Feb 20, 2017 0100 UTC Day 1 Convective Outlook
Updated: Mon Feb 20 00:45:03 UTC 2017 (20170220 0100Z Day 1 shapefile | 20170220 0100Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170220 0100 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 84,650 12,657,274 San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...Arlington, TX...
MARGINAL 86,418 9,308,202 Oklahoma City, OK...Tulsa, OK...Brownsville, TX...Norman, OK...Wichita Falls, TX...
Probabilistic Tornado Graphic
20170220 0100 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
2 % 74,974 11,371,784 San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...Arlington, TX...
Probabilistic Damaging Wind Graphic
20170220 0100 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 % 84,944 12,648,227 San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...Arlington, TX...
5 % 86,109 9,478,797 Oklahoma City, OK...Tulsa, OK...Brownsville, TX...Norman, OK...Wichita Falls, TX...
Probabilistic Large Hail Graphic
20170220 0100 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
15 % 72,014 11,640,160 San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...Arlington, TX...
5 % 45,667 3,209,418 Corpus Christi, TX...Brownsville, TX...Wichita Falls, TX...College Station, TX...Bryan, TX...
   SPC AC 200045

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0645 PM CST Sun Feb 19 2017

   Valid 200100Z - 201200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS
   PARTS OF CENTRAL TEXAS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS
   SURROUNDING AREAS OF THE SOUTHERN PLAINS...

   ...SUMMARY...
   Strong thunderstorm activity remains possible into and through the
   overnight hours across parts of the southern Plains, accompanied by
   a risk for severe hail and potentially damaging wind gusts.

   ...Plains...
   Aided by forcing for ascent ahead of increasingly sheared mid/upper
   troughing now progressing across the southern Rockies, there has
   been some recent thunderstorm development from portions of the Texas
   Panhandle into parts of southwestern Nebraska.  This is likely
   occurring in response to weak boundary layer destabilization
   associated with modest moisture return to the vicinity of surface
   troughing across the High Plains.  And isolated to widely scattered
   thunderstorms may continue another couple of hours across this
   region, before boundary layer instability wanes and mid/upper
   forcing spreads eastward.

   Highest thunderstorm probabilities appear likely to remain focused
   within the narrow plume of higher moisture content air (precipitable
   water in excess of 1 inch) farther to the south and east (currently
   from just east of Del Rio, Tx  into western Oklahoma).  This also
   appears to be along the leading edge of stronger lower/mid
   tropospheric cooling (around 700 mb).  While cooling aloft is
   expected to advance eastward through much of the remainder of the
   central and southern Plains tonight, the leading edge of the better
   low-level moisture return is expected to advect north of the
   southern Plains Red River Valley toward the mid Missouri Valley.

   At the moment, severe hail is probably the primary severe threat in
   the stronger storms, aided by modestly steep mid-level lapse rates,
   generally cool thermodynamic profiles and strong deep layer shear
   beneath 50-70 kt southerly 500 mb flow.  Low-level flow and shear
   where the most vigorous storms are currently ongoing is fairly weak.

   With time, further consolidation of convection into an organizing
   squall line within the moisture/instability plume is possible
   tonight.  As this spreads eastward with the mid/upper forcing,
   increasing interaction with a strengthening southerly 850 mb jet
   (40-50+ kt) across parts of central/eastern Texas and Oklahoma is
   possible.  This could be accompanied by at least some increase in
   potential for strong surface gusts, particularly across and east of
   the I-35 corridor of Texas, where surface dew points are higher (mid
   60s+ f) and instability probably will be based within the boundary
   layer.  A residual slightly cooler/more stable boundary layer to the
   north of the Red River may inhibit surface gust potential.

   ...Intermountain West and adjacent Rockies...
   Isolated to widely scattered thunderstorm activity lingers beneath
   the cold trough aloft.  However, with the loss of daytime heating,
   thunderstorm probabilities are expected to become increasingly
   negligible through the 02-03Z time frame.

   ..Kerr.. 02/20/2017

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z