Area Forecast Discussion
Issued by NWS Burlington, VT-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KBTV 280231
Area Forecast Discussion
National Weather Service Burlington VT
1031 PM EDT Wed Jul 27 2016
A few showers or thunderstorms possible this evening near the
Canadian border. Better chances for showers and storms arrive
Thursday as a trough of low pressure moves into the region.
Showers over the southern areas expected Friday and Sunday.
Saturday looks to be the drier day of the weekend. Seasonal
temperatures will close out the week and persist into early next
.NEAR TERM /UNTIL 6 PM THURSDAY EVENING/...
-- Changed Discussion --As of 1025 PM EDT Wednesday...Minor modifications to temps and
pops during the overnight hours. Adjusted temperatures based on
observed hourly and bumped up a little over Lake Champlain where
warmer water is now keeping min temps a couple degrees warmer.
Overal min temps unchanged, mainly radiational cooling but some
clodus moving in will introduce some variability. Reduced POPs
overnight along the northern border based on radar trends.
Convection to the north of Lake Ontario has died out, and there
were some showers moving to the north of Massena that would have
tracked near the US/Canadian border, but have since dissipated as
well. IR satellite still showing a couple of enhanced areas of
clouds associated with weak waves moving west to east. First is
north of Lake Erie, set to arrive after 06z, and the second north
of the western Great Lakes would arrive tomorrow afternoon. Based
on current radar trends have backed off on pops during the
06-12UTC timeframe, but second wave arriving with daytime heating
has better chances.
Thursday will be more active with showers and thunderstorms in
the forecast as 500mb trough affects the area. In the morning
hours, showers will develop becoming more numerous in the late
morning/early afternoon with thunderstorm activity expected.
Negative Showalters, Lifted indices of -2c to -6c, CAPE values
anywhere from 800-1400J/kg support convective activity. Looking at
wind shear, there will be light low level flow and, therefore,
minimal low level shear. Early Thursday, an 80-90kt jet at 250mb
with 0-6km shear of 30-35kts to start the day and weakening in the
afternoon. PWATs exceed 1.5 inches in areas by early afternoon
along with steepening lapse rates. Overall expect an early show,
with greatest potential for thunderstorms during the midday hours.
Few thunderstorms could become strong before vort max providing
lift begins to exit south and east and activity gradually
Max temperatures tomorrow will be slightly warmer than normal, in
the upper 70s to mid 80s.
-- End Changed Discussion --
.SHORT TERM /6 PM THURSDAY EVENING THROUGH FRIDAY NIGHT/...
As of 345 PM EDT Wednesday...Focus for the short term period will
continue to be a weak frontal boundary as it slowly sags southward
through the BTV CWA Thursday night, and stalls somewhere near/over
the VT/NH/MA border on Friday. Convective activity wanes going
into Thursday evening/night with the loss of instability due to
decreasing insolational heating. Moving on into Friday, latest
trends are for additional precipitation to blossom along the
stalled frontal boundary as weak shortwave energy aloft shifts
east from the Ohio River Valley into the Mid Atlantic states. This
places the best chances for scattered showers and isolated
thunderstorm across southern Vermont, while areas north will
remain largely dry. Much like on Thursday, instability and shear
are rather weak, so not expecting any strong storms, but a few
more robust cells that do develop will have the potential to
produce brief heavy rain as PWATs remain in the 1.5-1.75" range.
Br Friday evening, any precipitation will begin to dissipate while
shifting eastward as high pressure begins to build in from the
Great Lakes Temps remain on the mild side of normal to begin the
period on Thursday night, holding in the upper 50s to low 60s, but
trend back towards mid/late summer standards with highs Friday in
the upper 70s to low 80s, and lows Friday night ranging through
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 345 PM EDT Wednesday...Overall idea for the long term
period remains intact from previous forecast thinking with surface
high pressure over the eastern Great Lakes on Saturday slowly
shifting east to off the New England seaboard by early next week
while aloft the flow remains out of the west/northwest. This
offers mainly dry conditions through the period though latest
guidance indicates a weak shortwave will bring a chance for a few
showers to southern areas during the Sunday afternoon through
Monday timeframe as it tracks from the Ohio River Valley to Cape
Cod. Overall this energy is fairly weak, so will just offer some
low chance PoPs across Rutland/Windsor counties while northward
keep the forecast dry. Temps through the period begin very
seasonal with highs over the weekend in the upper 70s to lower
80s, and lows in the 50s. As the high shifts east of the forecast
area, increasing southerly flow will allow for a return of warmer
and more humid conditions with temperatures rising a couple of
degrees each day, reaching into the mid 80s to near 90 by
.AVIATION /03Z Thursday THROUGH Monday/...
Through 00z Friday...VFR conditions will prevail with exception
of IFR fog and possible LIFR cigs at KSLK and KMPV mainly between
07z- 11z. Few/isolated showers/tstorms north of Lake Ontario could
eventually affect Northern NY through 06z but did not include in
terminal forecasts until they make their move. During the day
Thursday surface front sags slowly south with increasing mid level
clouds and will interact with surface instability to produce
showers and thunderstorms. Introduced VCSH generally after 17-18z,
and there could be areas MVFR or even IFR vis in heavier rain.
Outlook 00z Friday through Monday...
00z Friday - 00z Sat: VFR with MVFR/IFR possible in isolated to
scattered showers and thunderstorms during the daytime Friday.
00z Sat - 00z Tue: VFR.