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SPC Activity Chart
Hazard Tue (07/08) Wed (07/09) Thu (07/10) Fri (07/11) Sat (07/12) Sun (07/13) Mon (07/14) Tue (07/15)
Severe Slight Marginal Slight No Area No Area No Area No Area No Area
Fire Elevated Elevated No Area No Area No Area No Area No Area No Area

Forecast Discussion - Convective Outlook

   SPC AC 080609

   Day 1 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   0109 AM CDT Tue Jul 08 2025

   Valid 081200Z - 091200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE
   ATLANTIC...

   CORRECTED FOR REGIONAL HEADER

   ...SUMMARY...
   Scattered severe thunderstorms are expected across the Mid Atlantic.
   More isolated activity is expected across portions of the Plains
   into the Mid Mississippi Valley.

   ...Middle Atlantic...

   Early-morning water-vapor imagery depicts a notable short-wave
   trough over the upper MS Valley, shifting east in line with latest
   model guidance. This feature is forecast to advance into the central
   Great Lakes region by the end of the period. As the short wave
   advances east, a corridor of higher PW (currently extending from AR
   into the upper OH Valley) will be shunted downstream as a
   low-amplitude disturbance ejects toward the Mid Atlantic. While some
   suppression of the height field can be expected late, it appears the
   weak disturbance should be the primary mechanism for encouraging
   somewhat stronger southwesterly flow which would extend as far south
   as central VA. Even so, 0-6km bulk shear is only expected to be on
   the order of 20-25kt, but favorably oriented for clusters and short
   line segments. Forecast soundings exhibit poor lapse rates, but
   high-water content suggests damaging downbursts are likely,
   especially with any organized clusters. Convective temperatures will
   be breached by 17-18z as readings climb into the mid 80s, and
   scattered thunderstorms should readily develop from central PA into
   central VA. This activity will then propagate toward the Mid
   Atlantic Coast with an attendant risk for damaging winds.

   ...Plains...

   Upper ridge is forecast to hold across the southwestern U.S. through
   the day1 period; although, northwesterly flow is expected to
   increase a bit along the eastern periphery of this feature over the
   High Plains. As a result, high-level diffluent flow will be noted
   across the southern Plains into southern MO. At the surface,
   low-level boundaries/convergence will prove weak, and left-over
   convective debris will likely prove influential in late-afternoon
   development. Early this morning, an MCS was propagating south across
   eastern NE/southwest IA. This complex will likely advance into
   southeast KS/southwest MO by sunrise. It's not entirely clear how
   organized this cluster will be at the start of the period, but
   convective outflow will likely contribute to additional development
   later in the day. Strong boundary-layer heating will also aid
   isolated thunderstorm development across the High Plains of eastern
   WY/CO/NM. This activity will spread southeast during the evening
   with a risk for hail/wind.

   ..Darrow/Weinman.. 07/08/2025

    

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

        
   SPC AC 080556

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1256 AM CDT Tue Jul 08 2025

   Valid 091200Z - 101200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
   NORTHERN PLAINS AS WELL AS PORTIONS OF THE SOUTHEAST INTO SOUTHERN
   NEW ENGLAND...

   ...SUMMARY...
   At least isolated severe storms are possible in the northern Plains
   on Wednesday, with locally large hail and areas of severe gusts.
   Isolated damaging gusts are also possible across parts of the
   eastern U.S.

   ... Synopsis ...

   A midlevel ridge centered over the four corners will begin to break
   down on Wednesday as a low-amplitude shortwave trough quickly moves
   from off the northern California coast into the Great Basin.
   Additionally, a larger amplitude trough will move across southern
   Canada. Elsewhere, broad mid-level troughing will persist across the
   eastern US.

   Surface lee toughing will exist across the northern Plains in
   response to westerly downslope flow. This westerly flow will help
   maintain steep mid-level lapse rates into the northern Plains atop a
   moist boundary layer supported by southerly surface winds on the
   east side of the northern Plains lee trough.

   ... Northern Plains ...

