Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kgyx 181938 

Area forecast discussion
National Weather Service Gray ME
338 PM EDT Wed Sep 18 2019

cool high pressure centers over the forecast area tonight and
will allow for a frost in many areas overnight. Increasingly
warm temperatures are expected to arrive by the end of the week
and remain for the weekend, most likely well above normal. A
cold front will approach on Monday and Tuesday with a chance of
showers as it moves through.


Near term /through 6 am tonight/...
a beautiful day will give way to a clear and cool night. Aloft,
ridging oriented from light snow shower NE will build in farther east through
Thursday. At the surface, high pressure was situated over the
St. Lawrence River valley and will shift south tonight, becoming
generally centered from southern New York state to eastern Maine

Water vapor imagery and this morning's sounding from gyx support
a deep dry layer building in overnight with precipitable water values dropping
below a quarter inch across much of the area. This and other
parameters will support radiational cooling and temperatures
dipping into the upper 20s to mid 30s. Have not changed the
frost/freeze products at this time as they remainder in sync
with the latest guidance. Areas that do not have a freeze
warning/frost advisory may still see patchy frost. In addition
fog is likely in mountain valleys and the Connecticut River


Short term /6 am Thursday through Thursday night/...
Thursday will be several degrees warmer than today with highs in
the mid 60s to lower 70s as heights increase aloft. Winds turn
to the SW at the surface as high pressure shifts southwest and
Humberto drifts to our east. For the most part we will see sunny
skies with some high cirrus mainly across the mountains.

Thursday night temperatures will be in the lower to upper 40s
across the region with winds remaining westerly.


Long term /Friday through Wednesday/...
overview: surface high pressure remains over New England through
the Saturday, keeping the beginning of the period dry and
quiet. An upper level ridge builds into New England through
Saturday. Our next chance for significant precipitation is looks
to be late Sunday/early Monday with chances for showers
continuing through Tuesday. A warming trend will push
temperatures well above normal on Friday and they will remain
there through early next week before things begin to cool down
again beginning Tuesday.

Impacts: no significant impacts anticipated.

Details: Friday begins with broad surface high pressure over much
of the eastern U.S. With an upper level ridge continuing to
build in from the southwest. Surface high pressure then remains
over New England through Saturday with dry and quiet conditions
expected throughout our region. The upper level ridge crests
over our region early Sunday as a large frontal system
approaches from the west. On Sunday, the flow becomes
southwesterly ahead of that frontal system, but the best chances
for precipitation will hold off until Sunday night and Monday.
The latest deterministic guidance continues to have some
differences in timing and evolution of this system as it moves
through our region so have kept chance pops in place for Monday
and Tuesday. Scattered showers will likely be all that we see,
but cannot rule out a few rumbles of thunder on Monday as well.

High temperatures on Friday will likely be up to 10 degrees or
higher above normal for this time of year. Similar above average
temperatures will continue through the weekend and into early
next week, but a cooling trend looks to begin on Tuesday as the
frontal system moves through and upper level troughing moves
over New England, pushing temperatures closer to normal for the
middle of next week.

Areas of fog will be possible in the northern river and mountain
valleys early Saturday morning.


Aviation /19z Wednesday through Monday/...
short term...VFR conditions will prevail except for patchy dense
fog between 08 and 13z Thursday, mainly at hie and leb.
Otherwise clear skies and light winds are expected.

Long term...VFR conditions are expected at all terminals through
the weekend. Winds will generally be light Friday and Saturday
under surface high pressure with southwesterly winds increasing
on Sunday ahead of an approaching frontal system. Clouds also
increase on Sunday with light rain showers possible at hie and leb
Sunday night. Light rain showers possible across the region on Monday.
Hie and leb may see brief periods of MVFR/IFR in fog in the
early/mid morning hours through the weekend.


short term...quiet on the waters with northeasterly winds as
Humberto moves by to our south and high pressure remains over
land. Seas will begin to increase Thursday night due to swell
from Humberto.

Long term...been mentioning it for a few days now, but looks
like we will see the arrival of long period swell from Hurricane
Humberto on Friday. Because of that, we have issued an Small Craft Advisory for
hazardous seas for the outer waters in effect from early Friday
morning through early Saturday morning. It is possible that
Casco Bay will need to be added to it. May need another Small Craft Advisory for
Sunday into Monday as southwesterly winds increase ahead of an
approaching frontal system.


Gyx watches/warnings/advisories...
ME...freeze warning from midnight tonight to 9 am EDT Thursday for
Frost advisory from midnight tonight to 9 am EDT Thursday for
New Hampshire...freeze warning from midnight tonight to 9 am EDT Thursday for
Frost advisory from midnight tonight to 9 am EDT Thursday for
Marine...Small Craft Advisory for hazardous seas from 2 am Friday to 2
am EDT Saturday for anz150-152-154.




National Weather Service Glossary of Abbreviations