Upper level southerly winds, though not strong, along with a dwindling season, yielded very light migration over the region last night. Heaviest returns were in the Puget Sound area and those were moderate at best. San Diego is reporting their first Buffleheads, so you know it is pretty late in the season.
And with that — i’m headed into the field for the next three days and shutting down the blog for this season. I will monitor the radar, as all radar junkies do, and if anything interesting pops up i’ll post it. But barring that and conditions permitting, i’ll be back in the spring with the Turkey Vultures.
Odd weather indeed. Light to moderate levels of migration last night, with Seattle and the Puget Sound seeing the heaviest. There is still directional movement being seen, but also a lot of just moving around. Migrants will continue to trickle south, but without urgency. This flat, stationary ridge is making for shifting winds but without any force. Migrants are not facing any challenging conditions. Here’s the current eBird map of Bufflehead sightings, and here is the map for Tundra Swans. The paucity of sightings clearly shows there arel plenty of birds to our north, but the meager radar returns indicates it’s only the winter residents that are left.
Migration is on it’s last legs. There’s still plenty of movement to be done but it will be more selective than driven.
The high pressure ridge is flattening out and bringing this mild and calm weather. Winds will be switching to out of the east as temperature and not pressure will be driving them. A small low pressure cell is organizing out in the Pacific and may bring some southerly winds 48 to 72 hours out. It’s not a full blown trough so it wont be dragging much arctic air in with it. We’ll have to see how this plays out.
Here are the radar loops from last night, except Seattle (ATX). It’s on the fritz.
Ho Hum. Under superb conditions only a moderate flight across the region. Still plenty of birds in the pipeline but it looks like they will be trickling in over the next month. With such unseasonably warm and rainless weather perhaps there is no urgency to leave the northern realms. I’m seeing lots of bugs and even good numbers of dragonflies out in the field. The local unmanaged seasonal wetlands are dry as well. I’ll keep an eye out for a pulse, but this is a signature of a waning season that is being drawn out.
The high pressure ridge remains stable and the winds will be driven out of the north. Some temperature differential winds will be driving an easterly component, but mainly during the daylight hours. Clear skies for a few more days at least.
Decent but not spectacular. You know we are on the back side of the peak when, under ideal conditions, we only see patches of heavy migration. There are still a lot of birds on the move, just not at green doughnut levels. So, now that i have said that i’m sure the birds will prove me wrong. I’m OK with that.
They have the opportunity and excellent conditions to do so for the next few days. The current ridge will be getting squished in the next 12 to 24 hours so there’s some iffyness to the upcoming flight tonight. It looks like the winds will still have a lot of northerly component so those headed southbound with urgency can still get a bit of a free ride. They may just have to deal with being pushed a bit to the west. However, this ridge looks like it is being replaced with another. With a center well above the 49th parallel it should give us at least a few more days of migration friendly conditions.
Friday night’s flight into Saturday morning was hampered by rain but a number of migrants left the area as the skies were a bit clearer to our south. Peak reflectivity shot is in the weather gallery.
Saturday’s flight into Sunday morning was more substantial but showing signs of a waning migration season. Peak reflectivity shot is in the weather gallery.
Last night’s flight was quite a bit more substantial under pretty ideal conditions. We are sitting on the leading edge of a high pressure ridge – clear skies and north winds. The ridge will be flattening out some 36 to 60 hours out so we should have decent conditions tonight, but it gets a bit dicey for Tuesday’s flight.
Here are the links to last night’s radar loops
ATX = Seattle
LGX = Gray’s Harbor
RTX = Portland
Most of the action was to our north, while the Portland/Vancouver Basin only saw moderate levels of migration last night. There were some pockets of heavy movement, just not widespread. However, along the coast and across the Strait, birds were heavily on the move. Maybe the localized rain dampened local spirits or they may just be happy to hang out for a while and enjoy our hospitality – we’ve got some really great bugs.
Whatever the case, it looks like some upper level instability will be moving into the area 24 to 48 hours out. Which may disrupt things a bit, but i don’t see any rain and the winds should remain out of the north. So we’ll see.
Tomorrow starts the weekend and i will be out in the field early. So updates, if any, will be for archival purposes.
Here are last night’s radar soundings from the PNW radars (left click will take you to the loop):
In spite of my Monday comments about shutting down early, i’m keeping the reports up until those Buffleheads show up like usual. This fall’s migration still has some legs.
Another night of excellent conditions and another night of birds on the move. From the US/CA border and down the I5 corridor birds filled the air space. We had some stronger winds out of the WNW that kept the birds inland – very few were out over the ocean last night.
Looks like we have another couple of days until the next significant low moves in. So we should see another good flight tonight.
With the discovery of the excellent (and i mean EXCELLENT!) weather site at the College of DuPage I have added one of their radar products to the loops – HCA. The HCA is explained in depth, with further linked resources, in a new page for the site. Look for it in the top banner with the other resources. But basically it is, “The HCA is a complex algorithm performed by the NEXRAD that attempts to determine the most likely type of the echoes in the radar beam.” And most importantly, for this blog, is that one of those echo types is classified as BI – biological. When you look at the HC loops note the scale on the right, look for the BI color, and get ready for your jaw to drop!
If you have ever wondered why the TV weather man has radar images up that do not show the birds — the HCA is the answer. They take the signal and eliminate unwanted echo classifications. Here are last night’s loops – (man, i am so f’n stoked to have these archived again!)
As the low passes through, the ridge continues to build in behind pushing the winds out of the north and bringing a flood of migrants. It was one of those signature nights the migrants wait for. Streaming across the Strait, torrents of birds along the coast, and a deluge down the I5 corridor. We are dripping with birds tonight!
A reminder about these links: The regional level loops will break in a few days, NCAR does not archive the images past that. Paul’s loop will remain in perpetuity — he’s like that. The forecast links are dynamic and constantly updated. That is; if you go to past posts and follow those links, they will look just like today’s link.
Peak Reflectivity (KRTX)
Peak Reflectivity (KATX)
Peak Regional Reflectivity
Winds Aloft at 850mb Heights
Geopotential and Vorticity at 500mb Heights
BONUS!! Left click and open the links below for full animated .gifs of the THREE regional Reflectivity Loops. Yes, THREE. Whereas NCAR does not archive the Langley Hill radar College of DuPage does. Not only that, but that is where the .gif downloads are from. Sweet, sweet, sweet!