WKU Meteorology

Update: Sunday, 2/4 9:54 pm
I will score how well the NWS and MOS fared against the arctic air mass over the Saturday-Wednesday period. I will group the Bowling Green and Lexington forecast by day to make scoring easier. By the way, I made a pretty bad call on the high Saturday. I neglected to account for the lack of cold air advection (CAA) into Kentucky at 850 mb. Since we’re at the bottom of the trough, our winds aloft were westerly. Note how the winds aloft shift more to the northwest as the trough axis swings through the region on Sunday/Monday. This NW flow coincides with the coldest air of the season. I should have noticed this before I criticized the NWS forecast for Saturday. I am somewhat justified though as even the NWS admitted they were too warm with temperatures for the weekend in today’s discussion…

MAIN STORY MONDAY MORNING WILL BE THE COLD LOWS…0-5 ABOVE IN THE NE TO 5-10 ABOVE IN THE SW. THIS IS
CONSIDERABLY COLDER THAN THE MOS AS ITS SUFFERING FROM A WARM BIAS OF LATE. WEAK RIDGING WILL BUILD IN FOR MONDAY ALLOWING SKIES TO BECOME PARTLY SUNNY. HOWEVER…EVEN WITH GOOD INSOLATION…TEMPS NOT GOING TO GO UP VERY MUCH. TRENDED TEMPS DOWN FROM PREVIOUS FCST WITH MID AND UPPER 10S ACROSS THE NORTHERN HALF TO THE LOWER 20S ACROSS THE
FAR SOUTH. LOOKS LIKE COLDEST NIGHT WILL BE MONDAY NIGHT/TUESDAY MORNING WITH LOWS VERY CLOSE TO 0 IN THE BLUEGRASS REGION…COULD EVEN SEE SOME BELOW ZERO READINGS IN SHELTERED AREAS.

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The students in my Synoptic Meteorology course last fall know my feelings about the ability of model output statistics (MOS) to accurately predict temperatures of an arctic outbreak. Even better, my students know how I feel when forecasters use those MOS values even though they have no known basis in reality during arctic outbreaks. In fact, the inability of MOS to accurately predict highs and lows during arctic outbreaks is so well known there have been a number of research articles to prove this, as seen here, here and here. If this problem is so well known, then why is the NWS forecasting temperatures for much of Kentucky over the weekend that are in some cases higher than the MOS ensemble average? Continue reading →

As a forecaster, the goal is to get the meteorology right (storm track, thermal profile, dynamics) when a storm is approaching. Once the meteorology is correct, it is fairly easy to predict the weather (temperatures and precipitation) and you will generally be correct 99% of the time.

When you get the meteorology exactly right but incorrectly predict the weather, all you can do is shrug your shoulders and chuckle. Continue reading →

The NWS, WNKY, and WBKO all mention that any snow that falls Thursday will mix with and possibly change over to rain during the afternoon. One reason they may be concerned about this is that as I mentioned in a previous post, there has been a model bias this winter that has often overestimated how much cold air will be present during all of the “near-miss” snow events we have had. To me, this appears to be a form of logical fallacy known as “proof by example”. Continue reading →

Anyone out there who wants to be a meteorologist (especially a TV meteorologist) should always remember to check the records when dealing with extreme cold. I have not heard any of the local TV mets nor the NWS mentioning the possibility of this arctic outbreak being a record-breaker, but a look at the Bowling Green temperature records suggests a couple are in jeopardy. Continue reading →

As expected, in the past few hours, both WNKY and WBKO have joined the NWS in drastically lowering their temperatures for the Sat-Tues period. But interestingly, both WBKO and WNKY are downplaying the Thursday/Friday storm (both are predicting one inch for Bowling Green) even though they now think the storm will be mostly snow. Normally, you raise amounts when you downplay the likelihood of a mix or changeover to IP/Z/R.

In fact, there is some evidence that south-central KY could receive 4″ plus of snow from this storm. What is that evidence? Continue reading →

As I was writing the previous post, the NWS has drastically lowered their temperatures for the upcoming Sat-Tues period, in agreement with my discussion from yesterday. As of Monday afternoon, they had high temperatures in the low 30s with lows in the upper teens for Sat-Tues while I had highs from 20-24 and lows 8-12 (with talk of the possibility of sub-zero temperatures). WBKO also had highs in the lows 30s and lows in the upper teens while WNKY had highs in the upper 20s and lows in the mid teens with no talk of sub-zero temperatures. Continue reading →

Everything from Monday’s discussion is on track. The NWS is starting to get on board with just how bitterly cold it will be across the eastern CONUS this weekend. The Duluth, MN forecast office noted Tuesday morning that some parts of northern MN may experience lows of -45 degrees F in the Sat-Tues time period. That same air mass will be coming our way and the amount of modification (see prior post) will determine whether or not BGKY will dip below zero or simply have lows in the single digits.

There is an interesting battle going on between known biases in the computer models that could affect the accumulation from Thursday’s snowfall. Continue reading →

The last time Bowling Green, KY had a low temperature below zero (-2) was January 24, 2003. The week of January 21-27 averaged 14 degrees below normal and featured an average high/low of 28/11 (relative to normals of 43/25). The coldest day of that week featured a high of only 14 degrees, a full 30 degrees below normal! The overall synoptic pattern of a southward displaced polar vortex is very similar to what will occur over Super Bowl weekend. In fact, the synoptic pattern is also quite similar to the record breaking cold outbreak of January 18/19 1994, which saw temperatures fall to -11 in Bowling Green and an all-time state-record -37 in Shelbyville. So if the overall synoptic pattern is very similar to these bitterly cold extremes, then why am I not predicting sub-zero low temperatures for Bowling Green? Continue reading →