Special Weather Statement, NWS St. Louis, MO

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1237 PM CDT Fri Jun 28 2019

.UPDATE...
Issued at 1128 AM CDT Fri Jun 28 2019

Grids have been updated to reflect the MCS which is dropping
southward out of Iowa towards NE MO and west central IL. The
primary severe weather concern with this thunderstorm complex will
be damaging wind gusts. The MCS has shown little sign of
weakening thus far, and its outflow boundary may also initiate new
thunderstorm development as it moves into a moist and unstable
environment. Corfidi vectors initially point to the southwest on
the western side of the complex and slightly to the southeast on
the eastern side of the complex, but model guidance shows that the
vectors become oriented more southerly after 18z. This suggests
that the thunderstorm complex would continue propagating with a
southerly component for as long as it holds together, although it
is unclear whether the initial motion will be more to the
southwest or more to the south.

Kanofsky

&&

.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 336 AM CDT Fri Jun 28 2019

A pattern more typical of summer has become established with an
expansive upper high/ridge currently centered in the southern
Rockies and the main band of westerlies across the north central and
northeastern tier of the CONUS where the primary baroclinic zone
resides. Also a key player is an upper low now in northern MS.

The upper low will move southwestward over the next 24 hours into
the lower MS Valley. A vort max rotating cyclonically around its
north side could help induce a few showers this morning across
southeast MO. Otherwise I think today will largely be dry and
seasonably hot and humid with high temperatures comparable to
yesterday and peak afternoon heat indices in the 95-100 degree
range.

The forecast for tonight is accompanied by a good deal of
uncertainty. The upper ridge will build northeastward with the
center shifting into the central Rockies/central high plains region.
Being on the eastern periphery of the anticyclone aloft will place
us in north-northeast flow aloft. This can be troublesome with the
main baroclinic zone residing across the upper MS Valley, as it can
result in convective complexes moving south or south-southwestward
into our area. The GFS and ECWMF suggest this is a possibility with
a MCS tracking into northeast and central MO and west central IL,
while the NAM largely keeps the system to our north bringing into
far northeast MO in a weakening state. Another factor limiting
confidence is the performance of the GFS and ECMWF QPF the last few
model runs, which has been extremely poor and a reflection of the
difficulties and limited skill of models with warm season QPF. For
what it's worth the HRRR at this time range is not very enthused.
At this point I think 20-30 pops across northeast MO and west
central IL overnight into mid-morning on Saturday are reasonable
and speak to the uncertainty. A full blown MCS or decaying one
could bring a strong wind threat with it.

Seasonably hot and humid weather continues on Saturday as the upper
ridge/high center continues to shift northeast into the north
central Plains, with highs near or slightly higher than today and
peak HI values again 95-100. This is based on the expectation that
Saturday will be largely void of precipitation from late morning
through the afternoon and any potential debris cloud would thin.

Glass

.LONG TERM...  (Saturday Night through Thursday)
Issued at 336 AM CDT Fri Jun 28 2019

Sunday through Monday look largely dry and seasonably hot and humid
with the upper ridge generally dominating. Highs remain in the lower
to middle 90s with peak heat index values of 95-100. By Tuesday the
upper ridge bifurcates with one center in the southwest U.S. and the
other portion centered in the southeast/Gulf Coast region with a
weakness inbetween from the southern into central Plains. By
Thursday/Independence Day the models diverge - the GFS has flow
aloft becoming weakly quasi-zonal with weak disturbances aloft
tracking across the area and an encroaching cold front, whereas
the ECWMF keeps the southeast upper ridge more intact. The GFS
scenario would have thunderstorm chances ramping up each day
Tuesday-Thursday, while the ECMWF is mainly dry until Thursday
when it shows potential for diurnally driven showers and storms.

Glass

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1157 AM CDT Fri Jun 28 2019

A thunderstorm complex near the IA/MO border did not dissipate as
previously anticipated, and it is likely to affect KUIN during
the first 0-4 hours of the valid TAF period. There have been
multiple reports of 40-50 kt wind gusts both with the line itself
and well behind it. The line is expected to turn southwestward
within the next few hours and will probably reach KCOU during the
first 2-6 hours of the valid TAF period, but it is not yet clear
whether or not the eastern part of the line will affect
KSTL/KSUS/KCPS. A separate thunderstorm complex is expected to
develop overnight and could affect KUIN after 29/06z, but there
is a high amount of uncertainty regarding whether the overnight
complex would move far enough southeastward to also affect
KSTL/KSUS/KCPS. Outside of thunderstorms, VFR conditions are
expected at all terminals.

