Update on Sunday Storms
We still have the potential for some strong storms Sunday, so here is an update to the forecast.
SETUP
The setup depends on this nearby front. It is keeping warmer, wetter air in Kentuckiana with cooler, drier air on the other side of the front.
The Storm Prediction Center is including Louisville and our southern Indiana counties in a Slight Risk for severe weather. That is level 2 out of 5. A Marginal Risk covers the area from the river down toward the Kentucky parkways. That is level 1 out of 5. The pale green color represents a general risk of thunderstorms that are less likely to be severe.
INGREDIENTS
High temperatures will be in the upper 80s to near 90ยบ during the hottest part of the day. That is contingent upon seeing more sun during the day. If the day begins with more clouds than expected, we won't be quite as warm.
Dewpoints will also climb. This is how we show moisture in the air. Dewpoints in the lower 70s are very moist; you will notice the air feels humid Sunday. That humidity is necessary for storm development and it supports a heavy rain potential.
The heat and humidity help support storm development and factor in to how much energy those storms will have to use. The instability numbers above are high and they show an energetic atmosphere.
The one factor not lining up is the wind higher up in the atmosphere. This low-level wind map should show numbers above 30 mph to help support storm development. The good news here is this particular factor will inhibit tornadic development. It's always tough to say "zero tornado threat" since they can be so unpredictable, but Sunday's tornado threat is very low.
TIMING & THREATS
The uncertainty in this forecast comes down to what happens in the morning. A few of the forecast models suggest scattered rain will be possible in just west of our WDRB counties during the morning. That won't have much impact on your life, but morning rain nearby will hurt our chances for strong storms in the afternoon.
The window for rain and storms opens around 3 PM. The threats will be heavy downpours (likely to cause visibility problems if you're driving in them), hail, thunder/lightning, and gusty wind. The heavy downpours and hail are the main threats.
We will likely see this as one round of storms. The AdvanceTrak image below shows a second wave approaching around midnight, but by that point the earlier storms will have used up most of the available energy. This second wave you see should fall apart as it approaches our WDRB counties overnight Sunday into Monday.
Katie will be on WDRB in the Morning from 6-9 AM to share the latest data with you and show you what, if any, rain is setting up and how that impacts the evening storm chances. Then I will be back with you Sunday night to track any storms that do move through. Make sure you follow me on social media using the links below to receive up to the minute weather information as theses storms form, move through, and eventually leave us alone.
-Hannah Strong
Thanks for all you do to keep us updated on the weather. To keep our family safe this time of year in this storm and tornado season.
Posted by: RENAE Bailey | 05/20/2018 at 07:47 AM