Severe Thunderstorm Warning 61, NWS Blacksburg, VA

Area Forecast Discussion
National Weather Service Blacksburg VA
120 PM EDT Fri Jun 5 2020

.SYNOPSIS...
A cold front will move southeast through the Mid Atlantic
region Saturday. Drier high pressure will follow for Sunday
through Tuesday. On Wednesday or Thursday another cold front
will pass across the eastern United States with a yet another
chance of showers and thunderstorms.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 100 PM EDT Friday...

Moist airmass in place with precip water of 1.5 to 1.7 inches.
Showers and a few storms have formed across the mountains, but CAPES
and low level lapse rates where they have formed plus a deep warm
layer cloud depth has made for more heavy showers as opposed to
deeper convection.

However, the airmass will destabilize through the afternoon with
best instability progged where sunshine was the greatest this
morning, namely along/east of the Blue Ridge. A few storms could
become severe with damaging wet microbursts, but the bigger issue
may be flooding potential as steering flow remains weak. Flash flood
watch configuration looks good and no changes planned.

Models are in decent agreement in showing higher concentration of
showers/storms along/west of the Blue Ridge in advance of shortwave
over eastern KY. Shortwave moves east to the I-81 corridor by early
evening, then east of the piedmont after midnight. As such will lean
toward likely to categorical pops this afternoon where the flash
flood watch is, tapering to scattered pops of 40-50 in the piedmont.

Support for convection lessens this evening across WV/far SW Va and
appears most will see dry weather by after midnight with lingering
pops possible well east of Danville and Lynchburg.

No change in airmass and clearing skies/wet ground could bring about
areas of dense fog, but some upstream cloud cover with another wave
and the front may hinder this. Will re-evaluate this later this
evening.

Saturday is looking drier despite the front moving in, per strong
subsidence aloft and limited moisture. Models are mainly showing low
chance pops across the mountains. With northwest flow and slightly
drier air by afternoon, temps should warm well into the 80s, with
lower 90s east.

Forecast confidence is moderate for storm coverage this
afternoon/evening and high for lower coverage Saturday.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 12:15 PM EDT Friday...

An upper level ridge will be situated to our west for the start of
the forecast period as we remain just down-flow from an upper level
jet on the backside of a trough. Through Monday, the ridge shifts
westward, bringing the associated surface high pressure with it.
This pattern will lead to a dry period of weather. The warmer
weather of the period will be for the start, then slightly cooler
weather as weak cold air advection arrives with the moving high.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 11:30 AM EDT Friday...

Outside the front/remains of Cristobal, the forecast period remains
calm. After Cristobal makes landfall Sunday into Monday, guidance
continues to show it being picked up by a frontal system that will be
lead by an upper level trough mid to late Tuesday. Before the
front/system arrives, high pressure remains overhead with mostly dry
weather. 00z ECMWF and 6z GFS remain undecided on arrival time for
the front with GFS being the more progressive, showing arrival later
Wednesday. Meanwhile, ECMWF is slower bringing the front in
Thursday, with the only POPs Wednesday being along the southern part
of the Appalachians where moisture will be increasing and
interacting with differential heating. Because of the differences in
models, most blended guidance is having a heard time generating
high, properly timed POPs for the front currently. For now, I'm
going with the ECMWF guidance given the GFS speed bias.

Temperatures before the front will be warm with an increasingly
humid airmass arriving. After, cooler weather arrives with a
notably drier/less humid airmass.

&&

.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
As of 115 PM EDT Friday...

MVFR to VFR ceiling this afternoon with coverage of
showers/storms greatest along/west of the Blue Ridge. Leaning
toward radar trends and 12z NAM allows for tempo groups for all
but the piedmont where a VCTS will be kept. Best threat of
storms will be 18z-23z. Some of these storms will produce very
heavy rain and MVFR to IFR ceilings and visibility.

