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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.

Monday, May 17, 2021

SPC May 17, 2021 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0717 AM CDT Mon May 17 2021 Valid 171300Z - 181200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS PARTS OF NORTHWEST TEXAS... ...

SUMMARY... Severe thunderstorms are forecast across portions of the southern Plains later this afternoon and overnight. Very large hail and a few tornadoes will be concentrated across northwest Texas. ...

West TX/Western OK... An active period of severe weather is forecast for later today across portions of west TX and southwest OK. The latest surface analysis shows an outflow boundary from overnight thunderstorms extending from southeast NM to near Midland, TX. This boundary is not expected to move much farther south before weakening and retreating northward by late morning. This will allow ample low-level moisture to return northward into parts of west/northwest TX by mid afternoon. Strong heating will eliminate the cap along the dryline, resulting in rapid thunderstorm development this afternoon from eastern NM into west TX near Lubbock. These storms will move into an environment of very high instability (MLCAPE over 3000 J/kg), steep mid level lapse rates exceeding 8.0 C/km, and effective shear values of 40-50 knots. Intense supercell structures are expected, capable of very large hail. Low-level shear is not forecast to be particularly strong, but given the unusually favorable thermodynamic environment, a few tornadoes may result this afternoon and evening along the western edge of greatest boundary-layer moisture/CAPE - therefore have added a 10% tornado area. Storms will expand in coverage through the evening, spreading across the TX Panhandle and western OK with a continued risk of large hail and damaging wind gusts. ...

Southwest TX... Strong instability will also be present along the dryline extending southward toward the Rio Grande. While model guidance is less confident in coverage/placement/timing of storms, there will be a conditional risk of supercells capable of very large hail and damaging winds. Have expanded the ENH risk slightly farther east to account for recent HRRR runs that depict greater coverage of convection. ...

Southeast TX... A cluster of supercell storms is affecting extreme southeast TX and southwest LA this morning. Local VAD profiles show favorable low-level shear for rotation, but weak winds aloft will limit the overall severe threat. An isolated tornado or damaging wind gust will be possible with this activity. Storms may also develop southwestward toward Houston with a similar low-end risk of gusty winds/brief tornadoes through the morning. ..Hart/Leitman.. 05/17/2021 Read more LIVE: spc.noaa.gov

NWS SPC Outlook provided by Arlingtoncardinal.com/weather

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