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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.


Thursday, April 27, 2023

SPC Apr 27, 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 1238 AM CDT Thu Apr 27 2023 Valid 271200Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE GULF STATES AND EASTERN FLORIDA PENINSULA... ...SUMMARY... Scattered severe storms are expected along much of the Gulf Coast Thursday, from portions of southern Texas and southern Louisiana into the Florida Panhandle. Damaging gusts, large hail, and a few tornadoes will all be possible. Isolated severe thunderstorms are also expected across the eastern Florida Peninsula. Hail/wind are the primary concerns with this activity. ...Gulf States... Upper low over the southern Plains is forecast to progress to near the OK/AR border by 18z, then weaken as it ejects northeast into the lower OH Valley late in the period. Substantial mid-level flow has translated through the base of the trough and will spread across the lower MS Valley early, then into the southeastern States where speeds should lessen by 28/12z. At the surface, substantial instability is currently suppressed to coastal regions and latest model guidance suggests the primary synoptic boundary will struggle to move appreciably north until late in the period over the Carolinas. Early this morning, an expansive MCS has evolved over east TX into northern LA. This complex of storms will propagate east-southeast along the Gulf Coast during the day, ultimately propagating toward the FL Panhandle by early afternoon. While deep-layer flow/shear will support supercells, the primary storm mode should be an MCS. Some tornado threat does exist with embedded supercells though. Otherwise, damaging winds are the primary threat. Significant buoyancy currently resides across deep south TX. This air mass is expected to support isolated strong/severe thunderstorms as the front surges into this region. Given the steep lapse rates, very large hail may accompany any supercells before they propagate south of the international border. Another region where a few strong/severe thunderstorms may develop is across the Mid-South. Cold mid-level temperatures will spread across AR into western TN and convection is expected to develop during the afternoon north of the mid-level jet. Forecast soundings suggest very steep lapse rates may be adequate for robust updrafts given the 50s surface dew points. At this time will maintain MRGL Risk for hail/wind, however probabilities may need to be adjusted for this region in later outlooks. ...FL Peninsula... Strong boundary-layer heating is once again expected across the FL Peninsula today. Diabatic heating proved instrumental in scattered severe convection Wednesday and this type of coverage may once again develop by afternoon. Mid-level temperatures remain seasonally cool and strong buoyancy is expected. Forecast soundings favor southeastward-moving supercells and hail/wind are the primary threats. ...Central High Plains Region... Strong 500mb speed max will dig south across MT/eastern ID/southwestern WY by late afternoon. Cold mid-level temperatures and steep lapse rates will result in thermodynamic environment favorable for surface-based convection. Forecast soundings suggest convective temperatures will be breached by 20-21z. Gusty winds will likely accompany this activity as it spreads southeast in association with a surging frontal zone. ..Darrow/Bentley.. 04/27/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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