SPC AC 051709

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1209 PM CDT Fri Jul 05 2024

   Valid 061200Z - 071200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   THE CENTRAL PLAINS...

   ...SUMMARY...
   Severe thunderstorms are possible from southern South Dakota into
   the southern High Plains on Saturday, with the highest coverage
   expected in parts of Nebraska and Kansas. Large hail (some greater
   than 2 inches) and severe winds are the expected hazards.

   ...Central Plains into eastern NM...

   Modest height falls are forecast across the region as a broad upper
   trough persists across much of the central U.S. Several shortwave
   impulses are forecast to rotate through northwesterly flow aloft and
   will support areas of convection through the period. At the surface,
   a weak surface low may develop over western NE/KS, while generally
   surface troughing extending into southeast CO/northeast NM.
   Boundary-layer moisture will be modest across much of the region
   given prior cold frontal passages in the past few days. However,
   south/southeasterly low-level flow will allow for upper 50s to low
   60s F dewpoints expanding northward across the southern High Plains
   into portions of KS/NE. Cool temperatures aloft and a plume of steep
   midlevel lapse rates spreading into KS/NE will support a corridor of
   moderate instability from the Raton Mesa vicinity north/northeast
   into western KS/central NE by mid-afternoon. 

   Some forecast guidance suggests convection may be ongoing across
   parts of SD/NE. This introduces uncertainty in convective
   evolution/timing, as this activity may slowly increase in intensity
   through the day. Or, convection may dissipate and leave an outflow
   boundary across central NE. Confidence is higher that convection
   will develop further south into western KS and the southern High
   Plains in the vicinity of the surface through during the afternoon.
   Vertical shear will support initial high-based supercells. Steep
   low-level lapse rates and high temperature-dewpoint spreads amid
   mostly weak low-level flow will support strong/severe outflow winds.
   This may allow for storm consolidation into an east/southeast
   propagating MCS during the evening. If this occurs, damaging wind
   potential will increase. In the absence of a strong low-level jet
   during the evening, eastward extent of the severe risk should
   diminish into central KS with time. Initial supercell storms also
   will pose a risk for large hail, with some hail up to baseball size
   possible. 

   With southward extent, vertical shear and large-scale ascent will
   weaken, and organized thunderstorm coverage should be somewhat lower
   into eastern NM and the TX Panhandle.

   ...Northeast and Mid-Atlantic...

   Showers may be ongoing Saturday morning across parts of NY and New
   England in a warm advection regime ahead of a cold front. This may
   limit heating and low-level destabilization into the afternoon. As a
   result, severe potential may be limited despite 35+ kt effective
   shear magnitudes and a very moist low-level airmass. A few strong
   gusts are possible, but confidence is too low to add unconditional
   severe probabilities at this time. 

   Thunderstorms are expected with southward extent into eastern VA and
   the Carolinas ahead of the surface cold front. While stronger
   destabilization is expected with southward extent, vertical shear
   will be very weak. However, steep low-level lapse rates and high PW
   values may support a couple of strong wet microbursts in otherwise
   disorganized storm clusters.

   ..Leitman.. 07/05/2024

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