Area forecast discussion
National Weather Service Caribou ME
643 am EDT Thursday may 23 2013
Synopsis...
a warm front will progress north of the state early this morning.
Low pressure will lift to our west today then gradually push a
slow moving cold front across the area tonight into Friday. A wave
of low pressure will move northeast along the front with rain
expected Friday and into the weekend.&&
Near term /through tonight/...
0640 am update: adjusted temperatures down for early this morning
based on current observations. Also, decided to add further
enhanced wording to thunderstorms this afternoon mentioning small
hail and gusty winds for areas along the Quebec border. Also made
some minor changes to probability of precipitation for this morning.
Previous discussion:
Active weather in store...
A weakening area of showers and thunderstorms moving in from
Quebec will move through mainly central and northern areas over
the next few hours while continuing to weaken.
During the day today an upper level trough will continue to slowly
migrate east across the Great Lakes region with a broad southwest
flow continuing aloft. At the surface...low pressure is expected
to slowly track northeast through southern Quebec as it pulls a
cold front east. The front will be slow to move east as it
parallels the flow aloft. Once this initial wave of showers moves
out by middle morning there should be a lull before seeing increasing chances
for showers and thunderstorms redeveloping from west to east through
the afternoon as the front moves slowly toward the region from the
west. Big question will be potential for any convection to develop
in advance of the front this afternoon. Both the GFS and the NAM
depict sb convective available potential energy in the range of 500-1000 j/kg however the NAM
depicts this are being limited mainly right along the western
border of the County Warning Area.There is also decent shear in the 0-6 km layer on the
magnitude of 30 to 40 kts. Again the big question will be how much
instability we see and this will be dependent on any breaks in the
clouds that might occur during the day. Still looks like the best
chance for seeing any thunder will be across western areas where
low level flow will become more southwest in advance of the front
later in the day. Have continued to indicate the highest probability of precipitation for
showers and thunderstorms across northern and western sections
during the day. Thinking is the best chance for any storms to reach
severe levels would be over extreme western areas along the Quebec
border where the potential for storms producing damaging winds and
large hail can't be ruled out. Will continue to carry enhanced
wording mentioning heavy rain as this looks to become the biggest
threat by late in the day as storms will tend to train along the
slow moving boundary. Worth noting, 3 hour flash flood guidance is
in the range of 1.6 to 1.8 inches over most of the County Warning Area and these
amounts over a brief period of time will be possible late today in
the north and west.
For tonight, expect the slow moving front to move only slightly to the
south and east. Shower and thunderstorms, potentially producing
heavy rain, will continue to be a concern in the evening over
northern areas. Instability will decrease heading into the
overnight but expect widespread rain to continue...now beginning
to encompass southern areas who will see limited precipitation through
this evening. Beefed up quantitative precipitation forecast amounts for the overnight period
utilizing a blend of the previous forecast and HPC quantitative precipitation forecast grids.
Thinking is most areas will see at least one to two thirds inches
of rainfall during the evening and overnight period with locally
higher amounts likely in area experiencing training thunderstorms
this evening.
&&
Short term /Friday through Saturday/...
Friday through Saturday will continue to be very cool and rainy
for most of the forecast area...although it is possible northwest
Maine may see a bit of a respite from the rain during the day
Saturday. Models are in reasonable agreement showing the surface
boundary moving southeast into the Gulf of Maine by Friday
night...where it stalls. Deep moisture will continue to stream into
the region...wrapping around the upper low as it moves northeast
toward the area. Precipitation amounts through this time frame are
expected to range from .5 to .75 in far northwest Maine...to
upwards of 1.5 inches across the rest of the area.
With the surface boundary south of the forecast area and abundant
clouds expected...a distinct cooling trend is expected from this
time frame. Highs on Friday are expected to be mainly in the 50s
and low 60s with expected highs on Saturday only in the 40s and
low 50s.
&&
Long term /Saturday night through Wednesday/...
the forecast has not changed for the better with the latest model
runs. Energy dropping into the base of the approaching trough will
force a low pressure area to strengthen over the middle Atlantic
region by Friday night. This low will then move northeast fairly
slowly along the East Coast into the Canadian Maritimes through
Tuesday. As a result the rainy period will persist through at
least Monday. By Tuesday...the center of the low should be over
the Maritimes with high pressure building across New England.
Temperatures will continue to be chilly on Sunday with highs in
the 40s and 50s. A gradual warming trend is then expected as the
low gradually moves northeast. Highs by Wednesday will generally
be in the upper 60s and lower 70s.
&&
Aviation /12z Thursday through Monday/...
near term: expect IFR/LIFR in the south to lift to IFR during the
day before likely going down to LIFR again tonight as rain and fog
develop. IFR/LIFR in the north should briefly improve to MVFR
during the day as breaks develop before IFR conditions return by
late day. Also will see the potential for thunderstorms this
afternoon into this evening..mainly from khul north.
Short term: poor flying conds are still expected through much of the
period as a slow moving frontal system crosses the region Thursday
night through Friday and stalls just east/southeast of the area as several
significant lows lift newrd along this boundary. Expect widespread
IFR/MVFR through the period with only some gradual improvement
possible by late Monday into Tuesday.
&&
Marine...
near term:
expect Small Craft Advisory conditions to develop by this afternoon for both winds
and seas and continue through tonight. Also will continue to see
reduced visibilities at times due to showers, rain, and areas of
fog for today and tonight.
Short term:
a frontal boundary will continue to gradually mv through the waters
Friday and then stall west/ several surface low pressure systems forecast to lift NE
along this stalled frontal boundary. Persistent srly winds ahead of
this system will help elevate seas west/ generic Small Craft Advisory conds expected
into Friday. Winds will abate as this frontal boundary stalls over the
waters but expect a prolonged period of elevated seas to persist into
the weekend. Current Small Craft Advisory headlines into Friday will likely need to be
extended.
&&
Car watches/warnings/advisories...
ME...none.
Marine...Small Craft Advisory from noon today to noon EDT Friday for
anz050>052.
&&
$$
Near term...fitzsimmons
short term...runyan
long term...runyan
aviation...fitzsimmons/runyan
marine...fitzsimmons/runyan
