Friday, October 17, 2014

*SPECIAL* - A Look at the Discrepancies Between the NWS Official Reporting Sites and Nearby Mesonet Sites

Subjects: Kentucky NWS Official Reporting Sites
                Adjacent Kentucky Mesonet Sites
Time Period: June - September 2014
Topic: Number of 90 degree days

First, let me throw several sets of numbers at you. The data you are about to see is a sampling of the number of this year's 90 degree days for adjacent or nearby Mesonet sites compared to that of the 'official' National Weather Service sites.

Ky Mesonet Caldwell County 12 days
Ky Mesonet Graves County 19 days
Ky Mesonet Marshall County 19 days
NWS Paducah   43 days

Ky Mesonet Oldham County 4 days
Ky Mesonet Shelby County 1 day
NWS Louisville  35 days

Ky Mesonet McCreary County 1 day
Ky Mesonet Casey County 2 days
NWS London  17 days

Ky Mesonet Fayette County 1 day
Ky Mesonet Madison County 1 day
Ky Mesonet Clark County 6 days
Ky Mesonet Nicholas County 12 days
Ky Mesonet Lincoln County 10
NWS Lexington  21 days

Ky Mesonet Barren County 16 days
Ky Mesonet Warren County(1) 27 days
Ky Mesonet Warren County(2) 36 days
NWS Bowling Green  41 days

Ky Mesonet Owsley County 5 days
Ky Mesonet Knott County 4 days
Ky Mesonet Breathitt County 7 days
NWS Jackson  7 days

Ky Mesonet Franklin County 4 days
NWS Frankfort  13 days

Remember, these numbers are for adjacent counties, sometimes within the same county, and nearest Mesonet sites in relation to the 'official' NWS sites. Except for the NWS at Jackson, all of the other 'official' NWS sites show large variations in the number of 90 degree days compared to other reporting stations of the Kentucky Mesonet.

I think you would agree that we need good continuity of data to provide fair representation for the state of Kentucky's climatological record. Of course, this does not have to pertain to the number of 90 degree days only.

Most, if not all, of Kentucky's NWS official reporting stations are located at airports. Now, each site must follow stringent guidelines about siting and exposure of equipment.

For example, the siting of temperature sensors should include locating them at least 100 feet from any extensive concrete or paved areas, or 500 feet from any building or area that might influence readings. Avoid swampy locations where water collects or artificial irrigation areas. Keep grass or vegetation within 100 feet of the site cut to less than 10" in height and provide unobstructed flow of air.

Special attention is to be given to any changes made in the station sensor that could affect data and necessitate the requirement for a temperature comparison routine.

Recently, complaints about the Lexington temperature sensor had technicians busy. I corresponded with one of the engineers and he told me they had conducted numerous tests and that the sensor met quality standards. Local media were invited to have their cameras rolling as to demonstrate the calibration process and show that the equipment was within appropriate quality assurance standards.

Yet, Lexington's sensor has altered things a little bit. But not as much as one thinks. Comparing data from this year to the same time last year (when the old sensor was still in play) Lexington NWS 2014 average high temperatures were 3.05 degrees higher than the nearby Mesonet site versus 2.65 degrees higher last year under the old sensor. But, this is compared to the Mesonet site a few miles away. Keep in mind,  the Lexington NWS recorded 21 days in the 90's. The Mesonet site recorded just 1 during the year 2014. Last year, Lexington NWS saw 17 days in the 90's. The Mesonet site again only recorded 1 day.

As a side thought, I do not understand why 'official' records should be kept at an airport, as this is not climatologically indicative or reflective of the surrounding area, which includes much more grass, trees, and a lot less concrete (attention NWS Louisville @ the Airport).

Well, what about the Mesonet sites? By analyzing the data above, it seems apparent that their data and means of collecting that data follow a different set of standards or guidelines. But, do they?

At least three times a year, technicians visit and perform required tasks to make sure the equipment still meets manufacturer's specifications. Any faulty sensor or equipment is sent back to the laboratory to be either recalibrated or decommissioned.

I wonder about the sites themselves, though. Why is there so much of a temperature variation from site to site, especially those in close proximity to one another?

For example, in Warren County, one site registered 36 days of at least 90 degrees. A few miles away, another site registered 27 days. For me, that's significant. One has to wonder if the site is not right for the equipment or the methods being followed for the equipment's data monitoring is substandard.

