Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
913 ACUS01 KWNS 300600 SWODY1 SPC AC 300559 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Thu May 30 2024 Valid 301200Z - 311200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF WEST TEXAS... ...SUMMARY... Scattered severe storms are expected this afternoon and evening across parts of the southern Plains and central High Plains, where large hail and wind damage will be possible. The greatest severe threat should be in parts of west Texas, where hailstones greater than 2 inches in diameter may occur. A more isolated severe threat is expected further east across parts of the central Plains, Ark-La-Tex and Sabine River Valley. ...Southern and Central Plains... An upper-level trough will move eastward across the northern High Plains today, as west-northwesterly mid-level flow remains over much of the southern and central Plains. An MCS is expected to be ongoing at the start of the period over parts of Nebraska, Kansas and Oklahoma. This convection is forecast to move eastward into the Ozarks and Ark-La-Tex during the day, and could be accompanied by a marginal severe threat. Further to the west, a shortwave trough is forecast to move eastward into the southern High Plains during the day. A moist and unstable airmass will be in place ahead of the shortwave trough across much of the region. During the afternoon, a dryline will likely become focused from southeast Colorado extending southward across far eastern New Mexico. As surface temperatures warm during the afternoon, scattered convective initiation is expected along and to the east of the dryline. As storm coverage increases during the late afternoon and early to mid evening, MCS development will become likely. The airmass to the east of the dryline is forecast to become moderately to strongly unstable by afternoon. The deterministic models suggest that MLCAPE will reach the 2500 to 4000 J/kg range by mid to late afternoon. RAP forecast soundings during the late afternoon near the western edge of the moist sector have surface dewpoints in the upper 50s F with 0-6 km shear around 40 knots, and 700-500 mb lapse rates near 8 C/km. This environment will be favorable for supercells with large hail. As cells mature during the late afternoon and early evening, hailstones over 2 inches in diameter will be possible with the more dominant storms. The greatest threat for large hail is expected from near Amarillo southward to near Lubbock, where the combination of mid-level lapse rates and instability is forecast to be most favorable. An isolated tornado threat could also develop, and will be dependent upon mesoscale factors. As an MCS organizes and moves eastward into western Oklahoma and the Texas Low Rolling Plains during the evening, a mixed mode is expected with supercell structures and short line segments. A threat for severe wind gusts and isolated large hail appears likely to continue through much of the evening. An isolated and marginal severe threat could continue into the overnight period, as the MCS moves southeastward across central and east Texas. ...Central Plains/Mid Missouri Valley... Westerly to west-southwesterly mid-level flow will be in place today across much of the north-central U.S. Low-level moisture advection will take place across much of the region. Surface dewpoints should increase into the mid to upper 50s and lower 60s F from parts of northeastern Colorado east-northeastward into eastern Nebraska and southeastern South Dakota. As surface temperatures warm across this moist airmass, isolated to scattered thunderstorms are expected to develop. A few clusters may persist and have potential for a severe threat during the late afternoon and early evening. RAP forecast soundings from near North Platte eastward into northeast Nebraska have 0-6 km shear in the 30 to 40 knot range. In addition, low-level lapse rates are forecast to be steep. This suggests that a marginal severe threat will be possible with the stronger storms. However, the lack of large-scale ascent will likely keep convective coverage more isolated, with any severe threat remaining widely spaced. ..Broyles/Barnes.. 05/30/2024 $$