Time to catch up: March so far, winter recap, frost, & garden weather

March 30, 2022

Plenty to talk about this evening! It’s been a bit busy at work recently, plus the weather itself really slows down in spring around here. The result is fewer posts now through October.

WINTER RECAP

First, we had a great Oregon AMS meeting about two weeks ago. I presented a recap of winter 2021-22. You can find the whole presentation here: https://oregonams.files.wordpress.com/2022/03/winterwxmeet2022.pdf

I think Karl Bonner (an AMS member) stated this best…this past winter was “abnormally normal”. He meant that in the end temperatures and precipitation departures were quite close to normal. It won’t be remembered as warm/cold/dry/wet…just a normal winter. But remember how mild it was through the first week of December, then 3-4 weeks of stormy/snowy/cold weather, then just about nothing for the following 7 weeks. That pretty much wrapped up winter. Here are two of the graphics

KPTV
KPTV

I think what is most surprising is that once again a La Nina winter did not give us a cold/wet winter. We (meteorologists and media) need to be more careful with our wording leading up to these winters. We need to emphasize that not all La Ninas give us a stormy/wet/cold winter and that’s never a guarantee. That said, we have done just fine with snowfall in Portland lately. 7 winters with at least a LITTLE snow each year. Everything you want to know about this past winter is in that presentation link above.

KPTV

MARCH SO FAR

March sure didn’t turn out cool & wet, but near normal or drier than average for many of us in Washington and Oregon. I’m feeling confident these numbers won’t change much in the next 27 hours.

KPTV

Temperatures have been a bit warmer than average across most of the West this month.

KPTV

This has been terrible for our mountain snowpack. Take a look at the numbers! Bad news everywhere except extreme NW Oregon and into western Washington.

KPTV

I’ve had lots of questions about the “last frost” or last 32 degree temperature in spring. Here in Portland, typically it’s about this time of year. But in outlying suburbs it tends to be in April. That’s a 30 year average. This graphic shows the last frost each of the past few years in Portland (blue) and Hillsboro (pink). It sure shows the cooler nights in outlying areas doesn’t it?

KPTV

I wouldn’t be surprised if some of the colder spots see frost either tonight or the middle of next week, but there’s a good chance the urban area is done with frost for this season.

GARDENING OUTLOOK

It has been pretty good weather for gardening so far this spring. Not crazy warm, but a bit warmer than average. And we’re not seeing week after week of soaking rain. I sure DO see a soaking coming up Sunday PM through Tuesday…maybe an inch of rain in the western valleys. I live in a cool spot (compared to much of the metro area), but I think I’ll get the cool weather stuff going: spinach, carrots, beets, etc…

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EARLY APRIL WEATHER

I still don’t see any long rainy period as we head into the first week of April either. We get a wet westerly jet early next week, then some ridging mid/late week, then occasional rain after that. ECMWF ensembles give the Willamette Valley less than 2″ rain in the next two weeks, and this is often overdone. One item that sticks out is brief and sharp upper-level ridging around next Wednesday-Thursday. The 6 hour maximum temperature product from the ECMWF ensembles really shows the good agreement with that idea. It might be our first episode of 75+ degree weather.

KPTV

That’s it for now, enjoy the mainly dry weather the next few days, and the soaking rain early next week too!


Typical spring weather for Oregon’s Spring Break

March 18, 2022

9:30pm Friday…

Here we are in the last two weeks of March and the forecast looks very much like…spring! Winter is in the rear-view mirror I suppose; we haven’t seen chilly weather in 3 weeks, and today was another warmer than average day

Oregon’s Spring Break has begun and continues through Sunday the 27th. I remember lots of years like this upcoming week, a real mix of cold showers plus warm sunshine. A chilly upper-level trough moves through the region tomorrow with morning rain then afternoon sunbreaks. In fact the 2nd part of the day should be quite dry!

Showers pick up a bit Sunday and then Monday will be a gloomy/wet day as a warm front passes by. But a high-amplitude upper-level ridge finally pushes the clouds and rain north of us Tuesday for a MUCH warmer day.

A mix of sunny skies, light offshore (easterly) flow, and warm atmosphere overhead means temperatures soar…by March standards. You can see the offshore flow on the surface map for Tuesday afternoon.

