Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Gray ME
311 am EDT Thursday Apr 17 2014

Synopsis...
cold high pressure over the area today will shift offshore on
Friday...producing a cool onshore flow. Weak low pressure passes
to our north on Saturday...and could produce a few showers. High
pressure builds in Sunday and Monday with more seasonable
temperatures. Another round of showers is possible Tuesday into
Wednesday as a cold front moves through.

&&

Near term /today/...
after a cold start to the day... temperatures will rebound into
the 40s. High pressure to the northeast will allow an east to
southeast onshore flow to develop during the day... adding a cool
marine influence along the coast. As a result... coastal areas may
be the coldest this afternoon while inland and mountain areas will
be about 5 degrees warmer. Should be a clear day although some
clouds may move into southeast New Hampshire later in the
afternoon as the onshore flow begins to transport moisture back
into the area.

&&

Short term /tonight and Friday/...
high pressure ridge continues across northern New England
tonight... so winds will likely go calm again for much of the
area. Some recovery of dewpoints today will prevent temperatures
from falling as far as they did this morning... but 20s will be
widespread overnight. Record low of 21 at Portland and 18 at
Concord are likely safe from being broken this year.

Continued southwest flow aloft will try to warm things up Friday.
But an onshore southeast flow will keep regions near the coast
cold again. Western New Hampshire will likely rise into the low
50s while coastal New Hampshire and Maine will stay in the low to
middle 40s. Will also see a better chance of clouds and fog
developing as the onshore flow persists.

&&

Long term /Friday night through Wednesday/...
weakly amplified zonal flow will persist at 500 mb through most of
the extended period...which will lead to couple weaker systems
moving through...with temperatures generally remaining around
normal levels. Models suggesting a more amplified pattern
develops middle- late next week.

First system will be weak 500 mb trough passing north of the forecast
area Friday night and Saturday...which drags a weak cold front
through the area. The model trends have been for less dynamic
support with this system...and thus less chance of showers...mainly
late Friday night into Saturday across the mountains and northern
zones. This weak cold front will actually warm things up as flow
shifts from onshore to west during the day Saturday and highs pop
back up to near normal...generally in the upper 40s and 50s
elsewhere.

After some 500mb ridging moves through Sunday into Monday...with
seasonable temperatures continuing...will see a southern stream
closed Low Pass to our southeast Tuesday and eventually phase with
northern stream wave to our southeast on Wednesday. This looks to happen
too far to our S and east to bring US any significant
precipitation... but northern stream could produce some showers
Tuesday... with middle level deformation or inverted troughing
perhaps producing some rain on Wednesday.

&&

Aviation /07z Thursday through Monday/...
short term...
winds become light east or southeast today with VFR conditions.
There is a chance for some marine stratus to bring MVFR or IFR
conditions primarily to Portsmouth later today. A better chance of
marine stratus or fog is possible tonight into Friday as onshore
flow continues.

Long term...
onshore flow could produce some flight restrictions...IFR or
lower in coastal terminals Friday night into Saturday morning. A
cold front will move through midday Saturday and should clear out
all terminals to VFR by Saturday evening. VFR expected Sunday-
Monday.

&&

Marine...
short term...
winds continue to get lighter with seas near 5 feet dropping to
below 5 feet this morning. Will likely be able to drop the Small
Craft Advisory sometime this morning.

Long term...
generally seas remain below Small Craft Advisory levels this weekend... although
they could reach Small Craft Advisory criteria Monday.

&&

Hydrology...
flood warnings remain in effect for several rivers across
northern and central parts of the forecast area. With the
exception of the Connecticut River at Dalton and the Androscoggin
at Auburn... which are cresting early this morning... all other
rivers are trending downward. However... it will be a slow fall to
below flood stage for the Connecticut... Kennebec and Androscoggin
rivers... with some points not falling below flood until sometime
Friday. See the latest flood products... pwmflsgyx and
pwmflwgyx...for more details. These products are also available on
our web site at www.Weather/gov/gyx.

&&

Gyx watches/warnings/advisories...
ME...none.
New Hampshire...none.
Marine...Small Craft Advisory until 6 am EDT early this morning for
anz150-152-154.

&&

$$

Synopsis...cempa
near term...Kimble
short term...Kimble
long term...cempa
aviation...cempa/Kimble
marine...cempa/Kimble
hydrology...cempa