8/22 – Brittany’s “Wet Pattern Continues” Monday Evening Forecast

Tonight through Wednesday Night, little change in the ongoing pattern is expected through Wednesday night as a broadly diffluent westerly upper level pattern, a weak shortwave trough, and favorable jet stream dynamics all remain centered directly over the Lower Mississippi Valley and Southern Plains. This broad region of increased upper level forcing will interact with a deep tropical airmass residing across the Gulf South as indicated by anomalously high precipitable water values of 2.25 to 2.5 inches. Sounding profiles also indicate that the airmass is quite warm in the mid-levels, and this will support smaller drop sizes and much more efficient rainfall rates through the middle of the week. Rainfall rates could easily approach 3 to 4 inches per hour with the deepest convection. Through tomorrow night, mean storm motion will be sufficient at around 15 knots or close to 20 mph to inhibit flood potential. A few areas could see a good 1 to 2 inches of rainfall from these fast moving cells, but overall flooding concerns will be limited. However, as a weak meso-low currently over North Texas drifts toward the Lower Mississippi Valley on Wednesday, mean storm motion will drop to around 5 knots or around 7 to 8 mph. This slower storm motion will result in a much higher flood risk for Wednesday and Wednesday night, and a flash flood watch may be necessary. The other impact from the extensive cloud cover and rainfall through the period will be much well below average daytime highs and risk of some fog development in more inland areas each night. Highs should only warm into the lower to middle 80s each day.