How warm? Models are forecasting somewhere between +10 and +13 deg (C) at 850mb over Salem/Portland. If all remains “perfect”, somewhere between 70-75 in Portland Tuesday. The record high for Tuesday & Wednesday is 73 degrees, it could happen. Regardless, it’ll be the warmest so far this season. It appears a weak marine push (cooler air from southwest) may happen Wednesday as the upper ridge weakens and a trough passes by to the north. Most likely we’ll just see some clouds that day and temps slightly cooler.

So the first 5 days of spring break feature chilly showers, a soggy/wet day, and then 2 very warm May-like days. Nice…

By late next week, the ridging has weakened quite a bit and a cool trough is approaching.

but it’s still a bit warmer than normal at that point and most likely dry. That gives us days 6 & 7 near or a bit warmer than normal and likely dry. Beyond that point I’m guessing we’ll slip into a cooler/wetter pattern, but that’s a long way out. Right now it appears the best ski conditions will be tomorrow and Sunday, then some spring skiing (sunburn!) midweek.

Watch out for icy/snowy roads tomorrow morning and again Sunday morning

If you are headed for the coastline, tomorrow looks surprisingly nice since the bulk of tonight’s cold front rain will be gone soon after sunrise. Lots of sunshine and a brisk northwest wind will be balanced out by strong late March sun angle.

Enjoy the weekend and your spring break!


The Ides of March will be wet! Weather pattern change arrives this weekend

March 10, 2022

10pm Thursday…

Enjoy the sunshine tomorrow and Saturday morning, because we are headed back to “normal” March weather starting Saturday afternoon. Of course, that means lots more clouds, rain, and occasional gusty southerly wind.

Make sure you get outside in the next 36 hours. Tomorrow WILL be a fantastic early spring day and noticeably warmer than today. I think we’ll hit 60 for the last day of the workweek and it won’t be quite as cold in the morning. Then on Saturday we’ve got a nice setup where a cold front suddenly arrives in the afternoon. By that I mean we’ll have sunshine, then quickly change to clouds and rain. That’s instead of steadily increasing clouds eventually leading to rain. I’m hoping to get outside in the morning and enjoy the early sunshine.

A strong cold front arrives Saturday afternoon/evening with solid rain and breezy southerly wind. It’s time for us to see a soaking again. Rain has been about normal for 1/3 of the way through March.

(KPTV)

Looking ahead, it’s obvious that we won’t be seeing a dry March this year. Do you realize that March has been drier than normal the last four years? The last real soaker was March 2017

(KPTV)

The last month has been dominated by strong upper-level ridging near the West Coast, or at least out in the Eastern Pacific. Most of the time we’ve just seen weak systems coming at us from the northwest or north. Look at that huge positive anomaly filling the Eastern Pacific from early February to now.

Wet March Ahead
Wet March Ahead(KPTV)

But the weather pattern changes these next two weeks. The ECMWF ensemble mean forecast for this Saturday through Saturday the 19th shows an upper-level low in the Gulf of Alaska and higher than normal heights to our south = strong westerly jet stream (for March) sending numerous wet weather systems inland.

(KPTV)

That trough is still there as we head into at least the first part of Oregon’s Spring Break.

Wet March Ahead
Wet March Ahead(KPTV)

And of course, the effect is lots of rain; well above average throughout the Pacific Northwest. Although I should point out that westerly flow isn’t the best for big snow/rain east of the Cascades. We want to see upper-level lows pass overhead for significant precipitation over there.

(KPTV)

In the short term, a relatively deep surface low pressure system will move inland Saturday night. Typically that could give us strong wind, especially now that we’re in spring and wind can “mix down” more easily (no inversions). But the low is weakening as it approaches the coastline. So we’ll see gusty wind along the coast and also inland, but just a few power outages here and there.

(KPTV)

How much rain? I think the WRF-GFS model through St. Patrick’s Day is pretty reasonable. Around 2″ or a bit under in the western valleys of Oregon and SW Washington

WRF-GFS Rain Forecast (UW)
WRF-GFS Rain Forecast (UW)(KPTV)

Snow levels will be varying between 2,000′ and 5,000′ over the next week or so…it’s catch up time in the Cascades and it appears we’ll see up to 2 feet of snow by late next week

Wet March Ahead
Wet March Ahead(KPTV)

So…to summarize, get all your outdoor projects wrapped up; we’re entering a wet week…or two.