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SPC Activity Chart
Hazard Sun (05/26) Mon (05/27) Tue (05/28) Wed (05/29) Thu (05/30) Fri (05/31) Sat (06/01) Sun (06/02)
Severe Enhanced Slight Marginal No Area No Area No Area No Area No Area
Fire Elevated No Critical No Area No Area No Area No Area No Area No Area

Forecast Discussion - Convective Outlook

   SPC AC 260600

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Sun May 26 2024

   Valid 261200Z - 271200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR
   CENTRAL/EASTERN MISSOURI...CENTRAL/SOUTHERN
   ILLINOIS/INDIANA...SOUTHWEST OHIO...KENTUCKY...NORTHERN
   TENNESSEE...EXTREME NORTHEAST ARKANSAS...

   ...SUMMARY...
   Widespread strong to severe thunderstorms will be possible across
   parts of the lower Missouri Valley into the Ohio and Tennessee
   Valleys, later today into tonight. Multiple rounds of storms with
   the threat for large hail, damaging wind gusts, and a few tornadoes
   are possible from parts of east-central Missouri into
   central/southern Illinois and Indiana, much of Kentucky and adjacent
   portions of northern Tennessee.

   ...Synopsis...
   A complex but potentially significant severe weather episode is
   expected later today, with the greatest threat currently expected
   from parts of lower Missouri and mid Mississippi Valleys into the
   Ohio and Tennessee Valleys. All severe hazards will be possible,
   including some threat for widespread damaging winds, isolated to
   scattered very large hail, and potentially a few strong tornadoes. 

   A seasonably deep mid/upper-level trough (with multiple embedded
   shortwaves) will move from the central CONUS eastward into parts of
   the Midwest and OH/MS/TN Valleys through the day. A surface cyclone
   initially centered over eastern KS will move eastward across MO
   through the day, before turning northeastward toward the southern
   Great Lakes region later tonight. A trailing cold front will move
   southeastward across the Ozarks region and eventually into the Mid
   South. A warm front initially near the OH Valley region may move
   northward during the day, though its progress may be limited by the
   effects of potentially widespread convection across the region. 

   ...Parts of MO/AR eastward into the OH/TN Valleys...
   The presence of intense and widespread convection across eastern
   portions of the central/southern Plains late Saturday night results
   in considerable uncertainty regarding the evolution of severe
   potential during the D1/Sunday period. 

   A rather large storm cluster and possible MCS may be ongoing later
   this morning across parts of MO and northern AR, with some embedded
   supercell potential. Moderate to locally strong instability and
   favorable low-level and deep-layer shear will support some potential
   for all severe hazards with the early-morning convection. While
   there may be some weakening trend through the morning,
   reintensification of ongoing storms, and/or development along the
   attendant outflow, will be possible by late morning into the
   afternoon. There may be some tendency toward a clustered storm mode,
   but wind profiles will remain favorable for supercells, and an
   increasing threat for large to very large hail, damaging winds, and
   a few tornadoes may evolve during the afternoon across parts of OH
   Valley and potentially into portions of the Mid South/TN Valley
   region.  

   Farther west, a shortwave embedded within the large-scale trough is
   forecast to approach parts of the mid MS Valley late this afternoon
   into the evening, in conjunction with the primary surface low.
   Scattered thunderstorm development will be possible near the remnant
   outflow generated by morning convection, as well as along the
   trailing cold front. The environment across the effective warm
   sector (east of the cold front and along/south of the anticipated
   outflow boundary) will remain favorable for organized convection,
   and initial supercell development could be accompanied by a threat
   for large to very large hail and a few tornadoes. There will be some
   strong tornado potential, especially if notable outflow modification
   can occur through the day, though the most favored tornado corridor
   remains uncertain at this time. 

   Eventual development of a large QLCS will be possible tonight
   along/east of the surface-low track and trailing cold front, with a
   continued threat for damaging wind, hail, and possibly a few
   tornadoes into a larger portion of the OH/TN Valleys and Mid South. 

   ...Northern IL into southeast WI...
   A secondary area of modest pre-frontal destabilization may develop
   this afternoon from northern IL into southeast WI. Modest but
   sufficient deep-layer flow/shear will support some storm
   organization, and a few stronger storms capable of hail and locally
   strong wind gusts may develop from afternoon into the early evening.

