Strong westerly winds at elevation, pockets of rain and generally nasty conditions kept most migrants still headed north grounded last night. There was a little pocket of birds taking off from the Gray’s Harbor area – probably stragglers of the shorebird and water fowl variety. They didn’t get very far. There were some moderate and widespread returns from California’s Central Valley so this isn’t over yet – but close.
The arctic low has moved south and is still dragging in a cold air mass, condensing moisture as it arrives – there’s even snow at higher elevations. The center is up in BC so we’re getting the westerly winds at the bottom of the trough. There is a high pressure ridge organizing out in the Pacific but it’s effects are a few days out.
Nationally the migration was heaviest in the northern fetches of the Mississippi Flyway. The Atlantic Flyway was active in the Mid-Atlantic States. For details refer to the regional NEXRAD trackers found in the sidebar links. To take a look at the national migration picture click here where Paul Hurtado has archived last night’s event.
Admin Note: This is the last update for this season. I will probably do a final post in June where i’ll put up the intervening local radar loops for documentation. Other than that — barring some meltdown — TTFN, be back in the fall.
Northbound migrants took to the skies shortly after sunset but only had a couple of hours of uninterrupted flight as a squall line came ashore and pushed inland. Since this was mostly a widespread band moving ENE the birds that put down were spread out along the storm front and put down about the same time. There may be a few pockets of concentration mainly to our north. Winds were mainly out of the WSW so birds were again bunched up along the flanks of the Cascades. Southern California and the Central Valley had heavy returns so we still have quite a few birds in the pipeline along the Pacific Flyway.
The cold air mass that is being drug out of the arctic is generating precipitable water bringing our current weater – rain. A look at the Jetstream plot shows the source to be a very organized low in the arctic and it’s interaction with the weaker high out in the Pacific.
The storms continue in Tornado Alley shutting down most of the Central Flyway. Pockets behind the storm track have continuance migration. The flight up the Mississippi Flyway was abbreviated as the storm front moved into the Midwest, and the Atlantic Flyway was only active in the northern reaches. Check out the regional NEXRAD trackers for details. For a national composite; Paul’s archived loop is here.
Current conditions kept the RTX NEXRAD station in precipitation mode all night. That obscures things a bit but if we watch the loops closely we can see birds are still on their northbound journey. Winds were generally favorable at elevation and the velocity plot shows our little buds booking it at over 30 knots up the Willamette Valley. Persistent showers along the Cascades kept the birds contained and we can see a heavy movement along the S-N fetch of the Columbia from Portland to Clatskanie. The coast had spotty migration and north of Gray’s Harbor was shut down.
Aided by the Jet Stream a little trough of low pressure is now asserting itself across the region. The cold front is laden with moisture so we’ll have some rain, but the winds will be out of the SSW. Migration will be opportunistic as the birds pick their way through the rain cells trying to take advantage of the tail winds. The high pressure system to our south is still quite strong and putting up NNW head winds in the southern portions of the Pacific Flyway.
Nationally the bulk of the action was up the Mississippi and Central Flyways with the Ohio River Valley once again just streaming with migrants. The Atlantic Flyway had only spotty migration. As always, consult the accounts by the regional commentators for details. National Reflectivity Composite loop brought to us by Paul Hurtado.
WSW winds and scattered squalls kept coastal migration to a minimum last night. Inland birds were once again pushed up against the Cascades. Overall the migration was moderate with a few heavy patches here and there. Showers to the south of Portland will probably limit the turnover in the area.
The low is having a hard time pushing ashore but the high is stripping moisture and cooler air from it and driving it inland. The surface winds are variable but aloft the flow is solidly WSW.
Nationally there was widespread migration along all three Flyways. Texas had a heavy influx of new birds and the north Plains were under siege. Check out the regional migration trackers for details. Always worth a look; Paul Hurtado’s archived national radar loop.
Moderate levels of movement with a patch, here and there, of heavy migration at times. Very little movement along the coast. Again last night the heaviest movement was to the north. The radar patterns i’m seeing are typically a few weeks early. They are much like late May rather than the first week of May. It could be the oddball high pressure system that has parked itself over the area — not sure.
There is a low pressure system building out in the Pacific and moving on shore. The leading edge will bring some south winds. If the timing is right we’ll get to see if birds are still in the pipeline, or if migration has peaked and we’re on the back side of the season.
Nationally, the Central and Mississippi Flyways were loaded with birds. The Atlantic Flyway was active in the southern reaches as far north as New Jersey, where it was particularly heavy – probably a release of weather trapped migrants. Our pipeline along the Pacific Flyway is still churning away and pumping out birds.
