Breaking down the weekend forecast. Did somebody say the "S" word???
With the St. James Art Fair going on and so much attention being paid to this weekend's forecast, I thought I would go over some of the latest weather model data with you to help you understand what to expect.
There have been some interesting developments over the last couple of days concerning a strong cold front and associated low pressure systems, both of which will have major implications on our weather this weekend.
One model in particular has peaked my interest. This morning's run of the NAM.
Let's take a look starting with temps at just above the surface.
This first image is valid late afternoon on Friday showing us on the warm side of a significant front.
The warmer colors here, in yellow and blue, are supportive of temps in the upper 70's to near 80° for the metro area.
A short distance to the northwest, it get's colder quickly!
This image is valid early afternoon on Saturday and notice how the yellows and oranges have been replaced by light blues indicating temps could remain in the 50's on Saturday if there is enough cloud cover.
Considering the average highs for this time of the year are in the mid 70's, that pretty cool.
However, according to the latest NAM, it get's much colder!
Take a look at these 850 temps valid Sunday morning. This is VERY COLD for this time of the year and could yield surface temps in the 30's!!!
Now let's talk about precipitation.
This image is valid late evening on Friday showing the initial developement of precip across the area. Some very good news for the art fair here. It looks like the first round of rain will hold off until late on Friday.
This image is valid late morning on Saturday. Although rain will be likely overnight Friday night, the NAM is showing the precip is already off to the east of us here.
Now let's talk about round number two. That's right, most models now agree upon a second round of precip over the weekend!
This image is valid late evening on Friday. As a wave of low pressure develops along the front, another batch of rain looks to develop. But like it's predecessor, it will also probably wait until late!
This image is valid during the morning on Sunday. Notice that it is still showing some precip in the area here and a wide area of precip to our east. If you look closely (highlighted in yellow) you will also see a low pressure area along the spine of the Apalachians.
This is a classic winter type of set up for us that sometimes brings SNOW. That's right, I did use the "S" word here.
Now remember, in image number three, I was showing you the amount of cold air the NAM was also bringing in?
What in the world is Critical Thickness?
This image is valid early morning on Sunday and is showing precip and (multi-colored) lines of "critical thickness". It's critical because it helps us forecast precipitation type.
Notice that some of the critical thickness lines have passed to our south. This means that temps are dropping to or below freezing at certain levels of the atmoshphere.
This image is valid late morning on Sunday, and almost all critical thickness lines have passed to our south. This would mean that our atmosphere would be cold enough to support SNOW. It should also be pointed out that precip has come to an end that this point too.
So what does all this mean?
A - It means that Friday will be the best day to go to the fair with warm conditions and rain should hold off until sometime Friday evening.
B - The first round of rain will occur Friday night and should be over by morning on Saturday.
C - Saturday will be much cooler and another round of rain is likely to occur for parts of the area Saturday night.
D - Temps will be colder still on Sunday and one of the weather models is indicating that a FEW FLAKES of SNOW might be possible for a portion of our area.
Now that I've mentioned this possibility to you, PLEASE KNOW, that this is just one weather model that we've looked at and there is NO SNOW in the forecast yet. I'm just going through some data with you. All other major point of this forecast, I completely agree with though.
Anyway, with that being said, if you are going to the art fair or you have outdoor plans this weekend, you'll want to pay attention to changes in the forecast.
Be sure to join Marc with the very latest starting at 4 on WDRB News!
Meteorologist Jeremy Kappell