A mix of heavy precipitation and strong unfavorable winds failed to trigger any migration over the mid-Atlantic and southeastern NY last night. Here’s the radar from 7:50pm last night through 5:30am this morning.

Frames are every 1/2 hour. Click on the thumbnail to view the full-sized animation.

From southeastern NY to the Delmarva Peninsula we were sandwiched between a very wet stationary front to our north and an equally unappealing stalled cold front to our west. Upper level winds were strong (20-30kts) and ranged from southerly (S. Jersey and the Delmarva Peninsula) to northeasterly (NYC) last night, while surface winds were light and generally from the ESE across the region. Looking at the regional composite you can really see the absence of migration over our region while points north of the front (where the precipitation has cleared and the winds are more northerly) show heavy migration heading NE->SW. Looking at the individual reflectivity loops you can see lots of precipitation heading NE along the frontal boundary while no migration signal appears after sunset at any of the three radars. The radial velocity loops show that target speed and direction across the radars is consistent with the prevailing upper-level winds, also supporting the ‘no detectable migration’ hypothesis.

Interestingly, while outside in North Cape May last night I heard some nocturnal flight calls over a well-lit parking lot. This was just after sunset so would represent an initial exodus of birds from the ground. I could make out Bobolink, American Redstart and Swainson’s Thrush in my several minutes of listening. I imagine these were birds checking out the conditions before either making a small localized movement, or deciding with the masses that indeed ‘tonight is not the night’. Regardless it does support the idea that birds shift in the landscape even on nights totally unfavorable to a regional migration event.

Looking ahead, low pressure over western PA will continue to churn counterclockwise over the region- which means southerly flow intensifying across the mid-Atlantic and northeasterly flow over the northeastern US and the Great Lakes region. This will convey birds from the northeast into the Mississippi and Central Flyways which will both be increasing in activity over the next few nights. As you can imagine, this means that we’re getting the short end of the migration stick. We’ll have to wait for Katia to move out of our waters before this front can clear and finally free up high pressure to build in with NW winds… but it’s going to feel like forever! Right now it looks like Friday night should be the next east coast migration event- so Saturday morning should exhibit favorable birding conditions both for arriving nocturnal migrants and for diurnal raptors.

Good Birding

David