This phase should be ready for heavy rainfall and possible flood concerns across the Mississippi River Valley and into the Midwest this weekend (Thursday-Friday). Favorable atmospheric compositions are poised to culminate to produce the aforementioned heavy rainfall, where we begin for the first time with a favorable upper-air pattern represented by the long-wave trench. large digs into the West Coast midweek. Downstream of this trench, divergence through short waves rotating through the bottom of the trench along with warm air ascent will side-by-side along the front of the surface, creating an enhanced lift from surface.
As this long-wave trough moves through, a low surface pressure will form forward boundaries. It is this system from which a cold front develops, where a new low pressure forms along it as we see the initial low enter the Northern Plains, where then the main new surface depression runs. across the Plains before turning to the Midwest/Atlantic Lake.
With higher-level divergence and low pressure on the surface riding an almost fixed cold front that bisects the central US, ahead and along the front, we see a low-level jet more than 60 knots (850mb) moving with the rich moisture of the Gulf northward from the South Deep Sea up to the Upper Midwest. We can then see this reflected through integrated steam transport that exhibits strong energy in the form of water vapor that will move northward, resulting in an environment favorable for heavy rain. This dynamic becoming parallel to the surface front can lead to training convection and slow-moving storms.
When we take these favorable components together, we see a 1-2″ wide (more locally) rain axis across the Mississippi River Valley up into the Lower Ohio River Valley. Regarding flash floods, while the overall model is somewhat progressive, local flash floods (especially in urban areas with poor drainage) are likely to occur when the synoptic diagram is established. There can be a difference in the amount of water falling in this area, but based on the meteorology behind it, you know heavy rainfall and floods are coming.
About the author
Hello! My name is Armando Salvadore and I am a Mississippi State graduate with a Bachelor of Professional Meteorology and an Activity Meteorologist working in the Private Sector. Stay tuned if you like technical, exotic, and general weather tweets! Also big on long-range forecasting as well! Twitter: @KaptMands