A Possible Mid-August Coastal Storm

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FXUS61 KCAR 140214

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

1014 PM EDT Sat Aug 13 2022

.SYNOPSIS...

Low pressure south of Nova Scotia will track north through the

Maritimes overnight into early Sunday. High pressure will

return Sunday afternoon into Monday. Low pressure will develop

to our south on Tuesday and lift north into the Gulf of Maine on

Wednesday, then into the Maritimes Thursday......

....Sunday: The mid to upper level low will pivot across Aroostook

County during the morning and exit into New Brunswick by the

afternoon. Surface low pressure will deepen along the coast of

Nova Scotia and move northward, remaining well east of the area.

Scattered showers are expected across Aroostook County, with

isolated showers over adjacent areas. Daytime heating should

enhance activity before it diminishes in the evening. Briefly

steeper mid-level lapse rates may lead to an isolated rumble of

thunder, mainly northeast of Caribou. However, if the mid level

low moves even slightly faster, more substantial convection

could be confined to New Brunswick instead. Bangor and the coast

should remain dry with skies becoming partly to mostly sunny.

High temperatures in the 70s are expected, with the warmest

temperatures along coastal Hancock County into the Bangor

region.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...

High pressure builds quickly Sunday night with clearing skies

and light winds. The high stability will promote a sharp

radiation inversion with the potential for patchy fog,

especially where precip fell on Sunday. Have reintroduced patchy

fog into the forecast in eastern zones. Lows will be in the low

to mid 50s. High pressure centered over James Bay remains in

control on Monday with continued light winds. Highs will recover

to the upper 70s to near 80F. There`s sufficient H850 moisture

for cumulus development and can`t rule out a few sprinkles but

will not include PoPs. The high slowly moves eastward Monday

night, providing another night of clear skies and light winds.

Resultant lows will again be in the 50s. For Tuesday, the high

will north of the state in northern Quebec and induce an

easterly low level flow. Expect more moisture and resulting

cloud cover. There`s just enough lift to mention a slight chance

of showers. High temperatures will be about the same as

Monday`s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...

The high to north of the area in Quebec will serve as a block to

a cut off upper low settling over the Mid-Atlantic states on

Tuesday night. A vort max rotating around the low is expected to

result in surface low development off the Mid-Atlantic coast.

The exact timing and positioning remain in question, but the

13/12Z GFS and ECMWF have better general agreement than the

previous runs. Both now show an August Nor`Easter. The low will

quickly deepen and draw deep Atlantic moisture northward. The

pressure gradient between the Quebec high and deepening low will

quickly tighten up with strengthening NE winds Tuesday night

into Wednesday. Precipitation will be increasingly likely to

pivot northward into coastal zones during Wednesday afternoon

and have upgraded to likely PoPs later Wednesday into Thursday

morning. This band of precipitation certainly would have the

potential to produce an inch or two of rain as it moves across

the CWA late Wednesday into Thursday. By Thursday morning,

expect a vertically stacked low slowly filling and meandering

northeastward. PoPs will slowly decrease later Thursday into

Thursday night. The air mass left behind the storm will be warm

and humid. Residual moisture will generate a lot of cloud cover

and hold down Friday`s highs, but next weekend should feature a

return to afternoon highs above 80F......