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
594 ACUS01 KWNS 191951 SWODY1 SPC AC 191949 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0249 PM CDT Wed Jun 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS COASTAL SOUTH TEXAS...AND PORTIONS OF SOUTHEASTERN MICHIGAN AND NORTHERN OHIO... ...SUMMARY... A few tornadoes are possible across south and southeast Texas this afternoon into tonight. Scattered strong to locally severe/damaging gusts are possible over portions of the southern Great Lakes this afternoon into the early evening. ...Discussion... No substantive changes appear necessary to the ongoing outlook at this time. Forecast reasoning and expectations as laid out in prior discussions remain valid at this time. ..Goss.. 06/19/2024 .PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Jun 19 2024/ ...Synopsis... Water-vapor imagery late this morning shows an East Coast upper ridge while a broad mid-level trough resides over the West. The upper ridge will build westward into the mid MS Valley as the primary belt of westerlies retreats north of the international border. This westward expansion will encourage the tropical system over the western Gulf basin to move into northeast Mexico, considerably south of the Rio Grande Valley. ...Lower Great Lakes to northern New England... While upper ridging will dominate this region, scattered convection will once again develop from portions of the Ohio Valley northeastward into New England, as surface temperatures warm through the upper 80s the lower 90s F. Area 88D VADs show a slightly stronger belt of mid-level southwesterly flow over the southern Great Lakes, which may act to influence storm organization and potential storm intensity/severe risk later this afternoon. Model forecast soundings show a seasonably moist/unstable airmass (2000-3000 J/kg MLCAPE) across much of this region. Strong to severe gusts (50-65 mph) capable of wind damage will be the primary hazard with the stronger storms, especially if small clustering of storms can occur. Based on the latest model guidance and visible satellite observations, this appears most likely across parts of northern OH into perhaps southeast Lower MI. ...South/southeast Texas... Despite an initially poor lapse rate/weakly unstable environment sampled with the 12 UTC Corpus Christi and Brownsville raobs, a moist-tropical airmass will continue to advect into the region on the northern periphery of Alberto, with MLCAPE likely rising into the 500-1500 J/kg range near the Lower and Middle Coasts of TX by later this afternoon. Model guidance continues to indicate low-level shear to increase, which will result in hodographs enlarging by mid-late afternoon into tonight across the coastal plain of TX (0-1 km SRH (100-200 m2/s2 0-1 km SRH). The likely cellular storm mode will also potentially be slightly more favorable for a tornado risk, considering the environment scenario described above. As such, have increased tornado probabilities to 5 percent (Slight Risk) near the Lower and Middle Coasts of TX. Reference the National Hurricane Center for the latest details on Tropical Storm Alberto. ...Southern High Plains... Radar/surface composite analysis late this morning shows a persistent area of weak convection north of a south-southwest moving outflow boundary from the TX Panhandle into northeast NM. Considerable lingering clouds and related convection will probably limit instability from near the TX/NM border and areas east. However, west of the outflow appreciable moisture and heating will contribute to scattered thunderstorm development later this afternoon/evening. Isolated large hail/severe gusts will be possible with the stronger storms before diminishing by mid evening. ...Northern Missouri/eastern Iowa to southern Wisconsin... To the east-northeast of lingering early morning convection across northeast Kansas/northwest Missouri, cloud cover should generally diminish today near the outflow augmented southwest/northeast-oriented synoptic front across the region. Potentially aided by an MCV, thunderstorms should redevelop and intensify this afternoon as the boundary layer destabilizes, with as much as 30 kt of effective shear maximized immediately near the synoptic front. Isolated instances of localized wind damage could occur. $$