Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 221503

Area Forecast Discussion
National Weather Service Blacksburg VA
1003 AM EST Thu Feb 22 2018

High pressure will remain off the Southeast coast, promoting
above normal temperatures. A backdoor cold front moving south
from northern Virginia, will enter the region tonight, then
return north as a warm front late Friday. A stronger front will
move through the region from the Ohio Valley this weekend.


As of 1003 AM EST Thursday...

High pressure off the Southeast coast will continue our
unseasonably warm weather this afternoon into tonight.
Several record temperatures will be broken today. Backdoor cold
front will slowly drop southward this afternoon into tonight.
Adjusted temperatures utilizing latest surface obs, their trends
and shaped toward NANdng/GLAMP blend. Attempted to capture the drop
into temperatures with frontal boundary. Made some minor
changes to pops and weather using HRRR, HiResW-arw and NAM. More
adjustments later this morning...

As of 330 AM EST Thursday...

A strong subtropical ridge of high pressure remains anchored
off the southeast U.S. coast providing our forecast area with
unseasonably warm temperatures, southwest flow, and pseudo
summerlike conditions. Meanwhile, a weak cold front was
approaching from the west, but will make little additional
progress eastward thanks to the strong upper ridge. However, the
front will be close enough during the next 24 hours combined
with a weak disturbance tracking around the northwest side of
the upper ridge and an approaching back door front from the
northeast to generate scattered showers mainly across our
northern CWA from the Greenbrier Valley into the southern
Shenandoah Valley and areas to the north and west. As the
backdoor front arrives from the northeast this afternoon, low
clouds, and drizzle and cooler temperatures will likely develop
in its wake. Impacts from this front during the daylight hours
will be mainly to areas north of Lynchburg and Appomattox, with
the remainder of the CWA remaining south of the front. It may be
until after sunset before it surges southward into Roanoke,
Danville and into the northern Piedmont of NC, thus most of the
CWA warming back up today similar to yesterday with near record
highs. Lynchburg will probably be the only climate site that
does not test records today. For tonight, the backdoor cold
front will introduce a cool wedge to areas east of the
Appalachian Divide that will maximize in intensity and areal
coverage around daybreak Friday, then begin to retreat northward
Friday afternoon.

Will focus highest rain chances today along and north of I-64,
then broadbrush the entire CWA tonight with the potential for
light rain or drizzle associated with the backdoor front.
Feel relatively confident temperatures will test 70 degrees
again today for all but the northeastern CWA. After the frontal
passage, favored the cooler guidance tonight, the surge of cool
northeasterly wind making inroads from NoVA.


As of 300 AM EST Thursday...

During this portion of the forecast, as a whole, the area will
continue under a almost Summer-like upper air regime.  An upper
level high pressure system will be anchored off the coast of the
Carolinas, while very mild and moist air streams north into the
region from the central and western Gulf of Mexico. A baroclinic
zone will be positioned across eastern Texas, northeast into the Mid-
Mississippi Valley, and farther northeast along the Ohio Valley.
Ever so slowly, the upper high will weaken and inch southeast, all
while the baroclinic zone makes gradual progress toward the region,
crossing it on Sunday.

This general pattern points towards one that allows for almost daily
chances of light rain or rain showers across at least western and
northern parts of the area, with increasing chances for all
locations heading into and through the weekend with the passage of a
cold front. Temperatures will continue to be well above normal,
averaging some 20 to 25 degrees above typical values. Guidance
varies as to how quickly the front heads to the south Sunday night,
and likewise, how much lingering precipitation remains over our
region on its north side. Have opted for a consensus solution for
Sunday night that allows for scattered showers to lingering mainly
near and south of the VA/NC border.

One feature will be brief hiccup in the above scenario.  On Friday,
we are expecting a shallow cold air damming influence along and east
of the crest of the Blue Ridge. This will impact the forecast will
more of a light rain, drizzle, foggy forecast through at least the
morning and parts of the afternoon within this region. Areas near
and north of a Lexington, VA to Lynchburg, VA line will be last to
experience its impact. Cooler temperatures will also abound in this
wedged area on Friday, with areas near Lynchburg reaching the lower
50s, which is actually around normal for this time of year, compared
to areas like Bluefield, WV and Richlands, VA outside of the wedge,
experiencing the lower 70s.

A slight chance of thunder will be mentioned a little bit during
this portion of the forecast. The first will be late Friday
afternoon across portions of southeast West Virginia where there may
be enough instability outside the influence of the wedge. Also, late
Sunday afternoon across eastern parts of Southside Virginia, and
neighboring north central North Carolina there may be a few
thunderstorms in association with the passing cold front.


As of 145 PM EST Wednesday...

Drier/cooler air follows the front for early next week as high
pressure builds in Monday and wedges in from the north on
Tuesday. This likely to return some clouds to the region by
later Tuesday with the wedge holding into Wednesday. May see
another weak shortwave pass along the boundary just to our south
Monday night per 00z Euro which could bring more rain back to
southern sections but iffy. Otherwise next impulse dropping out
of the Rockies may tag with the front to bring another area of
organized rainfall into the region by later Wednesday. Temps
cooler into next week, but still above normal with highs 50s to
lower 60s.


As of 645 AM EST Thursday...

Low clouds/stratus were observed along and east of the
Appalachian Divide with Cigs straddling the MVFR/IFR flight
categories. This cloud deck will likely persist through the
morning, then become BKN by mid-day with largely MVFR CIGs
expected for the afternoon.

A backdoor cold front will enter the region from northern
Virginia this afternoon. In its wake, a northeasterly wind will
develop with CIGS/VSBYs expected to drop into the IFR Category
tonight with areas of drizzle and fog.

Winds in advance of the backdoor cool front will be S-SW 5-10
mph becoming northeast behind the front.

Medium confidence in ceilings and visibilities through the TAF
valid period. Medium to high confidence in wind direction and

Extended Aviation Discussion...

Conditions will likely be IFR to start the day Friday and
likely remain IFR to MVFR throughout the day. Eventually, the
backdoor cold front will stall along the Virginia and North
Carolina line and retreat northward as a warm front toward
Friday evening. VFR conditions should return for most locations
during Friday night and Saturday aside from any typical low
clouds along the Blue Ridge on Saturday morning. By Saturday
afternoon, shower coverage should increase as a cold front
arrives from the west that could bring MVFR/IFR conditions
toward Sunday. Better flying weather should return later on


As of 400 AM EST Thursday...

Several record high maximum temperatures were set Wednesday.
These include 77 degrees at Roanoke, 79 degrees at Danville, 76
degrees at Lynchburg, 73 degrees at Blacksburg, and 74 degrees
at Bluefield. Bluefield also set its warmest ever high minimum
temperature for February!

Records are possible again today.

Thursday 2/22/2018
Site MaxT/Year HiMin/Year
BLF    67/1992    52/1980
DAN    73/1976    51/1981
LYH    73/1930    54/1913
ROA    76/1980    51/1955
RNK    65/1980    44/2017

Below are the all-time warmest minimum temperatures recorded
during the month of February, for our five climate sites with
long-established periods of record:

Warmest HiMin - February:
Site   HiMin Date
BLF       58 Feb 21 2018 - Broke old record of 57 from Feb 5 2008
DAN       60 Feb 18 2008
LYH       59 Feb 20 1939
ROA       57 Feb 12 1932
RNK       52 Feb 16 1990




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