerly...colder air
will flood south and transition much of the precipitation to snow
towards midnight. For this update I made a few adjustments to
reflect the current mesonet.
significant late season storm underway at this time...with 984 mb surface low
in vicinity of kjst. Strong warm air advection ahead of the low coupled with cold air advection
associated with northern stream is leading to intense frontogenesis in
the middle levels. With high precipitable water air mass approaching +2
South Dakota...significant precipitation is likely. At this time expect the greatest quantitative precipitation forecast to
align just to the cool side of the middle level forcing...which
places the mountains and foothills in the cross hairs. To the S precipitation
will be more showery in nature until low pressure moves closer to southern
Dual-pol indicates melting layer is advancing northeastward with
time...though it is struggling to push much farther into New Hampshire and ME
than the foothills at this time. Model guidance has been a little too
aggressive with this line so far today...so have used thicknesses
a touch cooler than the 12/12z European model (ecmwf) to produce the weather grids. Have
a brief period of mixing in the foothills...before a transition
back to snow later tonight. North of that heavy snfl will continue into
the night...with rates approaching 1 to 2 inches per hour at times
with strong forcing and slightly unstable layer aloft.
Meanwhile cold air is oozing southward from Canada...and is just now
starting to invade parts of northern New Hampshire. This will gradually and
steadily drop temperatures through the night. As it undercuts the warmth
aloft late tonight across southern New Hampshire and coastal ME...expect a period of
freezing rain...then sleet...before all snfl. As such will have winter weather
advisories up for those areas covering the mixed precipitation and
eventually flash freeze. All other warnings remain in place.
Short term /6 am Thursday morning through Thursday night/...
upper low pressure will cross the area Thursday...and deepen as it does so.
This will provide enough forcing for ascent to continue shsn through
midday. BUFKIT soundings indicate deep dendritic growth
zone...which remains saturated for the majority of the day. Snfl
as a result should be efficient...and an additional 2 to 4 inches
is possible. Cold air advection through the day will support maximum temperatures at
midnight...with readings steady or falling during the day for much
of the area.
Thursday night lingering gradient flow argues for leaning towards the
warmer met guidance vs the mav. However...should see below zero
readings regardless across the northern zones.
Long term /Friday through Wednesday/...
northern New England will be brushed by a couple more systems
through the week as we stay in fast but progressive flow aloft. In
the dailies...high pressure passes to our south Friday while
temperatures rebound into the 20s and 30s during the day and into
the teens and 20s Friday night.
A bit of mixed precipitation is possible late Friday night into
Saturday morning as warmer air arrives aloft ahead of a weak short
wave. This would be just a hundredth or so of freezing drizzle over
the coastal plain and into the foothills. This system will amount to
a few snow showers mainly for the higher terrain...with the pre
frontal trough/warm front bringing a few additional showers to the
midcoast region early Saturday morning.
Warm advection ahead of this system will result in highs in the 40s
area wide Saturday with middle to upper 40s along the coast. Additional
troughing/cold frontal structure pushes through Sunday with another
reinforcing cold shot again on Monday. This drops temperatures back
down a few degrees below normal for highs and well below normal for
lows for day 6/Monday and day 7/Tuesday.
Aviation /00z Thursday through Monday/...
short term...widespread IFR or lower conditions are expected through
tonight as low pressure spreads a mixed bag of precipitation across the area.
Occasional periods of VFR will be possible early along the
coast...before precipitation to the SW overspreads the area this evening.
Eventually all precipitation transitions back to snow...with areas of IFR
lingering into midday Thursday. Tonight into Thursday afternoon...winds
backing north to northwesterly will gust at times to 35 kts...especially near
Long term...prevailing VFR with MVFR or lower conditions Friday
night into Saturday morning in a chance of mixed precipitation at
short term...gales remain in effect...as low pressure is expected to
move into the Gulf of ME tonight. Cold air advection Thursday will keep winds gusting
around 35 kts on the outer waters especially.
Long term...seas and winds increasing to small craft advisories
Friday night into Sunday morning as low pressure crosses the
ME...Winter Storm Warning until noon EDT Thursday for mez007>009-
Winter Weather Advisory until noon EDT Thursday for mez023>027.
New Hampshire...Winter Storm Warning until noon EDT Thursday for nhz001>010.
Winter Weather Advisory until noon EDT Thursday for nhz013-014.
Marine...Gale Warning until 8 PM EDT Thursday for anz150>154.