SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Apr 08 2024 Valid 081630Z - 091200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF NORTHWEST INTO NORTH-CENTRAL/NORTHEAST TEXAS AND NORTHWEST LOUISIANA... ...SUMMARY... Multiple rounds of severe thunderstorms will develop from mid afternoon through tonight across a large portion of the southern Plains into the lower Mississippi valley. Large to giant hail will likely be the main threat, especially over northwest Texas, though a few tornadoes and severe gusts are also possible. ...Synopsis... Primary feature of interest related to severe potential today is a mid/upper-level trough digging over the Southwest. This feature will slowly move eastward across northern Mexico and AZ/NM through the period, while eventually evolving into a closed low. A broad zone of enhanced southwesterly flow is present downstream across northern Mexico into the southern Plains and lower/mid MS Valley. Rich low-level moisture, with surface dewpoints in the mid/upper 60s to low 70s, will continue to stream northward across much of TX through the day in tandem with a modest southerly low-level jet. A weak surface low analyzed over central OK this morning should develop northeastward this afternoon into MO, with a trailing cold front forecast to stall over parts of northwest TX into far southern OK. ...Coastal/East Texas into the Lower Mississippi Valley... A broad warm sector is already in place this morning along and south of an effective warm front. 12Z soundings from DRT/CRP show steep mid-level lapse rates, but warm low-level temperatures and related MLCIN. This, along with nebulous large-scale ascent, should act to inhibit convection for at least a couple more hours across east TX. But, continued filtered daytime heating and low-level moistening associated with the modest southerly low-level jet should encourage robust convective initiation along the northern extent of the returning moisture by early this afternoon (around 18-20Z/1pm-3pm CDT). With moderate instability and strong deep-layer shear, and elongated/nearly straight hodographs at mid/upper levels, initial supercell development will likely pose a threat for large to very large (2+ inch) hail. The tornado threat may initially be limited by modest low-level winds/shear, but the chance for a few tornadoes will likely increase through late afternoon and continue through tonight as a southerly low-level jet gradually strengthens. Additional supercells and clusters will likely spread eastward this evening and overnight along/near the warm front. While some of this activity may be slightly elevated, a continued threat for large to very large hail and tornadoes should continue overnight with embedded supercells. Severe/damaging winds may also occur with any cluster that can form. Given increased confidence in multiple rounds of supercells occurring, the Enhanced Risk for large/very large hail has been expanded eastward to include more of north-central/northeast TX and northwestern LA. ...Northwest into North-Central/Northeast Texas and Far Southern Oklahoma... Compared to locations farther east across TX, the northward return of rich low-level moisture will be delayed until later this afternoon and early evening. Still, strong daytime heating will eventually erode the cap in the vicinity of a weak front and dryline intersection across northwest TX. Ample deep-layer shear and steep mid-level lapse rates will aid in multiple robust supercells capable of producing very large to possible giant hail (2-4 inches) initially. These supercells should eventually encounter greater low-level moisture into north-central TX, with a continued threat for very large hail and a few tornadoes. The potential for a saturated temperature profile and neutral low-level lapse rates in various forecast soundings overnight along/near the warm front lowers confidence in a greater tornado threat. But, low-level shear will increase through the night, especially towards the ArkLaTex where an enhanced low-level jet should be focused. This activity may eventually merge with the low-level warm advection convection across the ArkLaTex late tonight, with messy modes possibly complicating severe hail potential. ...West/Central Texas Late Tonight/Early Tuesday Morning... Increasing forcing for ascent via stronger mid-level height falls will overspread much of west/central Texas tonight. Continued low-level moistening beneath steep mid-level lapse rates will foster moderate to strong MUCAPE. Elongated hodographs with 60-kt effective shear will promote supercells and mainly a risk for large to very large hail across parts of the TX Hill Country. Southerly low-level winds will also increase overnight and act to enhance initially limited hodographs. If a cluster organizes overnight (06-12z), a risk for severe wind gusts and perhaps a couple tornadoes could also develop. The dryline is expected to retreat westward across parts of west Texas overnight with strong instability building back to near Midland early Tuesday morning. As strong upper forcing overspreads this region, at least isolated to scattered storms will probably develop on the western periphery of a strongly unstable/sheared environment. ..Gleason/Karstens.. 04/08/2024