Storms will dissipate by midnight. MVFR to possible IFR or lower fog
may occur late tonight at all sites, especially BCB/LWB/BLF

Any fog/low cigs Saturday should scour out by 14-15z, with VFR
til 18z.

Average confidence on wind, ceiling, visibility and timing of
thunderstorms.

Extended Aviation Discussion...

A front moves across but appears moisture lacking with
only isolated showers/storms in the afternoon. A shift in wind
direction. to the northwest expected. Dry high pressure will
then build across the region with a period of mainly VFR for
Sunday through Tuesday.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flash Flood Watch until midnight EDT tonight for VAZ007-
     009>020-022>024-032>035.
NC...Flash Flood Watch until midnight EDT tonight for NCZ001>003-
     018-019.
WV...Flash Flood Watch until midnight EDT tonight for WVZ042>044-
     507-508.

&&

SYNOPSIS...WP
NEAR TERM...WP
SHORT TERM...RR
LONG TERM...RR
AVIATION...AMS/PM/WP

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Special Weather Statement
National Weather Service BLACKSBURG VA
355 PM EDT Fri Jun 5 2020

VAZ018-022-023-052030-
Botetourt-Craig-Roanoke-
355 PM EDT Fri Jun 5 2020

...A STRONG THUNDERSTORM WILL AFFECT
NORTH CENTRAL ROANOKE...SOUTHEASTERN CRAIG AND SOUTHWESTERN BOTETOURT
COUNTIES...

At 354 PM EDT, a strong thunderstorm was located near Catawba, moving
northeast at 20 mph.

Wind gusts up to 50 mph are possible with this storm. Torrential
rainfall is also occurring with this storm, and may cause localized
flooding. Do not drive your vehicle through flooded roadways.

Locations impacted include...
Troutville...
Catawba...
Fincastle...
Abbott...
Nace...
and Daleville.

LAT...LON 3733 8006 3742 8017 3760 7994 3745 7978
TIME...MOT...LOC 1954Z 230DEG 18KT 3741 8004

RR

Special Weather Statement
National Weather Service BLACKSBURG VA
358 PM EDT Fri Jun 5 2020

VAZ023-034-052030-
Botetourt-Bedford-
358 PM EDT Fri Jun 5 2020

...A STRONG THUNDERSTORM WILL AFFECT
SOUTH CENTRAL BOTETOURT AND WEST CENTRAL BEDFORD COUNTIES...

At 357 PM EDT, a strong thunderstorm was located over Troutville,
moving northeast at 10 mph.

Winds in excess of 30 mph and pea size hail are possible with this
storm. Torrential rainfall is also occurring with this storm, and
may cause localized flooding. Do not drive your vehicle through
flooded roadways.

Locations impacted include...
Troutville...
Montvale...
Fincastle...
Nace...
Laymantown...
Daleville...
and Lithia.

LAT...LON 3733 7981 3740 7993 3756 7984 3744 7961
TIME...MOT...LOC 1957Z 218DEG 11KT 3740 7985

RR

Special Weather Statement
National Weather Service BLACKSBURG VA
400 PM EDT Fri Jun 5 2020

VAZ017-033-052030-
Franklin-Floyd-
400 PM EDT Fri Jun 5 2020

...A STRONG THUNDERSTORM WILL AFFECT
EAST CENTRAL FLOYD AND SOUTHWESTERN FRANKLIN COUNTIES...

At 359 PM EDT, a strong thunderstorm was located over Callaway, or
near Copper Hill, moving east at 15 mph.

Winds in excess of 40 mph are possible with this storm. Torrential
rainfall is also occurring with this storm, and may cause localized
flooding. Do not drive your vehicle through flooded roadways.

Locations impacted include...
Boones Mill...
Ferrum...
Copper Hill...
Callaway...
and Wirtz.

LAT...LON 3693 8025 3704 8017 3712 8009 3713 7988
      3686 7995
TIME...MOT...LOC 1959Z 272DEG 12KT 3701 8010

RR