Severe Weather Potential With Our Storm System Friday/Saturday?
Coming off a strong cold front last week, a lot of people are wonder if this front Friday/Saturday could produce the same type of severe weather we saw last week. In this blog, I will be discussing that severe weather threat and if this is something you need to be concerned about.
Storm Prediction Center Severe Weather Outlook
The Storm Prediction has addressed the cold front moving across our area on Friday in their latest outlooks. Let's get right to that outlook.
SPC Categorical Severe Weather Risk For Friday/Saturday
Notice SPC has no slight risk for any part of our area late Friday/Saturday.
In addition, SPC does discuss the potential for severe weather in our area later this week in their long range severe weather discussion.
"DAYS 4-6 /FRIDAY-SUNDAY/...MODEL CONSENSUS IS THAT A COMPACT SHORTWAVE TROUGH WILL MOVE FROM THE UPPER MS VALLEY FRIDAY TO THE NERN U.S. BY 12Z MONDAY. THIS VORT MAX WILL EVENTUALLY INTERCEPT A COLD FRONT OVER THE OH VALLEY REGION BEFORE CONTINUING INTO THE NERN STATES SUNDAY. LIMITED MOISTURE RETURN THROUGH NRN EXTENSION OF PRE-FRONTAL WARM SECTOR SHOULD MAINTAIN LOW PROSPECTS FOR SEVERE WEATHER."
SPC also had no risk of severe weather on Friday during their Tuesday & Wednesday forecasts last week, but I disagreed with those forecasts and we all know the storms that did fire. I think it is a good idea for us to analyze that severe weather risk ourselves.
Severe Weather Discussion Later This Week
Before we dive full force into our severe weather evaluation, I want to quickly refresh your memory on the severe weather ingredients I look for when evaluating a severe weather threat.
The forcing Friday/Saturday comes from a front that will be moving into our area. The front last week was titanic, but this front is worth about 7 degrees of a cool down so it is not near as strong.
Forcing looks ok, but not that great.
The instability late Friday doesn't look that good either. The reason is that we won't have near the moisture in place that we saw last week. If you recall, we had the moist air mass from Isaac sitting in place waiting for that front. On Friday, the data suggests very weak instability and the GFS shows nearly nothing.
GFS Instability Late Friday
Notice the instability is basically non-existent on the GFS.
NAM Instability Late Friday
Notice the NAM only shows a very weak 500 - 750 units of instability late Friday.
Instability looks very weak on Friday and the storms would have terrible fuel to work with.
The wind energy is a critical component for severe weather because it is basically the the engine for storms. When I was a storm chaser doing research, we found that a minimum of 35 knot / 40 mph winds were necessary to support organized severe weather. There are a few exceptions to this rule, but not a lot.
GFS Winds 6 Miles Above The Ground Late Friday
Notice the GFS shows mid level flow of about 30 knots / 33 mph in the northern part of our area, but that wind never really makes it very far south.
My Thoughts On Our Severe Weather Threat On Friday
The latest data suggest it is more likely that the front will move across the area late Friday meaning the rain chances are higher Friday than Saturday. The moisture return will not be good at all on this system leaving me with only a 30% - 40% chance for our area late Friday. The lack of moisture return means instability will be nearly non-existent. The wind energy is below the critical threshold I look for to support organized severe weather and the forcing is nothing special. All the data shows a low to no threat of severe weather on Friday and I think SPC has an accurate forecast with respect to this system. I support no severe weather risk placed in our area and I think rain is not even a guarantee on this system. All the data suggest scattered showers and t-storms at best with minimal to no severe weather threat.
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