FXUS61 KBTV 250754
Area Forecast Discussion
National Weather Service Burlington VT
354 AM EDT Sun Jun 25 2017
Scattered showers and thunderstorms are expected to develop
later this morning and afternoon across the North Country. Gusty
winds and small hail will be possible with any of the thunderstorms.
The showers and storms will taper off tonight...but the potential
for additional showers or storms will develop once again Monday
afternoon. High temperatures will be right around seasonal
normals today and a few degrees below normal on Monday.
.NEAR TERM /THROUGH MONDAY/...
As of 157 AM EDT Sunday...Convection has come to an end early
this morning and dry weather is expected through mid-morning.
Deep layer shear has developed over the area and will persist
through tonight. Instability is expected to develop as
temperatures warm into the 70s and temperatures aloft cool a
couple of degrees. This will create nearly dry adiabatic lapse
rates in the 850-500 millibar layer...thus creating sufficient
instability. Meanwhile dynamic support will be increasing over
the area as a pronounced shortwave trough moves out of the
eastern Great Lakes and into our area tonight. This will all be
sufficient to create scattered showers and thunderstorms later
this morning and afternoon across the area. Forecast soundings
show low wet bulb zero values and drier air in the sub cloud
layer. As a result...the potential for gusty winds and small
hail will exist and will include in the forecast.
For tonight...convection will decrease in areal coverage toward
midnight as we lose instability and dynamic forcing shifts north
and east of the area. Should be relatively dry during the
Deep layer shear remains over the area on Monday and instability
should develop during the afternoon hours. Temperatures will be
a few degrees cooler than Sunday...thus instability will not be
as favorable as Sunday. And there will be less of a forcing
mechanism on Monday...thus looking at only a chance for showers
or storms during the afternoon hours. Activity should not get
organized enough to become strong...so no enhanced wording at
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 325 AM EDT Sunday...not much change in the overall
forecast for this period - still more unsettled weather. The
first half of Monday night will have a weak shortwave push
across the region. Models all show some disorganized convection
associated with the shortwave lifting southwest to northeast
through 08z, so have aligned the PoPs with a blend of some of
the hi-res models to show the evolution. One little feature to
see if it comes to pass will be the potential for a little bit
of lake effect showers come off Lake Ontario into the St
Lawerence Valley area first thing Tuesday morning thanks to
some cooler air aloft. A stronger upper trough approaches the
area Tuesday. Although there will be plenty of clouds and
temperatures on the cool side (upper 60s to lower 70s), the
temperatures aloft (around 500mb) are rather cold (near -22C),
so that should result in some instabilty to produce another
round of afternoon/evening showers and perhaps a few t-storms.
With the cold air aloft, wet bulb zero heights are quite low
(7000-8000ft), so chance for some small hail in any deeper
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 325 AM EDT Sunday...00z model suite still pointing toward
a continued lengthy stretch of unsettled weather. Not that it
will be cloudy and rainy continuously, rather we will see short
dry periods of 12-18 hours followed by 12-18 hour long periods
where scattered showers and t-storms will be around. At upper
levels, we will be in a region of fast mainly zonal (west to
east) flow with embedded shortwaves zipping through. It will be
these shortwaves, combined with daytime heating, that will be
the primary triggers for the convection. Given the uncertainty
in timing these shortwaves, it`s best to take a bit more of a
general approach to the forecast and use a model blend for day-
to-day PoPs. At this point, I don`t see anything indicating any
widespread severe weather through Friday.
GFS and ECMWF continue to show a more significant upper trough
develop to our west on Saturday, resulting in a deeper southerly
flow which brings in some very moist air (precipitable water
closes in on 2.0"). If this does come to pass, we could have
some hydro related issues by then, especially if we have enough
convective activity repeat across the same areas during the
week. Just something to watch at this point.
In general, temperatures will be slightly below normal through
much of the week though trending closer to normal late week as
the more southerly flow develops. Again, stuck with model blend
for temperatures, and there is considerable error potential if
we end up having much more sunshine than currently expected.
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
Through 06Z Monday...Overall looking at VFR conditions through
the period. There may be some low clouds and fog developing at
KSLK between 08z and 12z...which would result in MVFR/IFR
conditions. Otherwise main item of note will be potential for
showers and thunderstorms between 16z and 01z. Some of the
storms could produce gusty winds and small hail during this time
period. The threat for showers and storms will end after 01z.
Winds will generally be from the south and southwest through the
period...but speeds will generally be 10 knots or loss.
Sunday Night: VFR. Chance SHRA...Slight Chance TSRA.
Monday: VFR. Chance SHRA...Slight Chance TSRA.
Monday Night: VFR. Chance SHRA.
Tuesday: VFR. Chance SHRA.
Tuesday Night: VFR. Slight Chance SHRA.
Wednesday: VFR. Chance SHRA.
Wednesday Night: VFR. Chance SHRA...Chance TSRA.
Thursday: VFR. Chance SHRA...Chance TSRA.