SPC AC 130600

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Thu Mar 13 2025

   Valid 141200Z - 151200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
   MISSOURI...FAR SOUTHEAST IOWA...CENTRAL AND SOUTHERN ILLINOIS...FAR
   WESTERN KENTUCKY...FAR NORTHWEST TENNESSEE...AND EXTREME NORTHEAST
   ARKANSAS...

   ...SUMMARY...
   A regional outbreak of severe storms is expected across much of the
   Mississippi Valley, eastward to the Lower Ohio and Tennessee Valleys
   late Friday afternoon into Saturday morning. Widespread damaging
   winds (some greater than 65 kt), several tornadoes (some strong),
   and large hail will all be possible.

   ...Synopsis...

   An intense cyclone will develop from the central Plains to the Upper
   Midwest on Friday. As this system rapidly deepens, an intense jet
   streak (100+ kt at 500 mb) will overspread the Ozarks and Mid-MS
   Valley. Meanwhile, a large area covering much of the MS Valley
   vicinity will see 850-700 mb southwesterly flow around 65-80 kt.
   Southerly low-level flow will transport mid 50s dewpoints as far
   north as IA/northern IL (decreasing with northward extent across the
   Upper Midwest). Richer boundary layer moisture (60s F dewpoints)
   will be confined to the Lower MS Valley and Deep South/TN Valley,
   though near-60 F dewpoints may reach the MS/OH River confluence.
   Rapidly developing convection is expected to develop by late
   afternoon from near a surface low over eastern NE and arcing
   east/southeast along a dryline into the Ozarks. Convection will
   develop northeast across the Mid-MS valley, with additional storms
   develop with southward extent into the Mid-South and TN Valley
   during the nighttime hours.

   ...Mid/Upper Mississippi Valley to the Lower OH/TN Valleys...

   Cold temperatures aloft near the main upper low will support steep
   midlevel lapse rates. While boundary moisture will be modest, MLCAPE
   up to 1000-1500 J/kg is possible. This will support rapid storm
   development amid intense deep-layer shear. Heating ahead of the
   dryline also will support some boundary layer mixing and steepening
   of low-level lapse rates. As a result, a rapidly developing QLCS is
   expected. Convection will shift east/northeast into the nighttime
   hours. Given fast storm motion and the intensity of deep-layer flow,
   swaths of significant wind gusts (greater than 65 kt) are
   anticipated over a large part of the Mid-MS Valley. A gradual
   weakening of convection is expected after midnight with north and
   east extent.

   With southward extent from parts of eastern MO/western IL into the
   Mid-South, some potential for a mix of linear convection and
   supercells appears possible. Vertical shear will support tornadoes
   within linear convection. The environment will especially be
   favorable for strong tornadoes with any supercells that develop.
   This activity may develop a little later than initial convection
   further north, with much of the threat being after dark from
   east-central MO/west-central IL southward to western TN. 

   Given the intensity of maximum gusts expected, and widespread
   coverage of damaging gusts, a Moderate risk (level 4 of 5) has been
   included for portions of the Mid-MS Valley vicinity. 

   ...MS/AL/TN Overnight...

   Persistent southerly low-level flow will bring mid to possibly upper
   60s F dewpoints northward into the TN Valley overnight. Neutral to
   modest height falls are expected and a persistent, strong low-level
   jet will overspread the region. Forecast soundings indicate very
   favorable thermodynamic and kinematic profiles, which would support
   intense supercells. Forcing mechanisms will be somewhat modest over
   the region, which may limit convective coverage, and a somewhat more
   conditional risk. However, any storms that develop within this
   environment overnight will pose a risk for strong tornadoes, large
   hail and damaging gusts.

   ...Upper Midwest/Great Lakes vicinity...

   The severe risk will become more marginal into MN/WI/MI. Strong deep
   layer flow will overspread the region and any convection will pose a
   risk of strong gusts. An additional risk for hail also will exist,
   especially with any elevated convection near the warm front
   overnight.

   ..Leitman.. 03/13/2025

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z