Severe Thunderstorm Warning 138, NWS Louisville, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
311 PM EDT Sat Aug 31 2013

.SHORT TERM (Now through Sunday Night)...
Issued at 309 PM EDT Sat Aug 31 2013

This afternoon and early evening...

Main cluster of storms did fire up where moisture had pooled earlier
today over SW Indiana and north central Kentucky. These storms are
currently just SW of Louisville and will continue to slide southeast
toward Bardstown through the late afternoon. Meanwhile, outflow
boundary from this morning's convection is currently stretching from
Frankfort southeast to Mount Vernon, KY and will likely be the focus
for additional convective development over the next few hours as Cu
is already becoming agitated. Areas east of this boundary, including
Lexington, will only have a very small chance of a storm this
evening since this area remains somewhat stable. Do expect the best
coverage (40-50%) to be across central Kentucky where the two areas
of convective focus collide. Could still see gusty winds, brief
torrential rain, and numerous cloud to ground lightning strikes with
any storm. All other areas of the CWA should only see isolated to
widely scattered coverage through the early evening. Heat indices
are maxing out right at 105 this afternoon, however we should see a
slight decrease as cloud cover becomes thicker. Will hold off on any
headlines for due to the short nature of these heat indices.

Tonight...

Coverage of storms should quickly die off after sunset, with focus
shifting upstream for our next potential round of convection overnight.
Another shortwave embedded in the NW flow aloft and its associated
surface feature currently residing over NW Illinois will move across
the Wabash River Valley. A scattered complex of storms is expected
to develop just ahead of this feature and scoot toward our northern
CWA by around Midnight. At this point, not overly impressed so will
leave chances around 30 percent across the north and only 20 percent
elsewhere. Higher res models have been doing better today and will
base most of the forecast off of these solutions, as they have
recognized the boundaries and initiated afternoon storms well.
Expect lows tonight in the low and mid 70s. Fog may also become a
concern toward dawn in spots that saw heavier rainfall, however will
punt any mention for now until confidence in convective chances is
higher as this would impact fog chances.

Sunday...

Shortwave and weak surface trough will slide east through the area
on Sunday, with focus for scattered showers and storms mainly across
eastern portions of the CWA through mid afternoon. Will likely see a
lull across central and western portions of the CWA through the day
as subsidence behind the passing wave quells convective chances.
This will set the stage for another hot day with temperatures
topping out in the lower 90s and heat indices topping out in the low
100s along and west of I-65.

Sunday night...

Still very uncertain about Sunday night, however this time frame
continues to look like the best chance for storms into Monday
morning. This will occur as a stronger shortwave dives through the
northwest flow and the associated surface features drag a cold front
into southern Indiana by dawn on Monday. At least scattered coverage
of storms should be ahead of this front.

.LONG TERM (Monday through Saturday)...
Issued at 255 PM EDT Sat Aug 31 2013

A cold front will push through the area Monday bringing showers and
storms to the area.  By Monday morning the front should be close to
the Ohio River with elevated convection ongoing.  Storms should
mostly affect central KY during the afternoon hours as the whole
complex continues to push ESE.  Soundings reveal CAPE values in the
3000-4000 J/KG range in the Bluegrass area, but realizing that will
depend on the amount of cloud cover that is carried eastward from
the morning storms farther to the west.  Wind profiles look fairly
weak 15-25 kts in the first 0-6km.  Thus, think that strong storms
with maybe a marginally severe storm or two would be possible Monday
mainly over KY.  With clouds/scattered convection, think that high
temperatures will be limited to the mid 80s.

After the front passes through Monday evening, cooler drier air will
be ushered into the region for the rest of the week.  The area will
enjoy high temps in the upper 70s to mid 80s for the rest of the
week with the coolest day being Tues.  Low temperatures will be in
the upper 50s to lower 60s.  A dry, weak front looks to quietly
sweep through the area Thurs/Fri.  The next possible chance for rain
would be late next weekend, but long range models seem to be in
disagreement on how long ridging will remain in control of the
region.

&&

.AVIATION (18Z TAF Update)...
Issued at 655 AM EDT Sat Aug 31 2013

The immediate order of business is fog potential, especially in BWG
where the winds are the lightest. We still have a decent
temp/dewpoint spread, and just a few knots of wind to keep things
mixy. However, nearby METARs at GLW and EKQ have come in with IFR
and a couple area webcams have shown a hint of a fog bank. Will keep
a close eye on all available data until issuance time, but current
inclination is to maintain VFR.

Biggest challenge in this TAF set is still the low-confidence precip
forecast for this afternoon. Convection that was headed our
direction last evening dissipated over Indiana, but there is still
an outflow not too far north of SDF. Differential heating along the
edge of the debris cloud shield from the now-dissipated MCS means
southeast Indiana will probably be the favored spot for convective
initiation. Still difficult to time and to forecast any direct
impact, but it does warrant VCTS/CB wording in SDF and LEX beginning
around 18Z. BWG is far enough removed from any forcing that we will
keep the TAF dry. Prevailing conditions will be VFR, but if a
thunderstorm directly impacts one of the terminals there will be
brief MVFR or even IFR.

Can't rule out precip tonight given disturbances in NW flow and a
juicy air mass. However, confidence is too low to include even VCTS
at this time. Light SSW winds and SCT-BKN mid-level clouds will keep
fog from being a concern.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&

Short Term........BJS
Long Term.........AMS
Aviation..........BJS

<!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>

<!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>