Little Egg Inlet to Great Egg Inlet NJ out 20 NM Marine Forecast
|Today...Se Winds Around 20 Kt With Gusts Up To 30 Kt. Seas 6 To 7 Ft. A Chance Of Tstms Until Late Afternoon. Showers Likely Late This Morning. Tstms Likely Late. Swell Mainly From The Se With A Dominant Period Of 7 Seconds.|
|Tonight...S Winds 15 To 20 Kt With Gusts Up To 25 Kt, Diminishing To 10 To 15 Kt With Gusts Up To 25 Kt Late In The Evening, Then Becoming W After Midnight. Seas 5 To 7 Ft. Tstms In The Evening, Then Showers With A Chance Of Tstms After Midnight. A Chance Of Showers Late. Swell Mainly From The Se With A Dominant Period Of 8 Seconds.|
|Fri...Nw Winds 10 To 15 Kt With Gusts Up To 20 Kt, Diminishing To 5 To 10 Kt Late. Seas 4 To 5 Ft. A Chance Of Showers Until Late Afternoon. Swell Mainly From The Se With A Dominant Period Of 8 Seconds.|
|Fri Night...Sw Winds Around 5 Kt, Becoming Nw After Midnight. Seas 3 To 4 Ft. Swell Mainly From The Se With A Dominant Period Of 8 Seconds.|
|Sat...N Winds Around 5 Kt, Becoming W In The Afternoon. Seas 3 To 4 Ft.|
|Sat Night...W Winds 5 To 10 Kt. Seas Around 3 Ft.|
|Sun...W Winds 10 To 15 Kt. Seas 3 To 4 Ft.|
|Sun Night...W Winds 10 To 15 Kt. Seas 3 To 4 Ft.|
|Mon...W Winds 10 To 15 Kt. Seas 3 To 4 Ft.|
|Mon Night...W 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
618am EDT Thu September 23 2021
A cold front will move into the region today and pushing to the east through tonight. High pressure will build into the Mid-Atlantic from the southwest for Friday and Saturday. A weak cold front will cross the region later Saturday followed by a return to high pressure for Sunday through Tuesday. Yet another cold front will approach the region later Tuesday.
Near Term - Through Tonight
Main changes to the forecast today are in regards to the timing of the cold front impinging upon the region as it continues its quicker trend, moving through the region a hour or two earlier.
A few light showers have worked their way across the Delaware Valley this morning, but a stronger line of showers and possibly some embedded thunder is forming across the western Chesapeake Bay and is expected to push eastward to the Eastern Shore later this morning. Further to our west, a deeply occluded upper- level low is centered over the Ohio Valley, with a rigorous dry slot working northward between it and the associated cold/occluded front to its east.
One concern today with this front continues to be the flash flooding threat with the area of greatest concern being the Lehigh Valley and Poconos where orographic enhancement is likely to dump several inches of rain with localized amounts possibly exceeding three inches. A swath of PWAT (Precipitable Water) values exceeding two inches just to our west continues to move towards our region this morning. A big factor at play will be exactly how quickly the front moves east with a rather abrupt end to the rainfall as the dry slot moves into the region from west to east. Latest guidance has suggested this may push eastward a little more quickly, which has resulted in a slight decrease in rainfall totals, though the risk for localized amounts exceeding three to four inches still remaining across eastern Pennsylvania. A Flash Flood Watch remains in effect for much of the region along and west of the I-95 corridor.
Another item of concern is the severe threat. The impressive synoptic-level winds with the system will likely be mixed down to the surface with some of the stronger showers and thunderstorms with 40 to 50-knot winds only 4 to 5000 feet above the surface with a very rigorous low level jet shooting from south to north ahead of this front. With the more southeasterly flow at the surface and southerly to south-southwesterly winds in this jet, the threat for tornadoes continues to remain. Any updrafts that can tap into this pre-existing low-level wind shear will easily be able to rotate. 0-3km SRH values from 200 to 300 m2/s2 largely support this threat. The more surface heating and sunshine we see early today, the greater the threat is likely to be. With forecast ML CAPEs around 1000 J/kg across the I-95 corridor, this should be enough to get a few stronger cells going.
Otherwise, highs today will be seasonably warm in the upper 70s to near 80 and lows dropping into the upper 50s tonight behind the front. Warmer values near the coast with the front not clearing the region as fast. Highs tomorrow will be a little cooler in the low 70s.
