042
FXUS61 KBTV 132337
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
737 PM EDT Mon Jul 13 2026
.WHAT HAS CHANGED...
As of 301 PM EDT Monday...
Have added in enhanced wording to zone forecasts in northern
portions of Vermont and northeastern New York for damaging
winds.
&&
.KEY MESSAGES...
As of 301 PM EDT Monday...
1. A Heat Advisory is in effect for most of Vermont and
northern New York on Tuesday. Some localized fire weather
concerns are possible.
2. An enhanced risk of severe thunderstorms remains for
northeastern New York and northern Vermont Tuesday night when
significant severe weather and isolated flash flooding is
possible. A more typical potential for showers and perhaps some
thunderstorms returns for Thursday.
3. Near to slightly below average temperatures and dry
conditions are expected Friday before temperatures moderate back
to around average over the weekend as chances for showers and a
few thunderstorms return.
&&
.DISCUSSION...
As of 301 PM EDT Monday...
KEY MESSAGE 1: Following a stretch of warm days with low
humidity, significantly hotter and more humid air remains on
track for tomorrow. The 925 millibar mean temperatures across
guidance continues to suggest extreme heat building through the
day (values in the range of 26 to 28 Celsius at 5 PM translates
to temperatures in the mid to upper 90s at near ground level in
our deeper valleys). Statistical guidance continues to trend
slightly higher for surface temperatures. The most unusual heat
relative to climatology still looks to develop over the southern
Champlain Valley due to westerly downsloping, but not far off
will be the entire Champlain Valley and St. Lawrence Valley as
hot air surges in from the southwest. Looking at greatest
potential for near record high temperatures in this area with an
opportunity to approach 100, while low to mid 90s are common
elsewhere between 2 and 7 PM. The air mass does look humid but
not quite oppressive, which keeps us largely thinking higher end
Heat Advisory and not Extreme Heat Warning level for this
event, especially due to the gustiness and deep mixing we`ll see
through the day given the increasing pressure gradient as
temperatures soar. Note that the Adirondack region which is
currently not in the Advisory is borderline for our criteria
with slightly higher heat and humidity compared to the higher
terrain areas in Vermont, and may need to be added if forecasted
temperatures tick up any further. Depending on later
development of convection/rain cooled air, unusually breezy
conditions and humid air will slow the cooling curve into the
evening, supporting uncomfortable heat lingering into the night,
especially in more urban areas.
As sharply drier air returns behind a strong cold front on
Wednesday, low relative humidities in combination with gusty
west- northwest to near 25 MPH will pose a fire weather risk in
southern portions of our region. This area will have had an
extended dry period if they miss out on rain Tuesday night.
Think the Upper Valley and lower elevations in Addison, Rutland
and Windsor counties will be vulnerable to fire starts and
spread, so this is something to keep in mind following the
active weather on Tuesday.
KEY MESSAGE 2: A regionally higher end, unusual severe
thunderstorm setup continues to be on target based on the latest
forecast data. Both global synoptic scale and nested,
convection allowing models, with high CAPE and high shear along
with a clear trigger with a strong shortwave energy colocated
with a southward moving cold front. The overlap of CAPE and
shear of this magnitude per the ECMWF Extreme Forecast Index is
near the upper end of climatology (very extreme), especially
towards the International Border. While there is a lot of
typical spread in location/timing of the deep convection based
on different initiation and storm motions. The latest full run
of the HRRR shows a reasonable depiction of how things may play
out, with the targeted area primarily from northeastern Vermont
and points east. The NCAR hazard guidance using this model and
machine learning techniques shows a very high probability of
severe thunderstorms, again centered to our east in southern
Maine, but extending westward into northern New York considering
the inherent uncertainty in the location of these types of
systems. Risk timing is greatest between 7 PM and midnight. All
hazards are possible, including low probabilities of wind gusts
greater than 70 MPH and a tornado risk, although we emphasize
straight line winds are much more likely to be the hazard in
this environment given fairly straight hodographs in the low
levels. The risk dwindles somewhat as one goes south and west as
dwindling instability with time suggests a weakening trend with
these storms; however, a long tracked, well- developed line or
supercell poses some risk across our region, consistent with the
Slight (level 2) risk of severe thunderstorms south of the
Enhanced area (level 3).
