CAPE

Pretty decent writeup from Mount Holly on the development and likely impacts in their morning AFD. Excerpt below. Dry air in place across our region will start to give way to a plume of deepening Atlantic moisture wrapping toward the coast around the low as it approaches eastern North Carolina. Enhanced by low-level convergence and some warm-air advection, an initial batch of moderate to perhaps occasionally heavy rain will advance northward across the Delmarva Friday night, and perhaps into southern New Jersey by Saturday morning. However, the details from that point forward remain murky, as models disagree on the northward extent of steadier rain through Saturday, along with the timing and amounts of additional rain as the area of low pressure tracks toward our region on Sunday. The best compromise of forecast amounts suggests that from 0.75 to 1.5 inches will fall through Saturday night northwest of I-95, with 1.5 to 2.5 inches southeast, with the highest amounts right along the coast from Cape May to coastal Delaware. Those amounts have trended somewhat lower than earlier forecasts. While heavier rainfall amounts than those are still within the range of outcomes, those amounts do not implicitly suggest significant impacts or more than nuisance poor-drainage or localized urban/small-stream type of flooding. Even that would probably be confined to the period of time when the initial batch of rain is lifting northward earlier on Saturday. Precipitable water values do rise into the 1.5-1.75" range on Saturday southeast of I-95, with dewpoints into the upper 60s along the coast, with some potential for an isolated thunderstorm there. Otherwise farther inland, especially northwest of the urban corridor, the atmosphere looks progressively less moist and more stable, which may limit the heavy rain threat. Overall the greater threats from this system look to be along the coast, with the potential for a period of coastal flooding, gales over the coastal waters and rather strong winds along the immediate coast (gusts 40 to 50 mph). Temperatures will be rather cool as well, with highs only in the 60s away from the coast. The wild card in all of this is whether or not the system may take on some subtropical characteristics. That is probably not in much doubt, but whether or not NHC deems it worthy of being named remains to be seen. In either case, the main system will likely weaken as it tracks northward, and it`s effects may actually diminish as it arrives on Sunday, with the pressure gradient between it and the high to the north being the main driver of the inclement weather.

Its primary error seems to have been associated with the timing/orientation of that northern shortwave moving southward under the upper ridge in Canada. Previous runs had it sharper/further west and it was acting as a kicker.

So we all excited for our rainy weekend? Looks like it's happening! Plenty of football to watch.

Updated forecast for here now has amounts for Friday-Saturday. 1-3". Mt Holly following NBM given inconsistencies between the global models.

12z ICON looks Euro-ish

If the Euro is out, well, you know don't ya?

Tends to happen in a Nino. Need just enough cold concurrent with. In a Nina like last winter, the subtleties in the longwave pattern are often 'off' enough to screw us, even when we see the guidance advertising an apparently classic -NAO for example. Best shot during a Nina imo is a transient period with +PNA/-EPO ridge to deliver legit Polar air with a carved out trough along the east coast, and hope for a well timed wave to track along the baroclinic boundary. Risk is too far offshore/late developing, leaving the area cold and dry. This has worked out well esp for eastern areas the past few Ninas though.

Thoughts from Mount Holly based on the 12z suite- Low pressure lifts towards the Mid-Atlantic late Friday night and into Saturday morning. A piece of energy will spin off the main low and pass either right over the East Coast or just offshore. There are differences among the 12Z suite of models, with the GFS being fastest and closest to the coast. GFS has the primary low over the Mid-Atlantic by Saturday morning, while the ECMWF has the primary low still off the Southeast Coast. The CMC is somewhat in between. A slug of heavy rain moves into the local region during this time, with the heaviest rain east of I-95. The 12Z NBM has come in with higher PoPs over Delmarva and southern New Jersey, but will bump up to have likely PoPs along, south and east of the I-95 corridor, and chance to the north and west. Primary low will then track along the coast Saturday night through Sunday, but there are timing and placement inconsistencies among the models. Will generally carry chance PoPs for Sunday and into Sunday night. Depending on the track of the low, as much as 3 to 5 inches of rain could fall along the New Jersey and Delaware coasts this weekend, with an inch or so possible in the southern Poconos should the 12Z/19 GFS verify. This will be much lower if the 12Z/19 ECMWF verifies. If the 12Z/19 CMC verifies, then heavier rain is possible over more of the region.

Yeah its better than the 0z run. Implies a decent soaker but not some prolific subtropical deal.

Don't forget the Ravens season, and the injuries.

Yeah it has. It shifted the axis of heaviest rain east this run, but still soaks places well inland too.

12z CMC with region wide 2"+. Heaviest right up/along the bay.

Sorry friend. All things are relative.

6z ICON looked good.

We just can't know yet. Mount Holly AFD- Beyond Friday, the main question becomes whether the ridging to our north will "relax" enough for the coastal low to our south to move northward bringing rain to our area over the weekend. If this does happen, rainfall amounts could be significant due to both the slow movement of the system and its potential of drawing in tropical moisture with PWATs around 2+ inches. Forecast models are still struggling though with both variability from one model update cycle to the next and between the different models. The 0z deterministic runs of the GFS and the GEM Global continue to allow the low to track far enough northward to bring the area significant rainfall and strong E/NE winds beginning Saturday lasting into Sunday while the 12z ECMWF was more surpressed keeping the low and its heaviest rainfall farther south. The 0Z ECMWF has trended farther north however. We did increase POPs above NBM (National Blend of Models) with this update as we`re thinking it`s likely that the system will bring rainfall at least as far north as the I-95 corridor by late Saturday into Saturday night. There is uncertainty though regarding time of arrival and of course amounts.

The 0z op run looked fine, and 6z GEFS is actually slightly better than 0z GEFS wrt rainfall across the region.

WPC is buying the idea of significant rainfall for the entire area D5-7 on their latest qpf forecast.

12z run made a move to a stronger upper ridge over Hudson Bay, and thus a stronger surface HP just to the SE in eastern Canada. Acting as more of a block rather than a progressive high. Suppresses the SE LP/forces the deep moisture more offshore. GFS and CMC disagree.

1.01" total for the overnight/early morning event. 4.9" for the month

Potential for heavy rain this weekend based on current guidance, via a tropical moisture feed.

Rain fell pretty much all night here, mostly moderate in intensity. Still some light rain ongoing, but it looks like the heavier stuff has shifted off to the east. 0.83"

What a day indeed. Weed/beer/wine blend with some nice food makes it even better.

Big win for the Os! Good day for Balmer sports fans.