Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 241504

Area Forecast Discussion
National Weather Service Blacksburg VA
1104 AM EDT Fri Mar 24 2017

High pressure off the coast will establish a warmer and more moist
southerly flow across the Appalachians and central mid Atlantic region
into the weekend. A slow moving cold front will enter from the west on
Sunday with a chance for showers and possibly a thunderstorm. Our
weather then looks to remain unsettled through next week as a series of
disturbances move across the central and southern part of the country,
keeping a chance for showers and thunderstorms in our forecast through


As of 1100 PM EDT Friday...

The wedge has eroded over parts of SE WV this morning. A warm
front in northwesterly flow continues to track across the Mid
Atlantic region. With all this taking place, an isolated shower
or two may track across western Greenbrier early this

As of 345 AM EDT Friday...

It`s looking like a quiet end to the workweek as an upper level ridge
is the dominant weather feature over the Appalachians, though there
will be a fair amount of cloud cover around. At the surface, high
pressure along the middle Atlantic coast will continue to push offshore
today. Satellite imagery shows some lower clouds extending back from
the NC mountains toward the Gulf coast, guidance supports return flow
around the high drawing these clouds up into the region this afternoon
along and east of the Blue Ridge into Southside. Additionally, a short
wave will swing through the Ohio valley along a warm front on the rim
of the upper ridge. This is generating some shower/storms well off to
our northwest, but expect some showers to brush by to our north today
with lower clouds extending southward into the region. Quiet weather
then continues tonight as the ridge axis crosses the region and high
pressure at the surface remains parked off the mid Atlantic coast.

With a deepening southerly flow, temperatures will moderate
considerably from readings yesterday with highs about 10 degrees warmer
which will be above normal for late March.


As of 400 AM EDT Friday...

A very active, highly kinematic, westerly flow will be in place
across the U.S. with the Pacific wide open. A parade of
vigorous upper-level low pressure areas will march from west to
east across the U.S. through the period. At least four such
significant systems are noted during the 7-day period beginning

Saturday will bring one last day of dry weather to the area as
an upper ridge briefly moves across the area and temporarily
blocks the upstream system in the central U.S. A warm front will
continue to lift northward through the northern portions of the
Mid-Atlantic into NY and New England. The surface high that has
been providing us with the cool weather the last few days will
move to our southeast. The region will be solidly in the warm
sector with southerly to southwesterly surface flow. 850mb temps
will soar into the double digits allowing surface temps to warm
well into the 60s west to the 70s Piedmont. These readings are
about 10-15 degrees above normal for late March.

By Sunday, the first of the Pacific system will arrive. Models
are in general agreement on the details. Timing is faster than
has been indicated in recent days with this system now arriving
in the western part of the CWA Sunday morning and then into the
Piedmont by Sunday afternoon. The faster arrival of these system
also heralds better dynamics as well. Models are in pretty good
agreement on a near solid line of showers and thunderstorms
translating from the TN valley into western VA. The risk of
severe weather with this system appears low as instability is
meager at best with capes below 500 J/kg. Have included a slight
chance of thunder western areas, but left as showers east of
the Blue Ridge at this time. Rainfall amounts are expected to
range from 1/2 to 3/4 inch west of the Blue Ridge to 1/4 to 1/2
inch east of the Blue Ridge. Temperatures will remain warm
Sunday, but the clouds and precipitation will keep readings on
the order of 5-7 degrees cooler than Saturday. The clouds,
southerly flow, and warm, Gulf air in place will keep overnight
minimums very balmy, well into the 50s most areas.

On Monday, the first upper low will lift northward toward the
Great Lakes and weaken as yet another upper-low follows quickly
on its heels moving out of the Central Plains. This system
promises to be somewhat more progressive and transition into an
open wave as it moves into the eastern U.S Tuesday. This leaves
the CWA in an unseasonably warm, humid air mass Monday between
systems with little in the way of dynamics or forcing, yet with
lots of clouds and high RH. Any breaks in the sun could trigger
isolated pop up showers and thus have left in chance pops west
to slight chance pops east with no thunder. Temperatures will be
warm Monday with lows in the 50s and highs mostly in the 70s,
except 60s western mountains.


As of 415 AM EDT Friday...

As noted above, the next in the series of upper-level low
pressure system will arrive in our region early Tuesday.
Dynamics are marginally more favorable for thunderstorms than
the Sunday system, but instability is notably better.
Consequently, have included a chance of thunder for the entire
CWA. Still not impressed with this being a widespread severe
event for the CWA, but with the upper trough affecting eastern
portions of the CWA during afternoon heating, a few stronger
storms cannot be ruled out. The lack of shear, but greater
instability, suggests that hail would be the main threat.
Temperatures are expected to be close to those observed Monday,
mainly in the 40s and 50s for lows and the 60s to lower 70s for

Wednesday will bring a brief break from the active weather
before the next upper-low moves from the Southern Plains into
the eastern U.S. Thursday, which is about 24 hours faster than
previously expected. Weak high pressure should provide the
region with a mostly dry and slightly cooler day Wednesday, but
still with lots of clouds in place and possibly even a few
showers or sprinkles, especially during the morning.
Temperatures will still be well above normal ranging from the
50s in the morning to mostly 60s during the afternoon.

By Thursday, the Southern Plains system will move northeastward
into the TN and OH Valleys. Upper diffluent flow will begin to
impact the western parts of the CWA by afternoon and evening. Of
the three systems slated to impacted the CWA next week, this one
brings about the greatest threat of severe weather as notable
shear and instability will be in place. A line of strong to
severe thunderstorms would certainly not be out of the question
Friday afternoon. Expect little change in temperature Thursday
from previous days.


As of 745 AM EDT Friday...

High pressure along the Mid-Atlantic coast will continue to
push offshore today allowing winds to come around to the
south and southwest. The gradient will tighten allowing wind
speeds to increase and become fairly gusty during the late
morning and afternoon, especially east of the Blue Ridge.
Extensive mid and high clouds were spreading across the
region as a result of mid-level warm advection. The southerly
winds will also allow low-level moisture to increase resulting
in increased potential for MVFR ceilings overnight/early
Saturday. Otherwise, ceilings should remain VFR until after 00Z
with ceilings through the day generally AOA 050. Visibilities
will not be an issue through the TAF valid period remaining

Medium confidence in ceilings through the TAF valid period.
High confidence in visibilities through the TAF valid period.
Medium to high confidence in wind speed/direction through the
TAF valid period.

Extended Aviation Discussion...

Moisture continues to increase over the weekend ahead of an
upper-level low pressure area moving northeast from the
Southern Plains. 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.
Periods of unsettled weather will continue into the first half
of next week as a series of upper-level lows track from west to
east across the U.S.




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