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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.

Wednesday, May 4, 2022

SPC May 4, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0233 PM CDT Wed May 04 2022 Valid 042000Z - 051200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHEAST TEXAS PANHANDLE AND NORTHWEST TEXAS ACROSS MUCH OF OKLAHOMA... ...SUMMARY... Numerous severe thunderstorms are expected across parts of the southern Great Plains this afternoon through tonight. A few strong tornadoes and giant hail is most probable across the southeast Texas Panhandle into portions of southwest Oklahoma and north Texas. Wind damage as well as tornadoes are also possible across the remainder of central and eastern Oklahoma through tonight. ...Eastern TX Panhandle/South Plains into much of OK... The Moderate Risk has been expanded eastward across a large portion of OK, as the air mass continues to destabilize and remain free of storms. Visible imagery continues to show pockets of heating, and increasing CU fields near the Red River. Surface observations show an unbroken plume of 68-70 F dewpoints now into southern OK, with GPS water vapor sensors indicating a deepening moist boundary layer with values increasing to over 1.50" over northwest TX. Midday soundings reveal a capping inversion below 700 mb which is helping to maintain the pristine air mass and guard against early contamination. This inversion may also help to subdue the number of storms later today across OK and northern TX. Any supercell over the warm sector will have the potential to produce a strong tornado, aided by midlevel lapse rates near 8 C/km and dewpoints of 68 F or greater. Later this evening, storms moving out of the Panhandle may eventually merge into a severe MCS with significant wind damage potential. In addition, further supercell develop may occur tonight along the baroclinic zone extending eastward across OK. Farther west into the TX Panhandle and South Plains, rapid destabilization continues, beneath cooler air aloft. Supercells producing very large damaging hail are likely, with a threat of strong tornadoes as supercells interact with increasing low-level shear to the east. See mesoscale discussions 640, 642, 643 for more information. ..Jewell.. 05/04/2022 .PREV DISCUSSION... /ISSUED 1122 AM CDT Wed May 04 2022/ ...Southern Great Plains... Complicated forecast today/tonight as a broad/destabilizing warm sector enlarges as a warm front advances northward today. Considerable forecast uncertainty remains evident for a multitude of possible scenarios, some of which differ both spatially in terms of severe hazard and intensity. Nonetheless, with the lack of morning convection across northwest TX into the TX Panhandle, thinking is this area will remain void of convection through the midday/early afternoon. Consequently, it seems a categorical Moderate Risk is warranted for dryline/triple point storms. Visible-satellite imagery late this morning shows a cirrus canopy across much of the outlook area. A warm front is rapidly moving northward across north TX with upper 60s F dewpoints reaching the Red River as of 16z. A destabilizing boundary layer beneath a capping inversion, which seems likely to hold through the early afternoon, will become quite unstable by peak heating with 3000-4000 J/kg MLCAPE forecast over northwest TX by 4pm. The RAP/HRRR seems to have the best handle on morning storm activity compared to the ARW and associated CAM models. In general, model guidance indicates storms will develop over the TX Panhandle during the mid-late afternoon with more widely spaced thunderstorms farther south along the dryline. Very steep 700-500 mb lapse rates, enlarged low-level hodographs via easterly component to low-level flow, and long hodographs all suggest discrete supercells will be the preferred mode over the TX Panhandle into northwest TX late this afternoon. Very large to giant hail (potentially 3+ inches in diameter) and a few strong tornadoes are possible during the late afternoon into the early evening as this activity moves into parts of western OK/far western north TX. Less certain but a plausible scenario involves free warm sector development farther east across parts of OK and perhaps north TX. A potentially significant tornado risk could develop if discrete supercells were to develop within an increasingly moist/strongly sheared environment during the late afternoon/early evening. By early to mid evening, the strengthening of a southerly LLJ and coalescing of storms/outflow will probably lead to the development of a severe MCS moving east across parts of OK. Severe gusts, possibly greater than 65 kt, and tornadoes will become the primary severe hazards with time. As this activity approaches the western part of the Ozarks, a lessening in the severe risk is anticipated late overnight. ...Southeast VA and the Carolinas... Not much change from the previous forecast in the overall thunderstorm scenario for VA/Carolinas. A low-amplitude shortwave trough over the Lower Great Lakes will move east into southern New England this evening. To the south of this wave, a cold front will push southeast across the Lower Mid-Atlantic into the Carolinas. Convergence along the cold front and coastal sea breezes should support scattered thunderstorms this afternoon. While deep-layer shear will be modest, it should be adequate for multicells capable of isolated severe hail and damaging winds. Convection should largely shift offshore and/or weaken after dusk. Read more CHECK UPDATE ZOOM GRAPHIC