Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

FXUS61 KRNK 232300

Area Forecast Discussion
National Weather Service Blacksburg VA
700 PM EDT Wed Oct 23 2019

A high pressure system will drift northeast over the region 
tonight, and then linger along the mid-Atlantic coast Thursday into 
Friday - maintaining dry and seasonally cool weather through the end 
of the work week.


As of 657 PM EDT Wednesday...

Keeping the frost advisory as is, as drier air works in with
high pressure overhead and clear skies. Though latest guidance
suggest potentially less threat in the foothills/piedmont but
still enough low lying spots to not change the forecast at this
point. Its late October, so most should know that frost is
likely climatologically.

Previous discussion from early this afternoon...

Surface high pressure will drift northeast over the Blacksburg 
forecast area tonight. A good radiative cooling event is expected as 
winds become calm, skies remain clear, and dew points remain 
relatively low - setting the stage for the development of patchy to 
widespread frost in the deeper mountain valleys, and possibly
also in lower/protected areas of the Piedmont.

Duration and extent of frost expected to be sufficient to 
maintain Frost Advisory until shortly after daybreak on Thursday
for most of the Blacksburg mountain and foothill counties, and
after collaborating with neighboring NWS offices, have now also
expanded the advisory area east to encompass all of the
Blacksburg forecast area with the exception of the extreme
southeastern counties (Caswell, Halifax, and Charlotte) which
will not likely have enough frost for a long enough period of
time to justify an advisory (but an honorable mention will be
inserted into the Hazardous Weather Outlook). If temperatures 
fall more aggressively than currently anticipated in the extreme
southeastern counties this evening, the advisory area will be
further expanded.

Otherwise, after a chilly morning start, proximity of surface ridge 
will maintain another bright and sunny day with light winds. A
nearly 30F diurnal temperature rise is expected from morning 
lows in the upper 20s to mid 30s in many areas to the 60s - 
excluding the highest elevations which should top out in the 
50s - all close to respective climatological normals.


As of 210 PM EDT Wednesday...

Previous model runs have been in disagreement with each other 
regarding our next rain event. The 12Z runs are starting to come
together, but there are still some issues between them, 
especially with start time. Models are keeping the area dry 
through most of Friday as a surface high hangs over the region. 
An upper level trough is expected to swing out of the Rockies 
then become a cut-off low over the Southern Plains Thursday 
night. This low will slowly move to the Midwest on Saturday as a
blocking ridge over the western Atlantic remains stationary. 
This closed low will generate a surface low in eastern Texas 
Friday, tracking to the Tennessee Valley by Saturday morning. 
This system should pickup speed through the day Saturday and 
move over the Ohio Valley.

With the 12Z models, bulk of the jet dynamics stays west of the
region with the axis of heavy rain across central Tennessee 
Saturday. As this low pressure system moves over the Ohio 
Valley, a line of light to moderate rain showers will move over 
the area Saturday night into Sunday morning. Rainfall amounts 
will vary from a quarter to half an inch across most of the 
area. Slightly higher amounts are possible across southeastern 
West Virginia and the High Country of North Carolina where light
rain showers may fall starting late Friday afternoon and night.

Near normal temperatures are likely through the period.


As of 240 PM EDT Wednesday...

For the most part, early next week will remain dry. There is a 
possibility that a few short waves tracking around a ridge of 
high pressure in the western Atlantic will bring showers to the 
region Monday. The next chance for a soaking rain may not come 
until the end of the week.

Temperatures will continue to be near normal through most of 
next week.


As of 655 PM EDT Wednesday...

Expect VFR conditions through the period under high pressure.

.Extended Aviation Discussion...

Other than the potential for some localized early morning river
fog, no significant aviation concerns are expected on Friday.

Moisture is expected to return by Saturday associated with a 
slow moving area of low pressure that will approach from the 
southern U.S. Sub-VFR conditions are possible Saturday night 
into early next week associated with rain showers.


VA...Frost Advisory from midnight tonight to 9 AM EDT Thursday for 
NC...Frost Advisory from midnight tonight to 9 AM EDT Thursday for 
WV...Frost Advisory from midnight tonight to 9 AM EDT Thursday for 



National Weather Service Glossary of Abbreviations