Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
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FXUS61 KRNK 221142
Area Forecast Discussion
National Weather Service Blacksburg VA
742 AM EDT Wed Mar 22 2017
A large area of high pressure over the Great lakes will move
eastward today and be centered over western Pennsylvania tonight.
The high center will slide off the coast Thursday and push out into
the Atlantic ocean Friday. A warmer southerly flow will develop
Friday into the weekend ahead of a slow moving cold front that
should approach the region on Sunday.
.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM EDT Wednesday...
Upper trough over New England moves east today into the Atlantic
ocean, allowing the upper ridge to slide over our region. Cool high
pressure over the Great Lake Region will move east today and be
centered over Pennsylvania tonight. High temperatures this
afternoon will range from the upper 30s in the northwest Greenbrier
county in Southeast West Virginia to near 60 degrees in the
Piedmont. Under mostly clear skies and light winds, low temperatures
tonight will be cold with readings from the upper teens in the
northern mountains to near 30 degrees along the southern Blue Ridge
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
As of 400 AM EDT Wednesday...
A large area of Canadian high pressure will be drifting across
the region at the beginning of this period. 850mb temps will
range from -6C along the I-64 corridor to around 0C in the
southern areas. This will leave temperatures a bit below normal
at the start of the period, but this will be short lived and
generally the exception during this period as opposed to the
rule. By Friday, the large high pressure area will drift to the
east and bring a warm, moist southwest flow to the region. The
upper-level pattern will evolve from a prevailing northwest flow
to one of upper-level ridging. This ridging will occur in
advance of a series of mainly southern stream deep upper troughs
moving across the U.S. during the period. The ridging will
delay the arrival of the first of these systems until Sunday.
Thus, most of this period will be precipitation free as moisture
and dynamics are shunted northwest around the building upper
ridge. Although some light precipitation may accompany a warm
front that will lift through the region Friday.
Temperatures will trend from slightly below normal to much above
normal as 850mb temps climb into the double digit territory around
+12C or so. Look for highs in the 40s and 50s Thursday to rise
to the 60s and 70s by Saturday, with lows in the 20s Thursday
rising to the 40s and 50s by Saturday.
.LONG TERM /SUNDAY THROUGH TUESDAY/...
As of 425 AM EDT Wednesday...
The models have come into fairly good agreement that the first
of several upper lows slated to track through the southern
stream into the southwest/central U.S. during this time frame,
will lift northward into the Ohio Valley late in the weekend.
This will result in the eastern U.S. evolving into a rather wet
and unsettled pattern late in the weekend into the first of next
week. Due to the weakening nature of this system as it gradually
fills in the Ohio Valley and the lack of instability, partly
because of in-situ wedging, dynamics and instability for thunder
generally appear to be lacking. However, enough instability was
indicated to support some thunder in far southwest VA and
southern WV. The next in a weakening upper low will be moving
toward the region by Monday as the previous system lingers
across the northeastern U.S. Again, this will keep a
wet/unsettled pattern across the region. Temperatures will
remain unseasonably warm with highs in the 60s and 70s and lows
in the 40s and 50s.
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --As of 740 AM EDT Wednesday...
A cold front was moving southward through the region this
morning. Behind the front, high pressure will build south into
our region today into tonight. This will provide mostly sunny
skies. Any clouds across the Piedmont associated with the
shower activity to our south earlier this morning, will move
south and east out of the area. Some upslope mountain clouds
contributing to MVFR cigs will linger across eastern WV through
mid- morning, then dissipate by midday. Visibilities will be
VFR through the TAF valid period with a very dry air mass
advecting across the region.
The main aviation story today will be gusty northwest to north
winds at speeds of 15-20 mph with gusts of 25 to 30 mph at
times. Winds will veer more to the NNE-NE after 00Z and diminish
to 10 mph or less.
Medium to high confidence in ceilings through the TAF valid
High confidence in VFR visibilities through the TAF valid
Medium to high confidence in wind speed/direction through the
TAF valid period.
Extended Aviation Discussion...
Good flying weather is expected to linger into Friday before
moisture starts to increase over the weekend ahead of a cold
front approaching from the west. However, precipitation is not
expected until Sunday when sub-VFR conditions become more of a
possibility. Otherwise looking at overall VFR to start the
weekend with most lower cigs remaining west of the area until
later Sunday at this point.
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