Blue Flower

Outlook (Main)

Storm Prediction Center
SPC Forecast Products
  1. No watches are valid as of Mon Dec 4 13:23:02 UTC 2023.
  2. No Mesoscale Discussions are in effect as of Mon Dec 4 13:23:02 UTC 2023.
  3. SPC 1300Z Day 1 Outlook
    Day 1 Outlook Image
    Day 1 Convective Outlook  
    NWS Storm Prediction Center Norman OK
    0654 AM CST Mon Dec 04 2023
    Valid 041300Z - 051200Z
    Severe thunderstorms are not expected through tonight.
    In mid/upper levels, mean troughing will be maintained over the
    east-central CONUS as one strong shortwave trough effectively is
    replaced by the next upstream.  The leading perturbation -- located
    over the STL vicinity -- is supporting an area of large-scale ascent
    in the form of both DCVA and a warm-advection conveyor.  In turn, an
    arc of precip with embedded showers and isolated/episodic
    thunderstorms is apparent just ahead of the trough.  Meager yet
    sufficient moisture above the boundary layer, and cooling aloft,
    will continue to support elevated MUCAPE up to about 200 J/kg,
    sporadically extending into icing layers suitable for lightning
    generation.  The most probable corridor for related, isolated
    thunder potential will be into midday from parts of the lower Ohio
    Valley toward the southern Appalachians.  
    After that, the causative perturbation will weaken and move out to
    the Atlantic.  Another, similarly evolving shortwave trough --
    evident in moisture-channel imagery over portions of southern SK and
    eastern MT -- should dig southeastward and strengthen through the
    period.  This feature should reach the Mid-South and southern parts
    of the Mid Mississippi Valley by 12Z tomorrow, on a similar but
    slightly more southerly track relative to the leading shortwave. 
    However, forecast soundings suggest even weaker moisture, coupled
    with more stable lapse rates in typical lightning-generation layers,
    rendering thunder potential (if any) too isolated and uncertain for
    an outlook area.  
    Isolated lightning has been noted in a baroclinic-leaf pattern
    preceding a cyclone over the northeast Pacific (well west of the
    Pacific Northwest).  Weakly favorable low/middle-level moistening
    and destabilization in the related warm-advection plume may reach
    portions of the Olympic Peninsula late afternoon into evening, as
    the ridge aloft moves away.  Elsewhere, boundary-layer drying/
    stabilization from prior frontal passages (from the Plains eastward)
    and progressive, strong, synoptic-scale ridging aloft (across the
    West) will preclude thunderstorms.
    ..Edwards/Kerr.. 12/04/2023
    Read more
  4. Day 4-8 Outlook
    Day 4-8 Outlook Image
    Day 4-8 Convective Outlook  
    NWS Storm Prediction Center Norman OK
    0341 AM CST Mon Dec 04 2023
    Valid 071200Z - 121200Z
    ...Thursday/Day 4 and Friday/Day 5...
    A relatively dry airmass is forecast across much of the continental
    United States on Thursday. Strong moisture advection will likely
    develop across the southern Plains on Friday as an upper-level
    trough digs southeastward into the Four Corners region. As the
    system approaches the south-central states, isolated severe storms
    may develop Friday night in parts of the Ark-La-Tex and Ozarks, near
    the northern edge of a moist airmass.
    ...Saturday/Day 6 to Monday/Day 8...
    The upper-level trough is forecast to move into the southern Plains
    on Saturday. Ahead of the trough, surface dewpoints in the 60s F
    appear likely from east Texas into parts of Arkansas where moderate
    instability could be in place by midday Saturday. Thunderstorm
    development appears likely during the day from east Texas
    northeastward into the mid Mississippi Valley. The progressive
    nature of the trough, along with strong deep-layer shear and
    adequate low-level moisture, will favor severe thunderstorm
    development. All hazards will be possible including tornadoes, wind
    damage and isolated large hail. The models are now in good agreement
    concerning this scenario, and a 15 percent contour has been added
    for Saturday in parts of east Texas, northwestern Louisiana and the
    The upper-level trough is forecast to move quickly through the
    Southeast on Sunday, and then move northeastward into the Northeast
    on Monday. Although instability is forecast to be relatively weak on
    Sunday due to a cooler and drier airmass over parts of the
    Southeast, isolated severe storms could occur if a line of strong
    storms can become organized. The potential for severe storms appears
    to be reduced on Monday. However, an isolated severe threat could
    still develop across parts of the eastern U.S., especially if the
    system ends up being slower than forecast.
    Read more