Storm Prediction Center Update: 6/21/17

The Storm Prediction Center (SPC) Outlook shows some severe threats this week, primarily associated with Tropical Storm Cindy as well as a shortwave trough in the Great Plains.

Day 1: Slight Risk

There are two Slight Risks issued today; one is over a wide swath of the center of the country, and one is associated with Tropical Storm Cindy.

The Tropical Storm Cindy Slight Risk area also has a 5% Tornado Threat Ring, while there is a 2% Tornado Threat Ring in the northern Great Plains:

Tropical Storm Cindy is expected to make landfall southwest of Lake Charles this evening, and will continue to wreak havoc on the Gulf Coast.  That is obviously the primary threat today.

However, there is still a Slight Risk for the Great Plains.  This threat is based on a shortwave trough and adequate moisture that have created a few bowing segments and embedded supercell clusters through this area.  The higher tornado threat is in the north, where a small jetstreak is ejecting and creating stronger deep-layer shear profiles.


Day 2: Marginal Risk

Day 2 is very similar to Day 1.


We still have the remnants of Tropical Storm Cindy pushing north and inland.  While this system is weakening over land, it will still be a mess to deal with, and may spawn a few tornadoes across Louisiana and western Mississippi.

The Great Plains threat will be similar to Day 1, with a shortwave trough and adequate moisture (dewpoints reaching 60 F, in this case).  There will also be a cold front that will extend down from Manitoba as a closed low treks east.  This cold front may provide some additional lift, leading to squall lines and bowing segments.  There may be adequate shear to support a few supercells, however.


Day 3:  Slight Risk

There are two Slight Risk areas for Day 3.

The New England threat will be based on the advancing cold front from Canada ahead of the trough.  In this region, bulk shear will reach 40 kts, which could support a few rotating storms.

In the south, there will be the tail end of the cold front and its interaction with the remnants of Tropical Storm Cindy.  It may be a little early to tell how this region will develop, but I will be watching this system.


Day 4-8:  Predictability Too Low

There is some strong to severe storms possible in Virginia on Day 4, though the models are disagreeing on the timing of the components.  Day 5-6 show a chance of severe weather in the Great Plains, though, once again, the models are in disagreement with when and where this will happen.

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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