Welcome to your Thursday.
A decidedly easier day today (which is just fine with me). High pressure spends some moments with us following the front that moved through yesterday. There will be cooler temperatures today (60s), and given the clear skies and light winds tonight, expect another run at frost. However, the danger is less pronounced as it was earlier in the week, so no major problems are anticipated. Here is a rendering of the anticipated low temperatures overnight tonight into early Friday as determined by the GFS model:
The 29° spot in Elkins may be a concern, but that is not expected to translate across I-79 into most of our area (as a point of comparison, the Elkins area had a predicted low on the same map of 21° during our night of frost/freeze warnings earlier this week). Nevertheless, the valleys, dips, and hollows will be looking at temperatures in the mid/low 30s...good enough for frost.
Friday's weather brings early sunshine and soaring temperatures, followed by a late-day run of showers. Afternoon high temperatures may be a little overdone, especially if the rain arrives any sooner Friday afternoon:
|GFS - Fri PM Highs||GFS - 8pm Friday|
There will be warm air advecting out ahead of this storm system (as is usual with arriving storm-systems, so just like today hours of sunshine can make a big impact with establishing the afternoon high temperature. Expect another round of showers, with more thunderstorms-- though the prospects of severe weather do look weaker than what we had yesterday (this may be updated if necessary).
---Looking Ahead Wonky Thing--- (feel free to skip)
A couple days ago, we talked about a potentially 'interesting' (to say the least) storm system that was being advertised in the long-range models. One of the things that I said was that this sort of thing happens often in longer range models, and that it's more important to see how things develop before calling for something big. Well, it's been a bit, so it's time to revisit this situation.
I'm going to post recent runs of the GFS computer model starting with the first one I showed you the last time, so you can see the 'creep' (how the model has been changing run-to-run with regard to a specific point in time):
|GFS - Original Run (2 days ago)||GFS - Most Recent|
|GFS - 6 Hours Earlier||GFS - 12 Hours Earlier|
Needless to say, the model is having a little trouble resolving all of these features, though on the GFS there remains a continual effort to drag down cold air from Canada into this system (depicted by the red dashed line with the "540" next to it). That "540" line is a measurement of atmospheric thickness (5400 meters between the 1000 milibar and 500 milibar pressure heights-- don't worry about this). The important thing to discuss with regard to this line is that it's a generic broad-brush dividing line between rain and snow-- so when it shows up on the maps, the weather-folks take this in mind. Because of the inconsistent look of these features from run-to-run, it's unwise to make any calls regarding what might happen (like calling for snow, etc), but it's fine to play up the warmer weather we'll see locally out ahead of this storm, because that's rather consistent across all the models.
Now that we've gotten a little closer to the actual event, let's add another wrinkle to the mix, the idea of 'model consensus'. The Canadian (CMC) model is also another model that dabbles in the mid-range and can be prone to exaggerate various weather features. The actual arrival time of the the 'interesting' stuff in our area is now looking more like Wednesday morning, but look at the differences between the two:
|GFS - Weds AM||CMC - Weds AM|
So, the GFS is clearly driving in all sorts of colder air straight from Canada, and is positioning itself near the 'sweet spot' area of Lake Huron (I'm sure this will come up again one day on this blog during the winter)... while the CMC also advertises a decent closed low pressure area, but without the cold air. In fact, the temperature differences between the two models might be 30-degrees or more! In scenarios like this, I don't call for crazy weather but instead just keep an eye on things (and usually trend toward the solution that isn't completely out of season/character or unusually 'headline-y'-- most often that's the one that ends up verifying anyway). Now, if all the models were in agreement, that's something else. Now, just since you're playing along at home, the GFS scenario would be an indicator of arriving snowfall next Wednesday. It may be nothing more than flakes in the air, but that certainly would be another shock to the system considering multiple days of 80-degree weather in the past two weeks. But, since mathematics and physics can be applied to any set of data output, here's the calculated precipitation type imagery based on the above rendering of the GFS for Wednesday morning of next week:
The blue on the map is snow. I'm going to file this one under "pillow talk", because it shows up all the time in late-innings of longer range model runs, then fades away as we get closer. However, if it starts getting corroborated by other models, it'll become a different matter. It's certainly something to keep an eye on though ;-) I know a lot of folks who would shake their fists at the sky if something like this actually happened...
---End Wonky Thing---
So with that, your tracker tools... Since no severe weather will be out there today, and because the arriving cold night is interesting, we'll be looking at that this time around. Of course though, you will have your standard radar looks :-)
|Regional Radar/Satellite with Warnings Tracking||
|Current Temperatures||Current Dewpoints|
On clear, calm nights often the air temperature will cool to match the dewpoint, which is the lowest the air can cool to before fog ends up forming. Keep in mind that sometimes the maps have one or two numbers that seem way out of whack (ignore those and concentrate on the larger picture) :-) It's an exercise designed to get you into the general ballpark.
Have a great day today...and try to spend some time outside in the fresh air :-)