Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 281126

Area Forecast Discussion
National Weather Service Blacksburg VA
726 AM EDT Tue Mar 28 2017

Expect a cold front to move across the area today exiting the
piedmont by late afternoon. High pressure works in from the
north into Thursday. Friday, another storm system moves in from
the southwest with showers and storms.


As of 710 AM EDT Tuesday...

Made adjustments to morning forecast based on radar trends, and
shifting higher pops more over the piedmont of VA into the
Alleghanys with less in the NC foothills. Deeper moisture
evidenced on IR and WV satellite has shifted to the piedmont.
Upper low/trough over WV works eastward through early afternoon.
Where it is during peak heating to determine best coverage. At
the moment should be along and east of the Blue Ridge, but even
that should be mainly scattered.

Previous discussion from early morning...

Area of thunderstorms over the NC foothills/piedmont shifting
northeast toward southside VA picked up somewhat by high-res models
but as usual, the high-res models are too slow by an hour or 2.
Still should see higher pops in the piedmont this morning with this
batch, with another concentrated area ahead of the front over WV
into the Alleghanys.

Most support for convection in the east this morning, subsides west,
then as we head toward early afternoon, with the front, another band
of convection forms from Amherst to South Boston, per RAP, with
isolated/scattered showers lingering post frontal in the west. SPC
showing marginal risk in the piedmonts today, mainly for this
morning into early afternoon. Stabilization per rainfall/clouds will
inhibit a good chance of strong to severe storms, but a little bit
of sunshine per some of the models this afternoon could enhance the
updraft enough to produce a strong/severe cell or two. Appears will
see this threat mainly east of a line from Lynchburg to Danbury NC.

Expect decreasing trend in pops by dusk with lingering upslope rain
showers over WV til midnight.

High today will be dependent on sky cover/areal coverage of showers,
but leaned a little cooler than MOS. Still expect highs from the mid
to upper 60s west, to mid 70s east.

Tonight, should be cooler than this morning, but still about 10-15
degrees above normal, with lows in the mid to upper 40s mountains,
to lower to mid 50s elsewhere.


As of 350 AM EDT Tuesday...

High pressure will move out of the upper midwest and wedge down the
east side of the Appalachians for the latter portion of the workweek.
By Friday, an upper level trof will drive an area of low pressure into
the region to do battle with the wedge. Abundant moisture coupled with
good dynamic forcing and isentropic lift will make for an increasing
chance of precipitation Thursday night and Friday looks to be quite
wet. There are indications in the latest guidance that the wedge will
hold firm until the cold front passes and this will be a substantial
limiting factor in severe weather potential. However, if the wedge
retreats and allows warmer unstable air to move in from the south and
west there will be strong dynamics in play to support severe weather.
It is still a bit too far out to resolve the many details of this
nuanced forecast and possible severe threat so later model runs will be
watched closely.

Will be above normal on Wednesday, but once the wedge becomes
established readings on Thursday will be quite cool with most
locations in the 50s. Temperatures on Friday will be largely
dependent on the ability of the wedge to remain entrenched and
look to remain below normal.


As of 350 AM EDT Tuesday...

An upper level ridge will build over the region behind the departing
low pressure system. This will allow high pressure to build at the
surface and once again wedge down east of the Appalachians this
weekend. Overall precipitation chances will be low with some lingering
upslope showers west of the Blue Ridge early in the period, followed by
a few sprinkles with the building wedge. Temperatures will continue to
be well above normal into the first part of next week.


As of 713 AM EDT Tuesday...

Dealing with mainly VFR cigs this morning, though where showers
area, IFR cigs/vsbys likely, but more in a tempo or less time
frame. Also some lower cigs across the higher ridges this
morning, but not at the taf sites.

Front at 11z was located from PIT-HTS-TYS, and should be east of
the LYH/DAN area by 22z. Overall think thunder threat will be
low, but could still see some out toward LYH/DAN in the early
afternoon as upper trough axis moves overhead. Otherwise VFR
with clearing this evening. Some MVFR bkn cigs seem likely at
times mainly BLF this evening into overnight with wsw upslope
helping this.

Extended Aviation Discussion...

High pressure builds in from the north Wednesday into Thursday
with next storm system moving in the Mississippi Valley. A
threat for sub-VFR cigs appears likely as the high wedges
southwest Wed night into Thursday for most sites. The highest
probability of rain will be on Friday along with sub-VFR
cigs/vsbys with the showers. Post-frontal northwest flow sub-VFR
into Saturday with gusty winds possible.




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