SPC Outlooks: 8/17/15 to 8/24/15

It’s time to look at the potential severe weather threats for the week.

Day 1: For the remainder of the day, the primary focus of severe weather is over eastern Colorado. The SPC has had a Slight Risk on them all day, and a Tornado Watch for this afternoon and evening. The highest risk was east of the Front Range where upslope flow crossed into an area with steep mid-level lapse rates. The threat was enhanced by a shortwave trough that is digging southward into Colorado. While those conditions are still true, an elevated threat of tornadoes is present anywhere ongoing convection intersects outflow boundaries or other micro-scale boundaries.

Day 2: The SPC has issued a Slight Risk for a large area in the eastern Great Plains and The Missouri River Valley. The shortwave trough will continue eastward and continue to deepen. Low and mid-level cyclogenesis is probable ahead of the shortwave trough, and this plus strong forcing will likely lead to storms in this area. Farther south and west, into Oklahoma, the moisture plume from monsoonal flow in the southwest may contribute to storms as well.

Day 3: The SPC has issued a Slight Risk for parts of the Great Lakes region. The trough will continue eastward, though it will take on a negative tilt and begin to lift out of the country. However, a strong, ongoing low (that developed in Day 2) will move into the Great Lakes area, and its trailing cold front will provide plenty of forcing for storm development. However, the models begin to diverge concerning the timing of this feature.

Day 4: SPC has this day categorized as “Predictability Too Low.” The timing and location of smaller scale features becomes less and less predictable as time progresses. The upper low and trough will have moved northeast out of the country, meaning the dominant feature is the trailing cold front. However, the location of this was uncertain on Day 3, and varies by as much as 12 hours by Day 4.

Day 5: SPC has this day categorized as “Predictability Too Low.” While the trailing cold front has moved on and has little impact on the United States, another trough is forecasted to begin digging south into the Northern Rockies. At the larger scale, the models agree, but placing the small scale cyclogenesis is much more unpredictable.

Day 6: SPC has this day categorized as “Predictability Too Low.” Day 6 will be an extension of Day 5. As the trough deepens, there will be another severe weather threat, though the placement and timing are uncertain.

Day 7: SPC has this day categorized as “Predictability Too Low.” Today’s prediction hinges heavily on the location of the trough.

Day 8: SPC has this day categorized as “Predictability Too Low.” See Day 7.

Thank you for reading this post.

All data and images are from the Storm Prediction Center Website.


About highplainschasing

This blog is about my tales in storm chasing. My name is Seth Price and I am an instrumentation instructor at New Mexico Tech. My amateur radio call sign is N3MRA.
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