Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 241912

Area Forecast Discussion
National Weather Service Blacksburg VA
312 PM EDT Mon Jun 24 2019

A cold front will cross the area tonight. High pressure will settle
over the region Tuesday through Friday. A backdoor cold front
will approach the area Friday, and cross the region over the


As of 200 PM EDT Monday...

A negatively tilted shortwave trough will continue progressing
northeast through the Great Lakes region this afternoon and
overnight. Its associated cold front is currently extending
south into Illinois, before curving southwest into the Arkansas
and Texas. The atmosphere in advance of this cold front has
abundant moisture, and already across the region is unstable
enough at the surface to place surface based CAPES in the
neighborhood of 2000-2500J/kg. The 500mb-sfc mean shear vector
is averaging around 20 to 25 kts, but is expected to increase to
closer to 30 to 35 kts by early evening. A look at the NAM12
forecast soundings place 700-500mb lapse rates around 5.1C/km
and 850-500mb lapse rates around 6.2C/km, and DCAPE around
750J/kg across the western part of the region. This same
forecast sounding has an inverted-V signature from roughly 780mb
to the surface. This point was selected where SPC currently has
an Enhanced risk of severe weather potential this afternoon and
evening. These parameters lean towards damaging winds and not
so much, or if all, a large hail potential for any storms that
become severe.

As we head into the evening hours, we are expecting a line of storms
to develop ahead of the cold front over KY/WV and head rapidly
eastward, crossing our region between roughly 7pm and midnight. The
farther east these storms progress, the less organized and well
defined the line is expected to be. The potential for precipitation
will be over for most folks by 200AM or 300AM Tuesday as the cold
front crosses the area. In the wake of the cold front, winds will
shift west to northwest across the area. This trajectory and
lingering moisture across the area will result in low cloud
development across western portions of the area, as well as,
isolated showers. The cloud cover and isolated showers will continue
across this portion of the forecast area through the forenoon
Tuesday. Central and eastern sections should experiencing
clearing skies heading into Tuesday morning. Patchy fog
development is likely, especially in the mountain and river
valleys late tonight, and in those areas that receive a
generous rainfall with any of the heavy showers and storms this
evening and tonight.

Once the clouds clear in the west, most locations will experience
more sun than clouds along with temperatures about 5 to 10 degrees
cooler than those of today.

Confidence in the above portion of the forecast is moderate to high.


As of 210 PM EDT Monday...

Weak high pressure at the surface and zonal flow aloft will keep the
region dry through Wednesday night. An upper level ridge off the
Southeast Coast will move over the region, possibly stretching back
into the Ohio Valley Thursday. Heat and humidity associated with
this ridge may produce isolated afternoon showers and thunderstorms
across the North Carolina High Country, fading during the evening.

Afternoon temperatures Wednesday will range in the 80s across the
mountains (near normal) to the lower 90s east (slightly warmer than
normal). Thursday`s temperatures will be a few degrees warmer than


As of 230 PM EDT Monday...

An upper level ridge will remain over the region on Friday. Diurnal
heating along with muggy conditions should produce scattered showers
and thunderstorms across the mountains Friday afternoon and evening.
Afternoon temperatures will warm into the 80s west of the Blue Ridge
to the lower 90s east.

A backdoor front will approach the region Saturday increasing the
coverage of storms across the area. Timing of the frontal passage is
still in question (Saturday night or Sunday). Once the front moves
across the region, cooler and dry conditions are expected for the
first part of next week. Until then, temperatures will remain warmer
than normal.


As of 135 PM EDT Monday...

VFR conditions currently prevail across the region, and this is
expected to hold fast for a few more hours. By the late
afternoon and early evening, showers and thunderstorms will
start becoming more numerous across the region, especially along
an west of a KLWB-KROA-KTNB line. While prevailing conditions
immediately outside of the precipitation will still be VFR,
brief sub-VFR conditions are forecast under the stronger showers
and storms. Likewise regarding winds. For the most part,
prevailing winds will continue from the south or southwest just
shy of 10kts with some gusts approaching 20kts. However, under
the stronger showers and storms, gusts around 40kts will be
possible with a temporary variable wind directions.

By the pre-dawn hours of Tuesday, the bulk of the shower and
thunderstorm activity will have dissipated or progressed east of
the region. Winds will shift west to northwest in the wake of a
passing cold front. This newly developed upslope flow combined
with residual low level moisture will bring an IFR or lower
ceiling to western sections of the region, all while the east
remains VFR for ceilings. Visibilities will mostly be VFR except
for where patchy fog develops. Any fog that does develop isn`t
expected to last long after sunrise. The sub-VFR ceilings in the
west are expected to improve to VFR by the conclusion of the
valid TAF forecast period, 18Z/2PM Tuesday.

Confidence in the above portion of the forecast is moderate to

.Extended Aviation Discussion...

High pressure is expected to take up residency over the region
by late Tuesday through Friday. For the most part, VFR
conditions are expected outside of late night/early morning fog.
Also, as we approach the weekend showers and storms will be on
the increase, and these too may bring some temporary reductions
to visibility and ceilings.

Late Friday into Saturday, the chances of sub-VFR conditions
increase with the passage of a backdoor cold front and an
increase in coverage of showers and storms.

Confidence in the above aviation forecast discussion is




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