Abnormally Dry April About to Turn Wet

water droplets on clear glass

Much of this month has been the taste of Spring that many of us has needed as a sort of mood-booster during these uncertain times. There has been plenty of dry weather and sun to go around.

In fact, this mostly dry start is abnormal. Take a look at these charts showing the minimum 20 day precipitation total at both KSEA and KPAE:

Table 1
Table 2

These tables show the driest starts to the month of April on record for both Sea-Tac and Paine Field, respectively. Since records began in 1948, this has been the second driest start to the month of April at Sea-Tac…the driest since 1951! Paine Field isn’t quite as impressive, but it still sits at number 7 (although most of that total fell on April 18th).

This has been great to go outside for some walks or bike rides as we all continue to do social distancing. I know I’ve taken advantage of it by going on many bike rides!

Unfortunately (or fortunately, depending on who you are), our weather pattern is about to shift.

The first system is on deck by tomorrow, packing quite a punch for this April’s standards. You can see it on visible satellite imagery, lurking in the eastern Pacific.

Figure 1: Satellite image taken around 3:30 PM on 4.21.20

Take a look at the following GIFs, showing the 3-hour precipitation totals as the system moves into the area:

Figure 2: 12z Euro run of 3 hour precipitation for 4.22.20
Figure 3: 12z GFS run of 3 hour precipitation for 4.22.20

Much of the state looks to take a hit, with even Eastern Washington getting in on the action.

Figure 4: Euro Ensemble showing 24 hour QPF (accumulated rainfall) for KPAE

Figure 4 above suggests that this system could be one of the wetter ones on tap for the area in the next week or so. But it also shows that it’s not the only system on its way.

Showers decrease gradually throughout the day Thursday, with a mini ridge of high pressure taking shape. This should help keep Friday mostly dry, with the exception of some scattered showers. Yet, another system arrives late Friday into Saturday, with potentially a third following it (things could certainly change a week out from now). You can see the three spikes in the 24-hour QPF in Figure 4 corresponding to each system. The GFS shows similar spikes, as shown below.

Figure 5: GFS Ensemble showing 24 hour QPF for KPAE

By next week, both models are suggesting we could add an additional 2 inches of rainfall to our April total at Paine Field. The Euro and the GFS don’t agree as much at Sea-Tac, with the GFS showing just over an inch while the Euro is near the 2 inch mark.

If those totals came into fruition, our April rainfall deficit could be completely erased. To give some perspective, the normal rainfall for the month of April is 2.58 inches at Paine Field and 2.71 inches at Sea-Tac.

During this time, high temperatures should be close to normal.

This month has given all the sun-lovers something to rejoice over…but now it’s the rain-lovers’ turn!

One thought on “Abnormally Dry April About to Turn Wet

  1. Pingback: April 2020 Recap and Stormy Weekend Potential – Weather Bloggin' For The Common Noggin

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