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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, June 15, 2023

SPC Jun 15, 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 0101 AM CDT Thu Jun 15 2023 Valid 151200Z - 161200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHWEST KANSAS...WESTERN OKLAHOMA AND THE FAR NORTHEAST TEXAS PANHANDLE... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN PLAINS AND GULF COAST REGION... ...SUMMARY... Widespread severe storms associated with damaging wind gusts, large hail and a few tornadoes are expected today across parts of the southern and central Plains. Hailstones greater than 2 inches in diameter and wind gusts above 70 knots will be likely along the more intense parts of a fast-moving line of storms. A severe threat is also expected to develop in parts of the Southeast, and in parts of the Ohio Valley. ...Significant Severe Weather Event Expected Today Across Parts of the Southern and Central Plains... ...Southern and Central Plains... A shortwave trough will move into the central U.S. today, as an associated 80 to 95 knot upper-level jet moves into the southern Plains. Ahead of the jet max, a moist and very unstable airmass will be in place from parts of central and north Texas into western Oklahoma and the eastern Texas Panhandle. At the surface, a low will deepen across the southern High Plains as a cold front moves southward through the central High Plains. Ahead of the front, surface heating and increasing low-level convergence will likely result in convective initiation early this afternoon. Storms will rapidly increase in coverage along an axis of strong instability from southwest Kansas south-southeastward across the far northeastern Texas Panhandle and into western Oklahoma. As storms grow upscale, MCS development is expected to occur late this afternoon and be maintained through the evening. By midday, a narrow corridor of maximized low-level moisture is forecast from northwest Texas extending north-northwestward into southwest Kansas. MLCAPE is forecast to reach the 3000 to 4500 J/Kg range by mid afternoon. In addition, RAP forecast soundings have low to mid-level lapse rates approaching 9.0 C/km. This potent thermodynamic environment will be augmented by an increase of deep-layer shear throughout the day, as an upper-level jet moves in from the west-southwest. Upon approach, an increase in large-scale ascent will be coupled with strengthening deep-layer shear. RAP forecast soundings suggest that 0-6 km shear could reach 60 to 70 knots along the instability axis, which will be very favorable for severe storms. The current thinking is that cells will first initiate in the early afternoon, with supercells forming rather quickly. A small cluster is expected to rapidly expand during the mid afternoon, as a line of supercells develops. Hailstones of greater than 2 inches in diameter, along with a tornado threat will be possible with the more intense supercells. As the convective cluster grows upscale in the mid to late afternoon, a Derecho will become possible as an organized severe line segment moves southeastward across the southern Plains. Wind gusts ahead of the more intense parts of the line will likely be greater than 70 knots. A few tornadoes will be possible, along with a continued threat for large hail from late afternoon into the evening. The MCS, associated with a potential for damaging wind gusts, could move into the Ark-La-Tex by mid to late evening, and into parts of the lower Mississippi Valley during the overnight period. ...Southeast... A shortwave trough will move through the central Gulf Coast states today, as a cold front advances southward across toward the central and eastern Gulf Coast. Ahead of the front, surface dewpoints in the lower to mid 70s F, will contribute to strong destabilization by afternoon. MLCAPE is forecast to peak in the 2000 to 3000 J/kg range by afternoon. Thunderstorms are expected to form ahead of the front, and will likely be concentrated along pre-existing outflow boundaries. The greatest coverage could occur from far southern Alabama extending eastward into northern Florida, where strong deep-layer shear is forecast to be strong and low-level lapse rates are forecast to be steep. This should lead to a wind-damage threat in the late morning and early afternoon, as storms gradually intensify. An isolated tornado threat and potential for large hail will also likely exist with the stronger cells. The severe threat should move toward the immediate coastal areas during the afternoon as the cold front advances southward. Further northeast into southeast Georgia and southern South Carolina, moderate instability is forecast to develop by midday. A vorticity maximum is expected to move eastward across southern South Carolina around midday, which should support scattered convective development. Thunderstorms that form within the stronger instability could be associated with isolated damaging wind gusts and hail. ...Ohio... An upper-level trough will move southeastward today across the Great Lakes region, as a cold front advances southeastward into Indiana and Ohio. Ahead of the front, surface dewpoints are forecast to be in the lower 60s F. As surface temperatures warm along the moist axis during the day, a pocket of moderate instability is forecast by early afternoon. Thunderstorms will likely form along and ahead of the front, moving southeastward into the Ohio Valley. RAP forecast soundings near this maximum in instability have MLCAPE peaking in the 1500 to 2000 J/kg range, with 0-3 km lapse rates exceeding 8.0 C/Km. This should be enough for a marginal wind-damage threat with the more intense line segments. A threat for hail will also be possible. ..Broyles/Bentley.. 06/15/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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