SPC AC 190600

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Mon Jun 19 2023

   Valid 191200Z - 201200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE
   GULF COAST/SOUTHEAST STATES...

   ...SUMMARY...
   Severe thunderstorms capable of producing damaging winds are
   possible across parts of the middle Gulf Coast states and Southeast
   today. Additional isolated strong to severe thunderstorms are also
   possible into parts of the Carolinas, central/north Texas, and the
   northern Plains.

   ...Middle Gulf Coast/Southeast States...
   Clusters of strong/potentially severe storms are likely to be
   ongoing this morning from southern Mississippi into southern
   Alabama/southern Georgia and north Florida. A diurnal
   reintensification of these storms should occur today on the southern
   fringes of the lingering early day storms/cloud cover.
   Severe/damaging gusts will be the main hazard associated with this
   activity given its mainly linear/cluster nature as low-level lapse
   rates steepen.

   Other storms should develop later in the afternoon along the
   westward-extending portion of the front near the middle Gulf Coast,
   with these storms capable of large hail and damaging winds. This is
   attributable to ample instability coincident with a belt of
   moderately strong northwesterly winds aloft.

   As waves of large-scale ascent pivot around the upper low,
   additional bands of thunderstorms are expected further north and
   east across eastern Tennessee into the Carolinas. Instability will
   be weaker with northward extent. However, steepening low-level lapse
   rates and a high PW environment may support sporadic strong/damaging
   wind gusts. Additional clusters of strong storms may develop along
   sea-breeze boundaries across the Florida Peninsula. Water-loaded
   downdrafts may pose a risk for strong gusts here as well, along with
   occasional hail.

   ...Central/North Texas...
   Steady height rises are expected as the upper ridge builds over the
   Plains through tonight, with a related warming of mid-level
   temperatures and uncertainty regarding the likelihood/extent of
   late-day deep convective potential. Regardless, a thermally aided
   surface low should deepen across the Low Rolling Plains, with robust
   post-dryline mixing (surface temperatures 100+ F) and at least
   modest near-dryline/triple point convergence suggesting some
   potential for isolated semi-sustained convection late this
   afternoon.

   Any convection that develops and can sustain will have the potential
   to become a supercell in the presence of seasonally strong (40-55
   kt) mid/upper-level northwest flow. Given the presence of steep
   mid-level lapse rates and moderate to strong instability, isolated
   large hail may occur with any supercell. Severe-caliber wind gusts
   are also plausible, as the boundary layer should be very well mixed,
   with steepened low-level lapse rates due to the robust diurnal
   heating. Any severe risk should diminish by around, or shortly
   after, sunset as the boundary layer slowly cools.

   ...ArkLaTex/Louisiana...
   On the edge of strong capping aloft, storms are expected to develop
   tonight near the front across the region, with some potential that
   these storms will be strong to severe. Very steep mid-level lapse
   rates and ample elevated buoyancy in the presence of strong shear
   through the cloud-bearing layer could support some storms capable of
   large hail.

   ...Eastern Montana and western/northern North Dakota...
   The region will be influenced by the eastern periphery of a
   prominent upper trough centered over the Pacific Northwest and its
   preceding polar jet. This jet will interface with modest low-level
   moisture on the cool side of a roughly southwest/northeast-oriented
   front across the region, where forcing for ascent will be maximized.
   Widely scattered storms are expected to initially develop this
   afternoon across southeast Montana and northeast Wyoming near the
   Bighorn Mountains. This convection should persist/expand
   northeastward across eastern Montana and parts of western/north
   North Dakota through evening. Even while overall buoyancy will be
   modest, deep-layer shear should be strong enough to support some
   supercells and sustained multicells with an attendant threat for
   large hail and severe-caliber wind gusts.

   ..Guyer/Flournoy.. 06/19/2023

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