Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Remove Highlighting --
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FXUS61 KRNK 220837
Area Forecast Discussion
National Weather Service Blacksburg VA
437 AM EDT SUN MAY 22 2016
A series of low pressure systems will lift northeast off the mid
Atlantic and New England coasts through Tuesday as higher
pressure builds slowly east from out of the Mississippi Valley.
.NEAR TERM /THROUGH TONIGHT/...
As of 430 AM EDT Sunday...
Several spokes of short wave energy rounding base of upper trof
over the central and northern Appalachians will help to amplify
upper flow and support development of vertically stacked H7-H5 low
pressure that will drift south from out of upstate NY into eastern
VA by this evening - then drift east to the coast by daybreak
Mid-level lapse rates expected to steepen as daytime heating
combines with slight cooling aloft with approach of upper low,
once again supporting the redevelopment of scattered showers by
late morning/early afternoon - with the threat continuing until
at least mid- to late evening until thermodynamic support
However, increasing northwesterly winds throughout the day will
transport slightly cooler and drier air back into the area such
that despite steepening mid level lapse rates, amount of
convective available potential energy will be less than on
Saturday. As a result, forecast soundings not particularly
impressive in generating sufficient instability to warrant
inclusion of thunder in the forecast - although an isolated
rumble not entirely out of the question if insolation a bit
greater than currently expected.
Highest threat for precipitation today into tonight will likely
be north of a line extending from near Bluefield WV to Danville
VA, which will be closer to the deeper moisture and colder air
aloft in vicinity of the approaching upper low. Downsloping winds
and slightly warmer/drier air aloft over the NC foothills should
help to minimize threat of precipitation in that area.
Cool air advection and cloud cover in most areas should help to
keep daytime highs lower than those experienced on Saturday -
mainly mid 50s across the highest elevations, to around 70 across
southside VA into north central NC. Overnight lows should be
fairly uniform across the area - mainly mid to upper 40s in the
mountains, to the lower 50s across the Piedmont.
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
As of 320 PM EDT Saturday...
The blocky upper pattern which has been prominent for the past several
days will slowly be transitioning through the first part of next week.
The closed upper low and associated cold pool aloft over the mid
Atlantic region will be replaced by a broad low amplitude upper ridge
and a Bermuda high at the surface by the middle of the week. This will
bring a gradual improvement in our weather along with a significant
The influence of the upper low combined with diurnal instability will
still be great enough to keep a good chance of showers across most of
the region on Monday. By Tuesday as the ridging begins we will be down
to just a slight chance of showers across the eastern portion of the
area. However as the evolution of the pattern begins to pump steadily
warmer and more moist air into the region the chances for showers and
thunderstorms will start to increase again by Wednesday afternoon.
We will start the week with very cool conditions as temperatures remain
5 to 10 degrees below normal with highs in the lower 70s east of the
Blue Ridge and in the low to mid 60s to the west. However by Wednesday
we will be getting a taste of summer with highs in the middle 80s east
of the Ridge and in the mid 70s/around 80 to the west.
.LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 330 PM EDT Saturday...
The upper level low tracks northeast of the area and off the New
England coast Tuesday night. Behind this system high pressure and upper
level ridge will bring very warm weather to the region with
temperatures remaining above normal through Saturday. With the warmer
weather comes a better chance for showers and thunderstorms each
afternoon and evening. Storms do not look organized but pulse-like,
tracking slowly from the southwest to the northeast.
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
As of 150 AM EDT Sunday...
Mainly MVFR flight conditions expected at most terminal forecast
points overnight as gradually increasing upsloping winds maintain
clouds over the mountains. Further east, weakness in the pressure
gradient and influence of weak moist cool wedge should help to
keep low level clouds trapped, where some flight restrictions
into the ifr range are likely - most notably at/near Lynchburg
Persistent upper low will drop south over the area Sunday with
the next round of shortwave energy producing the best coverage of
showers across the north and east from late morning into the early
evening. Expecting a faster improvement in conditions early
Sunday as increasing northwest winds kick in and lower ceilings
and visibilities rise. However, once daytime heating
develops, will likely see ceilings fill back in with MVFR cloud
bases - especially in upslope areas such as KBLF, and where any
afternoon showers redevelop under the upper cold pool.
Surface gusts of 20 to 30 kts can be expected across the
mountains Sunday, with 10-20 kts possible east of the Blue Ridge.
850 mb winds are progged to increase to 25 to 40 kts, and
gradually veer northwest to north.
On Monday, winds will start to decrease as the center of the
upper low continues to exit the region. Isolated showers and with
periodic sub-VFR conditions will still be possible, especially in
the east, related to this feature.
Monday night through Wednesday, expect mainly VFR conditions as
high pressure settles offshore with southwest flow in place.
By Thursday we should start to see some potential for shower and
thunderstorms to pop during the heating of the day mainly in the
mountains. Fog may start to become an issue by the mornings
midweek, in the typical areas like KLWB and KBCB.