Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Caribou ME
842 am EST Monday Dec 29 2014

Synopsis...
a cold front will cross the region today. High pressure will build
across the region Tuesday into Wednesday.

&&

Near term /through tonight/...
8:45 am update...expanded coverage of snow showers up into
northern Maine where some streamers of flurries and snow showers
have been developing in the cold air advection. Otherwise, no
major changes this hour.

Expect cold front along with surface trough to move across the
state this morning. This will result in snow showers. A colder air
mass and high pressure will build in from the west later this
afternoon and tonight. Will use the gfs40 for probability of precipitation... sky and quantitative precipitation forecast
since it is handling probability of precipitation and quantitative precipitation forecast from frontal system. Have used
the consensus raw blend for temperature to better handle incoming
colder air mass. The mosg25 was used for wind grids.

&&

Short term /Tuesday through Wednesday/...
much colder airmass setting in place west/high pressure building in from
the Canadian region.

The pressure gradient is forecast to weaken Tuesday morning as the
high noses in from the west. The model soundings from both the GFS
and NAM point to some moisture from 925-850mbs across the northernand
western areas on Tuesday west/a west-northwest flow. Therefore, some clouds will
be around which will keep daytime temperatures down as well
keeping readings in the single numbers. Elsewhere, there should be
plenty of sunshine and west/temperatures quite cold only reaching the
low to middle teens by afternoon. Another concern will be the
possibility for some streamers to come off of the open St.
Lawrence. The wind trajectory from the soundings suggests the best
potential for this is it were to set up would be across the
western areas and northern Piscataquis County. Since the depth of
the moisture layer looks to be limited, decided to leave off the
mention of flurries or light snow. The daycrew can assess this
further today.

Some clouds are forecast to be on the increase Tuesday night into
early Wednesday mainly affecting northern and western areas. This
is due primarily to an upper disturbance forecast to move across
The Crown of Maine. Some weak middle level forcing and the depth of
the moisture through 700mbs will lead to a period of light snow or
snow showers. Decided to add 15-20% to account for this setup.
Overnight lows Tuesday night will be hit early and then they
should level off as the clouds work their way into the state.
Wednesday will be another cold day with below normal temperatures
for late December.

&&

Long term /Wednesday night through Sunday/...
a weak system is shown by the long range guidance including the
European model (ecmwf) and Canadian global to bring some light snow or snow showers
to the region on Thursday. As a matter of fact, all the long range
guidance are in good agreement of showing the potential for some
light snow west/the warm front on Thursday west/a slight warmup. The
associated cold/Arctic front is forecast to move across the region
Thursday evening west/another blast of cold air coming out of Canada.
The potential does exist for some decent snow shower/squall
activity west/this front especially right at the sharp drop in
temperatures just behind the front. Decided to bring the probability of precipitation up
to at least 30%. The daycrew can assess this more west/the later
guidance today. Temperatures will start falling back after
midnight but west/clouds hanging on especially across the north and
west, readings are forecast to stay above zero. Temperatures could
actually fall during the day on Friday as the colder airmass pours
in behind the Arctic front.

A big discrepancy shows up by the weekend in regards to a
potential system that could affect the region. The last few runs
of the European model (ecmwf) have been consistent west/bringing a low pressure system
across the northern 1/2 of Maine while the GFS has been slower
and much warmer west/this system. The Canadian global matches well
west/the European model (ecmwf). Therefore, decided to go west/high chance pops(50%) for
snow west/the highest probability of precipitation across northern and western areas. This
system looks to be a fast mover and not expecting a big event as
it looks right now. Temperatures during this timeframe are
expected to be back at normal levels.

&&

Aviation /14z Monday through Friday/...
near term: MVFR/IFR possible in snow showers kfve... kcar... kpqi
this morning then VFR conditions later today and tonight.

Short term: periods of MVFR could affect the northern terminals on
Tuesday west/VFR for kbgr and kbhb. VFR for all terminals Tuesday
night and then another round of MVFR on Wednesday from khul to
kfve W/-sn. VFR for all sites Wednesday night into early Thursday
and then conditions could drop to MVFR and perhaps a brief period
of IFR for Thursday. This will be the case especially for the
northern terminals west/the potential for some more -sn.

&&

Marine...
near term: have used the nam12 for sustained winds. Wind speed
expected to increase somewhat later this afternoon as colder air
moves across relatively warm sea surface temperature. For waves:
combined sea today and tonight composed of southwesterly wave
system 2-3 feet/6-7 seconds generated from southwesterly fetch
across the Gulf of Maine last 24 hours and local off-shore wind
wave with wave heights subordinate to fetch distance from coast.
Will use the near shore wave model run on forecast grids for wave
heights. Timing of Small Craft Advisory still looks good and will not make any
changes.



Short term: conditions look be below Small Craft Advisory for Tuesday but
conditions deteriorate to Small Craft Advisory levels by Wednesday west/the passing of
frontal boundary. Decided to bring wind gusts up to 25 kts west/near
30 kts for the outer waters. As a matter of fact, it looks like a
brief reprieve for Wednesday night but another round of Small Craft Advisory
conditions by Thursday. This second round of Small Craft Advisory is due to a
frontal system forecast to move across the region. Tried to show
the transition west/winds and seas dropping off Wednesday night and
then building again on Thursday to Small Craft Advisory levels.

&&

Car watches/warnings/advisories...
ME...none.
Marine...Small Craft Advisory until 4 PM EST this afternoon for
anz050>052.

&&

Car watches/warnings/advisories...
ME...none.
Marine...Small Craft Advisory until 4 PM EST this afternoon for
anz050>052.

&&

$$

Near term...mignone/mcb
short term...Hewitt
long term...Hewitt
aviation...mignone/Hewitt
marine...mignone/Hewitt

National Weather Service Glossary of Abbreviations