   ...Eastern KS into western MO...
   Lingering moisture/instability and favorable deep-layer shear behind
   the cold front could support isolated strong storm development late
   this afternoon into the evening from eastern KS into western MO.
   Some threat for hail and locally strong/damaging gusts will be
   possible within this post-frontal regime. 

   ...Carolina Piedmont into the Mid Atlantic...
   There is some potential for early-day convection to persist and
   eventually spread across the southern Appalachians into parts of the
   Carolina Piedmont and vicinity by late afternoon or evening. While
   the environment will tend to be less favorable with southeastward
   extent, some threat for damaging wind and/or isolated hail could
   spread into the region later in the day.

   ..Dean/Moore.. 05/26/2024

    

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

        
   SPC AC 260620

   Day 2 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   0120 AM CDT Sun May 26 2024

   Valid 271200Z - 281200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MONDAY INTO MONDAY
   NIGHT ACROSS PARTS OF EASTERN WEST VIRGINIA...SOUTHERN
   PENNSYLVANIA...MUCH OF VIRGINIA AND MARYLAND...NORTHERN NORTH
   CAROLINA...DELAWARE AND SOUTHERN NEW JERSEY...AS WELL AS ACROSS MUCH
   OF WESTERN GEORGIA...ALABAMA...CENTRAL AND SOUTHERN MISSISSIPPI AND
   EASTERN LOUISIANA...

   CORRECTED FOR WIND PROBABILITY GRAPHIC

   ...SUMMARY...
   Severe thunderstorms are possible across parts of the Mid Atlantic 
   and the Gulf Coast states Monday into Monday night, with severe wind
   and hail the primary potential hazards.

   ...Synopsis...
   Mid/upper flow still appears likely to undergo amplification across
   the northern mid-latitudes of the Pacific and western North America
   into and through the Memorial Day Holiday.  This is forecast to
   include digging troughing offshore of the Pacific Northwest coast,
   to the south of a broad low developing across the northeastern
   Pacific, and building downstream ridging across the northern U.S.
   Rockies and Canadian Prairies.

   Farther downstream, several short wave perturbations are forecast to
   consolidate into more prominent larger-scale troughing across the
   mid/upper Mississippi Valley into the northern and middle Atlantic
   Seaboard.  One of the more prominent perturbations appears likely to
   turn northeast of the Lake Huron/Georgian Bay vicinity during the
   day, accompanied by a relative compact, but deep, surface cyclone. 
   In its wake, a remnant plume of elevated mixed-layer air likely will
   become increasing suppressed across the Southeast and lower
   Mississippi Valley, while a surface cold front advances into and
   across the Appalachians.

   Preceding the front, surface troughing is forecast to deepen to the
   east of the Blue Ridge during the day, beneath increasingly difluent
   and divergent upper flow, downstream of a short wave trough pivoting
   east-northeast of the lower Ohio Valley.

   ...Mid Atlantic..
   Latest model output appears a bit weaker than prior guidance with
   regard to the wave emerging from the lower Ohio Valley, and a little
   more unclear concerning more subtle, perhaps convectively generated,
   perturbations preceding this wave.  However, a seasonably moist
   boundary layer to the east of the deepening lee surface troughing is
   still forecast to become characterized by sizable CAPE as 40-50+ kt
   west-southwesterly mid-level flow noses northeast of the southern
   Appalachians.  This is expected to contribute to an environment
   potentially conducive to organized thunderstorm development,
   including supercell structures.  It still appears possible that
   consolidating pre-cold frontal convection across and east of the
   Allegheny Mountains could intensify and organize further to the east
   of the Blue Ridge by late afternoon, accompanied by potentially more
   widespread strong to severe wind gusts into Monday evening.

