Today's GFS valid for Tuesday shows a large ridge of warmth building at 850mb. This could lead to temperatures in the 80s.

Growing signal for extended period of warmth starting next week

The grass is finally green, the trees are finally blooming, and Spring is finally here. Today is shaping up to perhaps be the nicest day of the year, with temperatures in the mid 70s with mostly sunny skies. Still, though, we have yet to have more than a couple of days in a row of truly spring-like weather, and one of the main reasons that April has been above average in temperatures is because of warm overnight lows, rather than a truly warm stretch of afternoon highs. Fortunately, this is about to change.

Before that, we’re going to have a 3-day period of somewhat chillier weather on Thursday through Saturday, as a coastal storm passes by and brings us onshore flow. However, this storm is expected to stay far enough away from us to avoid any direct impacts, other than increased clouds, a few scattered showers in an otherwise dry and partly sunny regime, and chillier temperatures.

After this storm departs, a building ridge across most of the US will finally press its way northeastward into our area, starting on Sunday.

Initially after today, we will be having a sharp trough and onshore flow, leading to chilly temperatures. The image below is valid for Friday.

Today's GFS valid for Friday shows a trough lingering in our area with an onshore flow and chilly temperatures. But warmth is building to our west and will be moving into our area.

Today’s GFS valid for Friday shows a trough lingering in our area with an onshore flow and chilly temperatures. But warmth is building to our west and will be moving into our area.

But look at what’s building to our west — a large ridge across most of the United States. The warmth isn’t some magical feature that the models are making up — it is already establishing itself just to our west and it’s a matter of it moving into our area, which makes it much more likely that this warmup will occur. Once the coastal storm passes by, it will take the trough with it and allow the ridge of warmth to build into the area.


Today’s GFS valid for Monday afternoon shows the ridge building into the area, with temperatures aloft warming quickly. This could support temperatures in the 80s.

Come Monday, the picture looks quite different. The trough has departed and the ridge — which was initially relegated to the western two thirds of the country — has pushed eastward into our area. 850mb temperatures have warmed above 10C with a westerly and southwesterly flow at that level, making temperatures in the low 80s possible on both Monday and Tuesday — especially Tuesday when a few mid 80s are possible.

This ridge looks to be a feature that lasts a while, as it could dominate the weather pattern next week and beyond. This ridging will promote general southwest flow and warm temperatures. We do run the risk of a cold front or two to the north where the top of the ridge meets some cool Canadian air, which could lead to a few scattered showers and thunderstorms from time-to-time, as well as a bit of an increase in humidity. But overall, the weather starting on Sunday looks to be absolutely fabulous, with temperatures generally in the 70s and 80s, and it could stay that way for quite some time.

The 7-10 day average of the ECMWF (European), GFS (American), and CMC (Canadian) models all agree on that ridge building and lasting through the period. This gives us increased confidence in an extended period of warmth.

In fact, as shown above, there is very good agreement among three of the top weather computer models that the ridge will build in and last through at least the end of next week. There are also signals that it could last even longer.

Unfortunately, the sustained period of warmth will finally lead to the allergy-season exploding. It has already begun to pick up somewhat, but the season had been lagged due to the very cold March and chilly start to April. A story done by New York Magazine a couple of weeks ago goes into more detail regarding why the allergy season could become a nightmare pretty quickly.