Wetand News

  I am often asked about how far into the future weather prediction is possible   My podcast (link below) reveals the answer and also provides a relatively optimistic weekend forecast. And don't forget the Northwest Weather Workshop tomorrow morning!   Three hours of local weather and climate talks, with time for questions. And it will end with a spectacular video by Greg Johnson of Skunk Bay Weather.  More information below.  Please register if you want to attend.  It will be completely online. Finally, for rainshadow fans, check out the visible satellite image this morning.  You see the clearing northeast of the Olympics?  A good example of the Olympic rainshadow. Compare the cams at Seqium and Seattle below--both take at the same time.  A classic. Here is my podcast: Click the play button to listen or use your favorite streaming service (see below) You can stream my podcast from your favorite services:   Listen on Apple Podcasts   Listen on Spotify Podcasts   Listen on Google P

Portland will probably achieve a record in a few days:  the driest April ever observed, with much of the rest of the region also sharing below-normal rainfall.   What is causing this dryness?   Have we been trending towards drier April conditions over the region?   What is the precipitation outlook for the next month?    All of these issues will be discussed in this blog. But first Portland.   The driest April on record was in 1956 when just 0.53 inches fell over the entire month.  With two days left to go, Portland's monthly total is 0.29 inches.  The latest precipitation forecast through 4 AM Saturday (below) shows only a few hundredths of precipitation falling on Portland.   The record will probably be broken. The past month has been drier than normal over our region.  The figures below the departure from normal over the past 30 days for precipitation over both Oregon and Washington.  Both western Oregon and Washington have been substantially drier than normal, with some locati

______________ Announcement The Northwest Weather Workshop, the annual gathering to talk about Northwest weather, climate, and major meteorological events, will take place on May 1, 2021. This year we will have a special session on the meteorology of the September 2020 regional wildfires. The meeting will be online. More information, the agenda, and registration information is found here:  https://atmos.uw.edu/pnww/ __________________________ The visible satellite imagery yesterday was intriguing, with the development of interesting cloud-free zones, driven by local sea breezes, land-water contrasts, and slope winds. Let me show you. At 9:16 AM (1616 UTC) there were lots of low clouds from the Cascade crest westward. By 11:51 AM, the heating by the strong late-April sun was having an impact, with the development of instability clouds.....cumulus clouds... over land.  But not over water , which does not change temperature much during the day.   Note the development of clouds over some o

The temperature yesterday in Seattle was extraordinarily flat-lined, varying by only a degree or two over 24 hours.  If the weather was a patient, we would be getting out the defibrillator paddles to shock the meteorological heart back into action. To show you this remarkable absence of temperature variation, here is a plot of surface air temperature at Seattle Tacoma Airport over the past two weeks.  Most days had a healthy diurnal (daily) range of temperatures, with some (April 17-21) with as much as 40F between the daily minimum and maximum.  April is generally a month with big temperature swings since the sun is quite strong (similar to August).  But look at the last day (through 8 AM this morning).....very little change at all. The temperature plot for the 27 hours ending at 8 AM this morning is stunning, ranging from 47 to 49F.   Looking at the past several years, I could find no April day so boringly dull. Why so dull?   Blame continuous cloud cover and steady light ra

 Weather radar is an extraordinary technology that both saves lives and helps keep us dry.  In my podcast, I will tell you about how weather radar works and describe its origins during World War II.  Interestingly, it was the obscuration of German bombers by heavy rain that suggested the potential for weather radar (see the image of the British Chain Home radar network below). British Chain Home radars at Dover In my podcast, I explain how weather radar works and suggest a smartphone app that can change your life...... at least keep you dry. The first part of my podcast will deal with the big weather change over the weekend, with Saturday being particularly cool and wet.  The precpitation forecasts for the 24-h amounts ending at 5 PM Saturday suggest that hiking in the mountains might be better planned for another day: Here is my podcast: Click the play button to listen or use your favorite streaming service (see below) You can stream my podcast from your favorite services:   Listen on

 The last week has been magnificent, with warmth and sunshine more reminiscent of mid-July than mid-April.   And it was a godsend for the battle against COVID, since it encouraged people to get out into fresh air (where transmission is nearly zero) and to open their windows during the day. While we were basking in the warmth, the eastern two-thirds of the nation has been hit by well below normal temperatures and even some snow.  To appreciate the contrasts, here are the temperature differences from normal for the week ending April 20th.   Stunningly cold in the central U.S,  and today it was even snowing in upstate New York. It is easy to explain the contacts between the warm West Coast and cold interior.   The upper-level pressure pattern was such that there was a major ridge of high pressure over the West Coast and a trough of low pressure over the central U.S. (see upper-level map for 11 PM on Tuesday).   Red indicates above-normal heights/pressures and blue below-normal. This patte

If you felt that the weather during the past week in our region has been the best you have ever experienced during mid-spring, with blue skies and perfect temperatures, you are not wrong. In fact, we broke a new April record at Seattle Tacoma Airport:  the longest run of days reaching 70F or higher during April.   Yesterday we tied the record, with five days in a row at and above the 70F mark.  Today at 3 PM, we beat the record, with Sea-Tac Airport reaching 70 F.  And we may do it again tomorrow. The graph of observed Seattle temperatures versus normal highs (purple) and lows (cyan) are shown below, with 70F highlighted with the blue dashed line. We went from cooler than normal before April 12th to the extraordinarily warm period of the past six days, with highs roughly 20F about normal for this time of the year.  July temperatures in April.  And no precipitation for the past week as well. The regional picture is similar.  For the past week (actually April 12-18th) temperatures have b