For the first time this season, the dreaded 4-letter “S” word (or the beloved “S” word, depending on your outlook) is in the forecast.
The National Weather Service’s Morristown Field Office has introduced a 40% chance of rain showers changing to snow showers late Friday night, and a 30% chance of snow showers early Saturday morning.
Snowflakes in the air on Halloween isn’t a terribly uncommon occurrence; most of us can recall scurrying about on our trick-or-treat missions as a kid while snowflakes fell. But what a change this is from just about 10 days ago when it appeared that Halloween might greet us with temperatures in the 70s (it’s also an example of why long-range forecasting is largely a waste of time — remember that the next time you look at The Weather Channel’s 15-day forecast when you’re trying to plan your two-weeks-away outdoors activity).
We’ve been talking about the upcoming cold snap on this blog since last week. This morning’s cold front obliterated the heat ridge that had gripped the region and will set the stage to allow a shortwave trough to drop southwest this weekend, delivering both the much colder temperatures and maybe enough residual moisture for a few snowflakes. As a refresher, here’s the latest raw data from the GFS model regarding this weekend’s temperatures. Remember, these are model-derived numbers, not an actual forecast. But it helps show what could happen, because the model has been fairly consistent with these temperature projections, which are colder than the official forecast from the NWS:
Saturday morning: Low of 30
Saturday afternoon: High of 38
Sunday morning: Low of 26
Saturday afternoon: High of 51
If you’ve been reading these posts for the past several days, you’ve no doubt noticed that the model just continues to trend colder with Saturday’s temperatures. This isn’t too surprising. The ECMWF model from our friends in Europe has been colder with this arctic shot of cold air all along.
So, if it were to snow, how much? Well, not much, obviously. The available moisture will be skimpy. And it should be pointed out that, technically, any rain-to-snow changeover isn’t likely to happen until after midnight, meaning that Halloween will be over.
But here’s what the NWS has to say in its area forecast discussion this morning for East Tennessee:
IN HIGHER ELEVATIONS…TOTAL SNOWFALLAMOUNTS ABOVE WATCH CRITERIA APPEAR REASONABLE AT THIS TIME…BUT SINCE WE ARE STILL ABOUT 72 HOURS FROM THE START OF ANYSNOWFALL…WITH HOLD OFF ON A WATCH AND MENTION THE THREAT IN THEHWO. LIGHT ACCUMULATIONS MAY BE POSSIBLE IN THE VALLEY.
“Higher elevations” refers to the mountains of East Tennessee, but it’s interesting to see the NWS mention the possibility of light accumulations for the valley areas.
If all this bums you out, don’t despair. As we’ve also discussed in previous posts here, this cold blast will be briefed and just a temporary disruption to the overall pattern. Temps will rebound into the 60s pretty quickly next week and there’s still the potential for much warmer temperatures as we headed towards the middle of November. As I pointed out in those previous posts, the GFS is being a little schizophrenic from run to run, sometimes showing another indian summer setting up about two weeks before Thanksgiving and at other times just keeping a zonal flow in place with mild but not overly warm temps. This morning’s 0z run of the GFS is back to its old tricks. It tops temps out at 75 degrees on Nov. 10, with highs hitting at least 70 degrees from Saturday, Nov. 8, into Nov. 11. The usual disclaimer applies: Those are raw numbers from a single run of a single model, not a forecast. But the overlying theme is that it looks like the mild fall will continue through at least the first half of November.
If you’ve rooted for temps in the 60s and 70s through October, I can get onboard with that. But if you’re rooting for 70-degree temps on Thanksgiving and while I’m trying to deer hunt, you and I can’t be friends anymore.
(I’m not a meteorologist, I have never studied meteorology and I’m not on a first-name basis with any meteorologists. In other words – I’m no expert and don’t claim to be! Be sure to stick with the National Weather Service or your favorite TV weatherman for your official forecasts.)