Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
1225 am EDT Wednesday Jul 1 2015
an area low pressure will approach from the west tonight and
will pass just north of the region on Wednesday. This system will
bring showers and thunderstorms to the region on Wednesday before
high pressure moves in on Thursday. High pressure then remains in
place into the Holiday weekend.
Near term /until 6 am this morning/...
1220 am...minor estf update to address current radar trends and
ingest the latest mesonet in 1st period grids.
update...a few tweaks...mainly to pop based on latest radar
trends. Most shower activity should be confined to interior areas
and mountains overnight...until early Wednesday when convection may impact
the coast. No major changes to the current forecast.
Previous discussion...area of precipitation moving through
Vermont and New Hampshire this afternoon. Most of the models are
not handling this well. However...the sref seems to be picking it
up decently. Have used it for the immediate short term probability of precipitation.
Precipitation is trending a little further east than the model
though. Evening shift may need to shift probability of precipitation into Maine more...but
it is possible that it will die off as we lose diurnal heating.
Similar to last night...expect patchy fog to develop over in
favored valley locations and along the coast.
Short term /6 am this morning through 6 am Thursday/...
fairly complex weather pattern for tomorrow and tomorrow night.
Low pressure system moving out of the Great Lakes will lift a warm
front across the region late tonight and tomorrow. It is looking
like the majority of the forecast area is going to see extensive
cloud cover and rain for a good part of the day. However...several
of the models are showing some late instability moving over
portions of New Hampshire. Forecast soundings from the nam12 are
indicating the possibility of up to about 1800j/kg of cape for
storms to work with by 5 or 6pm tomorrow. There is also some
decent shear as well. The key will be whether or not the
atmosphere can recover enough from the precipitation earlier in
the day. This seems to be a relatively common occurrence in New
England. Will bring in thunderstorm with gusty winds and hail for
now and then let the midnight shift evaluate again to see if
severe wording is needed.
Long term /Thursday through Tuesday/...
high pressure with just a few weak disturbances should dominate
the weather much of this forecast period. On Thursday a northwest flow
ahead of high pressure building in will result in a drying
airmass. The exception might be some up slope clouds and an
isolated shower or two over the mountains. High pressure to crest
over the region on Friday into early Saturday. One possible
complication to the weekend forecast is the possibility of a
backdoor cold front dropping down late Saturday and Sunday.
Latest GFS shows this possibility. At this time it would seem that
it has very little moisture to work with so this may be more of a
slight cool down with a wind shift and some broken clouds. GFS
model winds shift from SW to northwest Saturday night and Sunday.
High pressure will build back over the region on Monday. GFS is
slower in moving high out on Tuesday then European model (ecmwf)...which brings in
a shower threat on Tuesday. Will split the difference in probability of precipitation for
now as it is still 7 days out.
Aviation /06z Wednesday through Sunday/...
VFR conditions will drop to MVFR/IFR by morning in a mix of rain
and fog. Taf sites might recover a bit briefly early tomorrow but
will likely stay MVFR/IFR for most of the day.
Thursday through Sunday...VFR for most of the period as high
pressure will control the weather Thursday into Saturday. A
period of MVFR is possible late Saturday into Sunday as a backdoor
cold front approaches.
no flags expected...although winds and seas could come close to
Small Craft Advisory criteria late tomorrow.
Thursday through Sunday...wind and waves to remain below Small Craft Advisory
levels. West northwest winds Thursday to turn SW Friday into Saturday. Wind
will turn northwest on Sunday and Monday.