Severe Thunderstorm Outlook: Friday, May 29, 2020

Scattered strong to severe thunderstorms are possible this afternoon as a pre-frontal disturbance and associated cold front encounter a moist, unstable atmosphere.

WHAT

Friday is off to a warm and humid start and that atmosphere will become increasingly prone to thunderstorm development by this afternoon.

A disturbance in the atmosphere and a cold front will both touch off rounds of thunderstorms this afternoon and evening. Modest amounts of wind energy in the atmosphere will organize some of these storms into small clusters capable of localized severe weather.

With only scattered storms expected, some areas will not see any thunderstorms and most areas will not see severe weather.

ALERTS EXPECTED

The following severe weather alerts are *predicted* to be issued later today:

– A Severe Thunderstorm WATCH (probable). A WATCH means that conditions are favorable for severe thunderstorms/tornadoes. Watches are issued over large areas for several hours at a time.

– Several Severe Thunderstorm WARNINGS (likely). Severe Thunderstorm Warnings are issued over small areas for around an hour at a time to warn of ongoing damaging winds or large hail.

– Tornado warnings and flash flood warnings are NOT expected today.

WHEN

Thunderstorms will start to develop around Noon and will continue in waves until the cold front moves through this evening. The severe threat should diminish by 7 PM as daytime heating is lost.

TEMPERATURES/DEWPOINTS

Temperatures will peak in the upper 70s to near 80 degrees Friday afternoon with dewpoints between 63-68 degrees. This will result in a moderately unstable airmass capable of supporting severe thunderstorms.

DAMAGING WINDS

Scattered reports of damaging winds are possible. Most of these reports will involve scattered trees and wires down, resulting in isolated power outages. Top Winds expected: 60-70 mph

LARGE HAIL

Scattered reports of large hail are expected. Most of these reports will be for hail sizes around or under 1”. Hail at these sizes can dent cars and damage plants. One or two reports of larger hail is possible.

TORNADOES

Tornadoes are not expected today, but the chance of a brief spin-up is slightly greater than zero.

FLASH FLOODING

Thunderstorms should move quickly and be small enough that 1-hour rain amounts will be under an inch. Minor flooding could occur if a single, flood-prone location sees multiple storms.

LIGHTNING

Frequent lightning is possible with the thunderstorms. All lightning is dangerous. Seek shelter once thunder is heard. Lightning can and often does strike out ahead or behind the primary storm, sometimes even when it is not yet raining. Even if a storm is nearby, but not moving in your direction, seek shelter if you hear thunder.

FORECAST CONFIDENCE

Medium- The modest wind fields will limit this event. Atmosphere disruption from previous or nearby storms may also inhibit a more widespread severe event. I strongly considered even lower threat classifications, but opted for a Level 2- Scattered event given the ample heat and moisture present and the risk for pockets of locally severe storms. Again, most areas will not see a severe thunderstorm today.

Thunderstorm events are never 100% certain though, and each event often has its own unique subtleties and surprises that will not become clear until the event unfolds. It remains impossible to pinpoint when, where, and with what intensity a thunderstorm will strike hours in advance.

FUTURE THUNDERSTORM OUTLOOK

– With a cool pattern setting up behind the front, there are no near-term severe weather threats after today.

FUTURE UPDATES

• A LIVE BLOG may be posted early this, pending how the situation evolves through the morning.

ADDITIONAL INFORMATION

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