Kanofsky

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
405 PM CDT Fri Jun 28 2019

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-291200-
Adams IL-Audrain MO-Bond IL-Boone MO-Brown IL-Calhoun IL-Callaway MO-
Clinton IL-Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-
Greene IL-Iron MO-Jefferson MO-Jersey IL-Knox MO-Lewis MO-Lincoln MO-
Macoupin IL-Madison IL-Madison MO-Marion IL-Marion MO-Moniteau MO-
Monroe IL-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-Pike IL-
Pike MO-Ralls MO-Randolph IL-Reynolds MO-Saint Charles MO-
Saint Clair IL-Saint Francois MO-Saint Louis City MO-Saint Louis MO-
Sainte Genevieve MO-Shelby MO-Warren MO-Washington IL-Washington MO-
405 PM CDT Fri Jun 28 2019

This Hazardous Weather Outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Late this afternoon and tonight.

Thunderstorms have developed across the region. Some of the storms
could be strong enough to produce hail and damaging wind gusts late
this afternoon and this evening.

Major river flooding continues for a few locations along the
Mississippi, Missouri, and lower Illinois Rivers.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

There is a slight chance of thunderstorms across northeast Missouri
and west central Illinois on Saturday morning.

There is a chance of thunderstorms across parts of the area from
Tuesday through Thursday.

Major river flooding continues for a few locations along the
Mississippi, Missouri, and lower Illinois Rivers.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report any severe weather, if observed,
to the National Weather Service.

Kanofsky

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
241 PM CDT FRI JUN 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0226 PM     FLOOD            8 N MOUNT STERLING      40.10N 90.77W
06/28/2019                   BROWN              IL   LAW ENFORCEMENT

            BROWN COUNTY SHERIFFS OFFICE REPORTED WATER
            ON THE ROAD AT ROUTE 99 NEAR THE SCHUYLER
            COUNTY LINE. THERE WAS NO INFORMATION ON
            DEPTH OR MOVEMENT OF WATER.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
323 PM CDT FRI JUN 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0322 PM     HAIL             1 WNW MEXICO            39.17N 91.88W
06/28/2019  M0.25 INCH       AUDRAIN            MO   TRAINED SPOTTER

&&

MAB

Special Weather Statement
National Weather Service St Louis MO
400 PM CDT Fri Jun 28 2019

ILZ098-099-MOZ036-049>052-059>062-282145-
Calhoun IL-Jersey IL-Montgomery MO-Pike MO-Gasconade MO-
St. Charles MO-Franklin MO-Lincoln MO-Warren MO-Osage MO-Callaway MO-
400 PM CDT Fri Jun 28 2019

...SIGNIFICANT WEATHER ADVISORY FOR CALHOUN AND SOUTHWESTERN JERSEY
COUNTIES IN SOUTHWESTERN ILLINOIS...ST. CHARLES...LINCOLN AND
SOUTHERN MONTGOMERY COUNTIES IN EAST CENTRAL MISSOURI...EAST CENTRAL
CALLAWAY COUNTY IN CENTRAL MISSOURI...NORTHWESTERN FRANKLIN COUNTY IN
EAST CENTRAL MISSOURI...NORTHEASTERN OSAGE COUNTY IN CENTRAL
MISSOURI...WARREN COUNTY IN EAST CENTRAL MISSOURI...SOUTHEASTERN PIKE
COUNTY IN NORTHEASTERN MISSOURI AND NORTHERN GASCONADE COUNTIES IN
EAST CENTRAL MISSOURI UNTIL 445 PM CDT...

At 400 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Elsberry to near Troy to near
Williamsburg. Movement was south at 30 mph.

Penny size hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
O'Fallon, St. Charles, St. Peters, Wentzville, Lake St. Louis,
Washington, Dardenne Prairie, Troy, Warrenton, Weldon Spring, Wright
City, Cottleville, Montgomery City, Hermann, New Haven, Elsberry, St.
Paul, Moscow Mills, Winfield and Davis.

This includes Interstate 70 in Missouri between exits 170 and 227.

This also includes Deutschheim Historic Site, Cuivre River State
Park, Graham Cave State Park, and Pere Marquette State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in St Louis.

&&

A Severe Thunderstorm Watch remains in effect until 600 PM CDT for
southwestern Illinois...and central, northeastern and east central
Missouri.

LAT...LON 3889 9178 3905 9106 3934 9074 3917 9061
      3912 9060 3914 9060 3887 9038 3855 9089
      3840 9180
TIME...MOT...LOC 2100Z 345DEG 26KT 3922 9078 3899 9104 3885 9168

TES

<!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>