Morning low: 45
PM High: 54 (Seattle Normal High: 64)
CLIMATE NOTE: It’s been a pretty cold spring (April 1 to present) in the Northwest, but it’s not terribly unusual to be this cold when looking at historical records. Since records began at Sea-Tac in 1945, this period from April 1 to May 5 is only the 11th coldest. Chilly certainly, but not record. What has been very unusual is that we have had almost a decade of “beautiful springs” in Western Washington, with several of the last few years having had much warmer conditions with many sunny days in April and in May. Simply put, we’ve been ‘spoiled’ by so many warmer than expected spring months, our perception of what a ‘normal’ spring is has been ‘reset’. We’ve been cold this spring with this stubborn weather pattern in the Pacific where warmer high pressures have been locked in well offshore, while we’re getting cold troughs of low pressure reinforced by cold air from the Gulf of Alaska (photo attached._ When Well, for the rest of the month the outlook is still for cooler than normal weather, but it’s important to remember that we are gaining over two minutes of daylight every day right now.. gradually increasing the overall temperature in the northern hemisphere.. our temperatures are going to moderate (they have to) and finally in the second half of May we should see a lot more days in the 60’s (at least) with low temperatures out of the 40s and closer to 50. People who refrain from planting tomatoes should give it another week to ten days, but probably beyond that they can probably put them in the ground.
PROVIDE: Another cold day with weather locked in the northwest, with persistent low pressure from the Gulf of Alaska feeding us fresh air and occasional weather disturbances. However, during the Mother’s Day weekend we will have more sunshine and less showers, but we will add the outside risk of thunderstorms each day.
For tonight we have a low chance of a thunderstorm primarily south of Puget Sound through late evening. Otherwise, a few periods of rain and mostly cloudy skies. By Saturday morning, overall precipitation coverage will be significantly reduced, although some areas of rain are likely around Puget Sound and on the coast. Morning temperatures will be in the 40s. It will also be windy at times, so people heading to the Montlake Cut to watch the Windermere Cup should bundle up and be prepared for breezes with a chance of rain.
The good news is that on Saturday – compared to the last two days – there will be more sunshine. This is especially true after noon on Saturday. The typical “showers and sunbreakers” weather pattern will continue from Saturday afternoon to Saturday evening. Highs will reach lows in the mid-50s – ten degrees cooler than normal for this time of year.
We will monitor the development of a Puget Sound Convergence Zone from late Saturday morning through Saturday evening, from near Seattle north to Snohomish County. The exact location of this west-east trending band of rainfall is uncertain, but generally north of Seattle to south of Snohomish County (running west to central Kitsap) will be the most likely areas for the development of the convergence zone, then it could move a little north at the end of the day. Below the area, heavier rains can be expected with the possibility of small hail and lightning.
Outside of this area a few showers will dot the landscape but mostly will be dry after mid morning Saturday.
In the Cascades, the convergence zone could bring heavy snow above 3,500 feet to areas around Stevens Pass Saturday afternoon and evening. There could be travel issues on US 2 at Stevens Pass if the precipitation direction with the convergence zone is right. Travelers should keep track of conditions. Interstate 90 is expected to remain at times in rain or a rain-snow mix with little to no impact on travel.
Mother’s Day on Sunday will be a repeat of Saturday, except the atmosphere will be a bit drier, so overall expect less precipitation and potentially a less active convergence zone on Sunday afternoon, though it may grow. We will also see more sunshine. The highs will again be in the low to mid 50s.
A few sporadic showers could remain on Monday before the drier days of Tuesday and Wednesday. Some rain looks set to return Thursday through the end of next week with cooler than normal temperatures, though they will moderate a bit to highs in the upper 50s in Seattle by the end of next week.
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