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SPC Activity Chart
Hazard Sat (06/10) Sun (06/11) Mon (06/12) Tue (06/13) Wed (06/14) Thu (06/15) Fri (06/16) Sat (06/17)
Severe Enhanced Slight Marginal Severe No Area No Area No Area No Area
Fire Elevated Critical Critical No Area No Area No Area No Area No Area

Forecast Discussion - Convective Outlook

   SPC AC 101631

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1131 AM CDT Sat Jun 10 2023

   Valid 101630Z - 111200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS
   AFTERNOON/EVENING FROM THE ARKLATEX INTO CENTRAL TX...

   ...SUMMARY...
   Very large hail of 2-3 inches in diameter, damaging thunderstorm
   gusts of 60-75 mph, and a couple of tornadoes will be possible this
   afternoon through late evening from the ArkLaTex into central Texas.

   ...Southern Plains to the lower MS Valley through late evening...
   A cluster of thunderstorms is moving southeastward across the
   ArkLaTex as of late morning, with an MCV over eastern OK (trailing
   the initial convection/outflow).  Surface temperatures are warming
   into the 80s with boundary-layer dewpoints in the low 70s from
   northeast TX into northern LA/southern AR, which is boosting MLCAPE
   to the 2000-3000 J/kg range.  Vertical shear remains relatively weak
   near and ahead of the primary convective band along the outflow, and
   the strongest updrafts should remain along the southern flank of the
   cluster.  Thus, the expectation is for occasional damaging gusts
   with precipitation-loaded downdrafts, with a somewhat
   outflow-dominant structure to the cluster as is moves southeastward
   through the afternoon.  Other, more isolated storm clusters with
   isolated downburst potential, may occur this afternoon along the
   instability gradient into MS.

   Farther west, outflow with the morning cluster is moving southward
   into north TX.  Strong surface heating and a feed of steep midlevel
   lapse rates from the west will contribute to strong buoyancy (MLCAPE
   > 3000 J/kg) this afternoon, along and south of the outflow
   boundary.  Additional thunderstorm development appears probable by
   mid-late afternoon along the slowing outflow, and storms will
   subsequently spread southeastward toward southeast TX before
   weakening early tonight.  Vertical shear will become sufficient for
   supercells along the outflow boundary as a weak midlevel
   trough/speed max moves eastward over TX within the southern stream. 
   The steep lapse rates/large buoyancy, in combination with mainly
   straight hodographs and effective bulk shear of 35-40 kt, will
   support supercell clusters capable of producing isolated very large
   hail of 2-3 inches in diameter.  Some upscale growth will be
   possible this evening, with a corresponding increase in the threat
   for damaging outflow gusts.  Any tornado threat will rely on
   favorable storm interactions with locally backed flow/stronger
   low-level shear along the modifying outflow boundary late this
   afternoon. 

   ...Central Plains this afternoon into tonight...
   Scattered thunderstorms are expected this afternoon across the
   central Plains in associated with remnant MCVs and differential
   heating zones.  Buoyancy and vertical shear will not be strong, but
   isolated/marginal hail/wind events will be possible.  Other clusters
   of storms may form across the High Plains and move
   east-southeastward this evening into tonight.  These storms may
   produce isolated strong-severe outflow gusts from eastern CO into
   KS.

   ..Thompson/Jirak.. 06/10/2023

    

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z

        
   SPC AC 100458

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1158 PM CDT Fri Jun 09 2023

   Valid 111200Z - 121200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SUNDAY AFTERNOON
   AND EVENING PARTS OF SOUTHERN MISSOURI AND ILLINOIS...WESTERN
   KENTUCKY...WESTERN AND MIDDLE TENNESSEE...NORTHERN MISSISSIPPI AND
   ALABAMA...AND MUCH OF ARKANSAS...

   ...SUMMARY...
   An organized cluster of thunderstorms may evolve across parts of the
   Ozark Plateau and lower Ohio Valley into Mid South vicinity Sunday
   afternoon and evening.  Initial storms may pose a risk for severe
   hail, before damaging wind gusts become the more prominent potential
   severe hazard.

   ...Synopsis...
   Mean westerly flow across much of southern Canada and the U.S.
   appears likely to remain weak through this period, with a series of
   embedded, slow moving lower/mid-tropospheric cyclones in various
   states of evolution.  At mid-levels, the most prominent circulation 
   associated with a deep occluding surface cyclone may remain
   quasi-stationary over the northwestern Atlantic, to the east the
   Canadian Maritimes.  In the wake of a trailing cold front, much of
   the Mid Atlantic and Northeast will be slow to destabilize.

   Upstream, the center of another significant mid-level low (evolving
   to the east-southeast of a lingering mid-level high centered over
   southern Saskatchewan) is forecast to slowly redevelop
   south-southwestward across the upper Great Lakes region, in response
   to short waves pivoting around its periphery.  It appears that one
   convectively generated or enhanced perturbation may dig across the
   lower Missouri into Tennessee Valleys Sunday through Sunday night,
   along the southern periphery of the broader cyclonic flow.  This may
   at least temporarily suppress the northeastward progression of
   building mid-level ridging across the southern Great Plains, in
   advance of a weakening mid-level low slowly redeveloping inland of
   the southern California coast into the southern Great Basin by early
   Monday.  It does appear that the latter development will be
   accompanied by a belt of strengthening southwesterly mid/upper flow
   across northern Baja into the southern Rockies.

