Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
950 PM EDT sun Apr 26 2015
the persistent upper level low over the Canadian Maritimes will
shift SW into the Gulf Maine on Monday and this will provide US
with more numerous showers. The low will finally shift slowly
east Tuesday allowing high pressure to build in Wednesday and
Thursday. Low pressure passes south of the area Friday...with high
pressure building back in behind it next weekend.
Near term /until 6 am Monday morning/...
950 PM...this is a minor estf update to reflect the current
mesonet in first period grids.
615 PM...minor estf update to ingest the latest mesonet into first
the persistent 500 mb close low over the Maritimes picks up a
decent wave from the southern stream tonight and rotates the wave
around the low and back into northern New England on Monday...allowing
the western lobe of the low to deepen and pulling the whole system
back to the SW towards the Gulf of ME.
For tonight...as one weak wave wave exits southeast...should see any of
the light rain showers wind down around sunset...as these showers seem to
be popping up in areas with some break of sun...and are
instability driven. However as the energy begins to crest the
poleward side of the 500mb low from the NE will start to see rain showers
move into eastern zones around or after midnight. Temperatures fall back into
the 30s to around 40 again.
Short term /6 am Monday morning through Monday night/...
as the more potent 500mb wave pulls the low back to the south and
east will see some better dynamics and some thermal circulations
develop...which will mean the best chance for showers in the County Warning Area
since this low moved in on Thursday. It is not likely to rain all
day...but the threat of showers will be there...with the best
chance Monday afternoon into early evening. Overall quantitative precipitation forecast will not be
significant generally around one to two tenths of an inch at
best. Once again maxes will be stuck in the 50s most places.
Rain showers linger Monday evening...but should diminish later in the night with
some partial clearing late. Lows drop into the 30s to around 40
Long term /Tuesday through Sunday/...
the week begins with a closed upper level low in place over the
Maritimes and northwesterly flow bringing afternoon showers into
northern New England. This close low will begin to move east on
Tuesday... allowing for a ridge to build in for the middle of the
week. By Wednesday showers will exit to far eastern Maine.
Wednesday into Thursday will be mostly sunny with warming
Friday a split jet stream develops with a southern branch dipping
southwards to near Georgia and then returning northwards up the
eastern Seaboard. This sets US up for a classic coastal low
track... and indeed some models would like to bring a strong
coastal low up through the 70w/40n benchmark as early as Saturday
morning. This is a very low confidence scenario. Currently the
closed low over New Brunswick is partially blocked by high
pressure built in over Labrador... meaning the closed low may take
longer to move out than anticipated. With over 5 days to go...will
leave it at a blend of model guidance and note that the widely
varying options will average out to a chance of showers for now.
Aviation /02z Monday through Friday/...
short term...despite rain showers will see VFR varying to MVFR at times
tonight through the day Monday. Improvement to VFR expected Monday
Long term...generally VFR conditions expected to prevail in the
extended. Upper low pressure will remain nearby through about
Wednesday...so cannot rule out afternoon MVFR ceilings or
visibility in scattered showers. Beyond midweek low confidence on
short term...weak low pressure will provide very light winds
through Monday. Winds increase Monday night as surface low intensifies as
it moves east.
Long term...Small Craft Advisory conditions are possible later
in the work week depending on how close to the Gulf of Maine low
cool and moist conditions continue through the early week period
with light winds.