Apr 18, 2015 1630 UTC Day 1 Convective Outlook
Updated: Sat Apr 18 16:23:02 UTC 2015 (20150418 1630Z Day 1 shapefile | 20150418 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150418 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 96,562 6,486,635 San Antonio, TX...Oklahoma City, OK...Laredo, TX...Killeen, TX...Norman, OK...
SLIGHT 142,851 11,826,495 Dallas, TX...Austin, TX...Fort Worth, TX...Arlington, TX...Wichita, KS...
MARGINAL 370,949 29,010,315 Houston, TX...Kansas City, MO...New Orleans, LA...Omaha, NE...Tulsa, OK...
Probabilistic Tornado Graphic
20150418 1630 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 56,151 509,794 Grand Island, NE...Kearney, NE...North Platte, NE...Hastings, NE...Hays, KS...
2 % 383,543 36,540,572 Houston, TX...San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...
Probabilistic Damaging Wind Graphic
20150418 1630 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 225,119 18,007,469 San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...Oklahoma City, OK...
5 % 375,196 29,148,297 Houston, TX...Kansas City, MO...New Orleans, LA...Omaha, NE...Tulsa, OK...
Probabilistic Large Hail Graphic
20150418 1630 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
30 % 96,094 6,402,026 San Antonio, TX...Oklahoma City, OK...Laredo, TX...Killeen, TX...Norman, OK...
15 % 144,187 11,850,895 Dallas, TX...Austin, TX...Fort Worth, TX...Arlington, TX...Wichita, KS...
5 % 368,092 28,964,582 Houston, TX...Kansas City, MO...New Orleans, LA...Omaha, NE...Tulsa, OK...
   SPC AC 181623

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1123 AM CDT SAT APR 18 2015

   VALID 181630Z - 191200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PARTS OF SOUTH-CENTRAL
   KS...WESTERN OK...INTO CENTRAL TX...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CENTRAL AND
   SOUTHERN PLAINS...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER MUCH OF THE
   CENTRAL/SOUTHERN PLAINS AND GULF COAST REGION...

   ...SUMMARY...
   SCATTERED THUNDERSTORMS ARE EXPECTED TODAY FROM THE CENTRAL PLAINS
   TO SOUTH TEXAS...SOME OF WHICH WILL PRODUCE HAIL AND SEVERE WIND
   GUSTS.  A FEW TORNADOES CANNOT BE RULED OUT.

   ..CENTRAL/SOUTHERN PLAINS...
   MORNING WATER VAPOR LOOPS SHOW A PERSISTENT UPPER LOW OVER CO...WITH
   SEVERAL SHORTWAVE TROUGHS ROTATING THROUGH THE BASE OF THE LOW INTO
   THE SOUTHERN PLAINS.  ONE SUCH FEATURE IS EVIDENT OVER SOUTHEAST
   NM...WHICH WILL TRACK INTO WEST TX AND EVENTUALLY INTO WESTERN OK
   LATER TODAY/TONIGHT.  VISIBLE SATELLITE IMAGERY SHOWS POCKETS OF LOW
   CLOUDS ALONG THE DRYLINE FROM WESTERN KS INTO WEST-CENTRAL TX...BUT
   THOSE CLOUDS WILL LIKELY ERODE BY EARLY AFTERNOON ALLOWING STRONG
   HEATING TO TAKE PLACE.  DEWPOINTS IN THE 60S AND COOL TEMPERATURES
   ALOFT /-16 AND COLDER AT 500MB/ WILL HELP CONTRIBUTE TO AFTERNOON
   MLCAPE VALUES OF 1500+ J/KG AND ONLY A WEAK CAP.  

   SCATTERED THUNDERSTORMS ARE EXPECTED TO FORM ALONG THE ENTIRE LENGTH
   OF THE DRYLINE FROM WESTERN KS INTO WEST TX. SUFFICIENT DEEP-LAYER
   EFFECTIVE SHEAR WILL SUPPORT SUPERCELL STORM STRUCTURES CAPABLE OF
   LARGE HAIL AND PERHAPS DAMAGING WINDS.  ISOLATED TORNADOES ARE ALSO
   POSSIBLE...BUT WEAK LOW LEVEL VERTICAL SHEAR WILL BE A LIMITING
   FACTOR.  THE AREA OF PERHAPS GREATEST TORNADO THREAT WOULD BE OVER
   WESTERN KS INTO WESTERN NEB WHERE EASTERLY NEAR-SURFACE WINDS WILL
   ENHANCE SHEAR.  STORMS THROUGHOUT THE RISK AREA SHOULD PERSIST INTO
   MID-EVENING BEFORE SLOWLY WEAKENING.

   ...GULF COAST STATES...
   A LARGE MCS REMAINS OFF THE COAST OF LA/MS TODAY...LIMITING INFLOW
   INLAND AND MAINTAINING WIDESPREAD CLOUD COVER OVER THE GULF COAST
   STATES.  SLOW/PARTIAL CLEARING IS EXPECTED THROUGH THE AFTERNOON
   OVER PARTS OF LA/MS...WHERE DEWPOINTS ARE IN THE UPPER 60S.  THIS
   MAY LEAD TO POCKETS OF MLCAPE OF 1000 J/KG.  FORECAST SOUNDINGS IN
   THIS REGION ARE MOIST WITH RATHER WEAK MID LEVEL LAPSE RATES AND
   DISORGANIZED LOW LEVEL WINDS.  FOR THIS REASON...WILL MAINTAIN ONLY
   MARGINAL SEVERE PROBABILITIES ACROSS THE REGION.  IF STRONGER
   DESTABILIZATION CAN OCCUR THAN CURRENTLY ANTICIPATED...PORTIONS OF
   THE AREA MAY NEED TO BE UPGRADED TO SLIGHT RISK.

   ..HART/LEITMAN.. 04/18/2015

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z