Current SPC Activity Chart

See Current Severe US Wx Maps

SPC Activity Chart
Hazard Wed (03/22) Thu (03/23) Fri (03/24) Sat (03/25) Sun (03/26) Mon (03/27) Tue (03/28) Wed (03/29)
Severe Marginal Slight Severe No Area No Area No Area No Area No Area
Fire Elevated No Area No Area No Area No Area No Area No Area No Area

Forecast Discussion - Convective Outlook

   SPC AC 220559

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Wed Mar 22 2023

   Valid 221200Z - 231200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
   NORTHEASTERN KANSAS EASTWARD TO NORTHERN INDIANA...

   ...SUMMARY...
   Isolated/elevated strong to severe thunderstorms -- capable of large
   hail -- are possible from far northeast Kansas eastward to northern
   Indiana late tonight.

   ...Synopsis...
   An upper trough across the western U.S. will move gradually eastward
   with time, with the broader cyclonic flow field to encompass roughly
   the western half of the country through the period.  As this trough
   advances, downstream ridging centered over the Gulf of Mexico will
   amplify a bit, with a trend toward a bit of anticyclonic curvature
   within the westerlies across the central and eastern U.S. with time.

   At the surface, a low initially over the northern Minnesota vicinity
   is forecast to shift quickly northeastward into -- and then across
   -- Ontario through the period.  Meanwhile, the trailing cold front
   will become an increasingly west-to-east quasi-stationary front from
   the central Plains into the Midwest.  This boundary -- or more
   specifically, a zone of warm advection focused to the cool side of
   the front -- will focus a zone of elevated convection through the
   period. 

   ...Northeastern Kansas to northern Indiana...
   Elevated showers and isolated/embedded thunderstorms are forecast to
   be ongoing at the start of the forecast period across the northern
   Missouri vicinity -- i.e. portions of the MRGL risk area.  This
   convection is forecast to shift eastward across the Midwest region
   through the day.

   Meanwhile, as a southwesterly low-level jet redevelops later this
   evening, a gradual increase in new, elevated convection is expected,
   in tandem with the increase in low-level warm advection atop a
   surface-based stable layer.

   With continued low-level theta-e advection within the 900 to 700 mb
   layer, and some steepening of lapse rates aloft, the elevated
   destabilization will likely be sufficient to support locally
   strong/vigorous updrafts.  This, combined with favorably strong
   speed shear through the cloud-bearing layer, will likely support
   locally severe storms, capable of producing large hail.  With time,
   an expanding convective cluster is forecast to spread eastward,
   crossing central Illinois and eventually northern Indiana through
   the end of the period.

   ..Goss/Lyons.. 03/22/2023

    

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z

        
   SPC AC 220559

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Wed Mar 22 2023

   Valid 231200Z - 241200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM
   CENTRAL/EASTERN OKLAHOMA INTO THE TEXAS HILL COUNTRY...

   ...SUMMARY...
   Thunderstorms capable of hail, some very large, and damaging gusts
   are possible Thursday afternoon through Friday morning across the
   southern Plains.

   ...Synopsis...
   Presence of western CONUS troughing and subtropical ridging over the
   Gulf of Mexico will contribute to a belt of enhanced southwesterly
   flow extending from northern Mexico northeastward across the central
   Plains and Mid MS Valley early Thursday. A pair of shortwave troughs
   will be embedded within this belt of stronger flow, one initially
   near the Mid MO Valley and the other across southern AZ/northern
   Mexico. Both shortwaves are expected to progress northeastward, with
   the second shortwave moving through the southern High Plains during
   the afternoon/evening, reaching KS/OK by early Friday morning. 

   The surface pattern Thursday morning will likely feature a low near
   the northern IL/IN border vicinity, with a cold front extending
   southwestward to another low over northwest TX. This front is
   expected to move eastward/southeastward across the OH Valley, while
   the southern portion moves more southeastward/southward across the
   Ozark Plateau and much of OK. Guidance varies on the position of the
   front over OK. Secondary surface cyclogenesis is anticipated over
   the TX Low Rolling Plains Thursday afternoon, with the resulting low
   then moving eastward into north TX. 

   ...OH Valley Thursday morning...
   Elevated thunderstorms will likely be ongoing near the surface low
   across northern IL/northern IN early Thursday morning. Strong
   vertical shear and steep mid-level lapse rates will be in place,
   supporting the potential for a few strong updrafts capable of hail.
   These early morning storms are expected to continue eastward, likely
   outrunning most of the buoyancy as they move into OH during the late
   morning.

