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SPC Mar 7, 2025 2000 UTC Day 1 Convective Outlook

4 months 2 weeks ago

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0152 PM CST Fri Mar 07 2025 Valid 072000Z - 081200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS NORTHWEST TEXAS/TEXAS BIG COUNTRY... ...SUMMARY... Thunderstorms capable of producing isolated hail are possible across northwest Texas/Texas Big Country late tonight into early tomorrow morning. Additional thunderstorms are possible across the Southwest States this afternoon and evening. ...20z Update... The previous forecast remains on track. The only adjustment to the ongoing Marginal risk area was a slight longitudinal expansion to better encompass the range of possible solutions depicted by recent HRRR/RAP runs as well as experimental 12z MPAS runs. These solutions continue to show the best convective environment and QPF signal along the I-20 corridor to the west of the DFW metro area, but the envelope of solutions suggests that initial convective initiation may include portions of the DFW area/I-35 corridor. Regardless, the overall expectation of a relatively short-duration, localized severe hail threat early Saturday morning remains valid as outlined in the previous discussion below. ..Moore.. 03/07/2025 .PREV DISCUSSION... /ISSUED 1030 AM CST Fri Mar 07 2025/ ...Northwest TX/TX Big Country... Recent satellite imagery shows a well-defined upper low over the Lower CO Valley. This upper low is forecast to progress eastward across the Southwest States, with an expansive fetch of southwesterly flow aloft extending from the base of this low into the OH Valley. Recent satellite imagery also shows a low-amplitude shortwave trough over the central Plains, while the 15Z surface analysis places an associated low over the MCI vicinity. A cold front extends back west-southwestward from this low into the OK Panhandle while a dryline extends more southwestward through central OK into southwest TX. The central Plains shortwave is expected to progress quickly northeastward through the OH Valley, with the attendant surface low taking a similar path while gradually weakening/filling. The cold front will push southward through OK into north TX, gradually slowing its progress throughout the evening as surface pressures fall across the southern High Plains ahead of the approaching Southwest upper low. A modest surface low will likely develop along the southwestern periphery of the cold front (over the southwest TX/western TX Hill Country vicinity) early tomorrow morning. Low/mid-level southern flow will strengthen as this low develops, creating a region of focused warm-air advection over the TX Big Country/northwest TX. Resultant moistening of low levels (around 850 mb) beneath profiles characterized by cold mid-level temperatures and steep mid-level lapse rates will likely result in around 1000 J/kg of MUCAPE from 08/09Z through 12Z. This buoyancy coupled with continued forcing for ascent, from both warm-air advection and the approaching upper low, will support thunderstorm development. Strong southwesterly flow will exist through the cloud-bearing layer, and the resulting shear is expected to be strong enough to support organized storms capable of producing hail. This threat will be fairly localized and only last a few hours, but the anticipated strong/severe storm coverage merits the introduction of 5% hail probabilities. ...Elsewhere... Isolated thunderstorms are anticipated this afternoon across the Southwest, as ascent from an upper low traverse the region interacts with limited buoyancy supported by steep lapse rates and modest low/mid-level moisture. Highest coverage is anticipated over northwest/north-central NM this afternoon and evening. A few thunderstorms are possible along the central Gulf Coast early tomorrow morning as well. Additionally, a few lightning flashes are possible within any of the deeper convective cores across southern CA this afternoon/evening. Even so, overall coverage is currently expected to be less than 10%. Read more