Area Forecast Discussion
Issued by NWS Blacksburg, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS61 KRNK 250953

Area Forecast Discussion
National Weather Service Blacksburg VA
553 AM EDT Wed Apr 25 2018

An upper level low and related surface low pressure center will
track northeastward across our region today into tonight. A
disturbance could bring more rain during Thursday and Friday. High
pressure should arrive to provide drier conditions by the upcoming


As of 330 AM EDT Wednesday...

Surface low pressure across central North Carolina this morning will
rotate northeast today and reach New York by this evening. Then, the
low center lifts northeast into New England tonight.

This morning WSR-88d images showed pockets of rain lifting northward
across much of the region. The northeasterly flow is enhancing some
of the rain this morning in the east. Remnant convection to our
south weakened quickly as it encountered the stable wedge. Saturated
profiles, wet soils and light winds have lead to the development of
light mist, rain and patchy fog this morning. The cloudy, dreary and
rainy weather this morning will transition to drier and clearing
weather this afternoon in the east when the flow becomes northwest.
However in the west, upslope northwest flow will result in lingering
clouds and scattered showers. There may be enough instability in the
east this afternoon for an isolated shower or thunderstorm. Shaped
the pops this morning towards the HRRR and blended this afternoon
towards the NamDNG. A non-diurnal temperature curve was utilized
today with a slow warm up early followed by a late surge toward
sunset. High temperatures today will range from the lower 50s in the
mountains to the lower 70s in the piedmont.

Scattered upslope showers in the west will taper off this evening
into tonight as the low and the weak cold front move further away.
The combination of light winds and low level moisture may result in
some patchy fog tonight. Low temperatures tonight will vary from the
the upper 30s in the northwest mountains to the lower 50s in the


As of 500 AM EDT Wednesday...

A broad trough will persist across the eastern half of the
country within which will be embedded several more vigorous
upper-level short waves or closed lows. The first one of such
will moving northeast of the area Thursday while the second one
approaches from the south and southwest. These systems are
rather compact, but capable of producing substantial QPF over a
relatively small area. Thursday will bring the lull in
precipitation as the first one moves northeast of the area and
the second one will be approaching but still be in Alabama
during the day. Clouds will likely linger and there could be
periods of drizzle and areas of fog, especially during the late
night/early morning hours with abundant low-level moisture
remaining in place Thursday night into Friday morning, the
southeast U.S. system will take a turn to the northeast and lift
through the area with a negative tilt. Dynamics may be
sufficient enough for an isolated thunderstorm, mainly across NC
or the VA Piedmont area. Rainfall amounts should be in the 1/2
to 1 inch range, which should not result in any significant
flooding, but perhaps some nuisance poor drainage flooding and
minor rises on certain rivers/creeks again, such as the Watauga
River at Sugar Grove.

As we move into Friday, the northern stream trough across the
Great Lakes will deepen and absorb the southern stream short
wave as it moves north through the Mid-Atlantic. This will
finally eradicate the area of the deeper moisture in place
throughout the earlier part of the week and bring a deepening
northwest flow aloft to the area. Upslope rain and/or snow
showers may be possible across the Alleghanys of eastern WV
Friday night and Saturday as cold advection strengthens.

Temperatures will trend from near normal at the beginning of the
period to slightly below normal over the weekend as the trough


As of 500 AM EDT Wednesday...

A large area of Canadian high pressure will build across the
eastern U.S. under a slowly progressive upper ridge that will
move from the central U.S. into the eastern U.S. at the
beginning of the period. The increasingly strong upper ridge
will block any further precipitation producing systems from
reaching the area until perhaps the end of next week, with the
focus for excessive rainfall and thunderstorms focusing across
the Southern and Central Plains during most of this period.

A notable warming trend is expected through the period as the
upper ridge builds over the east and 850mb temperatures warm
from near 0C on Sunday to +16C or better by the end of the week.
This should bring highs in the 60s west to 70s east early in the
week warming to highs in the 70s west to 80s east by the end of
the period. It could well be our longest stretch of warm,
springlike weather so far this year!


As of 553 AM EDT Wednesday...

Poor flying conditions will continue during the taf period
with rain, and low clouds and fog. A vertically stacked low
over North Carolina this morning will move eastward today
into tonight. High pressure will continue to wedged down east
of the mountains today. Greatly varying ceilings this morning
will hinder aviation operations. Widespread IFR/LIFR conditions
will continue across the region today with a good chance of
rain at TAF sites. Pockets of fog will continue this morning
with some cooling, light winds and abundant low level moisture.
The heaviest rain this morning has been across the southwest
portion of the forecast area.

As the upper trof starts to pull away this afternoon into this
evening conditions will improve to VFR east of the Blue Ridge
but expect MVFR/IFR to linger from the Ridge westward due to
wind shifting to an upslope northwesterly direction. However,
some breaks of sun in the east may create enough instability to
get some thunder going so will mention VCTS at KLYH and KDAN
toward the end of the period.

Medium confidence in ceilings, visibilities and winds during
the taf period.

Extended Aviation Discussion...

Unsettled weather conditions should continue for the remainder
of this work week as another area of low pressure heads toward
the Mid Atlantic. MVFR/IFR ceilings along with rain showers may
take place during Thursday night and Friday. High pressure
should build overhead to bring VFR conditions for all sites by
Saturday afternoon. Good flying weather will persist through
the remainder of this weekend.




AVIATION...KK is the U.S. government's official web portal to all federal, state and local government web resources and services.