9/6/26 Sunday 5:30 am
Well, the models came together with the latest two releases. For Monday, we’re back to isolated showers across the mid- and lower-elevation areas, with scattered showers above 8,800 feet, mostly from Purgatory to the north. Some of those showers could start overnight early Monday morning… But not soo fast!
That would be the proper forecast if I relied upon only one model parameter that I use to “view” future precipitation coverage.
But I am not sure that parameter has caught up with some of the other parameters I am looking at. The most impressive is the subtropical moisture now pointed directly at us like a firehose. This looks like a preview of what we would see in the winter of a big snow event if it happened in late December or early January!
Here are the PWAT anomalies for Monday morning. Again, PWAT measures the total amount of precipitation available to fall over an area if it fell all at once. Just as CAPE is fuel for thunderstorms, PWAT is fuel for ‘heavy rainers”. Remember yesterday I said the models indicated the deepest moisture would set up from St George to Salt Lake? That has changed…
GFS Regional View
European Regional View
I like these regional views because you can see the source. Here are the state maps.
GFS
European
Why is this a big deal? It is a big deal because we have not seen this high of PWAT values since July when we were getting decent “monsoonal type” totals. Here is what I will be watching for.
The timing: If this type of moisture arrives overnight, it would typically indicate a “stratiform” precipitation. Locals call these wetting rains. Moderate, consistent, near constant rain. What would be missing would be convection to turn that moisture into thunderstorms with the potential for heavy rain. Heavy cloud cover in the morning often makes it difficult for thunderstorms to form. If the moisture is delayed that could allow CAPE to increase prior to its arrival.
The other parameters: What the models are struggling with processing, is how quickly the moisture departs the area. What they are neglecting is our terrain that tends to hold on to pockets of the deep moisture. I call this residual moisture when we are dealing with rain, and “left overs” when we are talking about snow.
The model consensus is about as close between these two models as you can get. So keep checking back as I am monitoring the situation.