Sep 30, 2014 0600 UTC Day 1 Convective Outlook
Updated: Tue Sep 30 05:29:15 UTC 2014 (20140930 1200Z Day 1 shapefile | 20140930 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20140930 1200 UTC Day 1 Outlook Graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 32,498 316,670 Norfolk, NE...Aberdeen, SD...Mitchell, SD...Yankton, SD...Huron, SD...
Probabilistic Tornado Graphic
20140930 1200 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 31,877 302,203 Norfolk, NE...Aberdeen, SD...Mitchell, SD...Yankton, SD...Huron, SD...
2 % 25,950 604,173 Sioux Falls, SD...Sioux City, IA...Columbus, NE...Brookings, SD...Pierre, SD...
Probabilistic Damaging Wind Graphic
20140930 1200 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 160,282 4,225,315 Omaha, NE...Wichita, KS...Lincoln, NE...Sioux Falls, SD...Sioux City, IA...
Probabilistic Large Hail Graphic
20140930 1200 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 25,596 275,123 Norfolk, NE...Mitchell, SD...Yankton, SD...Huron, SD...Vermillion, SD...
5 % 144,385 6,034,425 Omaha, NE...Wichita, KS...Lincoln, NE...Sioux Falls, SD...Topeka, KS...
   SPC AC 300529

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1229 AM CDT TUE SEP 30 2014

   VALID 301200Z - 011200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF SD AND NERN
   NEB...

   ...SUMMARY...
   ISOLATED SEVERE THUNDERSTORMS WITH HAIL AND PERHAPS A TORNADO ARE
   POSSIBLE TUESDAY FROM SOUTH DAKOTA INTO NEBRASKA. A FEW STRONG
   STORMS WITH HAIL MAY ALSO DEVELOP FROM KANSAS SOUTHWARD INTO
   NORTHWESTERN TEXAS BY LATE AFTERNOON INTO THE EVENING. ISOLATED HAIL
   WILL ALSO BE POSSIBLE ACROSS PORTIONS OF PENNSYLVANIA.

   ...SYNOPSIS...
   A NEGATIVELY-TILTED SHORTWAVE TROUGH WILL MOVE ACROSS THE DAKOTAS
   WITH SURFACE LOW OVER CNTRL SD AT 21Z. AT THE SAME TIME...A WARM
   FRONT WILL EXTEND EWD FROM THE LOW ALONG THE SD/ND BORDER AND SEWD
   INTO WRN IA WITH A DRYLINE FROM E-CNTRL SD INTO ERN NEB AND SWWD
   INTO THE ERN TX PANHANDLE. LOW-LEVEL MOISTURE WILL BE SOMEWHAT
   MEAGER...BUT WILL LIKELY SUPPORT ISOLATED STRONG TO SEVERE STORMS
   DURING THE AFTERNOON WHERE FORCING FOR ASCENT IS STRONGEST NEAR THE
   BOUNDARIES AND WITH AMPLE SHEAR IN PLACE.

   TO THE E...A SMALL UPPER LOW WILL SHIFT SEWD ACROSS OH...PA...WV AND
   VA WITH COOL AIR ALOFT AND ENHANCED SHEAR HELPING TO SUPPORT A FEW
   STRONG DAYTIME THUNDERSTORMS.

   ...ERN SD AND NEB DURING THE AFTERNOON...
   A N-S ORIENTED ZONE OF NON-SEVERE THUNDERSTORMS WILL EXIST EARLY IN
   THE DAY FROM NRN KS ACROSS NEB AND SD IN ASSOCIATION WITH THE WARM
   CONVEYOR BELT AHEAD OF THE LOW. IN THE WAKE OF THIS EARLY
   ACTIVITY...COOLING ALOFT WILL PERSIST COINCIDENT WITH STRONG HEATING
   W OF THE DRYLINE ACROSS SD AND NEB. DEWPOINTS INTO THE MID TO UPPER
   50S F ARE LIKELY TO EXTEND NWWD TOWARD THE SURFACE LOW OVER CNTRL
   SD. BY MID/LATE AFTERNOON...AN ARC OF STORMS APPEARS
   LIKELY...COMPRISED OF RELATIVELY LOW-TOPPED SUPERCELLS. A TORNADO OR
   TWO WILL BE POSSIBLE ALONG WITH LARGE HAIL.
   DUE TO THE NWD MOVEMENT OF THE UPPER LOW...FORCING FOR ASCENT WILL
   WEAKEN WITH SWD EXTENT INTO NEB...BUT ISOLATED HAIL WILL BE POSSIBLE
   THERE DURING THE AFTERNOON AS WELL.

   ...ERN NEB...KS...FAR WRN OK INTO NWRN TX OVERNIGHT...
   WEAK FORCING ALONG THE STALLING SFC TROUGH/DRYLINE MAY BE SUFFICIENT
   FOR ISOLATED STRONG STORMS CAPABLE OF MARGINAL HAIL FROM KS INTO
   NWRN TX. TEMPERATURES ALOFT WILL NOT BE PARTICULARLY COOL...AND
   SHEAR WILL BE MARGINALLY FAVORABLE FOR A LONG-LIVED CELL CAPABLE OF
   HAIL DURING THE PEAK HEATING HOURS.

   DURING THE EVENING...WARM ADVECTION WITH THE SWLY LOW-LEVEL JET WILL
   HELP INCREASE LIFT ACROSS NERN KS AND VICINITY...WITH PERHAPS
   MARGINAL HAIL.

   ...CNTRL AND WRN PA...NRN WV AND SWRN NY DURING THE AFTERNOON...
   A SHORTWAVE TROUGH WILL MOVE SEWD ACROSS MI AND ACROSS OH/PA/NY
   DURING DAY WITH COOLING ALOFT FAVORABLY TIMED WITH DAYTIME HEATING.
   A WEAK COOL FRONT WILL HELP FOCUS DEVELOPMENT ACROSS MAINLY WRN PA.
   ALTHOUGH MID TO UPPER-LEVEL FLOW WILL INCREASE ACROSS SRN AREAS
   UNDER THE JET MAX...WINDS IN THE LOWEST 3KM WILL BE RELATIVELY WEAK.
   THIS SHOULD RESULT IN LITTLE IF ANY TORNADO THREAT EVEN WITH A FEW
   CELLS PERHAPS EXHIBITING MIDLEVEL ROTATION...AND ANY WIND THREAT
   SHOULD BE QUITE LOCALIZED.  COOL TEMPERATURES ALOFT WILL STRONGLY
   FAVOR HAIL PRODUCTION...WHICH WILL BE THE PRIMARY THREAT.

   ..JEWELL/ROGERS.. 09/30/2014

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z