nWo

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.

Just received this from the NWS-Louisville office:

URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 201 NWS Storm Prediction Center Norman OK 155 AM CDT Wed May 8 2024 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Extreme southern Illinois Western and west-central Kentucky Extreme southeastern Missouri * Effective this Wednesday morning from 155 AM until 600 AM CDT. * Primary threats include... A couple tornadoes possible Isolated damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...A few more hours of severe-thunderstorm threat remains across this region in a favorable environment for damaging gusts and tornado potential, but messy storm modes. The tornado watch area is approximately along and 35 statute miles north and south of a line from 40 miles west southwest of Paducah KY to 20 miles north northeast of Bowling Green KY. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). 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.

From sections of the Ohio, Tennessee, and mid-Mississippi valleys into the southern Plains, numerous severe thunderstorms seem likely on Wednesday. All extreme risks are possible, including as tornadoes, large to extremely large hail, and possibly extremely damaging winds. There could be some powerful tornadoes. There is still a chance for a complicated but potentially large severe weather episode throughout a large area that stretches from the ArkLaTex area into portions of the mid-MS, OH, and TN Valleys. There will be a chance of strong tornadoes, large to gigantic hail, and destructive winds in broad swaths. All severe hazards will be possible. This morning, a highly moist and unstable warm sector is expected to be present across portions of Oklahoma and Texas, as well as extend eastward and southward along a warm front into the Tennessee, lower Ohio, and mid-Mississippi valleys. Through the day and into the evening, a potentially volatile severe thunderstorm environment will be supported by moderate to strong deep-layer shear and strong to extreme instability, which is enhanced by a plume of midlevel lapse rates migrating eastward from the Plains. Based on these data, the Storm Prediction Center has designated a portion of Kentucky as level 4 Moderate Risk, which is southwest of a line that runs from just south of Madisonville to Bowling Green. Level 3 Enhanced Risk of Severe Storms covers the remaining portion of the state. Except for the Cincinnati/NKY area.

The sun is already starting to come back out here in Richmond.

Everyone should be weather-aware later today into early Thursday morning. Have more than one way to get information for your area. This will be our weather motto: FOREWARNED is FOREARMED. (If you know about a problem or situation in advance, you will be able to deal with it when you need to.)

One thing I neglected to mention in my summary of the conference call was the flood threat. There is a marginal threat of flooding today. There is a slight risk of flooding tomorrow. Today Tomorrow

Here is a quick summary of the conference call I just got off with the NWS-Louisville office: Those under a supercell later today may see hail the size of golf balls. The individual cells should start to fire later today as a warm front lifts and travels into Kentucky. Keep your guard up despite the current cloud cover. Four rounds of powerful storms are possible as the atmosphere recovers, which could happen later today and into overnight. Next, Wednesday night and Wednesday afternoon. For tomorrow, we need cloud cover to keep the real threat contained. The more sunshine there is, the more dangerous tornadoes are. It is all on the table for tomorrow.

I would favor having western Kentucky added to the Enhanced Area. There is a remote possibility that it could become a level 4 Moderate Risk. I recently examined the most recent HRRR for the significant tornado parameter. Right now, it is at 5.5 out of 10. Most large tornadoes of F2 or higher have been linked to STP values greater than 1. Now, this does not imply that one will occur; rather, it indicates that the right circumstances exist for large tornadoes to form.

There is currently a severe threat over the region that is multifaceted and multi-episode. First, there was a continuous band of strong to isolated severe thunderstorms that could be seen over parts of northern Arkansas, southwestward over southeastern Missouri, and across areas of Illinois. The bigger worry is that thunderstorms that are expected to form this afternoon along or ahead of the cold front may subsequently impact on a warm, moist airflow corridor that is behind the morning's activity and provides favorable heating. Under a plume of steepening midlevel lapse rates, which is a remnant of somewhat modified dry air above and extending across the area of low-level destabilization, surface dewpoints should rebound into the mid-upper 60s F. Conditions suitable for supercells to form and remain relatively distinct should result from the superposition of these processes; hodographs (Sounding Analogs) in the lowest several kilometers appear favorable for tornadoes (some possibly strong).

From sections of the southern Plains into the mid-Mississippi, Ohio, and Tennessee Valleys, scattered to numerous severe thunderstorms are likely on Wednesday. There should be all of the severe risks, such as tornadoes, large hail, and damaging winds. There may be strong tornadoes among them. The northern extension of the more severe probabilities has been somewhat reduced in this area, based on the most recent guidance trends that indicate the warm front stalling or not moving as much northward into the Ohio Valley. If not, very large hail is likely, with the first clusters developing along the warm and cold fronts. This could happen across Missouri as early as mid-morning on Wednesday. By early Wednesday afternoon, more supercell development may also happen along or near the warm front, spanning portions of the mid-MS Valley and into the lower OH Valley. With enough 0–1 km shear to sustain low-level updraft rotation, there is also a risk of tornadoes with this warm-frontal activity in addition to the very large hail hazard. Considering the prediction, several of these tornadoes may be strong. An increasing threat for severe/damaging winds is also apparent through the late afternoon, and likely continues into at least the early evening, as convection should attempt to grow upscale into one or more intense bowing clusters. With that said, convective evolution is somewhat uncertain, and attempting to pinpoint areas of greater severe wind potential remains difficult. Given this forecast, the Storm Prediction Center now has almost the entire state of Kentucky under a level 3 Enhance Risk Area. For now the greatest tornado threat is west of I-75 and south of I-64. Remember, though that any severe weather mode will be possible in a level 3 area.