We're making the turn on this Labor Day weekend!
We've already been annoyed by the prowling showers and storms. Yesterday was interesting because we had a line develop and move through during what is typically the low-point of the day for convection (just after sunrise). The first weekend of soccer was canceled for the day prior to these storms, and given the downpours and lightning, I'm sure others had some things put off as well. I even lost power for a few hours.
The weather pattern for the past few days has also been interesting, as we've been following the approach of a cold front-- yet it doesn't really want to move in just yet. It is still out there to our north and west.
HPC - Surface Map - Sunday Afternoon
Heat: check. Humidity: check.
This front to our west has been very slow to move because every time it tries to do things, showers and storms spring up and take over, blurring lines and impeding progress. It's still summer-time, so the thermodynamic picture still holds sway over the front-based synoptic picture. Anyway, let's return to the 500mb charts to see where the 'agitators' are going forward.
Prior to the frontal passage, the upper-air picture is marked with choppy seas. Bits of vorticity rotating through the steering flow and stirring up showers and storms where'er they please. Once we get to the other side of the front (right-hand map), notice how the picture becomes more peaceful aloft. Two different forcings for shower formation, and we have to tangle with both in the second-half of our holiday weekend.
I just picked these frames because they lined up with the GFS model images from above... Just keep in mind that the showers and storms can scatter up in any part of the day. Just look for them on the radar tracking maps below, and you should be able to pick your spots well-- or at least know when to cover up the yard-sale, etc.
It's too bad our front doesn't finish out until Tuesday, because behind it comes some great camping weather: Highs in the upper 70s, rural lows in the upper 40s. It's not going to last very long though. By the next weekend we'll moderate back to above-normal levels.
Which reminds me: We've now passed our climatic peak for seasonal temperatures. From here on out our average expected high temperatures will be going down into winter. Average high for the date: 84°. Not exactly fall-like, but it used to be 85 :-)
Update - Here's a neat little ditty I stumbled across today: These are the heat and cold records for the month of August, marked by location:
Record low high temperatures beat out record high max temperatures by almost 4-to-1 in August. In keeping with our national climate-change picture, the morning temperatures continue to have more difficulty in setting record lows (3-to-1 more record high minimum temperatures in the month).
I'd love to be able to come out and say that this means we're going to have a ridiculously snowy winter (because so many of you like snow)... But alas, I only like to say things of which I have a modicum of confidence. Accuracy is important to me. This far out, there are not a whole lot of tea leaves to be able to read, but one of them is the projected ENSO picture (El Nino vs. La Nina).
CPC - El Nino Projection
In general, "La Nina" winters are better for snowfall (the negative numbers on the above chart), though "El Nino" winters give us the coastal Nor'easter thoughts more often. Anyway, only stuff above or below 1,-1 really 'count' for establishing an actual "El Nino" or "La Nina" event. The current projections are in keeping with the entire past year's worth of data: a whole lot of neutrality. ENSO-neutral years are a bit annoying for forecasters to say the least. As a case in point, the initial salvo from the Climate Prediction Center (CPC) on the upcoming winter is: "equal chances of everything".
Have a great day everyone!