DarkSky Temps | Gusts | WU KORD Data

CLICK for this month's BIG night sky ...




Cardinal SAT


Weather conditions on bar directly above are near Lakefront. Tabs under Moon Phases refer to O'Hare (official).

Archives for SPC Convective outlook are updated daily with a live map a the beginning of the article. Touch or click map to get possible update, and follow link at end of article for referral to NOAA/NWS Storm Prediction Center. Archives for Chicago's hourly weather data were updated 24-48 hours after end of each day prior to Dec. 2020.

Thursday, November 11, 2021

SPC Nov 12, 2021 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0657 PM CST Thu Nov 11 2021 Valid 120100Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN PENNSYLVANIA INTO THE DELMARVA... ...SUMMARY... A couple strong to severe thunderstorms may occur across the Mid Atlantic by early morning, towards the end of the period. ...Synopsis... A strong mid-level cyclone will continue to deepen while progressing eastward across the Upper Mississippi Valley through 12Z (the end of the forecast period). While the associated mid/upper level longwave trough deepens, a belt of 60-90 kt 500 mb flow will pivot around the trough and overspread a 50-70 kt southerly 850 mb jet centered over the Hudson Valley in the 07-12Z period. At the surface, strong convergence along a lee-trough axis/cold front will promote the development and organization of low-topped convection capable of producing strong wind gusts. ...Mid Atlantic... As the surface cold front crosses the Appalachians and approaches the lee trough, low-level convergence is expected to increase as the 50-70 kt low-level jet materializes and modest theta-e advection ensues. The 00Z GSO and WAL observed soundings depict upper 50s F surface dewpoints, but overall shallow moisture in the surface-850 mb layer. As such, buoyancy is expected to remain quite marginal when warm-air advection occurs, with MLCAPE likely remaining under 500 J/kg on a widespread basis. Nonetheless, a narrow, low-topped squall line is expected to develop along the immediate lee of the surface trough axis around 07-09Z. Point forecast soundings across portions of eastern PA southward towards Delmarva suggest that 50 kt southerly winds may occur as low as 400-500 m AGL. Despite the lack of buoyancy, any mechanically driven downward momentum transport within the line may support a couple strong wind gusts, with an instance or two of tree/power-line damage possible with the stronger gusts, hence the introduction of Category 1/MRGL probabilities. The damaging-gust threat is expected to persist past 12Z into the Day 2 period east of the current MRGL risk area. ..Squitieri.. 11/12/2021 Read more LIVE: spc.noaa.gov