SPC AC 201958

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0258 PM CDT Fri May 20 2022

   Valid 202000Z - 211200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR A SMALL
   PART OF EASTERN PENNSYLVANIA INTO NEW JERSEY...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   LOWER MICHIGAN...AND OKLAHOMA INTO NORTH TEXAS...

   ...SUMMARY...
   Severe thunderstorms are expected to be most concentrated over
   portions of the northern Mid-Atlantic states, Lower Michigan, and a
   small part of the southern Plains this afternoon and evening.

   ...20Z Update...
   Have trimmed severe probabilities behind a small cluster of
   thunderstorms over eastern PA. Damaging winds should continue to be
   the main threat with this activity as it spreads into NJ over the
   next couple of hours, but a tornado or two also remain possible. See
   Mesoscale Discussion 842 and 843 for more information on the
   near-term severe threat across this area.

   An intense supercell producing a tornado is ongoing at 1958Z over
   northern Lower MI. The 19Z sounding from APX shows a favorable
   environment for continued thunderstorm organization, and it appears
   plausible that this supercell will persist across the rest of
   northern Lower MI over the next hour or so. A threat for tornadoes,
   large to very large hail, and damaging winds should persist with
   this supercell in the short term, and with any other intense
   thunderstorms that can develop. Still, weak large-scale ascent will
   probably tend to limit overall coverage through the rest of the
   afternoon, with the overall severe threat probably remaining fairly
   isolated. See Mesoscale Discussion 844 for additional details on the
   near-term severe threat across northern Lower MI.

   Elsewhere, little to no changes were made to the outlook.

   ..Gleason.. 05/20/2022

   .PREV DISCUSSION... /ISSUED 1126 AM CDT Fri May 20 2022/

   ...Mid Atlantic Region...
   A well-defined MCV is noted on satellite imagery over southwest PA. 
   This feature will track eastward today across PA, northern MD, and
   into NJ, fostering the development of severe thunderstorms. 
   Destabilization ahead of the MCV, combined with strong low and
   mid-level wind fields near the circulation will promote the
   development of supercell and bowing structures capable of damaging
   winds, large hail, and a few tornadoes.  Given the rapid eastward
   motion of the activity, it should move off the NJ coast well before
   dark, ending the severe threat.

   ...MI...
   A strong surface cold front currently extends from southern WI
   northward into upper MI.  This front will cross Lake Michigan this
   afternoon and move into lower MI by early evening.  Thunderstorms
   are expected to form in vicinity of the front and move across parts
   of the northern Lower MI.  Forecast soundings suggest favorable
   parameters for large hail in the stronger storms, along with the
   possibility of isolated tornadoes.

   ...OK/TX...
   A cold front is sagging southward across OK today, and should stall
   for awhile this evening before progressing into TX overnight.  A
   strengthening southerly low-level jet atop the boundary will lead to
   scattered thunderstorms in a very unstable air mass.  Storms may be
   supercellular with large hail and damaging winds.  A tornado or two
   cannot be ruled out before activity becomes more linear after dark.

   ...FL...
   A moist boundary layer is present today across the FL peninsula,
   along with pockets of strong heating.  Scattered thunderstorms have
   begun to form over south FL, and this activity is expected to build
   northward through the day.  Relatively cool temperatures and modest
   westerly flow aloft will promote a few organized multicell storm
   clusters capable of gusty/damaging winds or perhaps hail.

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