Pattern Change Starts Later Today

6/17/22 Friday 5 am
For the “I will believe it when I see it crowd” it looks like the much-touted pattern change bringing sub-tropical moisture into the area is definitely going to happen. The models have kept a wide range of totals for the last several days, with the GFS and Canadian models being on the lower ends–but still several categories higher than long-term (120+ years) climatological norms.
Regarding the lower totals from the GFS and Canadian, in my experience, the models are shutting off the precipitation too early. Let’s say on the very conservative side, we have “just” an inch or so of rainfall over the next couple of days. Just because the spigot turns off (sub-tropical flow),  You have to take into consideration that there will be “leftovers” in the atmosphere in addition to the wet ground evaporating back into the atmosphere which will cause afternoon thunderstorms for a few days next week.
I have pointed this out many times in the past. Prolonged heavy snow makes it easier for more snow to develop, and prolonged heavy rains attract more rains. That is another reason I said we may look back at this event the first week or so of July and say “I guess that was the start of the monsoon”.
You tuned in this morning for the latest totals, so let’s get to that. These were the latest totals at the time of writing (3:45 am). I cropped the maps for “game time” viewing. If you are new, this is what I usually do immediately prior to a heavy precipitation event.
NOAA/Storm Prediction Center’s WPC high resolution
I will do an update on CAPE after 9 am. I still have some concerns about thunderstorm development this afternoon. I will also post an afternoon update with the latest model data. Thanks for following and supporting the site!

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