SPC AC 030545

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1245 AM CDT Sun May 03 2020

   Valid 031200Z - 041200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE HIGH PLAINS AND FROM THE OZARKS TO THE SOUTHERN DELMARVA...

   ...SUMMARY...
   A few severe thunderstorms are possible later today from the Ozarks
   eastward across Kentucky, Tennessee and toward the southern
   Delmarva. Additional isolated severe storms are possible across the
   northern and central High Plains, and over a small portion of
   west-central Texas.

   ...Northern/Central High Plains...

   Early-morning water-vapor imagery depicts a well-defined short-wave
   trough over WA/OR. This feature is forecast to eject across the
   northern Rockies later today suppressing heights to near I-70 by the
   end of the period. Latest model guidance suggests a notable lee
   trough will evolve across eastern MT - northeast WY - northeast CO.
   Along and east of this boundary, surface dew points are expected to
   hold in the low-mid 40s through peak heating. As surface
   temperatures warm to near 70F, low-level lapse rates will steepen
   such that convective temperatures will be breached within a
   favorably buoyant regime for robust updrafts. Forecast soundings
   suggest adequate deep-layer shear for organized rotating storms and
   a few supercells may ultimately evolve ahead of the approaching
   trough. Hail/wind are the primary threats due to marginal low-level
   moisture.

   ...West-Central TX...

   Surface front is expected to continue surging south across the High
   Plains to a position from central OK - northwest TX by 18z. The
   boundary should stall across the TX South Plains and serve as the
   focus for thunderstorm development as temperatures soar through the
   90s to near 100F south of the front. Convective temperatures should
   be realized around 21z and weak vertical shear should result in
   high-based multi-cell updrafts. Hail and wind can be expected with
   this strongly diurnal activity.

   ...Ozarks to the Southern Delmarva...

   Surface front will settle south across the TN Valley during the
   early afternoon while a frontal passage should occur later in the
   evening over the southern Middle Atlantic. Southern influence of
   Great Lakes short-wave trough will aid convective development along
   the wind shift as high-level diffluent flow overspreads this region.
   While deep-layer flow will be sufficiently strong for sustaining
   organized severe updrafts, forecast soundings across the TN Valley
   exhibit substantial warm nose near 700mb and profile adjustments
   ahead of the trough maintain relatively poor surface-3km lapse rates
   through the period. Given the less-than-ideal lower-thermodynamic
   profiles, will maintain 5% hail/wind probs to account for scattered
   multi-cell frontal clusters.

   ..Darrow/Squitieri.. 05/03/2020

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