Severe Thunderstorm Warning 3, NWS Aberdeen, SD

AREA FORECAST DISCUSSION FOR CENTRAL...NORTHCENTRAL AND NORTHEAST
SOUTH DAKOTA AND WEST CENTRAL MINNESOTA
NATIONAL WEATHER SERVICE ABERDEEN SD
324 PM CDT SUN MAY 9 1999

SHORT TERM DISCUSSION

THE THREAT FOR SUPERCELL DEVELOPMENT CONTINUES ACROSS PART OF
CENTRAL SD AND THEN LATER TONIGHT ACROSS PARTS OF NORTHEAST SOUTH
DAKOTA.  ALSO...IN CONCERN IS THE FLOOD THREAT FOR NORTHEAST SOUTH
DAKOTA.

ABR 20Z MODIFIED HODOGRAPH INDICATED A HELICITY OF 420 M2/S2.  ETA
FORECAST HELICITY VALUES WERE APPROX 400 M2/S2 PLUS.  MARGINAL
FORECAST CAPES OF 500 TO 1000 J/KG ALONG A WARM FRONTAL BOUNDARY
NEAR PIR WILL BE THE FOCUS FOR SUPERCELL DEVELOPMENT LATER THIS
EVENING.  AT 20Z...WATER VAPOR LOOP INDICATED A VORT MAX MOVING INTO
ND AT 20Z.  IT IS HARD TO PINPOINT THESE VORT MAXES ON SATELLITE.
THE NEXT ONE SHUD HELP TO ENHANCE VERTICAL MOTION ALONG THE WARM
FRONT BETWEEN 20Z AND 03Z.  THE ETA AND AVN CONTINUE TO HANDLE THIS
EVENT QUITE WELL.  THE NGM CONTINUES TO DIG THE 5H LOW DEEPER AND
HOLD
BACK THE SURFACE LOW.  WILL GO WITH A BLEND WITH THE ETA AND AVN.

IT ALSO APPEARS THAT CENTRAL SD WILL BE ON THE EDGE OF ELEVATED
INSTABILITY.  WILL CONTINUE THE ISOLATED TORNADO THREAT BECAUSE OF
THE HIGH SHEAR VALUE AND MARGINAL INSTABILITY.  IT APPEARS THAT AS
THE SURFACE LOW AND THE WARM FRONT SURGE NORTH TONIGHT TOWARDS
NORTHEAST SD MOST OF THE CONVECTION WILL BECOME MOSTLY ELEVATED.
THEREFORE... LARGE HAIL AND POSSIBLY DAMAGING WINDS WILL BE A PROBLEM.

WENT WITH CATEGORICAL POPS AND THE MENTION OF SEVERE IN THE CENTRAL
AND...NORTHEAST AND WEST CENTRAL ZONES TONIGHT.  BECAUSE OF HIGH
PRECIPTABLE WATER VALUES...HEAVY RAIN IS POSSIBLE.  FLOODING COULD
BECOME A PROBLEM WITH FLASH FLOOD GUIDANCE AVERAGING AROUND 1.5
INCHES.  WILL LET NEXT SHIFT ADDRESS THAT PROBLEM.

GUERRERO

EXTENDED DISCUSION

EXTENDED FORECAST WILL CONTINUE TO DEAL WITH UPPER LOW ACROSS THE
WESTERN UNITED STATES THROUGH THURSDAY. MOIST SOUTHWEST FLOW WILL
CONTINUE TO BRING A CHANCE OF SHOWERS ON WEDNESDAY. THEN A COLD
FRONT SWEEPS ACROSS THE REGION ON THURSDAY BRINGING A CHANCE OF
SHOWERS OR THUNDERSTORMS. SOME DRYING MAY TAKE PLACE AS COLD FRONT
MOVES OFF TO THE EAST ON FRIDAY. TEMPERATURES SHOULD TO CLIMB TO
NEAR SEASONAL NORMALS DURING THE PERIOD.

ECKBERG

.ABR...NONE.

<!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>

SDZ045-048-051-100300-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE  ABERDEEN SD
400 PM CDT SUN MAY 9 1999

...TORNADO WATCH IN EFFECT UNTIL 10 PM CDT...

THE STORM PREDICTION CENTER IN NORMAN OKLAHOMA HAS ISSUED A TORNADO
WATCH FOR THE FOLLOWING COUNTIES OF CENTRAL SOUTH DAKOTA... LYMAN...
JONES...AND BUFFALO.  SOME OF THE COMMUNITIES IN THE TORNADO WATCH
AREA ARE...KENNEBEC...MURDO...RELIANCE...PRESHO...LYMAN...FORT
THOMPSON...AND GANN VALLEY.

IF YOU LIVE IN OR NEAR THE TORNADO WATCH AREA...BE ON THE LOOKOUT FOR
THREATENING WEATHER AND LISTEN OR WATCH FOR LATER STATEMENTS AND
POSSIBLE WARNINGS.

GUERRERO