Author Archives: greg haworth

PNW Migration Update – 21 May 2013

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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.

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PNW Migration Update – 20 May 2013

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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.

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PNW Migration Update – 19 May 2013

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Winds with a mainly northerly component did not deter this last wave of migrants.  Except along the coast where the winds were up to 20 knots at altitude.  The migration pattern was again a signature of this season – moderate with patches of heavy returns.  The bulk of the birds were flying up the flanks of the Cascades.  We did see a very light but widespread flight come up out of the area around the mouth of the Columbia – captured in the Regional Composite.

A high pressure cell off the coast is dictating the conditions currently — clear skies and northerly winds.  There is a low squished between two highs that has some moisture associated with it, but it doesn’t look very strong and may only bring some cloud cover.  Notable is the high out in the Gulf of Alaska.  When the high pressure cells reach that latitude, summer is not far behind, but at this time of the year it can also pull down some cold arctic air.

Nationally the strong low that is wreaking havoc across the Plains States also pretty much shut down the Central Flyway. Some opportunistic migration between or behind squalls can be seen. The Mississippi Flyway was hopping however, especially up the Ohio Valley.  We are now seeing patterns that indicate this season’s migration is beginning to wain – not over, but definitely on the back side of the peak.  For details on migration back East check out the NEXRAD trackers in the side bar.  For a look at last night’s migration on a national level take a look at Paul Hurtado’s archived loop here.

Admin Note:  There will only be two more updates this season – i’m headed out on my annual trip to Malheur with the folks from the Audubon Society of Corvallis.  I may put up the archived loops without commentary once i get back from Malheur – depends on how they look.  But other than that — barring a meltdown in conditions — i’ll be back in the fall to watch the new crop of birds pick their way south.

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PNW Migration Update – 16 May 2013

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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.

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PNW Migration Update – 15 May 2013

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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.

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PNW Migration Update – 14 May 2013

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Northwest winds pushed the bulk of migrants over to the east counties last night, where  heavy migration returns were seen throughout most of the flight.  The flight along the coast was shut down around midnight along the northern reaches of the Olympic Peninsula by the first wave of squall lines.  Concentration of birds should be expected from Gray’s Harbor northward and along the Puget Sound as birds took refuge by heading inland.

The high pressure ridge is still hanging on by a thread giving us those NW winds, but an organized low is pushing inland which brought the squalls to the OP last night.  Depending on how strong it is the winds will be shifting to the W on a weaker system  or SW on a stronger one.

Nationally birds are moving on favorable winds up the lower Central and Mississippi Flyways with a notable push up the Ohio River Valley.  Check out the regional migration trackers in the NEXRAD side bar for details.

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Uncle – PNW Migration

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this is getting to be a real pain and way too much of a chore for a pass-time.

My server is putting up barriers to access the archived radar image files.  I’ll chase this down in due time but not right now.

Migration continues but it has been very different than the last two springs i’ve followed.  We have not seen one “green doughnut” all season.  Heavy migration has come only in patches.  The weather has been off the charts out of the norm as well and that may account for the odd migration patterns.  Onshore winds could bring some good birding opportunities along the coast.

Nationally a low pressure trough kept birds down along the Atlantic Flyway while the Mississippi and Central Flyways were active with heavy migration.  The Pacific Flyway had widespread moderate migration.  The MAX station in Medford shows, as i recall, the densest returns of the season.

PNW Migration Update – 08 May 2013

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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!

PNW Migration Update – 07 May 2013

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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.

PNW Migration Update – 06 May 2013

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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!