743
FXUS61 KBTV 261658
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1258 PM EDT Mon Jun 26 2017

.SYNOPSIS...
We will have a dry start to the day today...but scattered
showers and isolated thunderstorms are expected this afternoon
and evening. An even greater likelihood of showers and
thunderstorms is expected on Tuesday. Temperatures will be
several degrees below normal both today and Tuesday. The threat
of showers will continue into Wednesday...but then a change will
take place to a warming trend starting Thursday and continuing
through the weekend. However...this pattern will also be
conducive to more widespread showers and thunderstorms across
the entire area during this period.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 1006 AM EDT Monday...Minor update to tweak sky cover a
bit into the late morning and afternoon hours. This would
suggest slightly higher coverage of clouds across southwestern
portions of the forecast area today as weak trough line lifts
northward, sparking scattered garden-variety convection into the
afternoon and early evening hours. Rest of forecast remains on
track. Have a great day.

Previous Discussion...
Noticeable differences standout when comparing today to yesterday
with respect to the convective potential. Today we are lacking
the dynamic support as the shortwave trough that enhanced
convection yesterday is moving northeast of the region this
morning. No well defined dynamic support is expected across the
area today. Cooler temperatures today will not allow for as much
instability that developed yesterday and enhanced convection.
Enough instability will develop to support convection...mainly
scattered showers with only isolated thunderstorms. Deep layer
shear has shifted just a bit to our south today versus being
right over our area today. As a result...only looking at
isolated to scattered showers today along with a few
thunderstorms. Synoptic scale features and thermodynamic
profiles do not support any storms becoming organized today.
Highs today will only be in the mid 60s to lower 70s.

Tonight...the showers and isolated storms lift northeast and
most of the activity should be done by midnight. Lows will
generally be in the upper 40s to upper 50s.

Tuesday...Well defined shortwave trough moves out of the eastern
Great Lakes and provide sufficient dynamic support for the
development of showers and some thunderstorms. Colder air aloft
will move into the region and despite highs only in the mid 60s
to lower 70s...much like today... destabilization will occur and
sufficient instability should develop for convection as 850-500
millibar lapse rates become dry adiabatic. These two elements
should be enough to create more widespread showers than today
and the idea of many areas having likely precipitation chances
looks real good. If any storms do get organized on Tuesday...could
see some small hail with them as wet bulb zero values will be
on the lower side...much like on Sunday.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
As of 450 AM EDT Monday...Overall convective activity should
begin to wane Tuesday evening with the loss of surface
instability but expect a few showers and thunderstorms to linger
through the night as the driving mid/upper level shortwave
trough passes through the region. It`s a fairly cold trough for
late June so behind the feature temps will run about 5 degrees
below normal across the board with lows in the 50s across the
St. Lawrence and Champlain Valleys to mid/upper 40s elsewhere.

Wednesday features a drier northwest flow behind the exiting upper
trough with a mix of clouds/sunshine and temps seasonal in the
low/mid 70s. Could see some terrain driven showers and perhaps a few
thunderstorms with weak surface instability developing in the
afternoon, especially across northern areas, but with the lack of
any strong forcing aloft areal coverage should be low.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 450 AM EDT Monday...Another active period of weather is
expected for the end of the work week and through the weekend
with the highlights being the potential for widespread and
possibly heavy rain Thursday and again Saturday. Aforementioned
upper trough exits the region Wednesday night with possibly the
last dry night of the week before a fast westerly flow develops
aloft for Thursday through Friday. Shortwave energy moving
through the flow aloft combined with a warm front extended west
to east from low pressure moving through the Great Lakes will
provide the setup for widespread rain to develop along the
boundary during the day Thursday. Instability is rather weak,
and PWATs aren`t super high (1-1.5") so the heavy rain threat
shouldn`t be widespread, but this event may prove to be the pre
for potential hydro problems on the weekend. As the warm front
shifts over the region Thursday/Thursday night it stalls with
additional heat and moisture streaming into the region Friday
night into Saturday on increasing southwesterly flow aloft with
blocking high pressure anchored off Bermuda. While this is
several days away, indications are for a return of 70 dewpoints
and a plume of PWAT`s in excess of 2" presenting a heavy rain
threat Saturday and Saturday night. Depending on what QPF falls
through the week and especially on Thursday, flash flooding
could be possible this weekend. Stay tuned.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Through 18Z Tuesday...Mainly VFR with SCT/BKN cigs in the
040-080 AGL range through 12Z Tuesday under light south to
southwesterly flow. Scattered showers/isolated thunderstorms to
affect terminals in the 18-04Z time frame this
afternoon/evening, but most of the period should remain dry.
KBTV threat the highest in the 22-01Z time frame. Overnight any
lingering showers to end leaving mainly VFR. Some brief and
patchy MVFR cigs in the 015 AGL range possible at KMPV and KSLK
from 09-12Z but confidence low. After 12Z Tuesday more robust
energy pushing into the area aloft will spark better coverage of
showers/sct storms. Highest coverage initially at KSLK/KMSS from
14Z onward where MVFR will be offered. Further east
shower/storm probabilities increasing by 18Z but covered with
just VCSH at this point given timing uncertainty.

Outlook...

Tuesday: VFR. Chance SHRA...Slight Chance TSRA.
Tuesday Night: VFR. Chance SHRA...Slight Chance TSRA.
Wednesday: VFR. Breezy. Chance SHRA...Slight Chance TSRA.
Wednesday Night: VFR. Slight Chance SHRA...Slight Chance TSRA.
Thursday: VFR/MVFR. Chance RA...Chance TSRA.
Thursday Night: VFR/MVFR. Likely RA...Likely SHRA... Chance TSRA.
Friday: VFR. Chance SHRA...Chance TSRA.

&&

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

&&

$$
SYNOPSIS...Evenson
NEAR TERM...Evenson/JMG
SHORT TERM...Lahiff
LONG TERM...Lahiff
AVIATION...JMG