   ...Gulf States...
   Beneath a remnant plume of relatively steep lower/mid-tropospheric
   lapse rates, seasonably high boundary-layer moisture content is
   forecast to contribute to large CAPE on the order of 2000-4000+ J/kg
   by late Monday afternoon, along a corridor across the lower
   Mississippi Valley into the southern Appalachians.  Beneath modest,
   broadly cyclonic mid-level flow, the initiation of vigorous
   thunderstorm development appears probable by late Monday afternoon. 
   The latest NAM, in particular, is suggestive that upscale growth may
   contribute to a substantive surface cold pool and rear-inflow which
   may be accompanied by increasingly widespread strong to severe
   surface gusts across Alabama and adjacent portions of western
   Georgia, central and southern Mississippi.  It is possible severe
   probabilities may need to be increased further across this region in
   later outlooks, as model spread decreases.

   ..Kerr.. 05/26/2024

   WUUS02 PTSDY2 

   

        
   SPC AC 260730

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0230 AM CDT Sun May 26 2024

   Valid 281200Z - 291200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY
   AFTERNOON AND EVENING ACROSS PARTS OF THE TEXAS EDWARDS PLATEAU INTO
   EASTERN NEW MEXICO AND ACROSS PARTS OF NORTHEASTERN
   OREGON....CENTRAL AND NORTHERN IDAHO...AND WESTERN MONTANA...

   ...SUMMARY...
   Strong thunderstorms may impact parts of the Texas Edwards Plateau
   and Permian Basin into eastern New Mexico, as well as portions of
   the northern Rockies, Tuesday afternoon into Tuesday evening,
   accompanied by at least some risk for severe weather.

   ...Synopsis...
   Mid/upper flow across the northern mid-latitudes of the Pacific into
   western North America is forecast to remain modestly amplified and
   slowly progressive into and through this period.  This appears
   likely to include larger-scale troughing migrating inland of the
   Pacific coast through the northern Rockies, and downstream ridging
   shifting eastward across the eastern Canadian Prairies and northern
   U.S. Great Plains.  Downstream troughing, across and east of the
   upper Mississippi Valley, may be a bit slower, with one notable
   embedded short wave impulse forecast to dig southeast of the Upper
   Midwest into the lower Ohio Valley, but another notable impulse may
   accelerate east-northeast of the lower Great Lakes through the St.
   Lawrence Valley.  This will be accompanied by a weakening surface
   cyclone and trailing reinforcing surges of cooler/drier air into the
   Northeast and across the Ohio Valley into the Southeast.

   Cooler and drier air may also advance southward through the southern
   Great Plains, beneath ridging within weaker westerlies across the
   southern mid- into subtropical latitudes.  

   Seasonably high boundary-layer moisture may be in the process of
   shifting offshore of the southern Atlantic coast at the beginning of
   the period, and becoming confined to parts of the Edwards Plateau,
   Permian Basin and adjacent Rio Grande Valley.  However, there is
   notable spread among the model output concerning this and other
   synoptic/sub-synoptic details.

   ...Southwest Texas into Eastern New Mexico...
   It currently appears that the dryline within weak lingering surface
   troughing across parts of eastern New Mexico through the Permian
   Basin/Edwards Plateau vicinity will become the focus for strong
   thunderstorm development Tuesday afternoon.  It is possible that
   this may be aided by forcing for ascent associated with a weak
   perturbation progressing through the larger-scale ridging aloft.  In
   the presence of steep lapse rates, it appears that the low-level
   moisture to the east of the dryline may be sufficient for moderate
   to large CAPE with daytime heating, with deep-layer shear, aided by
   veering winds with height in lower through mid-levels, conducive to
   the evolution of a few supercells.  It is possible that severe
   probabilities could be increased further in later outlooks for this
   period.

   ...Northern Intermountain Region/Rockies...
   Models suggest that weak destabilization ahead of the inland
   advancing mid-level trough will support increasing thunderstorm
   development Tuesday afternoon and evening.  The latest NAM, in
   particular, suggests that activity may consolidate across the
   mountains of central Idaho into western Montana, where evaporative
   cooling within a well-mixed sub-cloud boundary layer may contribute
   to downward mixing of 40-50 kt southwesterly lower/mid-tropospheric
   flow and a strengthening cold pool.  It is possible that strong to
   severe surface gusts may spread east of the continental divide
   Tuesday evening, even as more weakly unstable inflow begins to
   weaken convection.

   ..Kerr.. 05/26/2024

   WUUS03 PTSDY3 

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