Sunday, May 17, 2015

Storm Outlook

Good Sunday morning. Brief thoughts about our upcoming storm chances.

First, some parts of the state got in on some hefty rain totals yesterday. In western Kentucky, some amounts were over 2". My house in Valley Station received 0.34".

Now, severe weather chances appear meager at best. Nonetheless, there will be a chance especially just ahead of an approaching cold front.

Best chances exist in far west Kentucky today into the overnight. Then for northeast Kentucky tomorrow. But again, low chances.

Then, more beautiful weather for the week ahead. Enjoy it.

�� MS

Monday, May 11, 2015

***NEW*** SQUALCON Index

Here is something new I developed exclusively for my blog, the SQUALCON Index. You have already heard of The Weather Channel's Dr. Greg Forbes and his TORCON Index. Well, this experimental index will help assign a numerical value for determining the strength of an expected squall line of thunderstorms (or non-thunderstorms).

There are many sources and references I use to establish the new index. Forecasts from numerical models like GFS and NAM, analogs, Storm Prediction Center, and other National Weather Service products are a few of the samples.

The SQUALCON Index is experimental because various challenges exist. For example, what defines a squall line? Does a derecho count or its cousins, the MCS and MCC, the cluster of storms that are defined as such based on size and shape?

Other questions and challenges may include whether to assign a value to the entire squall line or to a regional/local focus.

Below is the table with associated values and descriptors....

Scale of 1-5.

1 - Winds of 25 to 35 mph; scattered small twigs.
2 - Winds of 35 to 45 mph; numerous twigs and scattered small limbs.
3 - Winds of 45 to 55 mph; numerous small to medium-size limbs, isolated power outages.
4 - Winds of 55 to 65 mph; large limbs, susceptible trees uproot, widespread power outages.
5 - Winds > 65 mph; widespread damage to trees, power outages, shingles affected.

Applying this table to a regional focus, for later today, I've assigned a value of 3.3.

Therefore, I would expect a few severe reports, but this is not expected to be a widespread event, at least in our region.

Winds just above the surface should register between 44 and 62 mph. How much of that will translate to the surface? Not all of it, but we should expect winds of at least 40 - 50 mph on average with higher gusts. Also, the foliage will add extra weight to limbs, making them more prone to damage if wet.

MS

Saturday, April 25, 2015

Nowcast Severe Weather Vigilance

10:30pm...Final update...Primarily a large hail event. Reports of 2.50-3.00" size hail in Boyle county near Danville. Several rotating clusters but not many tornado reports.
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4:10pm...Filtered sunshine at my house and temperature is responding. Still in the low to mid 60's.
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2:00pm...My temperature is at 59...Pressure at 29.55"...Wind from NE.
New storms are beginning to break out in the warm sector near St Louis. These will be worth watching as this could mark the beginning of the severe outbreak. Temps across west KY into the 70's and dew point in the 60's. No change in my thinking for possible severe weather placement.
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12:20pm...Valley Station temperature at 54...Pressure at 29.63" and wind is from the NE.
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Good afternoon. The waiting game has begun. Location of the low is still well WNW of the region. The warm front is making some headway northeast. My calculations have low pressure tracking right along or just north of the Ohio River at Louisville. Up to 50 miles south of this feature along with its accompanying warm front will become a focal point for severe weather. This would be slightly north of my initial crosshairs. I'm still including the same areas of Campbellsville, E'town, and Columbia, but will include Rineyville, Radcliff, and Bardstown.

The 12z run of the NAM appears to have the low placed a little farther south of my thoughts but severe placement looks good.
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I will be reporting in a few times today, mainly updating where greatest data for severe weather resides. I may even get the chance to go and report from a location other than my home base in Valley Station.

At this time, my travels may take me to the Bernheim Forest, Clermont, Bardstown exit at I-65.

I will know something by later this morning or this afternoon.

MS

Friday, April 24, 2015

Severe Storms Looking More Likely

Severe Update
Still want to look at the next main run of the models compared with past systems.
Right now I have E'town, Campbellsville, Columbia, Upton, in the crosshairs. But, Bowling Green and points south into Tennessee could be hit particularly hard. Although some models are showing wobbling, the Ohio River could be the dividing line.
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Run to run of the NAM is consistent 00z to 12z), even though I would like to entertain the 00z run later this evening.

The NAM is leading the way suggesting a widespread severe weather event across Kentucky, Tennessee, northern MS and northern AL.

A recent NAM analog points to a March 28 1997 severe weather outbreak that killed at least 2 and injured 14 in Kentucky.

Of course, that does not mean it will happen again in the exact same fashion as that particular storm system then. After all, the 1997 weather map showed a Low pressure system several hundred miles north of where the upcoming low is forecast to trek. Nevertheless, most of the severe weather occurred along the warm front draped across Kentucky. And that is what is expected to happen in this instance.

In fact this scenario (the current one) has the potential to be more explosive than the 1997 storm system since the proximity of the low and thus the added spin in the atmosphere will be closer to Kentucky.

Severe storms are expected to develop in the vicinity of the warm front while the low pressure treks along its path. Dangerous setup indeed.

However, it is possible that the bulk of the severe weather, tornadoes, will be confined to southern KY, Tennessee, northern MS, and northern AL with the highest chance across Tennessee.

This storm system is still developing. I would not be surprised if Louisville gets in on at least a large hail threat. More updates later as more information becomes available.

MS