1/25 – The Chief’s “Heavy Rain, Flash Flooding” Thursday Morning Forecast
The primary concern through Saturday morning will be the threat of additional flash flooding from heavy rainfall and high rainfall rates. This concern is driven by two factors, very high atmospheric moisture content and the extremely favorable upper level dynamics that keep deep layer forcing in place through Saturday morning.
The primary driver of this favorable synoptic pattern is a persistent and slow moving longwave trough axis centered over the Rockies and Plains states. Additionally, the region will remain embedded beneath the right entrance region of a 100+ knot jet streak over this period further aiding in the deep and persistent upper level forcing expected.
Going into finer detail, three distinct features will slide through the region, and induce periods of heavier rainfall and a greater risk of additional flash flooding over the next 3 days. The first of these will slide through the area today. As this trough takes on a negative tilt and lifts to the northeast today, a convective line currently over east Texas will push east and sweep through the forecast area from early morning into mid-afternoon. This feature could support a couple of stronger storms within the convective line, but the severe potential is on the low end of the spectrum.
The next round of heavy rainfall is expected to take hold after midnight tonight and last through tomorrow afternoon. This rainfall will be driven by the passage of a weaker and more subtle disturbance. The third and final round of heavy rainfall and the greatest potential for strong to severe storms will take place late Friday night into Saturday morning. I fully expect to see a fast moving complex of t-storms with embedded bowing segments and the potential for a few tornadoes sweep through the area generally between midnight and Noon on Saturday.
Conditions will finally begin to improve Saturday afternoon into Saturday night as the longwave trough axis moves over the area. Drier and more stable air along with increasing subsidence as skies will gradually begin to clear.
