Administrators NorthGeorgiaWX Posted July 25 Administrators Posted July 25 SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0742 AM CDT Thu Jul 25 2024 Valid 251300Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF MONTANA... ...SUMMARY... Strong to locally severe thunderstorms with wind gusts will be possible today across Montana and the northern Rockies/Great Basin, southern Arizona, and Carolinas/Mid-Atlantic States. ...Montana/Northern Rockies to Great Basin... A prominent upper-level trough will spread eastward from British Columbia toward Alberta/Saskatchewan, with strengthening cyclonic westerlies overspreading the northern Rockies/Montana. Scattered thunderstorm development is forecast to initiate off the higher terrain this afternoon, and in advance of a cold front, across central Montana, where a hot and deeply mixed boundary layer may become characterized by modest instability. Forecast soundings are suggestive of 40-60 F temperature-dew point spreads by peak heating. A downward mixing of 30-40+ kt ambient southwesterly to westerly flow in the 700-500 mb layer may contribute to severe-caliber wind gusts in consolidating outflows, as convection spreads eastward into this evening toward eastern Montana and possibly western North Dakota. Other high-based storms capable of severe-caliber wind gusts could occur as far southwest as parts of the Great Basin later this afternoon and evening, within an unstable air mass ahead of a front across the northern Intermountain region. ...Arizona... Lingering early day outflow/cloud cover via yesterday's relatively active convection should generally abate by afternoon. As the boundary layer diurnally warms and destabilizes, thunderstorms are again likely to initiate across the Mogollon Rim and adjacent mountains of southwest New Mexico this afternoon. Given the position and movement of the mid-level high, somewhat stronger (around 15 kt) northeasterly steering flow will remain focused across southeast into adjacent portions of central Arizona. Localized severe-caliber wind gusts and blowing dust will again be possible this afternoon through early/mid-evening as storms progress south-southwestward onto the desert floor. ...Carolinas/Mid-Atlantic States... Cloud cover will likely remain prevalent regionally today with showers/some thunderstorms ongoing this morning to the south of the primary front that will be shifting south-southeastward across the northern and central Appalachians. Near the southern periphery of the larger-scale mid-level troughing, a belt of 30-40 kt south-southwesterly flow in the 850-500 mb layer may enhance convective development within a plume of seasonably high moisture content. While lapse rates and overall buoyancy will be modest, heavy precipitation loading and downward mixing of momentum may contribute to a few strong downdrafts with the possibility of locally damaging surface gusts/tree damage this afternoon. ...Middle/Upper Texas Coast and Southern Louisiana... Extensive showers and some thunderstorms are ongoing along the Texas coast early today. Influenced by a weak mid-level disturbance, some guidance suggests that a strengthening of low-level winds/shear will occur today. However, mid-level winds will remain weak, while the aforementioned convection should considerably limit destabilization inland. These factors seem likely to minimize the potential for anything beyond a few very weak/transient mesocyclones. ..Guyer/Jewell.. 07/25/2024 Read more View the full article Quote
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