Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 281824

Area Forecast Discussion
National Weather Service Caribou ME
224 PM EDT Wed Sep 28 2016

High pressure will build south across the region this afternoon into
Saturday. Low pressure will gradually approach from the south on


215 PM update...
Clouds are filling in per the latest Visible Satellite imagery and
more so across the northern 1/2 of the CWA. This has helped to cap
temps in this area. Adjusted the winds up just a bit to fit w/the
last 3 hr trends. No other changes needed attm.

Previous discussion...
Surface high pressure will remain centered just to our northeast
today and tonight. Meanwhile, a large upper low will meander
across the Great Lakes and Ohio River Valley. Afternoon highs
will range from the lower and mid 50s in the north to around 60 in
interior Downeast locations. Temperatures tonight will bottom out
around 40 in the north and in the upper 40s to around 50 Downeast.


A split flow omega blocking pattern will be in effect by the the
short term, with our FA downstream upper ridge psn from a large
upper low in the OH vly, near the confluence zone between the nrn
and srn branches of the upper jet. What this will entail is that
sfc hi pres ovr QB and Nrn Can maritimes will hold ovr the FA
during this tm, keeping deeper ovrrng cldnss and any rn just S of
our FA. Hi temps Thu will be a little below avg, followed by a
cool ngt across the N Thu ngt, which will be least impacted by hi
cldnss. Hi temps Fri look to be milder with fcst aftn 925mb temps
about 3 deg c warmer than Thu aftn. Low temps Fri ngt will not be
quite as cool as Thu ngt with a little more in the way of hi and
mid cldnss, even across the N and milder 925mb temps than Thu ngt.


The blocking ridge both at the sfc and alf will slowly give way to
the E durg the weekend as the upper low begins to dislodge from
the OH vly and move toward the ENE. The 28/00z dtmnstc GFS is a
little faster to show this than the 00z ECMWF, so our fcst grids
try to blend the tmg difference of the cld and rn advc NE into our
FA. Because of the tmg uncertainties between the longer range
models and relatively low fcst QPF attm, we kept rn PoPs in the
chc cat for now, slowly movg chc PoPs NE from coastal Downeast
areas late Sat aftn to far nrn areas Sun eve. The best chc of rnfl
for the region in the form of shwrs may be with whats left of the
upper low as it tracks toward and just S of the FA Sun ngt thru

Depending on the advc of thicker cld cvr on Sat, it is likely that
hi temps Sat aftn may be inverted, warmer across the N where more
sunshine is likely. Otherwise, fcst hi temps Sun and Mon will be
at or just below avg with abv normal ovrngt lows due to the
presence of deeper cldnss and shwrs.

The 00z CanGem model bridges the gap between the faster cooler GFS
and slower warmer ECMWF models in exiting the opening upper low E
of our FA by Tue and the drier llvl air mass following this system.


NEAR TERM: MVFR conditions are expected to prevail at all
terminals through this morning, though IFR ceilings will be
possible at BGR and BHB until 12z or so. Ceilings will lift to VFR
thereafter, but will likely drop back to below 3000 ft by 06z
Thursday at most spots; ceilings below 1000 ft will be possible at
BGR and BHB.

SHORT TO LONG TERM: Mainly VFR xpctd all TAF sites thru this ptn
of the fcst...possibly transitioning to MVFR clgs and vsbys across
Downeast sites with showers by Sun aftn.


NEAR TERM: The Small Craft Advisory is now in effect from 5 am this
morning through Thursday morning. Seas are already approaching 5
feet at both buoys in the outer waters, with gusts around 20 kt.
Therefore felt it appropriate to start the SCA a few hours earlier
than the previous forecast. Have left the inner waters out for now,
as most gusts will remain below 25 kt.

SHORT TO LONG TERM: SCA winds and seas should cont ovr the outer
MZs at least thru Thu aftn and then slowly diminish Thu ngt and
Fri. Primary wv pds will be arnd 8 sec for most of these ptns of
the fcst. Kept close to WW3 wv guidance for fcst wv hts this


MARINE...Small Craft Advisory until 5 PM EDT Thursday for ANZ050-051.



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