Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Caribou ME
208 PM EST Tuesday Feb 9 2016
weak low pressure systems will pass well south of the region
this afternoon into Wednesday. Another weak low will form along
the downeast coast on Thursday ahead of an Arctic front...followed
by very cold air for the region at the end of the week.
Near term /through Wednesday/...
207 PM...dropped the Winter Weather Advisory for central and
interior downeast as steady snow has ended west/just some flurries
being reported. Advisories remain for the northern areas.
Previous discussion: mid-level/500mb trough axis oriented west-
east continues to lift slowly northward across central Maine at
1415z. Broad region of saturated southeast-east flow in 850mb to 500mb layer
north of the 500 mb trough axis continues to maintain sufficient
moisture for mainly light snowfall across northern Maine...aided
by deep saturation in dendrite growth layer (-12c to -18c) per 12z
Mosaic composite reflectivity at 14z showing expected gradual
decrease in reflectivity values from south to north across
Maine...generally as middle-level trough passes. Back edge of any
remaining steady snow should reach the St John valley by early
this evening. Surface winds generally north to north-northeast at 5-10 miles per hour through
the remainder of the day. Temperatures will increase slowly under
overcast skies and north winds with afternoon highs generally in
the upper teens to low 20s for eastern Aroostook County...and middle
20s near kbgr and along coastal areas.
With continued NE low level winds and upper trough conditions persisting
aloft... skies will remain cloudy with scattered snow showers tonight...especially
across the north. Subsequently...with no advcn of colder air slated
through tonight... near normal hi temperatures expeceted or this afternoon will be
followed by above normal overnight lows.
Short term /Wednesday night through Friday/...
a somewhat amorphous weather pattern is expected for the middle
of the week. A large upper trough of low pressure will gradually
shift eastward across the Great Lakes and the northeast conus,
with small shortwaves rotating around it from time to time. These
sorts of waves and their associated weak surface lows are
notoriously hard to predict in timing, strength, and placement. As
such, expect there will be at least a slight chance of snow across
much of our forecast area through much of the period. At this
time, the strongest forcing looks to remain off to our south,
though the latest GFS run has one weak surface low developing
right along the Maine coast Wednesday night and then moving into
the Bay of Fundy on Thursday. This solution would bring snow to
the region, especially downeast. There does seem to be some
support for this from the sref and ECMWF, though both have a
weaker and less organized system. Have stayed with low chance probability of precipitation
over our southern areas as a result of the discrepancies.
Temperatures will be close to normal for early February, with
Wednesday a few degrees warmer than Thursday.
Long term /Friday night through Monday/...
the main focus through the weekend will be the turn to much
colder conditions. An Arctic airmass will settle over the region
Thursday night and Friday, with a reinforcing shot over the
weekend. Highs will mainly be in the 5 to 15 range, while
overnight temperatures will be -10 to 5. Saturday night/Sunday
morning will likely be the coldest period as everyone is expected
to drop below zero, and some of the cold locations in the North
Woods will plummet to around -15. The longer range model guidance
is indicating there may be a clipper-type system late Friday into
Saturday, with perhaps a secondary coastal low developing
somewhere along the Maine coast. This could bring some snow to the
region at the end of the week, especially downeast. A strong
Canadian high will slowly settle over the eastern United States
through early next week. Temperatures will remain cold through the
weekend, but some moderation is possible on Monday as the ridge
axis shifts east, placing US in weak southwest flow.
Aviation /19z Tuesday through Sunday/...
near term: IFR conditions with steady snfl across the taf sites
Erly this morning will slowly improve to MVFR from S to north across the
region from late morning downeast sites to Erly evening across northern most
sites. MVFR clgs and attms...visibilities will then continue for all taf
Short term: persistent cloudiness will keep prevailing VFR/MVFR
conditions around Wednesday and Thursday, with northern areas the
most likely to see VFR. Some snow will be possible on Thursday,
especially across Bangor and downeast, and conditions may lower to
IFR from time to time in this precipitation. Friday will see
decreasing clouds and all sites VFR, but another potential storm
system will bring MVFR/IFR chances along with snow for Saturday.
near term: winds down below 20 kts but seas still up above 6 feet
especially over anz050(44027). Decided to go west/a Small Craft
Advisory for hazardous seas through midnight. Conditions will
improves west/winds & seas below Small Craft Advisory into Wednesday.
Short term: a Small Craft Advisory, perhaps for seas only, will
likely be ongoing at the start of the short term as seas will be 5
to 7 feet. These conditions will persist through Thursday. Low
pressure will cross the waters late Thursday, and expect winds
will increase from the northwest once this feature GOES by. At the
least, expect a high-end Small Craft Advisory will be needed
Thursday night into Friday morning, but won't rule out a few hours
of low-end gales as well.
ME...Winter Weather Advisory until 7 PM EST this evening for
Marine...Small Craft Advisory for hazardous seas until midnight EST
tonight for anz050-051.