FXUS61 KBTV 182307
Area Forecast Discussion
National Weather Service Burlington VT
707 PM EDT Mon Jun 18 2018
Showers and thunderstorms will continue through the evening
ahead of a cold front. The showers will end from north to south
by shortly after midnight. Much cooler and drier air will
follow the frontal passage, leading to a pleasant sunny day on
Tuesday as high pressure builds into the area. Another weak
front will push through Wednesday night followed by slightly
cooler and drier air from Canada for the Thursday with
seasonably warm temperatures into the weekend along with a
chance of a shower or thunderstorm.
.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 707 PM EDT Monday...Atmosphere is changing with reduced
instability and convective threat diminishing. Still high
precipitable water values and we are getting more rain over the
northern portions of New York and Vermont...which is where
heavier rain fell earlier today. So if anything only threat that
remains is heavy rain and severe threat has come to an end. As a
result...have allowed the Severe Thunderstorm Watch to end at
7pm. Lowered precipitation probabilities a bit and removed
severe storm wording from the forecast. Rest of forecast remains
Rounds of showers and thunderstorms, a few severe with gusts to
60 mph, a few with very heavy rain will continue into the
evening and slowly sag southward ending overnight. Canceled the
heat advisory in the north due to rain cooled air.
Morning soundings at WMW and BUF show fairly decent low to mid
level lapse rates about 6.5 C/km with CAPES forecast in the
1000-2000 J/kg range. 0-6km shear values also 30-40 knots so
some organized severe thunderstorms are possible. Observed
precipitable water values ranged from 1.60 at BUF to 1.80" at
WMW so locally heavy rains a good bet. Flash flood guidance
ranges from 2.1 to 2.5" in and hour and 2.5 to 3.2" in 3 hrs, so
with rather fast moving storms it will likely take some
training of two or three storms to reach those numbers but we`ll
be keeping a close eye on that.
For tonight through Tuesday night...the front moves through the
area by midnight, ushering in cooler and drier air.
Showers/thunderstorms will come to an end and skies will
gradually clear by mid-morning Tuesday. Lots of sunshine
expected by the afternoon, along with a bit of a northwest
breeze. Tuesday`s highs will be in the lower to mid 70s, after
lows tonight in the mid 50s to around 60.
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 454 PM EDT Monday...Generally quiet weather is expected
during this period with mean surface high pressure in control of
regional weather conditions. After a mainly clear night and
seasonable temperatures overnight Tuesday (45 to 55 F) skies
trend partly cloudy over time by Wednesday afternoon as a weak
surface trough approaches from the north. This feature will
approach the intl. border/nrn tier of counties later in the day
with perhaps a stray sprinkle or shower as advertised in some of
this morning`s output. Dry lower levels and only a narrow mid-
level moisture axis along the wind shift should keep coverage
rather minimal and as such have only carried lower end pops
generally below 30 percent in these areas accordingly. Highs to
rebound quite nicely, topping out in the upper 70s to lower 80s
in most spots.
Any lingering spotty sprinkles/light showers across the
northern counties will end Wednesday evening as the surface
trough clears southward and skies trend mainly clear. Lows again
near seasonable norms in the mid 40s to mid 50s.
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 454 PM EDT Monday...Fair and seasonably mild to warm
weather is expected to round out the work week as surface high
pressure bridges atop the region. Thursday will be the cooler of
the two days as highs top out in the upper 60s to mid 70s under
light northerly winds. Then a nice rebound by Friday as the
high slides east, southerly return flow commences and air of
midwestern origin advects into our area - mid 70s to lower 80s.
The next chance of appreciable precipitation arrives by later
Saturday into Sunday of next weekend as a dampening upper
shortwave lifts northeast from the Great Lakes and Ohio Valley
states. This feature looks to have decent moisture and with
lower- end boundary layer instability showers along with a few
thunderstorms will be introduced into the forecast. Temperatures
on both weekend days to run on the warm side but not
excessively so - mainly upper 70s to lower 80s for highs and
corresponding lows in the 50s to lower 60s.
.AVIATION /23Z MONDAY THROUGH SATURDAY/...
Through 18Z Tuesday...Widespread organized thunderstorms with
brief local IFR Visibilities and MVFR cigs will continue
through 00z-03z Tuesday, then come to an end from northwest to
southeast with a cold frontal passage. Ceilings will drop to
MVFR at most terminals for a time late today into this evening,
then ceilings will thin and lift overnight with VFR and few
clouds by Tuesday morning.
Southerly/southwesterly winds will continue around 10 with gusts
to around 20 kt through much of today, with gusty winds
possible in any storms. Could also encounter some areas of
turbulence tomorrow due to the thunderstorms, particularly in
and around terrain. Winds will turn to the northwest this
evening behind the cold front, remaining at 5-10 kt.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. Slight chance SHRA.
Wednesday Night: VFR. Slight chance SHRA.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: Mainly VFR, with local MVFR possible. Slight chance
Numerous showers and thunderstorms will continue into this
evening. The combination of precipitable water values up to 2
inches and storm motions supporting some training of
convection, supports the threat for isolated flash flooding.
Given the available moisture in the atmosphere, any storms will
be capable of very heavy rainfall rates of 1 to 1.5 inches in an
hour, which over terrain or urban areas could cause isolated
flash flooding. Given the very recent dry weather widespread
large stem river flooding is not anticipated, but sharp rises on
smaller streams in complex terrain where multiple rounds of
storms occur is possible.