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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.


Tuesday, July 4, 2023

SPC Jul 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 1245 AM CDT Tue Jul 04 2023 Valid 041200Z - 051200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL GREAT PLAINS... ...SUMMARY... Greatest potential for scattered severe thunderstorms is over the central Great Plains beginning late afternoon Tuesday into Tuesday night. Severe thunderstorm gusts will be the primary hazard. ...Central Great Plains to the upper MS Valley... Northern Rockies upper trough is forecast to advance into the northern Plains later today, then into the upper MS Valley late in the period. Weak height falls will be noted as far south as the central Plains which will result in notable surface pressure rises across the high Plains. Latest model guidance suggests a strong cold front will surge across WY/western NE by 18z. This boundary will advance into the TX Panhandle by 05/12z, arcing across northwestern OK-eastern KS into WI. Early this morning, a well-organized MCS has evolved across the western Dakotas/northwestern NE. This activity has matured ahead of a weak short-wave trough that is forecast to progress into the upper MS Valley by 18z, then into northwestern ON/upper Great Lakes by late afternoon. Models may be a bit slow with the forward propagation of the MCS as it propagates across the northern Plains prior to daybreak. Current thinking is boundary-layer heating should contribute to moderate-strong buoyancy ahead of the remnants of this MCS. Scattered thunderstorms should easily develop by mid afternoon as CINH weakens with temperatures warming into the mid 80s. Modest deep-layer flow will be more than adequate for sustaining organized updrafts, including clusters and a few line segments. Damaging winds and hail can be expected with this activity. Farther south across the central Great Plains, pre-frontal wind shift will orient itself southwest-northeast ahead of the primary cold front across western KS into south-central NE. Latest data suggests strong boundary-layer heating will be noted across the central High Plains such that convective temperatures should be breached by 22-23z as temperatures soar into the upper 90s just ahead of the pre-frontal wind shift. Forecast soundings exhibit large surface temp/dew point spreads (40F) within the initiation corridor. Scattered high-based convection is expected to evolve within an environment that will be modestly sheared with deep southwesterly flow. Severe winds should be the primary concern with thunderstorms that grow upscale along a corridor from northwestern KS into south-central NE. Isolated strong/severe thunderstorms are also expected to develop over the higher terrain of southern WY then propagate southeast within a post-frontal environment characterized by strengthening westerly flow at 500mb. Forecast soundings suggest supercells should be the dominant storm mode across southern WY into northeast CO. Large hail and damaging winds should be the primary concern. ..Darrow/Weinman.. 07/04/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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