Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 201912

Area Forecast Discussion
National Weather Service Burlington VT
312 PM EDT Sat Jul 20 2019

Unseasonably warm conditions will continue across the North Country
tonight and Sunday before a cold front brings some relief Sunday
night. Along the frontal passage, some isolated to scattered
thunderstorms are possible Sunday afternoon with quieter and cooler
conditions expected Sunday night. The next best chance for rain
across the region comes Monday and Monday night as the cold front
moves back north as a warm front. Areas of moderate to heavy rain
are possible, mainly across central and southern Vermont.


As of 312 PM EDT Saturday...Heat advisories remain in place across
the North Country this afternoon with many areas in the 90s and
dewpoints in the upper 60s to low 70s creating oppressive heat
indices of 95-100 degrees. So far today a mid-level cap has limited
any development of cumulus clouds across the northern 2/3rds of the
forecast area, while southward the cap broke and some morning low
level moisture across the Tug Hill and southern Adirondacks lifted
into a cumulus field where a few isolated storms developed
through the early afternoon. This idea was hinted at with the
12Z NMM cored models and show the best chance of any further
development this afternoon and evening being across the southern
Adirondacks eastward into southern Vermont. Could see a rogue
storm to the north, but as of now the cap hasn`t broken so we`ll

Beyond sunset any afternoon convection should dissipate to a rinse
and repeat night like last night. It`ll be quite muggy with temps
only falling to 70-75 and dewpoints holding in the upper 60s to low
70s. Clouds will increase through the night associated with an
upstream MCS which will decay before reaching the forecast area, but
can`t rule out an isolated showers as its remnants pass over between
06-12Z. For Sunday, still seeing some timing differences in regards
to a cold front passage. Models indicate a pre-frontal trough will
bring relief from high PWATs currently plaguing the region passing
northwest to southeast from mid-morning to late afternoon, with the
trailing cold front moving through Sunday evening. While most of the
CAMs are not indicating much convective development, all the
ingredients are there for some showers and thunderstorms to develop
as we`ll actually have some forcing to work with. As such, we
continue to highlight this chance, mainly across central/eastern
zones based on the timing of the boundary passage. In addition,
based on the fropa timing temps/dewpoints still support a marginal
heat advisory for southern Vermont where heat indices will once again
be around 95-97F.

Sunday night the aforementioned cold front drops through the region
with after afternoon showers/storms dissipating to a quiet and
seasonably cool night with temps dropping into the 60s.


As of 312 PM EDT Saturday...There is still some uncertainty to where
the frontal boundary stalls out on Monday but models are starting to
come into better agreement. It`s now looking like the front will
stall somewhere near the Vermont and Massachusetts border. This is a
touch further southeast than yesterday but the 12Z guidance from
today is now all starting to become in phase with one another.
During the morning hours on Monday, a surface low is expected to
develop near the triple point near the Delaware coastline before
riding northward along the stalled frontal boundary. This will bring
another surge of moisture back into the North Country but given the
frontal placement, it seems the bulk of the moisture will only make
it into southern and central Vermont. When you couple this moisture
with increasing dynamics associated with a developing upper level
trough, you get the ingredients needed for a heavy rain event
starting Monday afternoon. Regardless of which model solution you
like, a large swatch of 1-2 inches with isolated 3+ inches possible
as well. Because of this, have added mention of heavy rain to the
forecast for southern and portions of eastern Vermont for Monday
afternoon and evening. The good thing is that the low is very
progressive so there is only a 12- 18 hour window for the heavy rain.
There is a slight risk for flash flooding according to the weather
prediction center so those with interests in southern and eastern
Vermont should stayed tuned to updates in the coming days.


As of 312 PM EDT Saturday...Any lingering rainfall Tuesday morning
will dissipate but the afternoon hours with the best moisture and
dynamics associated with the upper level trough shift east. It won`t
be until Wednesday afternoon that the trough axis makes it fully
through the North Country so it wouldn`t be surprising to see a few
diurnal showers and possibly a thunderstorms Tuesday and Wednesday
but the lack of moisture and marginal instability should help keep
widespread precipitation from developing. The big story for Tuesday
onwards is the break in the heat. After a long stretch of
temperatures in the mid 80s to mid 90s, we will see temperature
return to normal and even below normal for period of next week. The
coldest day looks to be on Wednesday with high temperatures in the
lower to upper 70s. Temperatures will gradually increase from
Thursday onwards but will remain near normal with highs in the mid
70s to mid 80s. No significant chances for precipitation are
expected after Monday so it`ll be a good time to get out and enjoy
the North Country!


Through 18Z Sunday...VFR is the forecast for the next 24 hours.
That said, there remains great uncertainty in the occurrence of
SHRA/TSRA this afternoon and evening where if anything does
develop a brief period of +RA and IFR will be possible if one
moves over a terminal. Best chances are at KSLK and KRUT where
a cumulus field has developed, but further north the probability
is much less. Mid/high clouds stream into the forecast area
overnight associated with a decaying convective complex which
could drop a few showers, but no flight restrictions are
expected. Additional chances for showers and thunderstorms are
possible for Sunday as a cold front moves through the region.


Sunday Night: VFR. Slight chance SHRA.
Monday: VFR. Chance SHRA.
Monday Night: VFR. Likely SHRA.
Tuesday: VFR. Chance SHRA.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: VFR. Chance SHRA.
Wednesday Night: VFR. Slight chance SHRA.
Thursday: VFR. Slight chance SHRA.


VT...Heat Advisory until 8 PM EDT this evening for VTZ001>008-010-
     Heat Advisory until 8 PM EDT Sunday for VTZ009-011-012-019.
NY...Heat Advisory until 8 PM EDT this evening for NYZ026>031-034-


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