Little Egg Inlet to Great Egg Inlet NJ out 20 NM Marine Forecast
|Tonight...Sw Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 20 Kt After Midnight. Seas 2 Ft Or Less, Then Around 3 Ft Late This Evening And Overnight. Swell Mainly From The S With A Dominant Period Of 6 Seconds. A Slight Chance Of Showers Late.|
|Wed...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 3 To 4 Ft. Swell Mainly From The S With A Dominant Period Of 7 Seconds. A Chance Of Tstms Late.|
|Wed Night...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt, Becoming W 5 To 10 Kt With Gusts Up To 20 Kt In The Late Evening And Overnight. Seas 3 To 4 Ft. Swell Mainly From The S With A Dominant Period Of 7 Seconds. Tstms Likely In The Evening, Then A Chance Of Showers After Midnight.|
|Thu...S Winds 5 To 10 Kt. Seas 3 To 4 Ft. Swell Mainly From The S With A Dominant Period Of 7 Seconds. A Chance Of Tstms In The Afternoon.|
|Thu Night...Sw Winds 5 To 10 Kt. Seas 3 To 4 Ft. A Chance Of Tstms. Showers Likely.|
|Fri...Sw Winds 5 To 10 Kt, Becoming S 10 To 15 Kt With Gusts Up To 25 Kt In The Afternoon. Seas 3 To 4 Ft. A Chance Of Showers.|
|Fri Night...Sw Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 3 To 4 Ft. A Chance Of Tstms In The Evening, Then A Chance Of Showers After Midnight.|
|Sat...Sw Winds Around 10 Kt. Seas 3 To 4 Ft. A Chance Of Showers In The Morning, Then A Chance Of Tstms In The Afternoon.|
|Sat Night...W Winds Around 10 Kt, Becoming Nw With Gusts Up To 20 Kt After Midnight. Seas Around 3 Ft. A Chance Of Tstms In The Evening, Then A Chance Of Showers After Midnight.|
|Sun...N Winds 10 To 15 Kt With Gusts Up To 20 Kt, Becoming Ne 5 To 10 Kt In The Afternoon. Seas Around 3 Ft.|
|Sun Night...N Winds 5 To 10 Kt. Seas Around 3 Ft. Winds And Seas Higher In And Near Tstms.|
| Area Forecast Discussion|
National Weather Service Mount Holly NJ
648pm EDT Tuesday Jun 2 2020
A warm front lifts north and east of our area later tonight. A cold front approaches our region Wednesday as low pressure moves out of the Great Lakes. That front is expected to become nearly stationary and remain over the Mid-Atlantic region through the end of the week. Another cold front will then approach Friday or Saturday as low pressure moves out of the Great Lakes. High pressure should finally start to build back in from the west by later in the weekend.
Near Term - Until 6am Wednesday Morning
As of 630 PM, a warm front continues to become better organized to our west and southwest. This front will lift across our region later tonight. Ongoing low-level warm air advection and the presence of northwesterly flow aloft is resulting in mostly mid level cloudiness across the area. This is thinning some to the west. A weak short wave embedded in the northwest flow aloft may result in some sprinkles this evening, otherwise we wait for a stronger short wave overnight. Just made some tweaks with this update to keep the forecast current with the latest observations and trends.
Otherwise, a better chance of heavier showers and some thunderstorms looks to occur late tonight into the pre-dawn hours of early Wednesday morning. The warm front will lift across the area overnight, while a stronger short wave moves across the area. At the same time, instability (mostly elevated) is on the increase with values rising to and above 1000 J/kg. This is expected to lead to an area of showers and some thunderstorms, especially across the northern half of the area. There will be enough shear of 40-50+ knots given an increase in the flow around 850 mb to potentially lead to some stronger storms overnight. The CAPE profile on the forecast soundings are thin but fairly tall therefore updraft strength may be on the weaker side. There is the potential for some small hail with a stronger core, and if a stable layer near the surface is weak or non-existent then locally gusty winds will be possible. PW values (Precipitable Water values) increase to 1.25-1.5 inches, so there will be a possibility of brief heavy rainfall with the stronger cores.
