Saturday afternoon (Feb. 28)
Weak atmospheric energy “ripple” coming our way tonight and tomorrow. The rain/snow line should be at least 30-40 miles north of Louisville, except at the beginning. Here’s my point of view:
Tonight: Cloudy and cold…temperatures holding in 33-35 range. Some periods of light snow are possible beginning after 10 P.M. Snow should change to rain by 2 A.M. Little, or no, snow accumulation expected.
Sunday: Cloudy and cold with rain most of the day…high…40. Rain should end by late afternoon. Colder a few flurries tomorrow night.
Wednesday Afternoon (Feb 24)
Cold air is still hanging around, but the rest of our weather certainly has been calmer this weekend. A couple of posts ago, I mentioned the southern storm track would be active this week. The second storm this week is bringing “winter” to the deep south today and the southeast tonight/tomorrow. That storm has spread moisture far to the north today (the clouds we’ve been seeing) and could drop perhaps an inch or two of snow tonight over far southeastern KY. Nothing for us from this system.
However, the northern stream is planning another big mass of unseasonably cold air for the lower Ohio Valley tomorrow. As that new cold air supply drops in tomorrow, we could see some snow flurries and perhaps a few snow showers. Most likely time for any snow will be afternoon and early evening. Little, if any, accumulation expected.
Earlier, I had mentioned the possibility of a third southern stream system phasing with a northern system to create a major storm system early next week over the central and eastern U.S. But, as always, things change. Strong indications now are that the northern system will be dominant and “cut off” the southern system without merging with it. The southern system will still feed in some moisture for some moderate rains early next week (possibly beginning Sunday). The lack of merger of the two systems is good news with respect to severe thunderstorms. Some severe weather will still be possible from TX/OK eastward Mon/Tue, but much less of an outbreak than it looked earlier.
Tonight: cloudy and cold…low…24
Tomorrow; mostly cloudy, windy and cold…high…30. Snow flurries and/or snow showers likely tomorrow afternoon and evening. Little or no snow accumulation expected.
Tuesday Evening (Feb 24)
Unseasonably cold weather will continue until the weekend when some warmer weather should return for a few mild, wet days early next week.
Main storm track should continue over the Gulf Coastal states through late week. Meanwhile the northern (Polar) jet does bring us yet another shot of very cold weather Thursday. That could also bring a shot at some snow flurries or snow showers Thursday.
Both the northern and southern jets show signs of getting much more energetic by late in the weekend, but they should phase into one very strong storm over the central U.S by Mon/Tue. Actual surface feature will pass north of us, so rain, not snow, will hit us. If things continue to shape up they way the models currently portray, we could well see the first big severe weather outbreak over the southcentral and southeastern U.S. Mon/Tue.
Becoming cloudy overnight…low…24
Partly cloudy tomorrow with a high of 34.
A post last week discussed the poor forecasting (and thus the badly misleading wind chill information) of overnight lows for Louisville last week. Well, they are at it again tonight.
1). Wind Chill Advisory from Midnight until 9 A.M. Mon A.M. Okay, that’s the headline. For Louisville, the Wind Chill Criteria for an advisory is -10 deg. to -25.
2), The NWS forecast for Jefferson County is for a low of 8 degrees and a wind chill of +1 to -9. The forecast doesn’t agree with the headline (Wind Chill Advisory)
3). Once again, the NWS forecast low (8) is far below available guidance. Latest I’ve seen say either 13 or 14 degrees). Even though the winds will be northerly (bringing us colder air), the models all expect a large amount of cloudiness to linger most of the night, reducing radiational loss. Thus, to me the guidance looks to be much better. I’ll give it a low of 12 by 8 A.M. tomorrow. Assuming the warmer temperatures, wind chills will be even farther away from advisory “criteria.”
Weather remains very cold, but calmer conditions should return for most of the week. The next two “major” storms should move across the Gulf Coastal states this week. That’ll keep the big problems south of us. A couple of northern stream disturbances will cross over us. One tonight and the second late Tuesday. Each one will serve to reinforce the cold weather, but will have only enough moisture to perhaps produce some snow flurries.
The third major storm to push out of the southwest this week should come in two sections. The first (Friday) could bring a little snow but the major energy with the system should arrive Sat. night/Sunday. Too early to tell whether it’ll bring rain or snow OR the whole mixed bag like this weekend.
Friday evening (Feb 20)
Confusion abounds. Each model tells a little different story, so I’ve decided to look at the overall large picture (the basic “rules” from years past. What appears below is for the Louisville area – more sleet/freezing rain/rain south of us; more snow north of us (especially northeast)
Here’s what I’m going with:
8P.M. – Midnight Light snow spreads over the area
Midnight- 6A.M. Snow intensifies but sleet takes over as primary precip. form after 3 A.M. Temperatures slowly rising. By 6 A.M. snow /sleet accumulation should be 2″ – 3″. No significant accumulations are likely after this time.
6 A.M. – Noon Sleet and freezing rain take over with freezing rain becoming heavy at times during the morning (no major problems from this). Temperatures should reach 32 or higher by Noon.
Noon-6 P.M. Rain (and possibly some light wet snow) diminish during the afternoon.
Watch for some urban street flooding, especially tomorrow morning.
Midday Friday (Feb.20)
I’ll have more details later, but here’s my current thoughts on weather tonight through tomorrow. (There’s still a fairly large difference between the NAM and GFS, so there’s a pretty large “margin of error” this close to the event.)
1) Increasing clouds this afternoon…high in mid 20’s.
2). Periods of light snow begin after 7 P.M. Snow becomes heavier after 10 P.M. with an accumulation of 2″-4″ by 3A.M.
