March 19 Severe Weather Forecast Discussion

This is an image of the 4-8 day probability for severe weather.

FORECAST DISCUSSION

The image above is the risk for severe weather 30% or above in the next 4-8 days. When you get a 30% risk, you begin to get into some hot water in the weather world. 30% basically means severe weather will happen and it could happen with strength.

Day 4 (D4), we see a risk area over the Plains into the Midwest. It is shaped in the form a bow echo storm would usually have.

That said, The Weather Centre is definitely eyeing the possibility of a bow echo storm. Should a bow echo develop, it would have potential to cause damaging winds.

The 6z GFS is even pointing at the prospect for a squall line after reviewing the Best Lifted Index images. However, there will be the Canadian air mass that will fight quite hard to keep the severe weather away from the Great Lakes and Ohio Valley. However, that air mass suddenly retreats, leaving the door open for the squall line to come through. However, it does weaken as it comes through, which many of the models have shown.

In Day 5, that squall line suddenly gets a second wind and fires up with more instability in the Ohio Valley. I am unsure of what type of storm it will be, but likely not a squall line or a bow echo. I would anticipate pop-up storms, possibly coming together to form a multi-cell storm complex.

Severe Weather Situation #007

This is Severe Weather Situation #007.

Severe Thunderstorms are forecast to occur this morning into this afternoon in the Oklahoma area.

At 8:09pm CDT... Radar detected thunderstorms developing in the Oklahoma Panhandle. The Weather Centre also indicated high Lifted Index values of -8 in a portion of Oklahoma (The 2nd image down).

A slight risk area has been warranted in the Oklahoma area due to the risk of these storms encountering this unstable atmosphere (First image).

Specific Concerns...

These storms are pop-up storms and will be hard to predict. However, unless you live in the area in the 2nd image down where the -8 circle is, you should be safe. But do keep an eye to the sky if you live in the -6 range.

March 19 9z RUC Best Lifted Index Forecast Discussion

This is an image of right now from the 9z RUC model.

FORECAST DISCUSSION

Weak area of moderate instability in Central Oklahoma providing breeding ground for strong to severe thunderstorms this morning into the afternoon.

At this time, thunderstorms have developed in West Oklahoma and are now moving east into Central Oklahoma.

Will definitely have to monitor the situation for several factors.

One is the image above of the Lifted Index. With values in the -8 range, the atmosphere is at least moderately unstable.

Another factor is Lapse Rate values. Right now at the time of this issuance, Lapse Rates were in the 8-8.5 region in Oklahoma. This provides more evidence of an unstable atmosphere.

This will be a situation to watch, and a Severe Weather Situation will be issued next.

Severe Weather Situation #006 Assessment

The Severe Weather Situation for this evening is now cancelled as the storms are no longer severe.

This is the follow-up assessment to this Severe Weather Situation.

Q and A

Why didn't the National Weather Service predict this?

Unless they were carefully tracking all the parameters, pop-up severe storms are extremely difficult to predict, let alone where. However, there were hints that severe weather could break out.

Hint: A cold front was moving in to the area.

Hint: Best Lifted Index reached levels of -8, which is considered fairly to moderate unstable.

I do feel the National Weather Service could have upped the chances of thunderstorms rather than 10-20%, but their forecast is their forecast, and I will not dispute it.

March 18 RUC Best Lifted Index Forecast Discussion

This is an image of the 00z RUC model Best Lifted Index 12 hours out.

FORECAST DISCUSSION

Instability will be present across the South Central US tonight into tomorrow morning. Due to this instability, I would not be surprised to see some spotty strong to severe storms along a cold front and low pressure system currently working their way across the US.

With index numbers down to -6, the atmosphere will be stable, but this is morning after all. Tonight's index numbers go as low as -8, which is considered fairly to moderately unstable. In summary, I do expect at least some more storms to develop, likely pop-up storms and not in an organized pattern.

With values in the 10-15 range above 0 up in the Midwest, I certainly don't expect much of anything to occur tonight into tomorrow morning.

That's all for tonight, keep an eye out for more discussions tomorrow.