nWo

I just received the following from the NWS-Louisville office.

Isolated severe storms will be possible today from parts of the mid-Mississippi Valley northeastward into the Ohio Valley and Lower Great Lakes. Today, as a pre-frontal trough oriented from northeast to southwest moves eastward through the Ohio Valley, a shortwave trough will travel northeastward into the western Great Lakes. From the middle Mississippi Valley northeastward to the lower Great Lakes, a short corridor of instability will form close to the pre-frontal trough. Isolated to dispersed thunderstorms are predicted to start when the front's surface temperatures rise during the day. During the afternoon, it is anticipated that many thunderstorm clusters will form and proceed eastward across the Ohio Valley. The environment will be favorable for the possibility of organized severe storms. Storms may have a propensity to organize into brief line segments despite the possibility of supercells because of flow that is parallel to the convective axis. Wind-related damage will be the primary threat, although hail and a marginal tornado threat will be possible in the lower Great Lakes, where deep-layer shear is forecast to be the strongest. The severe threat could persist into the early evening, as cells move into the central Appalachians.

On Wednesday, there is a chance of severe thunderstorms with hail and destructive gusts from northern Texas to the Ohio Valley and lower Great Lakes region. Large to extremely large hail and damaging gusts are most likely to occur from north Texas to the Missouri Bootheel area. The eastward-moving cold front and any MCVs from Tuesday's leftover convection on Day 1 will be the main factors causing the ascent in the area. These will be floating in the southwesterly flow. Over IN, OH, and KY, there will be a humid airmass with mid-to upper-60s dewpoints. This airmass will stretch northeast into NY/PA and the neighboring states in the low- to mid-60s. In the late morning and afternoon, moderate instability will be facilitated by a plume of steep midlevel lapse rates and significant heating. Cells that are organized will only need a minimal amount of vertical shear. Small hail and intermittently strong gusts of destruction are possible during thunderstorms.

On Wednesday, an upper low over the Upper Midwest will move across the Great Lakes and into Ontario to the east and northeast. There will be a sustained strengthened mid/upper southwesterly flow over a large section of the region. Strong low pressure over Minnesota and Wisconsin will occlude at the surface and gradually turn northeasterly and north into Ontario. A cold front is expected to move eastward over Lower MI, IL, and IN, while the boundary's southernmost point either stalls or moves slightly northward from southern MO into Oklahoma and northwest Texas. Along the cold front, convection might still be going on Wednesday morning. During the day, destabilization would be happening ahead of the boundary across the Ohio Valley. Convective evolution is less certain further south. Nonetheless, an extremely humid and erratic airmass is anticipated. It is possible for thunderstorms to continue during the morning and continue. There is still some doubt about the specifics, but given the existence of a surface boundary, enough vertical shear, and a moist/unstable boundary layer, a corridor of severe potential seems likely. With this information, The Storm Prediction Center has sections of Kentucky, WKY along the Ohio River to the Cincinnati area, with a % chance of strong to severe storms on Wednesday.

WKU will close it's campus at 1 pm CDT

URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 204 NWS Storm Prediction Center Norman OK 1025 AM CDT Wed May 8 2024 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Southern Illinois Western Kentucky Southeastern Missouri * Effective this Wednesday morning and afternoon from 1025 AM until 500 PM CDT. * Primary threats include... A few tornadoes likely with a couple intense tornadoes possible Widespread large hail and scattered very large hail events to 3 inches in diameter likely Widespread damaging winds and isolated significant gusts to 80 mph likely SUMMARY...A supercell cluster in Missouri will likely persist through the afternoon while spreading east-southeastward toward southern Illinois, southeastern Missouri and western Kentucky, with some potential for additional storm development this afternoon. The environment will become more favorable for surface-based storms capable of producing tornadoes (a couple of which could be strong/EF2+), severe wind swaths up to 80 mph, and very large hail of 2-3 inches in diameter. The tornado watch area is approximately along and 45 statute miles north and south of a line from 5 miles south of Vichy MO to 40 miles east of Paducah KY. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings.

Some school systems are starting to dismiss schools early today.

The level 4 Moderate Risk area now includes Madisonville and Bowling Green.

Clouds are breaking here in Richmond.

I figured I would verify today's cloud cover later. Recall from yesterday's conference call that things will get lot worse if there is any clearing or sunshine. Today's covered time frame is from 10 a.m. to 8 p.m. EDT.

Here are two new maps. The first is a significant tornado map. A majority of significant tornadoes (F2 or greater damage) have been associated with STP values greater than 1 within an hour of their occurrence. You can see 4s and 5s for most of Kentucky. This next one is the violent tornado map. Research using observed soundings found that 0-3 km CAPE and 0-3 km lapse rate were notable discriminators of violent tornado environments (verses weak and/or significant tornado environments). The 0-3 km CAPE is what I shorten to 3cape when I talk about it in my posts. It is showing 5s and 6s. With the indicated numbers, both maps show. I fully expect tornado watches to be issued later today.

This new map shows the possible hail size. The SARS method returns a maximum expected hail report by matching existing environmental conditions to historic severe hail cases. These forecast maximum sizes are conditional on severe hail of any size occurring. This graphic shows the "best guess" maximum hail report.

This watch has expired.