SPC AC 070608

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0108 AM CDT Tue May 07 2019

   Valid 071200Z - 081200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE TEXAS PANHANDLE AND WESTERN OKLAHOMA...

   ...SUMMARY...
   Numerous severe thunderstorms are expected across much of the
   southern High Plains from afternoon through Wednesday morning.
   Damaging hail and wind, as well as tornadoes, are expected.
   Significant severe is expected, especially from the Texas Panhandle
   into northwest Texas and western Oklahoma late afternoon through
   tonight.

   ...Synopsis...
   An upper low will move eastward across AZ and NM, with a broad zone
   of 30-50 kt midlevel southwesterlies spreading into the southern
   Plains during the latter half of the period. At the surface, low
   pressure is forecast to develop over eastern NM into the TX
   Panhandle, with a dryline just east of the NM border by 00Z. To the
   north, a stationary front will be near I-70 from MO into eastern KS
   during the day, extending southwestward into southeast CO and the
   western OK/TX Panhandles where a modifying outflow boundary will
   exist.  A moist air mass will remain south and east of these
   boundaries, which will lead to moderate to strong instability over a
   large area. As large-scale ascent increases with the upper trough,
   southerly 850 mb winds of 35-50 kt will enhance shear profiles, with
   numerous severe storms expected from late afternoon through the
   night. Damaging hail, wind, and tornadoes are all possible.

   ...Southern Plains...
   Scattered thunderstorms may be ongoing across parts of KS into MO
   early in the day, related to warm advection atop numerous outflow
   boundaries. By early afternoon, storms are expected to form over
   southeast CO into northeast NM, beneath cooling temperatures aloft
   and where moisture will back westward, possibly near the old outflow
   boundary. Hail and perhaps a brief tornado will be possible with
   this activity.

   Farther east, more substantial moisture and instability will develop
   from the dryline/front intersection southward across far western TX.
   Storms may form somewhat early in the afternoon over southwest KS
   and the OK and northern TX Panhandles, as warm air lifts atop the
   boundary or modifying outflow. Large hail will be possible with
   these storms. With time, storms will develop southward along the
   dryline where heating will be strongest. While low-level shear will
   not be strong initially, deep-layer shear combined with steep lapse
   rates aloft will support supercells capable of large hail. As the
   low-level jet increases during the late afternoon and evening, the
   threat of tornadoes should increase, especially across the Moderate
   Risk area where SRH will increase to 200-300 m2/s2. In addition,
   very large hail is likely. The damaging wind threat will increase
   into the evening and overnight as cells possibly bow/merge and
   expand southward across the remainder of west TX. Wind-driven hail
   will be possible, with perhaps areas of significant wind damage.

   While not in the Moderate Risk area, sporadic significant hail or
   wind is possible across much of northwest into southwest TX as well
   as the cold front pushes east overnight.

   ..Jewell/Bentley.. 05/07/2019

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