Tues 27 Sept 11

We’re still waiting out this cold front, so once again today there is not much to report.  The low pressure system is sliding northward so we are seeing westerly winds aloft at 20 to 25 knots across the northwestern part of the state.  This coupled with the precipitation will probably keep most birds grounded.

There is no apparent movement on last night’s radar, but it was in precipitation mode all last night which makes interpretation a bit more difficult for me.  Even with the unfavorable conditions we should expect some hardy souls to be moving south.  Probably flying at lower altitudes where the winds are not as strong, below the radar, so to speak.

Below is a snapshot of the base velocity which shows directionality associated with the prevailing winds.  These targets are what the radar is designed to monitor — clouds and precipitation.

The winds off the coast are WSW turning mainly west as they hit land.  Up north, once you move inland, the winds favor the staging of birds over to the Central Flyways.  Looking at the isotach chart below it is conceivable to speculate that some Alaskan and Berring Straight birds could take advantage of the trailing edge of this system and head out over the Pacific and make landfall along our coast.  Who knows?  Anyway, the strong westerlies could also push some pelagic species closer to shore.  So if you happen to be at the coast today keep an eye out to sea, conditions permitting.

Taking a national look at the chart above, note the low pressure system and associated winds that is centered over northern Illinois. Note the leading edge where there are 30 knot winds over Indiana, then a lull over Ohio, picking back up to 20 – 25 knots just west of the Appalachians, and really not effecting the Atlantic seaboard.  Note then the trailing edge where the winds are out of the north from Minnesota and down the central plain states.  Now look at the national composite radar from last night below.  Pretty cool!  This is why we are waiting for our current low pressure system to move eastward.  Once the northerly winds associated with the trailing edge moves across the state, bottled up migrants are going to move with them.

 

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