Area Forecast Discussion
Issued by NWS Burlington, VT

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382
FXUS61 KBTV 241136
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
736 AM EDT Mon Jul 24 2017

.SYNOPSIS...
Upper low pressure will cross the area today into tonight with
widespread rainfall and cool temperatures before exiting east on
Tuesday. High pressure brings a brief stretch of fair weather
on Wednesday before a weak cold front brings a renewed threat of
showers and storms on Thursday. Fair weather then returns for
Friday into next weekend with temperatures near seasonal late
summer norms.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 736 AM EDT Monday...The forecast by and large remains in
good shape as we progress through today with only some nominal
tweaks to hourly temperatures and dewpoints per recent trends.
An narrow, though impressive band of stationary heavy convection
developed across west-central St. Lawrence County overnight
with gage reports supporting radar estimates of 3 to 5 inches
with locally higher totals to near 6 inches from Russell to
DeKalb, Edwardsville and North Hammond. A few reports of
flooding have been received via St. Lawrence County 911 dispatch
though some uncertainty on the actual locations so we`ll pass
along any information on that as things become more clear.

Prior discussion...
A soggy, damp and dreary 24-36 hours remains on tap for our
area today into Tuesday morning as upper low pressure and an
accompanying 500 mb longwave trough slowly pivot through the
area. Good PVA and diffluence aloft will aid dynamical support
for upward motion and rainfall through the period, some of which
could be heavy at times across our northern New York counties
today into early this evening. Instability remains rather
marginal and have kept with prior thinking confining any lower
thunder threat in these western counties only into this evening
where modestly steep mid-level lapse rates exist. Given the
expected lack of intense rainfall rates and seasonable 3/6 hr
flash flood headwater guidance values, the threat of flash
flooding still appears low at this point, despite a marginal
risk area being maintained in our area by WPC. That said, model-
blended QPF totals shown for this event will range from 0.50 to
1 inch across VT and from 1 to 2 inches in northern NY through
Tuesday morning with localized totals to 2.5 inches in portions
of the SLV where some modest watershed rises will be possible.
Temperatures will trend quite cool by late July standards with
readings only topping out in the upper 50s to mid 60s today,
coolest across northern NY. Winds mainly light east to
southeasterly, though a brief window of southeasterly gusts to
perhaps 25-35 mph will exist along the western slopes of the
central and southern Greens this morning through mid-afternoon
or so.

By tonight showers will remain quite abundant in coverage,
though wane in overall intensity as the system continues to
pivot slowly east. Patchy br/fog also a good bet just about
anywhere as temperatures hold in the 50s. Winds light.

On Tuesday widespread morning showers gradually move east
and/or fade away as longwave trough exits east and building high
pressure advances east from the Great Lakes and Ohio Valley.
Plenty of clouds should be the rule most of the day, though some
partial sunshine will be possible from the Champlain Valley
west by later in the afternoon. Temperatures remain on the cool
side in the 60s, possibly touching the 70F mark in the SLV where
partial sun may arrive a bit earlier than other areas.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
As of 333 AM EDT Monday...Dry weather will persist Tuesday
night and Wednesday with upper level and surface ridging over
the area. Decreasing cloud cover Tuesday night will set us up
for some fog formation, locally dense, from 06-12z. Surface high
crests over the region on Wednesday, with warm southwesterly
flow developing. Cooler than normal temperatures Tuesday night,
mainly 50s with some 40s in the Dacks. Temps rebound nicely on
Wednesday with near seasonal normals expected, upper 70s to
around 80.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 333 AM EDT Monday...All of the weather in the long term
will be in the first few periods, mainly Wednesday night and
Thursday. A cold front will push across the region with showers
and perhaps thunderstorms Thursday afternoon. This will depend a
lot on the timing of the front which will become more clear as
we get closer to Thursday. Have mentioned likely pops for
Thursday, because this looks like the time period when the fropa
will happen. Showers should be ending during the first part of
Thursday night, though Euro does depict a slower system. Right
now the Friday through Sunday timeframe looks quiet with large
ridge of surface high pressure over the region. Temperatures
will be near normal through the week.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Through 12Z Tuesday...Deteriorating conditions expected across
the area today into tonight as upper low pressure brings
widespread rainfall to the region. Thunder threat rather low and
confined to northern New York counties. Lack of expected
coverage warrants omission from NY terminal forecasts at this
point. Generally looking at VFR trending MVFR at all terminals
in the 09-18Z time frame as rain arrives from southwest to
northeast. Exception at KSLK where patchy IFR stratus will
linger a few hours this morning before trending MVFR. Brief IFR
visibilities possible in heavier showers, especially in northern
NY. Showers trend a bit lighter after 00Z Tuesday, though
scattered coverage remains across the area as cigs lower into
the 005-015 AGL range (IFR/MVFR) with widespread 3-5sm br and
localized areas below 2sm. Winds east to southeasterly through
the mainly in the 5 to 15 knot range, though occasionally gusty
to 30 kts at KRUT in the 12-00Z time frame, trending light after
00Z.

Outlook...

Tuesday: VFR. Chance SHRA...Patchy morning FG.
Tuesday Night: VFR. Patchy dense FG.
Wednesday: VFR.
Wednesday Night: VFR. Slight Chance SHRA.
Thursday: VFR/MVFR. Likely SHRA...Chance TSRA.
Thursday Night: VFR. Chance SHRA.
Friday: VFR/MVFR. Slight Chance SHRA.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...JMG
NEAR TERM...JMG
SHORT TERM...Neiles
LONG TERM...Neiles
AVIATION...JMG



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