Nov 16: Coastal Storm Approaching

Nov 16: Coastal Storm Approaching

Written on 11/17/2019
Jonathan Carr

Discussion: The coastal storm is now rapidly developing off the SE US. You can see it here on satellite imagery a few hundred miles east of the GA/SC border: https://weather.cod.edu/satrad/?parms=global-northamerica-14-48-1-100-1&checked=map&colorbar=data

The high is currently over upstate New York and slowing the coastal storm’s northward track.  The high’s influence should be out of here by noon tomorrow (Sunday). From that point-on the coastal low should take over and drive warmer and wetter air onshore through the rest of Sunday night and Monday morning. The coastal low then pulls away by Monday afternoon and the upper-level disturbance associated with the approaching trough moves in for Monday night into Tuesday morning. Because the trough will likely not dive in in-time to phase with the coastal it becomes a secondary after-event altogether. With that said let’s break down the impacts:

Rain: I’ve never been concerned about the rain with this system. It is too difficult to anticipate the NW-extent of the precipitation shield. It might reach through most of NJ into EPA. It might only reach the I-95 corridor (NJ Turnpike). In either case it’s not large-drop heavy downpour rain. It’s the misty/drenching drizzle/light rain shower kind of stuff. A raw day. No one should see more than an inch of rain anywhere if that. Rain should start by Sunday afternoon (currently flirting with Cape May and moving N) and taper off by noon on Monday. This should allow for a break in any precipitation even for the immediate SENJ coast. The next batch of precipitation should move through between Monday evening and Tuesday morning. This batch could be wintry for EPA and NWNJ possibly points SE of such.

Wind: So far most of the onshore flow has been driven by the southern side of the high’s anti-cyclonic flow. We had some decent gusts earlier today (to 40mph along the ENJ coast) but it has since relaxed some. With these coastal systems the wind gusts are always higher along the ocean-facing coasts. Once you get more than 5-10 miles away from the coast winds diminish intensity due to land friction. It can still get breezy/gusty inland but the coast takes it to the face. I expect onshore flow to remain stiff overnight tonight and pick up through tomorrow as the coastal low approaches closer/higher in latitude. Wind direction should remain out of the NE quadrant and never really goes dead-east. This is due to the low’s eastward proximity to NJ and is better for coastal flooding concerns. Winds should remain gusty but switch to the N/NW by mid-day Monday indicating the coastal low pulling away. We then see NW winds Monday night into Tuesday as the upper-level disturbance moves through.

Coastal Flooding: The NWS issued a coastal flooding warning today for the concerns I’ve been describing the past few days. Between the high’s southern-side flow and the coastal low’s northern side flow there’s a lot of easterly fetch off the ocean out of the NE. The coastal low itself should also radiate swell into the coast. We luck out due to the lack of prolonged E or E/SE flow but there is still enough flow overall to warrant the coastal flooding concerns. The area between Cape May and Atlantic City is still favored for the highest water levels of the ENJ ocean-facing coasts. The high tides to watch are the two that occur tomorrow (Sunday AM and PM) and the two that occur Monday (AM and PM). Water levels should subside on Tuesday. Coastal flooding will likely be minor-to-moderate for the entire coast with Cape May-AC still not out of the woods for low-end major.

Wintry Concerns: The wintry concerns are wildcards. First between now and tomorrow it is cold enough aloft and at the surface for some (along/NW of NJTP) for frozen precipitation in the form of freezing drizzle. The current radar look indicates something happening but evaporating before it reaches the surface/lower-levels. It doesn’t look like standard clutter…more like virga. By noon tomorrow it should be warm enough at all levels for all areas to support rain only and this is when the rain chances mainly begin. When winds switch to the N/NW Monday evening cold will re-invade at all levels and at least NWNJ will be cold enough to support wintry precipitation. Since the approaching trough did not phase with the coastal it comes through as an upper-level disturbance. This should ring some more precipitation out of the sky which could reach the surface as sleet or snow. NWNJ would be most favored. SENJ would be least favored. Let’s take another look at this tomorrow. We have until about Monday morning to call it a go for Monday night into Tuesday.

In English: Raw conditions are on deck for Sunday into Monday. At least SENJ should see periods of rain between about noon tomorrow (Sunday) through noon on Monday. Some drizzle is already approaching Cape May from the S. Areas further inland could see the same but are less certain than the SENJ coast. Winds should remain more intense along the immediate ocean-facing coasts through Monday morning (less intense away from the ocean). Coastal flooding concerns remain especially for the two high tides tomorrow (Sunday) and the two on Monday. Cape May to Atlantic City is the area of greatest coastal flooding concern. Also watching Monday night into Tuesday for another batch of precipitation possibly wintry for some. I’ll try to do a video tomorrow evening as things are cranking. Have a great rest of your Saturday night and be safe! JC

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