Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 220524

Area Forecast Discussion
National Weather Service Burlington VT
124 AM EDT Sun Jul 22 2018

Our dry weather pattern will come to an end early Sunday morning
as rain showers spread northward into the region. The showers
will be fairly widespread in the morning then become isolated to
scattered in the afternoon. Plenty of cloud cover will exist
with highs generally in the mid 70s to lower 80s. South to
southwest flow aloft will persist through the first half of next
week and bring chances of showers and some thunderstorms to the
area during this period. Seasonal temperatures are expected.


As of 114 AM EDT Sunday...No significant changes were needed
with this update. Precipitation has been slow to make much
northward progress into the forecast area due to very dry
conditions across the region. However, it will move through
fairly quickly once the column becomes saturated, so have not
made any adjustments to precipitation timing for early this
morning. Did pull back on QPF just a bit, though. Also tweaked
temps a bit to match the latest trends. Overall the forecast is
in good shape and all changes were minor.

Previous Discussion... Area of precipitation over the mid-
Atlantic region this afternoon will continue to gradually work
its way northward and move from south to north across our area
after midnight tonight. Lows tonight will generally be in the
mid 50s to lower 60s.

On Sunday showers should be fairly widespread across the area
through mid-morning than lift north out of the area. The
precipitation for the remainder of the day will become either
terrain driven or upslope driven as stronger east to southeast
winds develop during the morning hours. This will favor
southeast Vermont and portions of Essex County New York for the
best chance of showers throughout the entire day. The thunder
threat remains low...but cannot be ruled out. We will need to
destabilize and thus if there is a thunder threat its isolated
and in the 2pm to 8pm time range. Highs will generally be in the
mid 70s to lower 80s. As mentioned earlier...gusty southeast
winds will exist during the morning hours and will contribute to
limiting precipitation totals across the area on Sunday.
Rainfall amounts will generally be in the tenth to a third of an
inch range.

Precipitation Sunday night will be isolated to scattered in
nature...but will start to increase in areal coverage toward the
morning hours on Monday. Plenty of clouds and low level moisture
will lead to low temperatures Sunday night in the mid 60s to
lower 70s.


As of 344 PM EDT Saturday...Moisture will continue to surge
into the region on Monday as a highly amplified upper level
trough over the eastern US ushers in moisture from both the
eastern Gulf of Mexico and the western Atlantic. Precipitable
water values will increase once again to near or above 2 inches
on Monday which when coupled with large scale forcing with the
upper level trough should help produce scattered showers and
thunderstorms. Latest guidance suggests the building appendage
of the Bermuda High in the western Atlantic may build further
west than expected in previous forecast packages which may lower
the overall areal coverage of these showers and thunderstorms.
The best chances for precipitation on Monday will be over the
western portions of the forecast area where the influence of the
upper level trough is stronger while subsidence with the
building ridge could inhibit chances over eastern Vermont. With
precipitable water values as high as they are expected to be,
showers or thunderstorms that develop could drop some locally
heavy rainfall.


As of 344 PM EDT Saturday...The appendage of the Bermuda High
will be at its strongest Tuesday morning and early afternoon
before it begins to retreat to the south and east. This may
bring a period of drier weather for the first half of Tuesday
before shower activity increases in the wake of the departing
upper level ridge. Upper level heights will continue to fall
Tuesday night and through Wednesday which will help introduce
cyclonic flow aloft on Wednesday which should help increase rain
chances as well as thunderstorm chances. Instability is rather
weak as lapse rates trend close to moist adiabatic with the
abundantly moist air mass overhead but some rumbles of thunder
are still expected.

Thursday currently looks like the best chance for widespread rain
and thunderstorms as a sharp shortwave trough  will dig across the
region. This trough will interact with the moist air mass and the
large scale ascent with this feature could easily produce a nice
swath of a half of an inch to three quarters of an inch of rain
across the North Country. Chances for strong to severe thunderstorms
look very marginal based on the early morning passage of this
feature which will limit instability. The highly amplified trough
mentioned earlier that hangs around through the middle of the week
will be displaced eastward by this sharp shortwave trough. That will
bring a return to a more progressive upper level pattern.

A trailing cold front will push through the region on Friday which
may help spark a few showers and a thunderstorm or two. While
temperatures really won`t cool all that much behind the front,
dewpoints will drop from the upper 60`s to mid 70`s to the low to
mid 60`s. Moisture aloft will also diminish rapidly heading into the
weekend which will likely help to inhibit more shower activity.
However, with southwesterly flow aloft, a weak impulse or two is
possible throughout the weekend so a few showers and/or
thunderstorms cannot be ruled out but should be very limited in
areal coverage.


Through 06Z Monday...VFR conditions will prevail through 09z or
10z as low pressure and associated shower activity approach from
the south. Ceilings will lower through daybreak, to 3500-5000 ft by
12z. Showers will move from south to north 09z-15z this morning,
and MVFR visibilities and ceilings will be possible in any
precipitation. Ceilings will remain VFR at most sites, with
clouds even decreasing in coverage at the valley sites after
16z. The exception will be KMPV where maritime flow will keep
ceilings around 2500 ft through the afternoon. These MVFR
ceilings will spread to KRUT after 00z Monday. A strong, 50
knot, southeast low level jet will be moving across the area
from 09-15z. This will result in 40-45 knots of LLWS primarily
at KMPV, KSLK and KRUT, however all TAF sites could see
potential for some low level turbulence and wind shear.
Additionally, the southeast wind direction of the low level jet
could see some downslope winds at KRUT with gusts up to 25 knots


Monday: VFR. Chance SHRA, Chance TSRA.
Monday Night: Mainly VFR, with local IFR possible. Chance SHRA,
Slight chance TSRA.
Tuesday: Mainly VFR, with areas MVFR possible. Chance SHRA,
Slight chance TSRA.
Tuesday Night: Mainly VFR, with areas MVFR possible. Slight
chance SHRA, Slight chance TSRA.
Wednesday: Mainly VFR, with areas MVFR possible. Likely SHRA,
Chance TSRA.
Wednesday Night: MVFR/IFR conditions possible. Likely SHRA,
Slight chance TSRA.
Thursday: Mainly MVFR, with local IFR possible. Definite SHRA,
Slight chance TSRA.




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