Short Term - 6am Wednesday Morning Through Wednesday Night
On Wednesday, there will be a couple of rounds of showers and thunderstorms, with the possibility of some storms becoming severe. After the overnight showers and thunderstorms move offshore by daybreak, a few hours of rain free conditions are expected as the warm front will have lifted to our north and we will be in between short waves/vorticity impulses. There may actually even be some partial clearing through the morning hours. However, this will be temporary as the first of a couple of short waves/vorticity impulses move into the area by midday, while a pre-frontal trough develops and moves across the area as well. With CAPE values remaining in the 1000-2000 J/kg range, an area of showers and thunderstorms is expected to move across the area, especially northeast Pennsylvania and northern/central New Jersey by late morning into early afternoon. As the afternoon progresses and we approach the evening hours, the cold front will be slowly moving into the area while slowing down. Showers and thunderstorms are then expected to develop along the cold front as it sags southward and a couple of more short waves/vorticity impulses move across the area. With the instability forecast, plus shear values of 35-45+ knots, some storms will have the potential to become severe. The flow is fairly unidirectional, and with 700-500 mb winds of 40-50 knots, damaging winds will likely be the main threat. However, with mid-level lapse rates of 7.0-7.5 C/km, there will also be the chance for some large hail for the tallest storms even though the freezing level/wet bulb 0 heigheights are fairly high.
The thunderstorms will continue into the evening hours as the front begins to stall across the area. Instability will begin to wane during the evening hours progress, therefore the threat for more widespread thunderstorms and severe weather will diminish as the evening moves into the overnight hours, although there will be a chance of showers through the night as multiple vorticity impulses move across the area.
Also, the heat and humidity builds. Temperatures will warm well into the 80s, even lower 90s for some areas. However, dewpoints will be low enough to keep heat index values from reaching Heat Advisory criteria, although it will be a hot and humid day.
Long Term - Thursday Through Tuesday
Heading into Thursday the region will be dominated by a stalled frontal boundary. The question is where will that boundary eventually stall and then the dominos will start to fall as a result. Based on a consensus of the guidance there is still too much spread to feel confident in exactly where the front stalls, however we are increasing in confidence in the overall threat of heavy rainfall.
From a synoptic standpoint, we'll be under zonal flow aloft with a modest west to east jet axis to our north. By Thursday morning, the right rear entrance region will be generally over western to west central PA. We'll see upper level divergence moving over northern VA into DelMarVa through the day which should promote modest lift locally. While this happens, we'll see moisture increase from the south and west and becomes maximized in a narrow ribbon somewhere along the Maryland/PA state boundary. The strongest axis of 850mb- 300mb moisture transport pushes right over the PHL metro area and we'll see PWATs (Precipitable Waters) in the area of 1.7" to 1.8". The other fly in the ointment is that the mean flow aloft will become parallel to the surface boundary meaning training storms will be possible. Projecting out the potential speed of storms, BUFKit soundings suggest MBE vectors will drop below 15 kts for portions of the region. This suggests that we could have slow moving training storms capable of maximizing efficient rain. While basin wide averages could be quite small, we could certainly see an axis of convective rainfall on the order of 1-2 inches and perhaps up to 2-3 of a highly localized region. Based on coordination with WPC and surrounding offices, WPC has bumped up the D3 marginal risk to include the PHL metro and areas south. We'll certainly continue to monitor and evaluate where the threat for highest rainfall will end up being maximized, or hopefully instead the threat doesn't materialize!
Heading into the weekend, the pattern remains unsettled and active. We'll see several rounds of scattered showers and diurnally driven thunderstorms. Forcing remains around the stalled frontal boundary and the boundary eventually slides offshore as a weak upper level trough pushes a stronger cold front through the region Friday night into Saturday.
We should see a reprieve in the active weather starting the new week as high pressure and quiet sensible weather returns. Temps should be a tad on the chilly side to start next week but it will be under light winds and clear skies.
Tonight...Conditions expected to remain below advisory levels tonight, although winds could gust around 20 knots at times.
Wednesday...Conditions expected to remain below advisory levels, although winds will gust around 20 knots at times, and may approach advisory levels. However, a low level inversion is expected to keep the stronger winds from mixing down. There is a chance of showers and thunderstorms, some which could be strong to severe during the afternoon.
Wednesday night...Conditions are expected to remain below advisory levels, although winds could continue to gust around 20 knots at times. A chance of showers and thunderstorms continues into the evening hours, before chances diminish overnight.
Outlook... Thursday through Saturday...Winds and seas should stay mostly below SCA (Small Craft Advisory) criteria. Several rounds of widely scattered showers are expected to track through the region and locally higher winds and waves will be possible in the vicinity of stronger storms, especially on Wednesday.
Rip currents... A LOW risk for rip currents is forecast for today and Wednesday.
NOAA Mount Holly NJ Office: Watches - Warnings - Advisories
PA...None. NJ...None. DE...None. MD...None. MARINE...None.