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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.


Monday, September 4, 2023

SPC Sep 4, 2023 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1238 AM CDT Mon Sep 04 2023 Valid 041200Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated to widely scattered severe wind and hail will be possible Monday afternoon and evening across parts of the northern Plains. ...Northern Plains... Strong short-wave trough is currently located over the Great Basin, progressing inland in line with latest model guidance. This feature is forecast to advance into WY/western CO by late afternoon as associated 500mb speed max ejects into the central Rockies and gradually weakens. This evolution favors a lee surface low forming over western SD by late afternoon. A synoptic front is expected to be oriented northeast-southwest across the Dakotas into northern WY by peak heating. Boundary layer is expected to warm rapidly across the High Plains from western NE into the Dakotas south of the aforementioned synoptic wind shift. While readings will be somewhat cooler across WY, convective temperatures will be breached by 20z, and scattered convection should easily develop ahead of the short wave. HREF guidance depicts a strong signal for high-based convection to initiate over eastern WY then spread/develop northeast into a much warmer air mass, with a deeper boundary layer characterized by temp/dew point spreads around 40F. Forecast soundings exhibit ample deep-layer flow and shear for organized updrafts. Current thinking is a few supercells may be noted early in the period, but possibly transitioning into more clusters/bowing line segments downstream over the Dakotas. Forecast buoyancy is not that strong, but there is some concern for significant, organized gusts with these clusters, especially given the steep lapse rates and large-scale support ahead of the short wave. There may be a need for higher wind probabilities across the northern Plains, but will maintain SLGT Risk at this time. Convection, potentially organized, will spread northeast across the Dakotas during the evening. ...AR/MO... Weak upper low over north-central TX should open up and eject towards the Ozarks later today. Seasonally cool mid-level temperatures are noted with this feature, and modest 500mb flow will spread across this region just ahead of the short wave. Forecast soundings exhibit substantial buoyancy and multicell storms should evolve as temperatures warm through the upper 80s to near 90F. Local gusts and perhaps some hail could accompany this diurnally enhanced convection. ..Darrow/Wendt.. 09/04/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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