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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, August 1, 2023

SPC Aug 1, 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 1239 AM CDT Tue Aug 01 2023 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS... ...SUMMARY... Severe thunderstorms capable of producing large hail and damaging winds are expected Tuesday across parts of North Dakota into northern Minnesota. A few strong/severe storms are also expected across the central High Plains into the mid Missouri Valley. Thunderstorms capable of producing occasional damaging winds may also occur over parts of the coastal Southeast. ...Northern Plains... Water-vapor imagery depicts a ridge-topping short-wave trough ejecting east across AB/SK region early this morning. This feature is forecast to dig southeast and should progress into northwest ON/Arrowhead of MN by the end of the period. While appreciable height changes are not expected south of the international border, it appears this short wave will encourage deep convection downstream. Latest model guidance suggests low-level warm advection ahead of the short wave/surface front will spread south across MB into northern MN by 18z. This activity could evolve into an MCS as it propagates south along a corridor of warm advection. Additionally, strong boundary-layer heating will occur across the northern Plains, extending across ND into eastern MT. This will ensure CINH weakens by late afternoon along the southward-moving surface front that should extend from southern MB-northern ND-northeast MT by late afternoon. This boundary will focus additional thunderstorm development as temperatures warm through the lower 90s. Forecast soundings exhibit modest 500mb flow, but low-level shear should remain weak. While some early-day weak convection may drift across the SK border into the US, surface heating is expected to be the primary mechanism for renewed convective development by 21-23z along the boundary. Large hail and gusty winds are the expected threats. ...Central Plains/Mid MO Valley... Early-day MCS will likely be ongoing at the start of the period over the lower MO Valley. This activity will be supported by low-level warm advection as 850mb west-southwesterly flow is forecast across eastern KS into northwestern MO at daybreak. LLJ is expected to weaken during the day, and high-res models subsequently allow this activity to weaken. It's not entirely clear how soon convection will weaken but convective debris and showers will likely linger across much of MO through the period. However, strong surface heating across much of KS will allow surface temperatures to warm to near 100F. Convective temperatures will be breached with these readings, and isolated thunderstorms may redevelop along the old convectively reinforced boundary that will be draped from southwest MO-northern KS-eastern CO. Scattered storms will also evolve over CO which will spread downstream into an air mass seemingly favorable for supporting at least gusty winds and some threat for hail. ...Southeast... Low-level convergence corridor will likely extend from northeast FL to the Carolina Coast. Scattered convection should develop early in the period then spread south within strengthening northwesterly mid-level flow in the wake of the east-coast trough. Modest lapse rates and high PW values suggest gusty winds are the primary concern. ..Darrow/Bentley.. 08/01/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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