Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 221905
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
305 PM EDT Mon Apr 22 2019

.SYNOPSIS...
Low pressure south of New England will move northward tonight to
a position just south of Nova Scotia Tuesday evening. This low
will bring the region more rainfall, the heaviest of which will
be on the coastal plain. Another low pressure system will
approach from the west Tuesday night bringing more rain to the
region Tuesday night into Wednesday. More rain is expected by
the end of the week with another low pressure system.
Temperatures will be colder than normal to near normal through
much of the forecast period.

&&

.NEAR TERM /THROUGH TONIGHT/...
Stacked low pressure south of New England this Monday afternoon
will slowly move northeastward to a position in the Gulf of
Maine Tuesday. Rain is already spreading northward into southern
NH as of this writing and will continue to spread northward this
evening.

A period of moderate midlevel frontogenesis this evening and
overnight will move northward over the coastal plain aiding in
moderate to locally heavy periods of rain. While the main plume
of high PWATS will be located offshore, CCB will contain PWATS
over an inch over portion of Maine and New Hampshire, possibly
aiding in total rainfall amounts between 1-1.5" in spots. The
heaviest rainfall is expected on the coastal plain, with the
Seacoast of NH and York County ME the best candidates to see
those higher amounts.

At this time, we are expecting the heaviest QPF axis to stay
south and east of the mountains so any river rises should not be
overly troublesome. Will continue to watch trends, however. In
any case, urban and small stream flooding will be a possibility
overnight on the coastal plain. Thunder not out of the question
on the immediate coast tonight, but probabilities too low at
this time to include in forecast.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
Low pressure will continue to move northeastward through the
Gulf of Maine on Tuesday, with the rain moving out of southern
New Hampshire late tonight or early Tuesday morning, and most of
our Maine zones by midday. However, a quick-moving short wave
trough will approach from the west late in the day bringing more
showers to the region Tuesday night.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Upper level low moving through the Great Lakes will
generate some residual showers Wednesday morning. Upslope conditions
in the mountains will keep showery precipitation in place longer
there. Upper level flow turns more westerly behind the system on
Thursday. This will allow temperatures to warm a little bit from
Wednesday and should result in a dry day as well... probably the
nicest day of the work week. Low pressure begins to develop over the
mid Atlantic states Friday morning, with precipitation moving into
the forecast area by midday. The system turns into a bit of a
coastal low as it deepens over the Gulf of Maine. Precipitation
Friday afternoon and evening could be fairly heavy in places. This
system pulls off into the Canadian maritimes rather quickly, with
northwest flow returning for Saturday. It looks like there will
probably be a decent pressure gradient behind the system on
Saturday, so would expect gusty winds. The dry weather on Saturday
will be short lived as another low pressure system moving through
the Great Lakes will approach the region Saturday night. This looks
like a very fast moving system and will likely produce at least some
precipitation.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Short Term...MVFR to higher-end IFR expected for most terminals
tonight in low clouds and rain. However, LIFR conditions will be
possible on the immediate coast. Some improvement is foreseen
for Tuesday, especially midday onward. However, lower conditions
will re-enter the picture Tuesday night with more rain.

Long Term...Expect VFR conditions on Wednesday and Thursday,
deteriorating to IFR/LIFR conditions on Friday as a coastal low
generates some widespread rain.

&&

.MARINE...
Short Term...Northeasterly SCA-level winds are expected on the
ocean waters tonight through Tuesday as low pressure gradually
passes off to our east. Seas will build accordingly as well.

Long Term...May need an SCA for winds on Wednesday in the
wake of low pressure moving through the area. A stronger system
will affect the waters on Friday, with SCA criteria being met
or possibly even reaching Gales.

&&

.HYDROLOGY...
Rivers will remain high through the week with additional
snowmelt and several chances for rain. We will have to monitor
this situation closely, as it would not take too much rain to
cause the rivers to rise again, especially tonight and Tuesday.
At this time, highest rainfall amounts are likely to be on the
coastal plain tonight. However, up to a half inch will be
possible in some basins in the foothills which could result in
some modest additional rises. On the coastal plain, some small
stream, urban and poor drainage flooding will be possible. Will
also have to watch for a potentially significant rainfall Fri-
Sat as some deterministic guidance and ensemble members suggest.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 6 PM EDT Tuesday for ANZ150-152-154.

&&

$$

NEAR TERM...Ekster
SHORT TERM...Ekster
LONG TERM...Pohl



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