Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
757 PM EDT Tuesday Jul 28 2015
warm and humid air will remain over Maine and New Hampshire for
the next few days. Showers and thunderstorms will be possible
mainly during the late afternoon and evening hours today... with
some severe thunderstorms possible. A cold front will cross the
region on Thursday with more thunderstorms possible. A weak
disturbance may bring a few showers to the mountains Friday. Upper
level trough remains in place through early next week bringing
periodic frontal passages and unsettled weather.
Near term /until 6 am Wednesday morning/...
8 PM update: all convection has ended with air mass stabilizing.
Took out any chance of any additional convection for the rest of
the night. Some valley fog and ocean fog likely to develop later
tonight. No other changes.
7 PM update: no major changes made. Input latest mesonet data.
Still widely scattered strong to severe thunderstorms persist so
probability of precipitation and weather grids look good for the rest of the evening.
scattered convection will continue into the evening hours in
vicinity of weak surface front...across our northern and eastern
forecast area with cells occasionally producing damaging winds and
marginally severe hail. Elsewhere...activity should be widely
scattered. Convection should end by late evening with loss of
daytime heating. Overnight...expect partly cloudy skies with
patchy fog developing.
Short term /6 am Wednesday morning through Wednesday night/...
stalled frontal boundary situated from northern New Hampshire
eastward to middle coast Maine could serve as the focus for widely
scattered showers and thunderstorms again tomorrow. Otherwise...a
mostly sunny and hot day with highs in the 80s and lower 90s...but
tempered a bit near the coast as the flow turns onshore by
Any convection should once again die off by late evening with
partly cloudy skies and patchy fog developing overnight. Low
temperatures should be mainly in the 60s.
Long term /Thursday through Tuesday/...
500 mb pattern becomes more weakly amplified into the weekend and
next week...with a trend back toward toughing over Hudson Bay.
However...the weak amplification will tend to keep the cooler air
north of the border and allow warm air to remain in place over New
England...so temperatures will remain above normal through the period.
Also...given the proximity of the 500 mb trough will see several
waves move through the flow...which will mean a few rounds of
shra/tsra...mostly focused around maximum daytime heating in the
afternoon and early evenings. The extended forecast has a lot of
chance probability of precipitation...esecially in the north...but no day is likely to be a
washout...and an overall drier pattern will persist.
Specifically a cold front comes through late Thursday and will produce
some shra/tsra...mainly Thursday after into evening. Pre-frontal should start
the day with onshore flow along the coast...and this will keep
things cooler on the coastal plain...especially east of
pwm...where highs will be closer to 80. Inland areas to the S and
west of Portland will once again rise to the upper 80s and lower 90s
ahead of the front. Could see some strong to severe storms once
again with this front...mainly away from the coast.
Behind the front...will see T/dew point drop off some on Friday...and surface
ridging will keep things dry...but highs still in the middle to
upper 80s in the S...and low 80s in the mountains and on the coast.
Generally have afternoon chance probability of precipitation in the north and southerly probability of precipitation toward the
coast both Sat and sun as weak waves move through the almost zonal
flow aloft. Temperatures will be closer to normal over the weekend, but
still on the warm side. Flow shifts more SW early next week and
things warm up a bit again.
Aviation /00z Wednesday through Sunday/...
short term /through 11z Thu/...areas of MVFR overnight in stratus
and fog with local IFR possible between 06 and 12z Wednesday. VFR Wednesday with
local MVFR possible after 18z in widely scattered rain showers and thunderstorms and rain vicinity of kaug
and krkd. Areas MVFR after 00z Thursday in stratus and fog with local IFR
possible between 08 and 12z Thursday.
Long term...mainly VFR Thu-sun. Thunderstorms and rain a good bet Thursday
afternoon...especially at inland terminals. May see a break from
valley fog Thursday night...but should return Friday and Sat night.
short term /through Wednesday night/...weak pressure gradient
should keep winds and seas below small craft threshold.
Long term...weak flow will generally continue Thursday through sun...and
keep seas/winds comfortably below Small Craft Advisory levels. Only exception may be
late Thursday and Thursday night as SW flow surges a head of a cold front
and could approach Small Craft Advisory briefly.