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NWS Area Weather Forecast Discussion
County Warning Area [CWA]: RNK
Regional NWS Weather Office: Blacksburg, VA

FXUS61 KRNK 211109

Area Forecast Discussion
National Weather Service Blacksburg VA
709 AM EDT Thu Sep 21 2017

High pressure will cover the region today through Saturday. A
cold front will approach the Mid Atlantic region the middle of
next week.


As of 325 AM EDT Thursday...

Upper ridge and 500MB heights building over the Ohio Valley and
Great Lakes today and tonight. This pattern pushes the upper
troughing over Virgina and North Carolina gradually south. One short
wave over eastern Kentucky and eastern Tennessee and another over
central North Carolina may be able to spark isolated showers and
thunderstorms this afternoon across southern Virginia and northern
North Carolina. By late this evening these features will be far
enough south of the region that any threat of showers and
thunderstorms will be very minimal.

Models showing light northeast wind today with relatively more
stable air advancing into southwest Virginia from the northwest.
This also favors confining probability of precipitation to the
south and west.

Area remains under high pressure with little to no change in air
mass. Temperatures will stay above normal today and tonight.


As of 310 AM EDT Thursday...

Anomalous 500 mb ridge over or just northwest of the western
Appalachians projects to be the main driver of sensible weather
conditions through the weekend. Synoptically quiescent conditions
should be the rule for our area, with the focus for more active
weather staying away from us - either in the intermountain
west/northern Plains or along the Atlantic seaboard to about 70
degrees W longitude related to Jose and Maria. Summerlike warmth
with good diurnal ranges looks to continue in this pattern, with at
least mostly sunny skies and +16 to +18C 850 mb temperatures pushing
high temps each day into the upper 70s to mid/upper 80s. Largely
clear skies should permit good radiational cooling and lows in the
mid/upper 50s to mid 60s.

Precipitation chances are generally nil through the weekend, with
the best chance being Friday along the NC high country and the
southern Blue Ridge in conjunction with daytime heating and some
weak/subtle easterly convergence. May see some showers or
thunderstorms in this general area Friday, though convective
development may be stunted to an extent by marginal CAPE values
around 1000 J/kg and dry mid-level air. PWAT values then plummet to
values under 1" by the weekend, and despite otherwise steep daytime
PBL lapse rates, dearth of columnar moisture may keep even fair
weather cumulus to a minimum. All in all, looking at a real nice
weekend for outdoor activities with mild temperatures but with
rather comfortable humidity levels.


As of 310 PM EDT Wednesday...

We will remain in an amplified pattern across the country with two
storms in the western Atlantic to watch. Will see Jose continue
to weaken this period. Will see Hurricane Maria head north to
off the NC coast, with question remaining on how close and if
Maria comes ashore. Model ensembles and consensus from NHC keep
it east of the mainland.

Meanwhile, the central U.S. will be active with deep upper trough
and slow moving front. Will see this translate to upper ridge across
our area but expect potential for some clouds and possible showers
to flirt with our piedmont counties Tuesday per leftovers of Jose
interacting with coastal front/trough. However, threat of any
appreciable rain looks low for the next 7 days and even beyond the
front washes out as it moves into the eastern U.S. by Thu-Fri next

Temps remain above normal during this time frame with lows in the
upper 50s to around 60 west, to lower to mid 60s east. Highs ranging
from the mid 70s to around 80 west, to lower to mid 80s east, with
some upper 80s not out of the question, especially if Maria stays
strong and we get on the western subsidence side of the system
without any mid/high clouds Tuesday.


As of 705 AM EDT Thursday...

At 11Z/7AM GOES-16 Fog images were showing fog in the river
valleys in West Virgina and Virginia, including the Greenbrier
and New Rivers. Fog and stratus will lift from 13Z-14Z/9AM-
10AM this morning. VFR ceiling and visibility then expected for
the rest of the day. Isolated showers and thunderstorms are
expected this afternoon but coverage will be too limited to add
to the TAFS at this time and the best probability of
precipitation will be south and west of KROA, KBLF, and KBCB.

Extended Aviation Discussion...

Overall persistence forecast to prevail for the rest of the
week. Strengthening high pressure remaining in place between
exiting Jose offshore and a weak cold front approaching from the
west. This should maintain good flying weather outside of
isolated diurnal showers and thunderstorms. Dry weather is
expected Friday through Monday.





Forecast Discussion from: NOAA-NWS Script developed by: El Dorado Weather