Outlook (Main)
Storm Prediction Center
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SPC - No watches are valid as of Mon Dec 4 13:23:02 UTC 2023
No watches are valid as of Mon Dec 4 13:23:02 UTC 2023. -
SPC - No MDs are in effect as of Mon Dec 4 13:23:02 UTC 2023
No Mesoscale Discussions are in effect as of Mon Dec 4 13:23:02 UTC 2023. -
SPC Dec 4, 2023 1300 UTC Day 1 Convective Outlook
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0654 AM CST Mon Dec 04 2023 Valid 041300Z - 051200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Synopsis/Discussion... 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
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SPC Dec 4, 2023 Day 4-8 Severe Weather Outlook
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0341 AM CST Mon Dec 04 2023 Valid 071200Z - 121200Z ...DISCUSSION... ...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 Ark-La-Tex. 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.
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