Area Forecast Discussion
Issued by NWS Caribou, ME-- Remove Highlighting --
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FXUS61 KCAR 210750
Area Forecast Discussion
National Weather Service Caribou ME
350 AM EDT THU JUL 21 2016
High pressure will build south of the area today. A cold front
will approach Thursday night and cross the region Friday. Another
secondary cold front with an upper level low will approach the
region from the northwest on Saturday and cross the region
.NEAR TERM /THROUGH TONIGHT/...
High pressure will gradually shift south of the area today, allowing
a return southwest flow to set up across New England. Scattered
showers will develop over northern Maine late this afternoon in
response to warm air advection and spread south through the evening
as a pre-frontal trough crosses out of Canada. Instability looks
meager as much of the guidance is topping SB CAPE out at 350 J/kg or
so, and the SREF indicates only a 40% chance of CAPEs over 500. So
have only included isolated thunderstorms for this afternoon. It`ll
be a warm day with highs in the lower to mid 80s across much of the
Showers will continue overnight as the aforementioned pre-frontal
trough pushes south. Isolated thunderstorms will continue as well as
there will be plenty of elevated instability. Lows will be on the
uncomfortable side as temperatures will remain in the lower to mid
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
SPC still has much of New Eng in a slight risk of svr tstms for
spcly Fri aftn into erly eve, so we introduced enhanced tstm
element wording for winds...hail and hvy rnfl for Fri aftn/erly
eve as the first sig s/wv tracks W to E across the FA. Max tstms
cvrg will be in the sct to bkn range, so for now we max PoPs in
the high likely category for msly Nrn/Cntrl ptns of the FA. Max
potential SBCAPEs will be in the 1500-2000 J/kg with mdt 0-6km
bulk shear vectors of arnd 30 kt.
Another s/wv with an associated secondary cold front from Cntrl
Can will bring another round of shwrs/tstms to most of the region
on Sat, spcly the aftn into eve hrs again were we max PoPs in the
low likely cat. Lower fzg lvls and lesser shear vectors by Sat
aftn suggest the potential of larger hail and slower movg tstms
capable of producing hvy rn, but will hold off on enhanced tstms
element wording given that its still out in day 3, but will keep
mention in the HWO. Temps will be a abv normal, with hi temps both
days dependent on some available sunshine in the morn to midday
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Any remaining organized shwr/tstm activity from the eve hrs
should diminish and move E of the FA durg the ovrngt hrs Sat ngt
as the upper trof/closed low alf slowly moves E into NB prov. Sun
will be ptly to msly cldy, with isold shwrs possible across Cntrl
and Ern ptns pf the FA Sun aftn, as whats left of relatively cold
air alf only slowly moves E out of the FA as the upper low moves
across the Gulf of St Lawrence.
Clrg skies are then xpctd Sun ngt, contg into Mon morn before
cldnss increases Mon aftn with the apch of the next s/wv alf from
the great lks in a contd progressive wrly zonal ptn alf. Sct
Shwrs and possible aftn/eve tstms will then move W to E into the
FA from QB prov late in the day thru Mon ngt and perhaps into Tue.
Kept max PoPs in the chc cat for now. Tue ngt and Wed should be
drier. Temps will cont aoa normal.
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
NEAR TERM: VFR conditions will prevail today and tonight. Mid
clouds will increase this afternoon and evening as a warm front
lifts across the region. Scattered showers with isolated
thunderstorms are expected to move into northern Maine late this
afternoon and gradually push southward overnight. Localized IFR
conditions will be possible in any thunderstorms, especially at
the northern terminals.
SHORT TO LONG TERM: Msly VFR for the TAF sites Fri thru Mon, xcpt
ocnl MVFR clgs/vsbys in mdt rn shwrs and lcly IFR vsbys with hvy
rnfl associated with tstms.
NEAR TERM: No headlines will be needed through the near term. High
pressure will build south of the waters today, allowing winds to
turn to the south and increase to 15-20 kt. But any mixing will be
very limited due to the cold Gulf of Maine waters, so gusts will
remain below 25 kt. Seas will build from 2-3 ft this morning to 3-4
ft late this evening.
SHORT TO LONG TERM: An SCA for seas is possible for spcly the
outer MZs later Fri into Sat morn as a steady and fairly long
SSW wind fetch of 15 to 20 kt occurs Fri aftn into Fri ovrngt
generating 5 to 7 sec pd wvs of 4 to 6 ft. Stronger winds alf
are not xpctd to reach below 20M abv the sfc due to a strong
marine invsn. Wv hts should then slowly begin to diminish later
Sat and cont thru the remainder of the weekend. Only went with
about 75 percent of WW3 wv ht guidance for fcst wv hts for these
ptns of he fcst.