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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.


Friday, August 4, 2023

SPC Aug 4, 2023 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0744 AM CDT Fri Aug 04 2023 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE NORTHEAST...MISSOURI...AND CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Northeast, Missouri, and the central High Plains later today through early tonight. ...Northeast... An upper trough will remain anchored over Quebec today, as an embedded mid-level impulse shifts east from the Upper Saint Lawrence Valley across New England. To the southwest of this impulse, pockets of more robust insolation will result in a moderately buoyant air mass from PA across the Hudson Valley into southern New England with MLCAPE of 1000-2000 J/kg. Scattered thunderstorms will develop towards midday north of the larger buoyancy plume, and become widespread during the afternoon as they spread east-southeast. While low-level flow will be weak, the presence of strong mid to upper winds coincident with peak instability will favor mid-level updraft rotation in several semi-discrete cells centered on northeast PA to southern NH. Isolated severe hail will be possible, with a tendency for clustering primarily supporting a damaging-wind threat from mid-afternoon to early evening. Clusters should approach coastal areas and tend to weaken near/just after sunset. ...MO vicinity... An MCV over north-central KS attendant to a decaying MCS will drift east into northern MO this afternoon. Convective outflow has spread into eastern KS through northern OK, but should slow its progression as the cold pool further wanes this morning. A high PW air mass characterized by low to mid 70s surface dew points ahead of this outflow to the persistent northwest/southeast baroclinic zone across MO should support a confined corridor of large buoyancy at peak heating. Most 00Z HREF members and recent HRRR guidance indicate redevelopment of thunderstorms near the MCV by late afternoon, with activity potentially intensifying towards the larger CAPE air mass in central to southern MO. Adequate signal exists to upgrade both the tornado and wind probabilities, but with moderate uncertainty on the overall spatial extent and intensity of these threats. ...Central High Plains... To the south of a low-amplitude mid-level impulse drifting over the northern High Plains, convergence along a surface trough from southwest SD to northeast CO should strengthen this afternoon. Isolated to scattered thunderstorms are expected along this trough with a moderately unstable and modest deep-layer shear environment ahead of it. Those should be sufficient for multicell clusters and a few transient supercell structures capable of producing mainly isolated large hail and severe gusts. The lack of a stronger nocturnal low-level jet intensification and increasing MLCIN over the lower Great Plains will probably limit the severe threat to a marginal one tonight. ...Southeast... A broad swath of thunderstorm clusters are ongoing from parts of GA to southeast MO along a northwest/southeast-oriented baroclinic zone. One of these clusters may grow upscale later this morning into the afternoon, closer to the larger buoyancy impinging from the Mid-South and Lower MS Valley. In general, weak deep-layer flow/shear will tend to limit storm-scale organization, and the most favored corridors for somewhat greater damaging-wind potential will be dependent on mesoscale details that remain unclear at this time. ..Grams/Broyles.. 08/04/2023 Read more CHECK UPDATE ZOOM GRAPHIC
SUNRISE AND SUNSET TIMES IN UTC (if you're not logged in to Google)
CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)