   ...Southern Great Plains into Ohio Valley...
   Models continue to indicate that the Great Lakes low will be
   accompanied by modest surface cyclogenesis across the Ohio Valley
   into lower Great Lakes region during this period, with a reinforcing
   intrusion of seasonably mild/dry air forecast to reach the upper
   Ohio Valley into Mid South and southern Great Plains Red River
   Valley by 12Z Monday.  This likely will be preceded by an influx of
   seasonably moist boundary-layer air from the southern Great Plains
   into lower Ohio Valley, which may contribute to sizable mixed-layer
   CAPE ranging from 1500-3000+ J/kg.

   The environment with the larger CAPE in the presence of steeper
   lapse rates across the Red River Valley vicinity may remain capped
   beneath the mid-level ridging, and there are lingering uncertainties
   concerning possible impacts of outflow from prior convective
   development.  However, the latest NAM and Rapid Refresh suggest that
   a remnant MCV embedded within the cyclonic mid-level flow may
   provide a focus for intensifying thunderstorm development across
   parts of east central/southeastern Missouri into the lower Ohio
   Valley by late Sunday afternoon.  Additional storms may develop
   within an axis of stronger heating and destabilization trailing back
   across the Ozark Plateau, before gradually growing upscale and
   organizing in the presence of favorably sheared 30-50 kt
   westerly/northwesterly flow in the 850-500 mb layer.  A few embedded
   supercell structures appear possible, accompanied by a risk for
   severe hail and perhaps a tornado or two, before potentially
   damaging wind gusts become the more prominent hazard into mid to
   late evening, while convection propagates southeastward.

   ...Colorado Front Range into Sangre de Cristo Mountains...
   Beneath strengthening difluent southwesterly mid/upper flow, models
   suggest that moistening east to southeasterly low-level flow may
   contribute to sufficient instability and shear to support scattered
   strong thunderstorm development near the higher terrain late Sunday
   afternoon and evening.  This may include a few supercell structures
   posing at least some risk for severe hail and wind.

   ..Kerr.. 06/10/2023

   WUUS02 PTSDY2 

   

        
   SPC AC 100710

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0210 AM CDT Sat Jun 10 2023

   Valid 121200Z - 131200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS MONDAY AFTERNOON
   AND EVENING IN A CORRIDOR FROM THE MIDDLE AND SOUTHERN ATLANTIC
   SEABOARD THROUGH THE GULF COAST...PARTS OF THE SOUTHERN GREAT PLAINS
   INTO PORTIONS OF THE COLORADO FRONT RANGE...

   ...SUMMARY...
   Widely scattered strong thunderstorms may impact a corridor from the
   middle and southern Atlantic Seaboard through parts of the Gulf
   Coast and southern Great Plains, into the the Colorado Front Range,
   Monday afternoon and evening.  Some of these may pose a risk for
   severe wind and hail.

   ...Synopsis...
   Models indicate little change to the prevailing mid/upper flow
   Sunday into Monday.  A deep cyclone may shift a bit farther offshore
   of the Canadian Maritimes, with trailing mid-level ridging becoming
   a bit more prominent ahead of a significant upstream low, which is
   forecast to remain centered near/just west of the lower Great Lakes
   vicinity.  The southern Great Basin low appears likely to weaken
   further, with one emerging perturbation progressing across the
   Colorado Rockies.  

   In general, some further strengthening of mid/upper flow is forecast
   around the northern periphery of ridging across the Mexican Plateau
   through the southern Great Plains, and the southern periphery of the
   downstream cyclonic flow, across the lower Ohio Valley and Mid South
   into parts of the Southeast.  As an occluding surface cyclone
   associated with the Great Lakes low migrates north/northwest of the
   lower Great Lakes region, models indicate that a trailing cold front
   will advance east of the Appalachians and across much of the
   Atlantic Seaboard by late Monday night.  It appears that this will
   precede the more prominent perturbations pivoting around the
   mid-level low closer to its center.  Across the lower Mississippi
   Valley into the southern Great Plains, the front will stall beneath
   the mid-level ridging.

   Despite the mostly weak/uncertain forcing for ascent, moderate to
   large CAPE may develop in a corridor along and/or ahead of the
   front, as well as within a lingering narrow corridor to the east of
   the Colorado Front Range and Sangre de Cristo Mountains by late
   Monday afternoon.  This may provide support for widely scattered
   strong thunderstorm development.  In the presence of at least modest
   deep-layer shear, some of these could organize and pose at least
   some risk for severe wind and hail, before weakening as
   boundary-layer instability wanes Monday evening.

   ..Kerr.. 06/10/2023

   WUUS03 PTSDY3 

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