Monday, June 29, 2015

Tornado Watch...Why?

A low-end Tornado Watch is now in effect for locations primarily along and east of Interstate 65. I have not heard any rumbles of thunder with a couple of these small cells.

Hail could become a threat in the stronger storms. Since low pressure has created some spin in the atmosphere and surface heating is intensifying, there is a small chance for tornadoes.

Is it a good call? Well, the SPC  knows the dynamics of what variables constitute a Watch. Admittedly, I think it's overdone. But, I am all for safety and it only takes one brief spin-up to verify their reasoning.

Pay close attention to the skies and have access to local media or your programmed weather radio.

MS

Friday, June 26, 2015

Analogs Favor Severe Weather

UPDATE 7:00pm edt
Finally received confirmation of a 93 mph gust and tree damage around the Mesonet site near Bowling Green. I say it was a brief spinup or an awesome microburst. I would hope NWS investigates the damage because there was rotation before the storm hit the area and there was large hail just north of the site.
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UPDATE 4:55pm edt
Strong and severe thunderstorms approaching Louisville. Expect winds of 35-45 mph on average.

No confirmation on 92mph wind gust near Bowling Green. Did get reports of 1" hail. Unless there was a brief spinup, that gust could be an error.
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UPDATE 4:25pm edt
92 mph wind gust from Mesonet site from Warren County near Bowling Green. Waiting for confirmation.
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As part of my tool pack for the SQUALCON Index, I use the top 15 analogs, find the 5 closest ones that fit our region and average them out by rank.

Lately, our region has been averaging about 9.0 or a little higher. If we had the top 5 analogs in our region, you would add 1, 2, 3, 4, 5 and the sum would be 15. Divide that by 5 and get an average of 3, which is the most bullish scenario for severe weather coverage. So, 9.0 is somewhat low.

However, my latest calculations have Kentucky in the crosshairs for severe weather in 5 of the top 7 analogs for an average of 4.8.

This is a very bullish sign for widespread severe weather. As long as the atmosphere does not get worked over too much from earlier convection, we are primed for a severe weather episode that includes the whole arsenal of damaging storms, yes, including tornadoes.

MS

Thursday, June 25, 2015

SQUALCON Watch

UPDATE 4:00PM
Dewpoint reading at my house is running between 72 and 73 degrees...parts of western KY coming in at 77 degrees. Ick! Heat index in Bowling Green at 102 according to Mesonet site.
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UPDATE 2:30PM
Cloud cover limiting convective potential near Louisville...Short-range models are in pretty good agreement that only scattered coverage of storms will be with us this afternoon. Tonight, around or after 11pm edt, storms will begin impacting the region from the west-northwest. Heavy rain potential exists along with lightning chances and high winds. Cannot tell if severe potential will be favorable, but since storms will be most prevalent after dark, only an MCS type storm may be able to generate enough umph to bring about isolated severe reports. Otherwise, heavy thunderstorms look to be the case.
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UPDATE 11:00AM
SPC downgrades severe risk to slight for today...now includes slight risk for Louisville on Friday. I am still keeping my SQUALCON Index heightened today/night, only shaving off a miniscule amount at 3.6 for the region with Louisville at the center of the region. I will include numbers for Friday later tonight.
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It's still several hours away, but residents should prepare for a potential damaging wind threat. SPC places parts of the region of north central Kentucky in an enhanced risk for severe weather.

In addition, while analogs do not support a widespread severe weather outbreak, I have calculated an average number of 9.0 / 13 based on the 5 top analogs that involve our region.

That is still rather low, but closer to a low-end moderate risk. I would rather see a value of 8.0 before putting us in a moderate risk category ( 3 being the most bullish and 13 the least bullish).

Of course, the usual suspect that could hinder severe development is cloud debris that may preclude aggressive storm initiation at the best time in the afternoon. Nevertheless, for the Thursday time frame, I am using the SQUALCON Index. Any value above 3.0 indicates an increasing likelihood for severe weather.

I have calculated a 3.7 for the region, which is one of the highest values I have assigned to the Louisville region this season, which encompasses Hancock County in the west to Fayette County in the east and LaRue County to the south.

I may have to use the SQUALCON Index again for Friday.

MS

Monday, June 22, 2015

High Winds Cranking Across Upper Midwest

UPDATE 10:40 am edt
Parts of Iowa reporting damage to buildings including a roof blown off of a school. 60-90 mph winds in Independence, IA. A wind report of 93.9 mph in the area. I have seen observations of 68 and 74 mph in non-thunderstorm winds in southern MN.
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Despite the heavy rains, intense lightning for some, and damaging winds for others in our region, check out some of the weather conditions in parts of southern Minnesota, northern Iowa, and eastern South Dakota.

High wind warnings are in effect for a couple more hours. These are non-thunderstorm winds wrapping in behind a small scale low pressure area producing sustained 40-55 mph winds with gusts near 70 mph.

A recent observation at Worthington, MN, close to the southern state line shared with Iowa in the southwest part of Minnesota, had a sustained wind of 56 mph and gusts of 74 mph. Partly cloudy skies were noted.

True, there are mean storms ahead of the system, but the most likely scenario for damaging winds exist as low pressure scoots by.

This is only a brief event lasting a few hours but how remarkable a small scale storm system like this can have such a dramatic impact on one's weather. Definitely not something I would like to wake up to.

MS