7/13 – The Chief’s “Rain Moving In” Wednesday Morning Forecast

A broad upper level high pressure system is centered near the 4-Corners region extends from Mexico to Canada and CA to around MS. This eastern portion of the ridge is rapidly eroding as an upper trough is digging south across the Great Lakes to the Appalachian Mountains. Adding more complexity to the setup, there’s also the Bermuda ridge extending into the far eastern Gulf of Mexico and a weakness between it and the ridge to the west. Abundant moisture exists along the western edge of the Bermuda ridge from the northern Gulf of Mexico…northeastward towards the Carolinas. There’s a fairly sharp gradient in moisture with well above average instability in the area.

Convection this morning should move in from the gulf and decrease slightly in coverage and intensity this afternoon. I will say confidence is a bit on the low side in regards to how much coverage we’ll see this afternoon. However, hourly rainfall rates could be quite intense…on the order of 3 to 5″ in an hour (though may only last for 30 minutes).

Thursday will just be a continuation of diurnally driven convection, mainly focused along the stalled frontal boundary that may sag southward across the area. As Friday comes, the boundary should effectively be dissipated and subsidence looks to creep in from the ridge still situated west of the region. This should result in a drop in coverage and overall intensity. A very stagnant pattern looks to set up across the country for the remainder of the forecast period. The upper ridge remains centered near AZ/NM with weakness in place over the eastern half of the country. Models suggest the trough will erode the eastern extent of the ridge over the area. This time of year, if there’s not a strong ridge right over the area, it’s going to be raining.