Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
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FXUS61 KGYX 291539
Area Forecast Discussion
National Weather Service Gray ME
1139 AM EDT Thu Sep 29 2016
High pressure will continue to build into the region from the
north through Friday. Low pressure over the midwest drifts slowly
north and east through the weekend. This low will eventually bring
the chance of showers to the region Friday night through at least
Monday. High pressure will again build in from the north by the
middle of next week.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Have updated the grids based on current conditions and latest set
of morning mesoscale models. Dry air continues to funnel
southward, leaving the forecast area with plenty of sunshine.
A cool, maritime flow will limit high temperatures to remain in
the 60s this afternoon, however maximums where raised a couple
degrees from previous forecast.
A large blocking upper air pattern continues with a stationary
upper low centered over the Ohio Valley while to the east an upper
ridge axis has become wedged across northern New England. At the
surface a large ridge of high pressure has become draped across
northern New England supplying a dry but cool persistent low level
Northeast flow. Central and mountain areas of Maine and New
Hampshire will have enough dry air entrained southward to allow
mostly sunny conditions while southernmost areas will have the
effects of the moist Northeast maritime low level flow with
clouds. Also early this morning some patchy early morning valley
fog can be expected where skies clear. Temperatures will remain
cool today with highs reaching around 60.
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.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
High pressure will continue draped across the area tonight. By
early Friday a wave of low pressure develops along the mid
atlantic coast well to the east of the stationary upper low over
the Ohio Valley. This wave of low pressure will move slowly north
and push the northern fringe of moisture into extreme southern
areas of the forecast area so will mention a chance of showers
developing in those areas during the day on Friday. All models agree
on keeping the northern fringe of precip only into far southern
areas. Further north another dry but cool day expected under the
axis of high pressure. Used a blend of models for min and max
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Chance of high impact weather: Minimal.
No real changes to forecast thinking at 500 mb over the last 24
hours as closed low over the midwest CONUS remains separated from
the main flow well to the north, with weak Rex blocking holding
this low to our west through Saturday, before it starts lifting NE
toward New England. The low eventually joins the northern stream
flow as strong troughing digs equatorward over the west and pushes
up a ridge over the central CONUS early next week which eventually
moves into New England by the middle of next week.
As for sensible wx, confidence is low as to when it will rain,
but the continued slowing of the low and the strength of the
ridging over the area will likely hold back precip for all but
srn NH Friday night into Saturday morning, and even here will only
have chance pops, as models look to produce convection over the
mid-Atlantic region and then push that into the ridging over the
southern CWA Fri night into Saturday. Large scale forcing and
ascent look weak, so precip will either be light or the result of
flattening convection moving in from the south. Will see a lot of
clouds in the Fri night to Saturday frame across the south, but
northern and eastern zones are likely to see some sun on
Sunday and Monday look to be the best chance for showers CWA-wide,
but when and where remain the big questions. It will likely be
more dry than wet both days, but will be be mostly cloudy to
overcast, although could see DZ working in late Sunday into early
Monday Should see improvement by the middle of the next week as
low moves out and ridging moves in.
Temps through the period will run close to normal for highs, and
above normal for for lows, as clouds and cooler E-NE flow will
limit the how much we can mix down the above normal 850 temps,
running around or slightly above 10C. Highs will generally be in
the 60s, with overnight lows mid 40s N to low 50s south.
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
Short Term...Variable conditions through Thursday with VFR
conditions over central and mountain areas with mainly MVFR
conditions over southernmost areas. Some overnight and early
morning valley fog til 13z will allow for lcl IFR conditions.
VFR conditions expected inland through Saturday, although could
see IFR at coastal terminals and KMHT Fri night. Higher potentialfor
flight restrictions Sat night into Monday in low clouds fog and
DZ, especially on the coast.
Short Term...Persistent Northeast flow will continue SCA
conditions outside the bays through Friday.
Persistent NE flow will be weakening by Saturday but should be
enough to keep seas around SCA levels into Saturday before they
diminish. Weak NE flow persists through Monday.
MARINE...Small Craft Advisory until 7 PM EDT Friday for ANZ150-152-154.