Cherry Weather Worries

Eastern Washington State is one of the premier growing regions for sweet cherries in the world, possessing both good soils and climate.  But cherries have weather vulnerabilities that can cause severe loss of fruit.    One of them is frost during the budding season, but that has not been much of a problem during the past few years due to our unusually warm weather.

But there is another: rain just before harvest that can cause fruit to split.  Recently, unusually heavy rain hit California, halving their harvest.  Very bad.

Typically, the Washington State cherry harvest starts around June 1st.   But with unusually warm weather, the date will probably move up to May 23rd, according to what I have been reading in the Ag magazines.  Very soon.  

The problem is that with a trough of low pressure moving over us, significant rain is forecast during the next several days (see the WRF model 24h total ending 5 PM Saturday)... .5-1 inches over some of the cherry growing region over the eastern slopes of the Cascades.  Heavier amounts in some location.  This is very good for general moisture over eastern WA and  to keep the fire threat down.

According to the agricultural experts at WSU,  when cherries are close to harvest the pressure inside increases.  Rain, particularly when the weather is warm, can be absorbed through the outer surface of the cherry (called the cuticle),  sometimes leading to the bursting of the cherry.  Heavy thunderstorms during warm weather are particularly problematic.  Burst cherries may not look great, but are certainly valuable for many uses (juice, jam, etc.).  They are less valuable.

Growers have a number of approaches to deal with rain on cherries, including blowers and running helicopters over orchards.

The main rain threat is on Friday/Saturday as the upper low passes south of Washington and precipitation swings northward over eastern Washington, accompanied by easterly (upslope flow)--see upper level (500 hPa) map for Friday at 11 PM.

 Since we are very early in the cherry season, only a limited amount of the crop is vulnerable.   But orchardists and meteorologists will be watching the situation closely.   I certainly will--I love cherries and limited supply can cause the price to rise.