PNW Migration Update – 02 May 2013

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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.

PNW Migration Update – 01 May 2013

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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.

PNW Migration Update – 30 April 2013

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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)

PNW Migration Update – 29 April 2013

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Minimal migration in the area last night.  Strong NW winds proved to be too much of a hassle to deal with and, by and large, the birds decided to stay put.  Those that did take flight were probably strong flyers or perhaps it’s just short flights shuffling the deck a bit.  The dawn chorus is quite active this glorious morning.  So, while there wasn’t much turnover last night there are still plenty of migrants up and foraging.

The predominant high pressure system is asserting itself a bit as it gets pushed ashore.  Surface winds out of the NNW gusting to 15 knots and reaching 30 knots aloft kept the birds grounded.  Looking at the wind plots we can see a bit of a change in the dynamics as the next low is organized quite a bit further south.  This looks set to dislodge this long standing high but it wont happen soon.  If the high persists in it’s current location and it continues to compress i’d expect the wind to remain strong and out of the north.  We’ll just have to wait and see.

Nationally the Central and Mississippi Flyways were flooded with birds.  After a week of dodging weather the birds had clear air with favorable south winds. They were moving with fervor and presented the heaviest and most widespread flight of the season.  The Atlantic Flyway saw action but only in the southern reaches as a remnant high pressure cell threw north winds and some rain in the area.  Possible fallout conditions along the Texas coastline.

Program interface with RAP is buggy again this morning so the Reflectivity and Velocity plots are static captures instead of loops today.

PNW Migration Update – 28 April 2013

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A couple of extra loops today covering Friday and Saturday’s migration stories.  Both nights had moderate to heavy, in places, migration.  Friday more so than Saturday.

Last night we can see birds getting up into the air to our south and disappear into the cloud cover and scattered rain.  Conditions may present localized concentrations of birds but it happened very early in the exodus so it won’t be pronounced.

Winds are being driven  by the interface of the two fronts; passing low to our north and the persistent high off shore.  The interaction has brought some instabilities and the winds have a heavy westerly component.  Along the central and southern coast the winds remain out of the north.  Birds are still pushing through and some may get funneled up the Columbia with the westerlies. ah, who knows.

Nationally we had widespread, heavy migration up the southern and central portions of the Central and Mississippi Flyways.  Weather cut it off in the north.  The Atlantic Flyway was under heavy weather and only spotty migration was taking place.  Some new birds in Florida and some continuance in the Northeast.

Quick Update

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I’m on vacation for the day but…

Heavy migration last night throughout the area — if you can, get out there and see those birds!  That’s where i’m headed.  Be back Monday.

PNW Migration Update – 24 April 2013

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Mild headwinds not withstanding, birds were headed north. Heavy migration was the scenario for the Willamette Basin last night, mainly in the east county.  Coastal movement was not as pronounced as yesterday.  There should be some pretty good turnover today.

The high pressure system that has been dictating our weather is showing some signs of weakening as a competing low is building in the Bearing Sea.  It probably wont displace the high but it may entrain some colder air and bring in some clouds and instabilities over the next few days.  We’ll see.

Nationally – the Atlantic Flyway, and especially in the SE, was quite active from Florida to Maine.  The Mississippi and Central Flyways were shut down again.  But of major interest to us over on the West Coast — the Pacific Flyway was on the move.  On the National Composite check out the Las Vegas radar!  That is the densest returns from that station that i can recall.  The central valley of California was lit up again last night.  Those birds are headed this way — look busy, they’re coming.  Compare the Winds Aloft plot and the National Reflectivity Composite to get perspective on how migrating birds interact with weather conditions.

The problems in programming have been fixed (for now) and we once again have Reflectivity and Velocity loops for today’s gallery.

PNW Migration Update – 23 April 2013

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Locally the birds were headed north at moderate levels.  But, along the coast, it was hot and heavy with returns in the 20 to 25 dBz range.  Shore birds and sea birds are obviously on the move.  The chatter on the state listserve has coastal observations of diurnal movement as well.

Our weather pattern is holding for now with the high pressure ridge entrenched in the Gulf of Alaska.  This is deflecting any lows east which ….

… is hammering the Central Flyway.  Taking a look at the National Composite we can see the system draped across the Midwest shutting down migration.  But it continues apace east of the system. up the Ohio Valley and into New England — heaviest in the SE.

Crud — my script has died for now and i’m not archiving the plot loops.  I really don’t have the time to debug this right now.  So, the Reflectivity plots will be static images until i can get this fixed.  In the mean time head on over to Real-Time Weather and generate your own loops.

PNW Migration Update – 22 April 2013

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We’re in the thick of it now.  Heavy migration last night, up to 25 dBz – concentrated on the east side from 9 PM to 4 AM.  The west side saw plenty of action as well, especially along the ridge line of the coast range.  We’ve got plenty more on the way as the entire stretch of the Pacific Flyway was hot again last night.  As the high pressure ridge moves up into the Gulf of Alaska, the leading north winds are just not strong enough to keep the birds down, the skies are clear and fine weather is on the way.

As it is also the height of wild flower season it’s been hard for me to keep up on the listserv chatter, so i’m not sure what other folks are seeing on the ground. I’ve had a smattering of shore birds on my patch — Greater Yellowlegs, Black-bellied Plovers and peeps.  Yesterday there was a large, 4 – 500, flock of staging Ridgeway Cacklers.  Haven’t seen any flycatchers yet, but i’m pretty sure the vanguards are in the area by now.

Nationally it looks much like yesterday: lower Central and Mississippi Flyways very active until northern progress is cut off by weather and the Atlantic Flyway is, by and large, shut down.  For in-depth commentary visit the folks found on the sidebar NEXRAD links.

My script should have returned the loops by now — it’s probably sick.  So the Reflectivity plot today is static. (sigh)

PNW Migration Weekend Recap – 21 April 2013

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We had moderate to localized heavy migration throughout the weekend, with Saturday night being the most active.  Not much more to say than that.  I have been out of the loop this weekend with other endeavors and responsibilities, but will get back up on top of this this week.

The National Composite from last night is attached as well, and as always — the weather and associated winds are driving migration.  Nice strong southerlies on the back side of the clearing high has the Mississippi and lower Central Flyways full of birds.