   ...Southern Plains Thursday afternoon through Friday morning...
   Low 60s dewpoints are expected be in place along the front
   early Thursday morning, likely increasing into the mid 60s by the
   late afternoon. Recent guidance has trended slower with the front,
   keeping more of central and eastern OK ahead of the front during the
   afternoon. Increasing low-level moisture coupled with modest daytime
   heating should destabilize the airmass south of the
   front by the late afternoon. This instability coupled with
   convergence along the front is expected to result in thunderstorm
   development, likely beginning over central OK. Vertical shear will
   be strong, and the initial more cellular development may produce
   large hail. Front-parallel deep shear should result in any
   near-front development tracking northward over the front quickly,
   likely limiting the surface-based warm sector development. Even so,
   a brief temporal window for may exist for damaging gusts and/or a
   tornado.

   Thunderstorm development is also anticipated farther south, ahead of
   the deepening surface low expected to move into northwest TX during
   the early evening. A more cross-boundary vertical shear
   vector is anticipated here, which could support a greater potential
   for storms to stay surface-based. However, the presence of low-level
   stability suggest an elevated storm mode, with the cold front acting
   as the initiation mechanism. Like the storms farther north, hail is
   the main severe threat, with some very large hail possible. As the
   low and associated front continue eastward, storm coverage should
   increase southward across the TX Hill Country/Edwards Plateau. Hail
   and damaging gusts are possible with this line of storms as it moves
   eastward toward central TX early Friday morning.

   ..Mosier.. 03/22/2023

   WUUS02 PTSDY2 

   

        
   SPC AC 210724

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0224 AM CDT Tue Mar 21 2023

   Valid 231200Z - 241200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM TEXAS HILL
   COUNTRY ACROSS NORTHWEST/NORTH-CENTRAL TEXAS INTO SOUTHEAST
   OKLAHOMA...

   ...SUMMARY...
   Thunderstorms capable of hail, some very large, and damaging gusts
   are possible Thursday afternoon through Friday morning across the
   southern Plains.

   ...Synopsis...
   The upper pattern early Thursday is forecast to consist of a western
   CONUS trough and subtropical ridging centered over the Gulf of
   Mexico. Enhanced mid-level westerly/southwesterly flow will persist
   between these two features, extending from northern Mexico into the
   Great Lakes region. A pair of shortwave troughs will be embedded
   within the belt of stronger flow, one initially near the Mid MO
   Valley and the other across southern AZ/northern Mexico. Both
   shortwaves are expected to progress northeastward, with the second
   shortwave moving through the southern High Plains during the
   afternoon/evening, reaching KS/OK by early Friday morning. 

   The surface pattern Thursday morning will likely feature a low over
   southern MI, with a cold front extending southwestward to another
   low over northwest TX. The northern portion of the cold front will
   remain progressive, moving eastward across the OH Valley. The
   southern portion of the front (from northwest TX across OK) will
   only make modest eastward/southeastward progress throughout the day,
   as another low develops over west TX. This second low is then
   expected to push northeastward along the front from Thursday evening
   into Friday, moving from the Permian Basin into southeast OK. At it
   does, an associated dryline will move eastward across southwest and
   central TX.

   ...Southern Plains...
   Low to mid 60s dewpoints are expected be in place along the front
   early Thursday morning, likely increasing into the mid/upper 60s by
   the late afternoon. This increasing low-level moisture coupled with
   modest daytime heating should destabilize the airmass south of the
   front by the late afternoon. Consequently, convergence along the
   front is expected to result in thunderstorm development, likely
   beginning over OK. Vertical shear will be strong, and the initial
   more cellular development may produce hail. However, the slow-moving
   front combined with the front-parallel orientation of the deep-layer
   vertical shear suggests numerous storms and messy storm mode. This
   could limit the overall severe potential across much of OK. 

   Farther south, thunderstorm development is anticipated ahead of the
   deepening surface low expected to move into northwest TX during the
   late afternoon/early evening. A more cross-boundary vertical shear
   vector is anticipated here, supporting a greater potential for
   supercells for at least a few hours. Very large hail is possible
   with these storms as well as damaging gusts. As the low and
   associated front continue eastward, storm coverage should increase
   southward across the TX Hill Country/Edwards Plateau. Hail and
   damaging gusts are possible with this line of storms as it moves
   eastward toward the I-35 corridor early Friday morning.

   ..Mosier.. 03/21/2023

   WUUS03 PTSDY3 

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z