April 2020 Recap and Stormy Weekend Potential

April 2020 is now in the books, and what a month it was (obviously not just relating to weather). We started the month with drier than normal conditions (you can read more about that here), and ended with slightly wetter than normal conditions. The graph below clearly supports that the total precipitation for the last 10 days of April was above normal at Paine Field.

Figure 1: Rain accumulation data for 4.21.20 to 4.30.20

In total, however, we were still unable to make up for the deficit at the start of the month, and we still ended up below average for the whole month (see Figure 3 below).

Here is a graphic that shows an overview of the temperatures for the month at Paine Field. No records were broken in terms of highs or lows, as illustrated by each blue bar staying within the bounds of the shaded red and blue areas. However, the average high temperature was just slightly above average.

Figure 2: Temperatures at Paine Field for April 2020

To summarize the month, take a look at the following graphic. It is important to note here that in the temperature category, the first column of data (“average”) refers to what actually happened in April 2020, while the second column is the average over several years of data.

Figure 3: April 2020 Summary at Paine Field

Shifting gears here, it is officially May, and after a great start to the month today, things start to get a little bit exciting.

After a weak system moves in overnight, a stronger one moves in Saturday, which brings with it rain and the potential for thunderstorms. The Storm Prediction Center (SPC) has included the area in the general thunderstorm category. Parts of Eastern Washington are even included in the “marginal” category of severe storms.

CAPE (Convective Available Potential Energy) values are forecast to be quite decent for our standards. Take a look at 21z tomorrow (which is 2 PM local time):

Figure 4: CAPE values according to the NAM for 2 PM Saturday

This run of the NAM puts 649 J/kg of CAPE at Paine Field, which is decent for our neck of the woods. NE Oregon and SE Washington looks to be a great setup for thunderstorms, some of which could be severe.

As a side note, in order for a thunderstorm to be considered “severe,” it must “contain one or more of the following: hail one inch or greater, winds gusting in excess of 50 knots (57.5 mph), or a tornado” (according to NOAA).

The primary threat for our neck of the woods should be wind gusts, so make sure to secure loose objects that could get potentially carried by strong gusts. The following graphic is for 3 PM tomorrow, showing wind gusts according to the NAM. Gusts of 36 mph are shown for KPAE, but it easily could exceed that if a strong storm develops.

Figure 5: NAM wind gusts at 3 PM tomorrow

The strength of storms that we get is contingent on whether we get sun breaks. The sun greatly destabilizes the atmosphere through surface heating–which enhances upward motion and thus, storms. If we get enough of a sun break tomorrow, our chances of thunderstorms will go up.

The chance for thunderstorms should decrease as the sun goes down because of the lack of surface heating from the sun. However, the chance again returns on Sunday. Although, the risk seems to be greater on Saturday.

If you see anything exciting, send it to me by posting it on my Facebook page or tagging me on Twitter!

I’m hoping that we get some action tomorrow, and I know I’m not the only one…here’s to some exciting weather to start out the month of May!

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