Winter Throws A Punch?
It has been threatening for months, but only landing soft jabs. Is this the last stand for winter 2018-2019? All of the guidance and long range indicators from NOAA say the next 2 weeks will be very cold compared to the average temperature for this time of year.
I really like to look at what are called the teleconnective indexes. For truly cold air and for lasting cold air, you want to see the arctic oscillation(AO), north Atlantic oscillation (NAO), and the eastern Pacific oscillation(EPO) all negative. The AO and the NAO are positive to strongly positive. Only the EPO is negative. With that said, we have had cold shots with only a negative EPO, but if my memory is correct, they don't last long. I will save a discussion on these indexes for a later time. That's something I keep going back to in the back of my mind.
Now onto model performance. The GFS is either the biggest joke of the week or brilliant. I came into work Sunday and Monday and looked at its guidance. It had highs this Thursday and Friday in the 70s!!!! Other guidance has highs in the 40s and 50s. Needless to say, it did not want to bring a boundary into central Arkansas. Today (Tuesday) it now has the boundary a bit further south. GFS 2 meter temperatures show 62° Thursday and 57° Friday. The Euro 49° and 52°. The NAM has it around 40° all day Thursday. Quite a range, huh?
Now onto the weekend. The cold arrives, but I question the magnitude of it. Winds will howl out of the north and east Saturday into Sunday. The models are even trying to bring a disturbance over Arkansas with cold air in place. Since it is in the long range, timing of this is not known and most of all, how much moisture?
I have really tried to avoid showing models in the long range here on the weather blog lately. People will look at them and think it's a forecast! They are not! They get shared all over the internet when they show wintry weather, but when the models take it away, it's radio silence. LOL.
Those models should be referred to as guidance. They guide us into making a forecast after careful consideration of many factors. If we received the amount of snow and cold the models have predicted this winter, we would be crossing over a frozen Lake Maumelle and retrofitting all our trucks and cars with snow plows. They have been that bad!!!!
Cold air does return this weekend. The strength of this cold is questionable.
How long does it last? NOAA seems to think for at least a week or two. There are arguments against that length of time.
Yes, the models are showing moisture over the cold air. The timing of that is not known. Also, is it substantial or light? Too early to say.
There's a lot riding on this forecast since thousands will be participating and attending the Little Rock marathon. I would prepare for cold and wind. Precip? Way to early to pinpoint. If there is, let's hope it happens after!