Another Major Cold Front On Friday ... Any Severe Weather Threat?
With another powerful front moving across the area late Friday, I wanted to address if this front could bring any severe storms to our area. Let's dive right into this discussion by looking at the current SPC forecast.
Storm Prediction Center Severe Weather Risk Late Friday
SPC has placed no locations in the US in a severe weather risk on Friday. Their discussion mentions the lack of moisture return as the main reason they don't feel severe weather is possible in our area.
Severe Weather Discussion For Friday
Severe storms require three main ingredients ... instability, wind energy, and strong forcing. When each of these three ingredients are not present, we just don't get organized severe weather in our area.
I am going to approach this blog a little different today because this severe weather forecast is not the most difficult forecast ever. I say this quite often, but it is important to note that instability is a feature that is non-negotiable for severe weather. Instability is simply the fuel that the atmosphere uses to create t-storms. Without fuel, there are no t-storms. Let's start by looking at dewpoints.
Dewpoints Late Friday
Notice the 60+ degree dewpoints never make it north of southern Kentucky. This is important because it means instability values should be low.
One would expect low instability values with the low dewpoints on Friday. The GFS and NAM show just that.
NAM Instability Late Friday
Notice the NAM basically shows no instability whatsoever in our region on Friday.
GFS Instability Late Friday
The GFS is a little more generous but not much. The GFS only shows instability values near 250 units in our area on Friday.
My Thoughts On Severe Weather Potential Friday
Rather than drawing out this blog for no reason, I wanted to get right to the point. The instability is pathetic on Friday and this means the organized severe weather threat looks tiny right now. I don't really see a way the moisture can return before the front arrives late Friday, so I really don't see this forecast changing at this point. The GFS which is the more robust of the two models only show scattered showers late Friday night.
It doesn't look like there is any concern for severe weather late Friday based on the latest data, but I will continue to watch this front closely.
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do you expect most of the rain gone by early saturday morning? (only a 3-6 hr precip window late friday?)
Posted by: chrisb | 09/18/2012 at 04:51 PM
chrisb, as things stand I do expect it to be gone.
Posted by: Marc Weinberg | 09/18/2012 at 04:52 PM