Admin Notes: I will be attending to other responsibilities for the next four or five days, so there won’t be any updates until 14th or 15th of next week. Consult the resources found in the sidebar to the right to keep abreast of this season’s migration. Cheerio!
It seems the plague of technical difficulties will define this season for me. My internet connection was down throughout the night until now. So, no loops and only a short post.
Migration in the local area continues apace and was heavy at times last night. There was a huge movement to our north which can be seen on the Regional Composite. Migration along the coast was subdued, moderate and localized.
The high pressure system is weakening a bit and will bring some transitional weather and winds will be variable. We’ll have to wait and see how this plays out for our migrants.
Nationally the picture speaks for itself. The Central flyway and the lower Atlantic were the hotspots last night. See the regional NEXRAD Trackers in the sidebar for details.
Due to a power supply failure on my workstation i was unable to update the blog yesterday. Today, without much commentary as i catch back up, are the Reflectivity loops from the past few nights.
Only local comment: if you watch all of the loops, note the unusual density of east to west migration over the coast range over the weekend. Birds were moving out of the Willamette Valley to the coast. I don’t recall seeing that in past years and would love to hear of any hypotheses on it’s derivation. HEAVY movement last night. Late evening development as the winds switched around and came out of the south.
Last night — oh to be anywhere along the Central Flyway!
Moderate migration densities, with pulses of heavy movement mostly east of the Willamette and along the flanks of the Cascades last night. Regional plot shows an unusually dense movement across the Umatilla Plateau. Plateau drainage canyons with riparian habitat would be prime opportunities. The dawn chorus in eerily quite this morning.
The moderate NW winds associated with the current, but shifting high probably accounts for the birds being pushed to the Cascades. Onshore flows will bring migrants closer to shore, but the flight wasn’t as pronounced as the past couple of days.
Nationally the storm track has compressed with wind speeds picking up on both sides of the disturbance. The Pacific Flyway continues to be quite hospitable to migrants. The Mississippi Flyway had the bulk of migration while the Central Flyway and Gulf Coast were shut out of the action. Check the regional discussion by clicking through on the NEXRAD Trackers in the side bar.
Migration started out heavy but only lasted the first hour or so as birds left the area. Throughout the rest of the night densities dropped to moderate levels. Strong flight offshore again last night which can be seen in the Regional Composite.
As the low was pushed to the north our high pressure ridge shifted a bit south to accommodate. We had light and variable north winds which really didn’t deter our avian companions. The drop in density is probably just a lull, but there are plenty of birds headed our way.
Nationally, a storm line across the Great Plains kept the Central Flyway shut down. Continuance migration behind the squall line can be seen and fallout conditions will exist along the leading edge. The Mississippi Flyway was open from Texas north and the Mississippi and Ohio river valleys were packed with birds. The Gulf coast from Texas to Mississippi was the hot spot again and there are localized storm cells that may cause local fallout conditions. The Atlantic Flyway was active only in localized parts of New England. By regional standards the Pacific Flyway was quite active.
Moderate migration over the area this past evening. We were given the classic “doughnut hole” treatment last night. Watch the radar loop and note the lack of returns close to the signal. What this represents is an absence of birds at low elevations. Few birds leaving or landing in the area. They are, for the most part, about a mile up and not stopping here.
The winds were out of the north for most of the night but not too terribly strong (5 – 10 knots) except along the coast (10 – 15 knots). Around midnight they dropped off. I put in a static shot of what happened after that. From the mouth of the Columbia and Willapa Bay an explosion of birds takes off and heads out to sea to continue their journey north. We still do not have station level data for the new radar along the Washington coast — too bad, it would be great to get that data. So you’ll have to do with the static Regional level plot in today’s gallery. But you might want to head on over to RAP and run your own loop — it’s pretty cool.
This high is proving to be pretty stubborn. It has pushed the low we saw yesterday north again, relieving some of the strain, lowering the wind speeds, and keeping the arctic air entrainment to moderate levels. As the low passes to our north we may see some instabilities develop but should present only as cloud cover. I’m looking for mild north winds and no rain for tomorrow night’s flight. Migration will continue apace.
Nationally it was a repeat of last night with a few developments. The Atlantic Flyway had a wind blockage from the Carolinas to New Jersey. The gulf rim was quite heavy and some fall-out conditions could present in the Florida pan-handle area westward along the squall line. The Mississippi and especially the Central Flyways were ablaze with birds. Until they met the storm track running from Nebraska to Wisconsin. Concentrating events are likely along the southern boundary. (LaPuma is probably peeing his pants in anticipation of today’s possibilities)