Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Thu Apr 20 2023 Valid 231200Z - 281200Z ...DISCUSSION... ...Sunday/Day 4 to Monday/Day 5... A moist airmass will likely remain over south-central Texas on Sunday, possibly advecting northwestward into west-central Texas on Monday. At upper-levels, a trough is forecast to move through the Desert Southwest early in the week. As surface temperatures warm each day, isolated thunderstorm development will be possible in the afternoon and evening. Although instability is forecast to remain relatively weak across most of the southern Plains, mid-level flow may be strong enough for an isolated severe threat. The greatest potential would be in south-central and west-central Texas, along the northern edge of the moist airmass. ...Tuesday/Day 6... On Tuesday, a lead shortwave trough ahead of the upper-level system, is forecast to move eastward into the southern High Plains. Low-level moisture is forecast to advect northward into much of the southern High Plains. It appears that moderate instability could develop across much of the moist sector as surface temperatures warm during the day. Moderate deep-layer shear combined with the instability should be favorable for severe storms. Some solutions suggest that a dryline will setup by afternoon across west-central Texas. Thunderstorms would likely form to the east of the dryline and move eastward across the southern Plains. Under that scenario, the greatest severe threat would be in parts of central and north Texas. Large hail and wind damage would be possible, especially if supercells can develop. ...Wednesday/Day 7 and Thursday/Day 8... An upper-level low is forecast to move across the Four Corners region on Wednesday, opening up into a trough over the southern Plains on Thursday. Isolated to scattered thunderstorms will be possible across the moist sector each day as surface temperatures warm. Although a severe threat may develop in areas that become sufficiently unstable, uncertainty is substantial concerning the location of the moist sector. A threat area could be added to either Wednesday or Thursday once this becomes more clear.