If the equipment's sensors fall within the range of quality standards, then there has to be either a site issue or a methodology issue when it comes to the various Mesonet sites across the commonwealth.

I do not know what it's going to take to get someone's attention to make sure that the data collected is fairly representative and contributes to the overall homogeneity reflecting the current affairs of our climate. But when one sees the wide discrepancy between each of the sites I presented to you, would you accept these numbers as legitimate?

And this is just one aspect that I'm looking at, the number of 90 degree days. What about the other measurements that are taken? Wind, precipitation, dewpoint readings? Are these fairly representative when we compare the official data versus the Mesonet sites. Well, I may investigate those as well. But, I think this will do for now.



Monday, October 13, 2014

Following Severe Storm Reports...and a Blizzard?

8:30pm Update
Extensive line of thunderstorm warnings west of Louisville. At this time, the supercell with a history of funnel and touchdowns is showing signs of dissipating. This was the same cell that started pretty far south and tracked through Clarksville TN into southwest KY and produced amazing tornado signatures. Latest radar image shows no signature. I would not let my guard down if I were you.

Damage reports are coming in from western KY. Paducah is reporting a roof off of a building.
In addition, other communities such as La Center in Ballard County have downed trees and lines.
Check out the following storm report below....

Wickliffe actually reported thunderstorm damage with fallen trees, even some blocking roadways. That was a separate report. No reports of tornadoes yet. However, Watch boxes are lined up all the way to the I-65 corridor.

More updates later..



327 PM CDT MON OCT 13 2014


..TIME......EVENT...  ...CITY LOCATION...  ...LAT.LON...

..DATE.......MAG....   ..COUNTY LOCATION..ST....SOURCE....



0325 PM     BLIZZARD     4 E WICKLIFFE      36.97N 89.01W

10/13/2014               BALLARD       KY   TRAINED SPOTTER



Sunday, October 12, 2014

Updated Severe Weather Forecast

Both the GFS and the NAM are displaying severe weather breaking out along a squall impacting Arkansas, southeast Missouri, western Tennessee, western Mississippi, and possibly far western Kentucky tomorrow afternoon and evening.

Widespread destructive winds exceeding 70mph at times along with possible brief spin-ups are expected anywhere along this line.

It is still indeterminable if central and eastern parts of Kentucky will be affected by the strength of this line, as it appears it will lose some of its high energy punch after 10pm eastern daylight time as the entire line becomes more of a flooding threat with 2" amounts common in several locations. Amounts of up to 4" are possible and may give way to high water issues along creeks and streams.

Still, I cannot rule out isolated wind damage/brief tornadoes along this line for central and eastern Kentucky. The longer we get into the night, though, the lesser the danger of destructive winds and tornadoes.

This is just a preliminary outlook based on my opinion and does not reflect the views of the National Weather Service or other AMS Meteorologist.

Updates likely tomorrow....


Storm Weary Residents Brace For More Possible Severe Weather Monday-Tuesday

The current, prolonged active weather pattern is about to come to a climactic conclusion. Following a week of quick-hitting tornadoes and damaging microburst winds along with very heavy rainfall, a vigorous storm system appears to be taking shape and aiming for us in the Ohio Valley.

What does that mean for many of us? At least another round of possible severe weather. Indications are pointing to a widespread severe weather event at least for western KY. At this time, there has been no official mention of a widespread event for central and eastern parts yet, but a real possibility exists. You know the song and dance. We will have to wait for computer models to chew on the data and spit out some possibilities.

In a situation like this, I like to look at analogs, or past similar weather patterns/systems that align with the current thinking of the approaching storm system.

The NAM analogs for the period showed a few solutions.

One was confining the widespread severe weather south of the region, say, from Tennessee into Alabama and Mississippi.

Another showed the bulk of the severe weather hitting parts of southern Indiana.

Then, there was a particular troubling analog that showed central Kentucky getting hammered with widespread wind damage. This analog was November 9-10, 2000. Numerous reports of winds exceeding 70 mph and isolated tornadoes occurred along the main squall as it raced across Kentucky.

Let's see how the models digest the data. But be prepared for another round of severe weather. This has the look of a potentially widespread event that, in my opinion, combines all three solutions above, from Indiana through Kentucky and into the south. Timing, instability, upper level winds need to be fine-tuned yet.

Here's one look of the NAM model currently...