3). 3A.M.-7A.M. Sleet mixes with snow and eventually becomes all sleet (and possibly freezing rain.
4). 7A.M. – Noon Temperatures warm to around 32 degrees around Noon. Meanwhile sleet changes to freezing rain and then to liquid rain. (Rain/freezing rain could be heavy at times, but no major (damaging) ice accumulations expected.
5). Afternoon: Temperatures rise above freezing for several hours. Rain continues, but lightens as time wears on.
6). Some snow flurries are possible as temperatures drop below freezing again
Unbelievable!!! After a badly busted forecast of this morning’s lows, local weather authorities are poised to do it again tomorrow. My guess is that they haven’t learned anything from this morning’s fiasco. Anyway, they’re shooting for -11 tomorrow morning while four of their major forecast tools predict 3, zero, -2 and 5. On average, slightly warmer than their forecasts for today. This morning, the busted forecast was due to the winds. Tonight it’ll be due to increasing clouds after midnight.
NOTE: Missing a temperature forecast by 9 degrees or more has become a real rarity these days. I’d guess it happens less than 10 times a year here. Coming with all the Watches and Warnings in place (dependent on the forecast), it was a real embarrassment for us forecasters.
We’re getting close enough to the arrival of the next storm to be able to try to make some sense out of it (although a few doubts remain).
In general, the models are thinking along the same lines although the NAM is faster (and cooler) than the GFS models. The upper trend is for another polar jet disturbance to sink southward over the western Plaines and Rockies. Unlike the past several storms. this trough will hold back in the western U.S. and send us ripples of energy over the weekend. But, the main part of the system does not play a major role in the weekend’s activities.
Meanwhile, the subtropical jet is available to send plenty of moisture our way. Here’s how it’s shaping up: Increasing clouds begin tonight with a cloudy cold day Friday. We could see some very light snow or flurries during the afternoon. High near 24 degrees. Temperatures continue rising tomorrow night as snow becomes heavier. In fact, 2″-4″ of snow appears likely before a changeover to sleet and freezing rain Saturday morning. By Saturday afternoon temperatures will rise above freezing so freezing rain will change to rain and begin a long cleanup.
Doubts: models have backed off a bit on the 1″-2″ rain totals, so the prospect for flooding will be much lower. HOWEVER , many urban streets/intersections will flood because the storm sewers will be blocked by snow.
Biggest question mark remaining is the duration of the sleet and freezing periods. At this time, it looks like the freezing rain will be the biggest threat – a lot of ice is possible, especially if the NAM is better than the GFS. More tomorrow.
Zero is tomorrow’s record low. From what I’ve been reading and hearing, breaking that record is a “no-brainer.” Most of the forecasts locally have -5 to -10 as the low (the NWS says -11 for the city). It very well may get that low, but I doubt it. Two reasons: clouds and winds.
For the past several days, the forecast for Thursday morning has been around -10, But, for the past two days the Models have made an abrupt change to forecasting a low just above zero. Yes, the models know we have a deep snow cover, so that’s not the reason for the change. But every forecast I’ve heard today has IGNORED what the models are trying to tell us. I don’t think that’s wise.
To get extremely cold readings like -10 around here you need very cold air (we’ve got that), deep snow cover (we have that), clear skies (iffy) and near-calm winds (very iffy). So, it’s not a sure thing, and some of the temp/wind chill forecasts I’m hearing seem far too low. First, the clouds. Satellite/model trends have the clouds diminishing this evening and going clear after midnight. So that should only retard the cooling a little. The winds, however, will play a much more important roll in tonight’s low. If the winds die down to less than 5 mph, we’ll see a good shot at -5 to -10. However, the winds are predicted to remain 6 to 12 mph most of the night. If that is correct, you can say goodbye to -10 and probably even -5!
By Louisville standards, it is extremely cold – and it’s going to stay this way for the next 36 hours. But, most of the temperatures and winds chills being tossed around seem far too extreme! I’ll go with a low in Louisville of 0 to -2 and wind chills about -15 to -20. As usual, it’ll be colder in rural areas.
BIG MESS for Saturday
Storm shaping up in the Rockies will keep the winter weather coming. Look for light snow developing Friday, then a changeover to freezing rain/sleet Friday night, and finally to liquid rain Saturday. Lot’s of flooding on city intersections due to clogged sewers Saturday. More specifics tomorrow as the amounts/timing.
Another strong upper level disturbance will drop southward over the Great Lakes and the northern half of the Ohio Valley. It has two things in store for us: 1). The coldest air of the winter so far (Wed-Fri). Before the cold comes snow late tonight. This newest “clipper” is moisture-starved, but has plenty of energy. The system should be able to squeeze out some snow for us, starting after Midnight and ending during rush hour. Snow will be much less than the last one, but still should be on the order of 1″ to 2″ by morning. Then, the COLD.
P.S. Could be a real mess brewing for Saturday!
As expected, the heaviest snows are over by midday. Radar indications and model data confirm that we will see the snow fading away this afternoon. But, the periods of heavy snow we saw this morning are over. Light snow may accumulate another inch or two over the next 3-4 hours, but it should all be over around 5-6P.M. Looks like snowfall totals will end on the lower side of my earlier estimates.
NOTE: Heard local officials this morning say that it was too cold for salt to do any good. So they weren’t salting the roads. MOST OF THE TIME, that statement is correct. But, salting between 9 A.M. and 3 P.M. would do a lot of good even at 15 degrees. Why? APRICITY (look it up and you’ll see why. Apricity is also why Wind Chill temperatures are far from accurate during daytime hours.