Day 1 Convective Outlook
Issued: · Valid: –
Summary
Severe thunderstorms capable of producing large hail and damaging wind gusts are possible this afternoon and evening across parts of the Upper Midwest, central High Plains, coastal Carolinas, eastern Idaho, and the central Gulf Coast. Other areas, including the northern Great Basin and parts of Maine, may experience isolated severe wind or hail this afternoon.
Product Text
000 ACUS01 KWNS 242002 SWODY1 SPC AC 242000 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Aug 24 2026 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS/UPPER MIDWEST...EASTERN IDAHO...CENTRAL HIGH PLAINS...LOWER MISSISSIPPI RIVER VALLEY/CENTRAL GULF COAST...AND COASTAL CAROLINAS... ...SUMMARY... Severe thunderstorms capable of producing large hail and severe wind gusts will be possible this afternoon and evening across parts of the Upper Midwest as well as the central High Plains. Other severe thunderstorms with mainly a damaging wind threat are possible across the central Gulf Coast, eastern Idaho, and coastal Carolinas. ...20z Update... ...Northern Great Basin... A targeted upgrade to a Level 2/Slight risk was introduced for portions of eastern Idaho where the latest HRRR/RRFS runs and TLE probabilities suggest a corridor of locally greater damaging/severe wind gust coverage may materialize in association with developing convection across southern Idaho given a favorable thermodynamic environment. Similarly, the 5% wind probability and CIG1 areas have also been expanded across adjacent areas of the northern Great Basin given the potential for high-based, loosely-organized convective clusters to produce isolated damaging/severe wind gusts. See MCD 2115 for additional short-term details. Elsewhere, the forecast remains generally on track with only minor adjustments made to the existing outlook. See the discussion below and MCDs 2116 and 2117 for additional short-term details. ..Chalmers/Moore.. 08/24/2026 .PREV DISCUSSION... /ISSUED 1122 AM CDT Mon Aug 24 2026/ ...Central Gulf Coast... Satellite/radar mosaic late this morning shows a cluster of storms moving south along the MS River. Mostly clear skies will promote additional heating to the south over the coastal plain, which will further destabilize the airmass and lead to steepening 0-2 km lapse rates (in excess of 8 deg C/km) as temperatures warm into the lower 90s deg F. Deep-layer northerly steering flow will favor southward movement of the thunderstorm cluster and new updraft development on the leading edge of the cold pool. As this convection likely continues to develop and become surface-based through the mid afternoon, there will be a corresponding increase in potential for scattered wet microbursts (55-65 mph gusts capable of wind damage) with the stronger cores. This activity will likely push south of the coast by the early evening. ...Dakotas/Upper Midwest into the Central High Plains... A mid-level shortwave trough over Alberta/Saskatchewan will move eastward across the Canadian prairie provinces through tonight, with a belt of moderately strong flow aloft and multiple MCVs influencing the northern Plains to Upper Midwest. Widely scattered thunderstorms are forecast to develop late this afternoon into the early evening within a moist/unstable airmass near an eastward-moving front and weak surface wave across central/eastern ND. Other convection may initiate and then move southeastward from south-central Canada. Around 35-45 kt of deep-layer shear will support supercells initially with a large hail threat. The development of east/southeastward-moving clusters should eventually occur this evening, with scattered severe gusts possible. Farther south and a bit more removed from the stronger cyclonic flow aloft, additional high-based thunderstorms are expected to form by late afternoon/early evening across the Black Hills/western NE in the vicinity of the surface front. Strengthening and sufficient veering of winds with height through the mid levels should support initial supercells capable of large hail, prior to a clustering of these southeastward-moving thunderstorms. The risk for scattered severe gusts may linger through mid/late evening across the central High Plains before increasing MLCIN encourages gradual weakening. ...Coastal Carolinas... A larger-scale low/troughing centered over the St. Lawrence Valley will maintain cyclonic mid to high-level flow over the region this afternoon. The 12 UTC Charleston, SC and Newport, NC raobs showed a very unstable airmass in place to the southeast of a cold front draped over the Carolinas. Veering and strengthening flow with height will support deep-layer shear (30-35 kt) favorable for storm organization. The stronger storms will be capable of a hail/wind-damage risk this afternoon. See MCD #2112 for short-term details through early afternoon regarding severe potential. ...Northern Great Basin into the Central Rockies... Isolated to scattered high-based thunderstorms are expected to develop this afternoon across parts of the northern Great Basin into the central Rockies amid steepening low-level lapse rates with a very well-mixed boundary layer. Since this convection will develop along the periphery of stronger flow aloft, modest organization is possible even though low-level moisture and related instability should remain weak. Occasional dry microbursts may occur, some of which could pose an isolated threat for severe gusts. ...Maine... Partly cloudy skies will promote some heating and resulting in weak instability (500-1000 J/kg MLCAPE) by early to mid afternoon. Forecast soundings show elongated hodographs due to a 100+ kt upper speed max overhead. A few of the stronger thunderstorms may be capable of a localized hail/wind risk for a few hours before this marginal threat subsides by early evening. $$