Short Term - Friday Through Saturday Night
The cold front pulls off to the east on Friday, allowing for dry air to quickly push into our forecast area. With clearing skies and plenty of sunshine, it will feel quite fall-like on Friday as highs only rise into the 60s to lower 70s across the region. With dew points in the 50s, it will feel much more comfortable than it has in recent days.
With the skies remaining clear into Friday night and winds dropping off, we should radiate fairly well. Overnight lows will drop into the mid 40s to lower 50s across the area.
Saturday will feature high pressure building cresting overhead. A few clouds around the region during the day but otherwise mostly sunny skies are expected. Highs will be similar to Friday, through with some slight warming aloft in the southwest flow it should be a couple of degrees warmer. A weak cold front will approach from the west as a deep upper trough pushes towards the area, moving through later Saturday night. While there will be quite a bit of energy available aloft, the front itself is moisture starved and we are not expecting any showers to develop as it moves through and makes its way offshore Saturday night.
Long Term - Sunday Through Wednesday
Surface high pressure will build across the region for Sunday through Tuesday, keeping the region dry. Aloft, a trough will dig down and cross the region Sunday into Monday. While there is no moisture associated with this trough passage, there should be some cooler temperatures which will keep the highs on Sunday slightly below normal and in the 60s to lower 70s through much of the region. As we go through Monday and Tuesday, the air mass will moderate and warm a few degrees each day.
A weak cold front will approach the region on Tuesday, passing through Tuesday night. Some rain showers may accompany the front and we can't rule out a few rumbles of thunder.
Ridging aloft along with surface high pressure will once again move over the region for midweek with warmer and drier conditions expected.
Today...Southeasterly winds from 15 to 20 knots with gusts to 30 knots. Seas building to 4 to 7 feet with a few 8-foot breaking waves possible. An SCA (Small Craft Advisory) remains in effect for the coastal waters through the day. A Gale Warning remains in effect for the Delaware Bay from 6 am through 6 pm.
Tonight...Winds turning westerly and dropping to 10 to 15 knots but seas will linger from 4 to 6 feet through the night, thus the SCA (Small Craft Advisory) remains in effect through the overnight.
Friday...Northwesterly winds from 5 to 10 knots with gusts to 15 knots. Seas remaining elevated through 4 pm from 3 to 5 feet.
Outlook... Friday night through Monday...No marine headlines are anticipated. Westerly winds around 10 to 15 knots, with some gusts around 20 knots on Sunday. Seas generally around 2 to 4 feet.
Rip currents... We have forecast a HIGH risk of dangerous rip currents for today for both NJ and DE beaches, as winds become a little stronger with an increasing swell.
A HIGH risk will continue for the NJ beaches on Friday with a MODERATE risk expected at the DE beaches.
A Rip Current Statement is in effect for the DE beaches through tonight and for the NJ beaches through Friday evening.
Tides / Coastal Flooding
Strong southerly flow in advance of the system moving through the region today has already allowed for elevated water levels on the eastern shore of Chesapeake Bay, which is expected to continue through at least this morning. A coastal flood advisory remains in effect for the eastern shore of Maryland through late this morning as a result.
Water levels on the tidal Delaware River are also showing signs of being elevated. At this time, confidence remains too low for the issuance of an advisory, but we will continue to monitor the levels closely through this morning. Rainfall today may exacerbate the situation for this afternoons high tide, but confidence is not particularly high, since the heaviest rainfall may occur after the time of high tide.
NOAA Mount Holly NJ Office: Watches - Warnings - Advisories
PA...Flash Flood Watch from 11am EDT this morning through late tonight for PAZ070-071-102-104-106. Flash Flood Watch through late tonight for PAZ054-055-060>062- 101-103-105. NJ...Flash Flood Watch from 11am EDT this morning through late tonight for NJZ001-007>010-012-015. High Rip Current Risk through Friday evening for NJZ014- 024>026. DE...High Rip Current Risk through this evening for DEZ004. Flash Flood Watch from 11am EDT this morning through late tonight for DEZ001. MD...Coastal Flood Advisory until 10am EDT this morning for MDZ015- 019-020. Coastal Flood Advisory until noon EDT today for MDZ012.
Small Craft Advisory until 4pm EDT Friday for ANZ450>455. Gale Warning until 6pm EDT this evening for ANZ430-431.