   Strong diurnal heating should allow temperatures to warm into the
   mid-to-perhaps-upper 90Fs across much of the Dakotas by mid
   afternoon. This heating, coupled with surface dewpoint temperatures
   in the 60Fs, will support surface-based CAPE in excess of 2500-3000
   J/kg with little to no convective inhibition. Additionally, modest
   northwest mid-to-upper-level flow on the northeast periphery of the
   four corners ridge will support somewhat elongated hodographs and
   effective-layer shear around 30 knots. 

   Despite the region being displaced from the stronger large-scale
   ascent associated with the aforementioned shortwave troughs,
   isolated thunderstorms are still expected to develop by late
   afternoon. The overall thermodynamic and kinematic environment
   should support multicell clusters to transient supercell structures
   capable of producing large hail -- perhaps in excess of 2 inches in
   diameter. By early evening any thunderstorm clusters persisting will
   pose an increasing damaging wind threat. 

   A categorical upgrade to Level 2/Slight Risk was considered with
   this forecast. However, given the nebulous forcing mechanisms for
   initiating thunderstorms, uncertainty remains as to the coverage of
   severe thunderstorms. As such a Level 1/Marginal Risk was
   maintained, even though a potential for significant hail exists. 

   ... Southeast US to Southern New England ...

   Scattered to widespread thunderstorms will develop during the late
   morning into the afternoon within a moist, unstable, and weakly
   capped airmass. Precipitable water values around 2" will support
   water loading of updrafts and a resulting potential for strong
   thunderstorm winds capable of scattered wind damage.

   ..Marsh.. 07/08/2025

   WUUS02 PTSDY2 

   

        
   SPC AC 080726

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0226 AM CDT Tue Jul 08 2025

   Valid 101200Z - 111200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHEAST SOUTH
   DAKOTA...EASTERN NEBRASKA...NORTH-CENTRAL KANSAS...FAR NORTHWEST
   MISSOURI AND WESTERN IOWA...

   ...SUMMARY...
   Severe thunderstorms capable of producing large hail, damaging
   winds, and perhaps tornadoes will be possible across portions of the
   Central Plains. Elsewhere, strong to locally severe thunderstorms
   may occur across the High Plains, northern Plains, and portions of
   the Southeast US into the Mid-Atlantic.

   ... Synopsis ...

   A low-amplitude shortwave trough will eject into the central Plains
   during the late afternoon and evening ahead of a larger shortwave
   trough that will impinge upon the northern Plains. At the surface, a
   broad area of lower pressure associated with an initially diffuse
   front will extend from northeast Colorado northeast to northwest
   Minnesota. 

   ... Central Plains ...

   By mid afternoon surface temperatures will warm into the upper 80Fs
   with dewpoints in the 70Fs beneath an area of steep mid-level lapse
   rates. This combination will support most-unstable CAPE values in
   excess of 3000 J/kg across portions of the region. At the same time,
   the northern Plains trough will begin to interact with the central
   Plains trough resulting in the central Plains trough taking on a
   neutral to negative tilt as it is absorbed into the larger scale
   flow. As this transition unfolds, strong forcing for ascent will
   develop/overspread much of the central Plains. The expectation is
   that thunderstorms will rapidly develop across portions of the area
   -- currently anticipated across eastern Nebraska where a Level
   1/Slight Risk is found. The degree of instability and effective
   layer shear will support all modes of severe initially, with a
   tendency toward large hail and damaging winds with time.

   ... Northern Plains ...

   Here more uncertainty exists in the forecast evolution. Despite the
   presence of extreme instability and a diffuse surface boundary by
   midday, most guidance fails to develop robust convection. That said,
   given the degree of instability will maintain a Level 1/Marginal
   Risk to note the conditional threat for severe thunderstorms should
   convection initiate. 

   ... Southeast US into the Mid-Atlantic ...

   Once again thunderstorms will develop within a very warm, moist, and
   weakly capped atmosphere. Precipitable water values should be near 2
   inches across a large portion of the area leading to water laden
   downbursts capable of sporadic wind damage.

   ..Marsh.. 07/08/2025

   WUUS03 PTSDY3 

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1930Z