SPC AC 300537 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1237 AM CDT Sun Mar 30 2025 Valid 301200Z - 311200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH TONIGHT ACROSS MUCH OF SERN IL...IN...WRN AND CENTRAL OH...SERN MO...CNTRL AND ERN AR...KY...TN...NWRN AL...NRN AND CNTRL MS...NRN LA...NERN TX... ...SUMMARY... Thunderstorm development is likely to become widespread across the Ohio Valley southwestward through the Tennessee and lower Mississippi Valleys this afternoon into tonight. Initially, this activity will pose a risk for large large hail. A few tornadoes are also possible, before damaging wind gusts become the more prominent potential severe hazard this evening into tonight. ...Discussion... To the north of an intense, zonal jet across the southern mid-latitude eastern Pacific, a significant mid-level low is forecast to progress slowly eastward across the northeastern Pacific, toward the Pacific Northwest coast, accompanied by a deep occluded surface cyclone. This has been preceded inland by a series of less prominent perturbations, a couple of which may be consolidating into more notable larger-scale mid-level troughing to the east-northeast of the southern Rockies. Models continue to indicate that this evolving mid-level wave will accelerate into a broadly confluent regime across the Ohio Valley through lower Great Lakes region, between a significant short wave trough digging across Manitoba/Ontario and downstream ridging overspreading the St. Lawrence Valley/Northeast. Models suggest that an associated surface low, likely initially over eastern Iowa at the outset of the period, will continue an east-northeastward migration into and across the Great Lakes, but it may not undergo substantive further deepening until late this afternoon into tonight across the lower Great Lakes into southeastern Ontario/southwestern Quebec. Trailing this cyclone, a notable cold front is forecast to progress southeastward through the southern Great Plains, and eastward through the mid/lower Mississippi Valley and middle Ohio Valley by late tonight. The front will continue to be preceded by a moistening southerly return flow, which may include surface dew points increasing through the lower/mid 60s F as far north as southern portions of the Great Lakes region, at least initially beneath a remnant plume of elevated mixed-layer air emerging from the high plains. ...Ohio Valley into southeastern Great Plains... Models suggest that thermodynamic profiles will become supportive of sizable conditional and convective instability, with a fairly broad reservoir of CAPE in excess of 2000 J/kg evolving across the southeastern Great Plains through lower Mississippi Valley, as far north as the confluence with the Ohio River by late this afternoon. Farther north, mixed-layer CAPE is likely to increase in excess of 1000 J/kg during the day, within a narrower corridor across/north-northeast of the middle Mississippi Valley, where mid/upper forcing for ascent is likely to initiate intensifying thunderstorm activity by early to mid afternoon. This may include a few supercells posing a risk for large hail and potential for a couple of tornadoes, before convection tends to gradually consolidate and grow upscale, accompanied by increasing risk for damaging wind gusts. This initial activity may be maintained northeastward and eastward through much of the Ohio Valley by late this evening, before tending to weaken while acquiring less unstable inflow. Meanwhile, subsequent initiation of storms is likely southwestward ahead of the cold front, across the lower Ohio Valley/Mid South toward the Ark-La-Tex later this afternoon into this evening. It appears possible that this may coincide with strengthening lower/mid-tropospheric flow accompanying a trailing jet streak. And a period of intensifying discrete supercell development might not be out of the question, before activity tends to grow upscale into one or more organizing clusters. Depending on how quickly this occurs, there may be a conditional risk for a couple of strong tornadoes, before damaging straight line winds, and perhaps brief tornadoes with evolving near-surface meso vortices, becomes the more prominent hazard southeastward into the Gulf Coast states overnight. ...Florida Peninsula vicinity... HREF and NCEP SREF guidance indicates rather high probabilities for thunderstorm development, as weak mid-level troughing overspreads the peninsula today. Beneath modestly cool mid-level temperatures, it appears that boundary-layer moisture will support moderate CAPE, and thermodynamic profiles may become conducive to a few stronger storms with small, melting hail contributing to potential for localized damaging downbursts. ..Kerr/Weinman.. 03/30/2025 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
Category: Watches, Warnings, Advisories, & Hazards