Early Northeasterly wind events unfold along the SE Region
Forecast Blog by WeatherFlow meteorologist Shea Gibson 10/16/13.
With this year showing many differences from the years past, we have additionally seen an early arrival of Canadian High’s push NE winds into the SE Region multiple times during this early fall Sept 2013 season. Typically we would be seeing the finishing rounds of late season Seabreeze frontal developments produce afternoon thermals with Bermuda High’s still occasionally building in the Atlantic as the warmer months ebb and water temps hold into mid 80’s. However, weaker cold fronts and stronger High pressures from the Northern tier states and up into Canada have been able to strengthen down into our area as post frontal build – even from central dome of High pressure remaining as far away as the NE United States. SST’s cooled to upper 70’s a few weeks early and cool advecting winds have been able to saturate the coastlines during the warmer points of the day with localized lowering of pressure along beaches.
Here are the Wind Roses from September 2013 from 3 major points from all 3 forecast zones…shows the predominance of NE/ENE wind events to hold majority along the SE Region.
Georgia South Carolina Southeast North Carolina
These pictures below are derived from a WSI product I like to edit and re-render as user friendly frontal boundary and pressure location tool – which I use to show extended forecast trends in the “Chucktown Wind Report” on Facebook. These are saved maps for extended forecasts at different intervals, but represent the weather pattern for NE’erly setups along the SE region. Dates start August 30 and move forward from there.
Here is the anatomy of Sept 14 where we somewhat got a forecast right along the GA/SC coast, and got a mixed bag of NNE –> E directions and speeds along the SENC coast.
This one is from Sept 12 that shows trends into the 13th and 14th .
We can see the early morning values at Georgia sitting well above estimates from NAM 12k in Quick Look off of iKitesurf:
The area readings reflect a forecast on track from the night before…was a decent forecast for most of the morning to all areas, then afternoon values changed with frontal activity sagging through the forecast zone and slowly pushing south. The model build I used was off of the WW3 Atlantic 0.5° model with definitive edits – I could see where the frontal boundary cut right through the middle of these two points up through noon. After that, it was all speculatory to the south.
NOTE: Tybee Island and Jekyll Island are ~100 miles apart.
And here were the all day graphs for Tybee and Jekyll for what actually occurred…
Wrap up notes for Georgia….We got Jekyll right through morning with a bit more of a NNE to the north, then multiple switching of directions caused some inconsistencies through early and mid afternoon- BUT it looks like we got it later in the day with the E/ENE direction settling in with a few higher values. North Tybee was a bit more of a roller-coaster ride and speeds settled in later after 5pm. Another way to see how gradients meander in and out of the coast during these events.
SOUTH CAROLINA 9/14/13:
Cold frontal boundary already south of the area…here is the NAM 12k Quick Look that morning from iKitesurf:
And again…the area readings reflect a forecast on track from the night before… The model build I used was off of the WW3 Atlantic 0.5° model with definitive edits as lighter speeds were showing in the AM over to building speeds throughout the day. The offshore readings reflect where the gradient boundary pretty much showed as a precursor, but not necessarily what would happen along the coast. (Seems to happen quite a bit with coastal readings sometimes shooting up multiple knots higher than what offshore readings hold. A sign of that cool air advecting into the coast. )
Here is the forecast for the day- I left room for a few higher numbers with mention of gradient enhancements.
And here is what happened all day – you can really see how that NEbE/ENE/EbN lean past 55° in azimuths really ramps up numbers several knots. This is magnified exponentially with high wind events.
Folly Pier Isle of Palms Pier
Wrap up notes for SC….We can see how gradients meandered in and out of the coast during the day here. Most speeds stayed within parameters unless gradients ebbed and surged, making it very difficult to predict. Typically, we have to wait for that + 55° lean in for the onshore flow to show the true speeds. Otherwise, land shadowing from NNE/N flow has an adverse effect along most sensors.
Here is a wind rose overlay for one of our kiteboarding ride spots in Charleston – at Sullivan’s Island:
SOUTHEAST NORTH CAROLINA 9/14/13:
And again…the area readings reflect a forecast on track from the night before… The model build I used was off of the WW3 Atlantic 0.5° model with definitive edits as lighter speeds were showing in the AM over to building speeds throughout the day. The offshore readings reflect where the gradient boundary pretty much showed as a precursor, but not necessarily what would happen along the coast.
NOTE: I use “Oak Island” for Cape Fear alot simply because it seems to get those NE winds better without all the heavy shadowing – and it gets 5 minute updates of course!
You can see, Cape Lookout was pretty much on track to start the morning and the Cape Fear area was well below, which showed a hole in gradients from Cape Fear all the way down to Tybee Island, GA where the gradient boundary was edged back into the coast.
Here is the forecast:
And here is what occurred:
Cape Lookout Oak Island (Cape Fear)
Wrap up notes for SENC….We can see how gradients meandered in and out of the coast, staying well hidden offshore to southern zones down into Myrtle Beach. Most speeds stayed within parameters unless gradients ebbed from those areas, making it very difficult to predict the entire SENC zone as a whole. Was a win for the forecast from Cape Lookout and northwards. South of that, speeds bottomed out.