Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
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FXUS61 KGYX 210315 AAC
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1115 PM EDT WED JUL 20 2016
High pressure will move to the southeast of the Maine and New
Hampshire tonight. A warm front will approach the southwest
Thursday night ushering in much warmer and humid air. A cold
front will approach Friday and move off the coast Saturday
morning. A secondary cold front will move through the area
Saturday afternoon ushering in some slightly less humid air. High
pressure will build overhead Sunday. Warmer and more humid air
will return Monday with a cold front moving through late Monday
.NEAR TERM /THROUGH THURSDAY/...
-- Changed Discussion --Update...A few minor changes to temps and dewpoints overnight.
Keeping an eye on low temps in the far N...where decoupling may
allow for a few readings in the 40s again. I bumped min temps down
a couple degrees in these zones.
Previous discussion...A fine night on tap for tonight. Low
temperatures will be similar to last night. Expect the cumulus to
dissipate after sunset. I do expect some patchy fog to form
overnight after 06Z.
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.SHORT TERM /THURSDAY NIGHT/...
After any fog burns off in the AM Thursday looks like a fine day
but warm with high temperatures climbing into the mid to upper 80s
south of the foothills. The saving grace will be the dew points
will only rise into the mid to upper 50s. The very humid air will
stream in Thursday night with dewpoints in the 60s by Friday
morning. There is the chance of showers and maybe a thunderstorm
late Thursday night or early Friday morning as this warm and humid
air streams in. Low temperatures Thursday night will only drop
into the mid and upper 60s in southern locations. It will feel
very unpleasant out there by Friday morning.
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
High impact weather: Strong to severe thunderstorms possible
Friday begins with a very strong ridge of high pressure in the
central CONUS. Northern New England remains on the periphery of
the high with disturbances moving across the top of the ridge into
our area. The ridge breaks down towards the end of the weekend
allowing a more progressive flow to move in.
Friday morning a warm and humid airmass will be in place across
northern New England. Southerly flow will bring dewpoints into
the low 60s and allow temperatures to climb to near 90 in the
south. Aloft a short wave will move in around 18Z... helping to
touch off thunderstorms. MUCAPE values range from around
1500-2000 J/kg as a region of steep mid-level lapse rates moves in
providing plenty of instability and moisture for thunderstorms.
Severe thunderstorms are possible as a 50-60kt tropopause jet will
help to support storm top divergence and a lower level jet of
around 40kts at 3km will result in increased surface shear. While
winds aloft remain westerly the mountains will help to channel the
surface level winds more southwesterly in the coastal plain
increasing the wind shear. With all the progs pointed to the
potential for severe storms Friday afternoon have added the gusty
winds and small hail wording. The only concern would be for early
morning or overnight thursday convection to result in more clouds
which would limit surface heating and destabilization and this
uncertainty kept the severe wording out of the grids for now.
Friday night convection will decrease after midnight as the upper
level disturbance moves out. Saturday will see a few scattered
showers and thunderstorms as the trough moves overhead. Some
spread in the coverage of showers between the deterministic
models but have hedge PoP a bit lower due to the westerly flow.
Sunday a weak high builds in with clear skies and no
precipitation. Another cold front approaches from the northwest on
Monday afternoon which will again touch of thunderstorms.
Strongest lapse rates look to remain a bit to the west so will go
with just scattered thunder.
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Short Term...Expect VFR tonight except IFR possible at LEB and HIE
in fog. VFR expected Thursday. MVFR may move in Thursday night in
Long Term... Thunderstorms will impact all terminals on friday
afternoon with gusty winds and small hail. VFR conditions remain
through the weekend with the next chance of IFR late Monday
afternoon in rain.
Short Term...Winds and seas will remain below SCA criteria but
will be increasing Thursday night.
Long Term... Scattered thunderstorms will impact the waters on