SPC AC 171252

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0752 AM CDT Wed Apr 17 2024

   Valid 171300Z - 181200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   SOUTHERN LOWER MICHIGAN INTO THE OHIO VALLEY...

   ...SUMMARY...
   Scattered thunderstorms capable of producing damaging winds, large
   hail, and a few tornadoes should develop across parts of the Ohio
   Valley and Lower Great Lakes this afternoon. Thunderstorms with
   mainly a large hail threat may occur tonight over parts of the
   central Plains.

   ...Synopsis...
   An upper trough/low over the Upper Midwest this morning will
   continue to move east-northeastward across the Great Lakes and OH
   Valley today while gradually de-amplifying/weakening. An associated
   40-60 kt mid-level jet will accompany this trough and overspread
   much of the OH/TN Valleys. At the surface, a low over southeastern
   MN/western WI should continue to gradually occlude through the day
   in tandem with the weakening upper cyclone. An attendant cold front
   will sweep eastward over the Lower Great Lakes/OH Valley through
   this evening, while a warm front advances as far north as parts of
   Lower MI and perhaps far western NY.

   ...Lower Michigan into the Ohio/Tennessee Valleys and
   Mid-Atlantic...
   Upper 50s to low 60s surface dewpoints are expected to be in place
   ahead of the cold front late this morning/early afternoon. A
   pronounced mid-level dry slot evident on water vapor satellite
   imagery should aid in diurnal destabilization via a general lack of
   mid/upper-level cloud cover across parts of the OH Valley. As the
   boundary layer gradually warms/moistens, around 1000-1500 J/kg of
   MLCAPE should develop across southern Lower MI, eastern IN, and OH.
   Sufficiently strong low/mid-level winds will support 40-50 kt of
   deep-layer shear and updraft organization. Current expectations are
   for convection to develop along or just ahead of the cold front by
   early afternoon, and subsequently spread quickly east-northeastward
   across Lower MI, OH, and western PA through this evening. Tendency
   may be for thunderstorms to quickly organize into a line, especially
   across Lower MI which will be in closer proximity to the large-scale
   ascent attendant to the upper trough/low. If this evolution occurs,
   then severe/damaging winds would be the main threat with this
   activity. Have expanded the Marginal and Slight Risks northward
   across Lower MI to account for this potential.

   Farther south across eastern IN and OH, forcing will gradually
   become more limited, which may allow for somewhat lower thunderstorm
   coverage initially. Even so, deep-layer shear will be strong enough
   to support supercells, with large hail, damaging wind, and a few
   tornadoes all possible. The best tornado potential may be focused
   across parts of southeastern Lower MI and northern OH, in closer
   proximity to the warm front and greater low-level shear. Some
   upscale growth may also occur with this activity as it moves into
   eastern OH and western PA, with a potentially greater threat for
   damaging winds through the early evening before convection
   eventually weakens.

   Overall convective coverage should be lower across the TN Valley
   into the Southeast, with weaker large-scale ascent present over
   these regions. Still, isolated strong thunderstorms may occur this
   afternoon and early evening in a weakly unstable but strong
   deep-layer shear environment. Occasional hail and gusty winds appear
   possible with the more robust cores. Based on latest guidance
   trends, have trimmed the western extent of the Marginal Risk over
   western KY/TN and northern MS.

   Across the eastern Mid-Atlantic (northern VA/MD/DC/DE/south-central
   PA), a well-mixed boundary layer and steep low-level lapse rates
   forecast by some guidance may support occasional strong to damaging
   winds with convection spreading eastward off the higher terrain of
   the Appalachians and Blue Ridge Mountains. With limited instability,
   the overall severe wind threat will likely remain isolated.

   ...Nebraska/Kansas into Iowa/Missouri...
   An upper-level trough will move eastward across the north-central
   CONUS tonight. A 40-45 kt southerly low-level jet will develop this
   evening across parts of the southern/central Plains in response.
   Thunderstorms should eventually initiate near the northern edge of
   the low-level jet late this evening from central KS into far
   southeast NE. Ample MUCAPE, steep mid-level lapse rates, and strong
   shear in the cloud-bearing layer should support some threat for
   large hail with this mainly elevated convection. The large hail
   threat should to be greatest in the 04Z to 08Z time window with
   initial development, but it may persist through the end of the
   period. If convection can grow upscale into a small bowing cluster,
   then isolated damaging winds may also occur.

   A conditional threat for a supercell or two will exist farther south
   across south-central/southeastern KS into far northeastern OK. Here,
   modest low-level convergence along the intersection of a developing
   warm front and dryline may be sufficient to initiate isolated
   convection early this evening as the low-level jet strengthens. If
   this occurs, then all severe hazards appear possible.

   ...Texas...
   Very isolated thunderstorms may develop late this afternoon and
   early evening across parts of south-central into central TX along a
   surface dryline. If any convection can be sustained, it could
   produce severe winds and hail. But, this threat currently appears
   too conditional and uncertain to add low severe probabilities.

   ..Gleason/Bentley.. 04/17/2024

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z