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490
FXUS61 KRNK 181330
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
930 AM EDT Mon Sep 18 2017

.SYNOPSIS...
High pressure will remain over the region this week resulting
in mainly dry and mild weather during the next few days. Jose
should track north, off the east coast today through Tuesday,
before sliding just east of New England on Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 930 AM EDT Monday...

Made some quick adjustments to temperatures and dewpoints for
this morning utilizing the surface obs,trends and GLAMP.
Modified the cloud cover for late morning into this afternoon.
Low clouds and fog are lifting and mixing out this morning. Some
sunshine will return by this afternoon. Hiresw-arw-east, HRRR
and NAM still support isolated to widely scattered convection
this afternoon mainly across the high terrain. The combination
of low level convergence and orographic lift will help generate
a few showers especially in the west. Both limited instability
and strong inversion aloft will hinder convection development.
In general, expected another good afternoon with limited shallow
convection thanks to high pressure. Temperatures will be
pleasant with highs from around 70 in the mountains to the mid
80s in the piedmont.




As of 300 AM EDT Monday...

Not a lot of change today with the region remaining within a
weakness between building high pressure to the southwest and the
Bermuda ridge to the east of Jose. Axis of the main vort lobe within
this weak troffiness to finally pivot across and east of the
mountains this afternoon allowing slightly higher heights to briefly
slide in from the southwest. However beneath this still seeing a
weak low level convergence zone once again over the west this
afternoon in the col area between better northeast flow out east and
weak northwest flow far west. Latest guidance still showing an
overall shotgun pattern to shallow convection espcly northwest
sections but perhaps a little better progged coverage than seen in
recent days. This despite limited instability and only weak
mainly orographic lift under a very strong inversion seen aloft
off overnight soundings. Thus went ahead and included more in
the way of chance pops across far northwest sections, with
possibly a band or two along and west of the I-81 corridor this
afternoon, but still without any thunder mention.

Otherwise looking at areas of clouds/fog to start, followed by more
sun then mainly isolated showers which could even pop up out east
within better onshore flow. Highs likely a bit cooler under the
deeper onshore trajectory and more clouds, although still appears
some low/mid 80s east and mainly 70s west.

Region will spill into the broad circulation aloft associated with
the passage of Jose offshore of the Va Capes late. This should turn
the low level flow more northwest/west with time overnight as we
pass well to the west of the system. May again see isolated showers
linger early out west, with perhaps more trapped strato-cu during
the evening before better subsidence starts to result in clearing
overnight. Should also see fog/stratus mainly confined to the
western valleys overnight with little out east where the gradient
will likely keep some mixing going. Lows mostly 60s east to
mid/upper 50s west, except locally cooler in the deeper
western valleys.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM EDT Monday...

Our persistent pattern featuring an eastern ridge and western trof will
become amplified through the middle of the week as a closed low digs
into the northwest. While this will provide us with rather uneventful
weather through Thursday, it will also open the east coast to tropical
systems moving across the Atlantic.  so current and future
storms/hurricanes will continue to be monitored closely for potential
impacts in our neck of the woods. The strong ridge aloft will be
working against convection with large scale descent providing a cap.
However, the cap weakens with time and upstream short wave energy will
be undercutting the ridge and moving through the region. Expect the
result will be to keep a diurnally biased chance/slight chance of
showers and possibly a thunderstorm in the forecast generally along and
west of the Blue Ridge through Thursday.

Expect little change in the temperature regime with a continuation of
above normal warmth. Look for highs generally in the low to mid 80s
east of the Ridge with mid 70s/near 80 to the west. Lows will generally
be in the low to mid 60s east, mid/upper 50s west with some cooler
readings in the valleys.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 1230 PM EDT Sunday...

500MB heights rise and upper ridge continues to build over the east
through Friday. Seeing a small probability of precipitation on
Monday along the southern Blue Ridge and foothills where there
will be weak easterly upslope winds. No organized synoptic
scale for precipitation through Sunday. Temperatures will remain
at or just above normal.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
As of 700 AM EDT Monday...

Wide ranging conditions will linger through mid to late morning
with areas of sub-VFR in fog/stratus across the valleys and in
spots east of the mountains. However outside of these IFR to
MVFR conditions will see spots without fog and under VFR cigs
early on.

Expect the morning fog/stratus to erode around 14z/10am but
could persist around KDAN longer as well as in some of the
deeper valleys where could be midday before seeing all the
lower cigs/vsbys improve. This suggested with lower cigs off
the latest Nam into early afternoon so something to watch given
slightly deeper northeast flow. Could again see some isolated
afternoon showers develop along the eastern side of the Blue
Ridge and Appalachians. Left out of the TAFs attm due to low
confidence and isolated nature. Winds light east to
northeasterly overall but around 10 kts across the east this
afternoon.

Lingering showers may persist across the mountains early this
evening before clouds again spread out under the inversion.
However expecting a bit more of a north to northwest wind
component in the wake of Jose later tonight which should allow
for better subsidence and less cloud cover late. Expect some
added fog to develop mainly western valleys where likely looking
at sub-VFR late with less out east per a bit stronger wind
gradient.

Extended Aviation Discussion...

Overall persistence forecast to prevail for most of the upcoming
week with strengthening high pressure remaining in place
between Jose offshore and weak cold fronts approaching from the
west. This should maintain good flying weather outside of early
morning fog/stratus through late next week, with only isolated
diurnal showers possible each afternoon.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...JH
NEAR TERM...JH/KK
SHORT TERM...MBS
LONG TERM...AMS/MBS
AVIATION...AL/JH/KK