To summarize the convective threat: the pre-storm environment
Tuesday evening will likely have effective shear of near 60
knots, associated with upper level winds near 70 knots and 700
millibar winds near 40 knots, and MUCAPE near 2000 J/kg; local
research shows these parameters are conducive to a combination
of supercells and quasi-linear convective systems, which produce
widespread damaging wind along with localized, brief tornadoes.
The chances for significant impacts (wind damage and/or
isolated flooding) in northeastern Vermont continue to be
favored, with somewhat lower chances towards the south and west.
One failure mode for this event (severe weather does not occur)
is if the initial deep convection misses to our east; in this
scenario, showers ahead of the cold front only come through our
area later in the night when instability has waned. As with all
deep convection, isolated flash flooding will be possible,
especially if thunderstorms redevelop on the western periphery
of linear segments while the mesoscale system shifts southward.
Guidance in the latest forecast cycle has backed off a little
bit on this potential, but bears watching.
Following this activity and any additional showers ahead of the
cold front early Wednesday morning, the next chance for showers
and thunderstorms comes on Thursday ahead of a weaker variety
cold front. This front will also come from the north, but with
much less heat and humidity to work with and more limited wind
shear, expect much less impact with perhaps a couple of
afternoon/evening thunderstorms depending on the timing of
convection.
KEY MESSAGE 3: Model consensus is strong for dry conditions
Friday with temperatures in the mid/upper 70s to around 80
degrees as a northern stream continental airmass tracks over the
region. Spread in models solutions increase over the weekend
especially in timing of the next precipitation features. Blended
and ensemble guidance are leaning towards periods of showers
moisture lifting southwest to northeast Saturday while mid-range
deterministic models have a more defined gap of drier
conditions with precipitation shunted south of Vermont due to a
trough digging more sharply southward. The forecast for the
weekend is tracking more closely to blended guidance and
persistence at this time with widespread 30% chances of showers
and potentially some afternoon thunderstorms, but will reserve
some judgment and watch trends closely over the next couple of
days given the drier trend in deterministic runs. Shower chances
later Sunday into Monday continue to line up with another
passing trough that is nearly universally present across model
guidances suggesting an increase in statistical confidence that
forecast 30-50% chances of showers remain valid.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Through 00Z Wednesday...VFR conditions will continue with the
primary threat to aviators being some LLWS overnight into
Tuesday 05-14Z. Winds will decrease overnight under nocturnal
stability. As westerly flow aloft increases, some LLWS will
develop and continue through daybreak. Coupling south to
southwest surface winds 12-15Z will remove the threat of LLWS,
but will result in some SFC gusts 20-25kts in general and up to
30kts at MSS where flow aligns with the St Lawrence Valley.
Weather will mainly hold off until after 00z Wednesday.
Outlook...
Tuesday Night: VFR. Chance SHRA, Slight chance TSRA.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. Slight chance SHRA, Slight chance TSRA.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. Chance SHRA, Chance TSRA.
&&
.CLIMATE...
High temperatures on Tuesday will be hot, but we are at the
climatological warmest part of the year. Therefore, it is far
from a certainty that any records will occur.
MSS looks most likely to set a new record. PBG also is
currently forecast to set a new record. MPV, and especially BTV
and SLK, are unlikely to do so. See below for current records:
Max Temp Records
Date BTV MPV MSS PBG SLK
07-14 100|1995 94|1952 92|2012 95|1952 95|1934
High Min Temp Records
DatePBG
07-14 70|1974
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Heat Advisory from 11 AM to 8 PM EDT Tuesday for VTZ001>011-
016>018-020-021.
NY...Heat Advisory from 11 AM to 8 PM EDT Tuesday for NYZ026>029-
031-035-087.
&&
$$
WHAT HAS CHANGED...Kutikoff
DISCUSSION...Kutikoff/Boyd
AVIATION...Neiles
CLIMATE...NWS BTV
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