Delaware Bay south of East Point NJ to Slaughter Beach DE Marine Forecast
|Overnight...Se Winds Around 5 Kt. Waves 2 Ft Or Less.|
|Thu...S Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 20 Kt Late In The Morning, Then Becoming W 20 To 25 Kt With Gusts Up To 40 Kt In The Afternoon. Waves 2 Ft Or Less, Then 3 To 5 Ft Early In The Morning. A Chance Of Tstms In The Morning. Showers Likely. A Chance Of Tstms In The Afternoon.|
|Thu Night...W Winds 20 To 25 Kt With Gusts Up To 35 Kt. Waves 3 To 5 Ft.|
|Fri...W Winds 20 To 25 Kt, Increasing To 25 To 30 Kt Late. Gusts Up To 40 Kt. Waves 4 To 6 Ft.|
|Fri Night...Nw Winds 25 To 30 Kt, Diminishing To 15 To 20 Kt After Midnight. Gusts Up To 35 Kt. Waves 4 To 6 Ft.|
|Sat...Nw Winds 15 To 20 Kt, Becoming W 10 To 15 Kt In The Afternoon. Gusts Up To 30 Kt. Waves 3 To 4 Ft.|
|Sat Night...W Winds 5 To 10 Kt, Becoming Sw After Midnight. Waves Around 3 Ft In The Evening, Then 2 Ft Or Less.|
|Sun...S Winds 10 To 15 Kt, Increasing To 15 To 20 Kt With Gusts Up To 25 Kt In The Afternoon. Waves 3 To 4 Ft.|
|Sun Night...S Winds 15 To 20 Kt With Gusts Up To 25 Kt. Waves 3 To 5 Ft. Showers.|
|Mon...Sw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Waves 3 To 4 Ft. Showers In The Morning, Then Rain Likely In The Afternoon.|
|Mon Night...W Winds 10 To 15 Kt With Gusts Up To 25 Kt. Waves Around 3 Ft. A Chance Of Rain In The Evening. Winds And Waves Higher In And Near Tstms.|
Area Forecast Discussion|
National Weather Service Mount Holly NJ
944pm EDT Wednesday April 8 2020
A frontal boundary remains stalled south of the area today but will lift north as a warm front this evening and overnight. Low pressure will deepen to our north across New England Thursday, dragging a strong cold front across our region. Another round of strong to potentially severe thunderstorms is possible with this front in the early portion of the day. Strong gusty winds will move into the region behind this front through the day Thursday and into early Friday. This low will gradually pull away Friday as high pressure begins to build eastward into Saturday. Meanwhile, another low pressure system will begin to organize to our west, eventually passing across the Great Lakes Monday and dragging a cold front through our region. Another wave of low pressure looks to affect us late Tuesday into Wednesday.
Near Term - Until 6am Thursday Morning
930pm Update: no major changes made since the 730pm update. Mainly adjusted the temperature a dewpoint forecast to match current trends with the marine layer pushing inland. Also added mention of damaging winds to the thunderstorms for tomorrow.
See Short Term discussion for changes made with the 730pm update.
Previous discussion... Weak high pressure lies over the Great Lakes, while an old frontal boundary extends across southern Pennsylvania and southern New Jersey. Low pressure will continue to develop over the Midwest as it lifts to the northeast tonight, and a strong cold front will develop behind it. That system will move into western new York and western Pennsylvania by daybreak Thursday.
Some weak shortwave energy will pass through the region through this evening, and this may touch off a few showers. South of the frontal boundary, conditions may be just unstable enough for a rumble of thunder, but not expecting much more than that.
Meanwhile, a sea breeze will move through eastern New Jersey, and onshore flow develops for tonight ahead of the approaching system.
Clouds will build in from the west, but there should be a period in southeast New Jersey where skies are mainly clear for the first part of the night, and then patchy fog and low clouds may develop after midnight.
Showers should move into portions of the southern Poconos and Berks county prior to daybreak.
Short Term - 6am Thursday Morning Through 6pm Thursday
Synoptic Overview: By early Thursday, a shortwave trough will be moving quickly from the southern Great Lakes region eastward across Pennsylvania and New York state throughout the day as it turns from a neutral tilt to a more negative tilt. At the surface, the primary low pressure center will move from western New York northeastward into the Saint Lawrence River Valley. The associated jet streak on the heels of the shortwave will be quite strong, especially for this time of year, with values of 110-130 kts. The left exit region of this potent jet will be positioned just to our north by the afternoon yielding strong divergence aloft and explosive deepening of the surface low.
As the forcing aloft outpaces the occluding surface low, a new low pressure center will develop across southern New England near the triple point and pass toward the Maine coast during the late evening hours as it intensifies rapidly to around 975 mb.
Mesoscale Overview: A pre-frontal trough appears to pass across the region around sunrise and will likely bring an initial round of showers and embedded thunderstorms with a stable surface layer still in place from overnight cooling and marine layer influences. Mesoscale guidance and CAMs are in good agreement that this layer will mix out by late morning as the primary cold front approaches quickly from the west and low-level warm air advection increases. The cold front is forecast to pass across the area starting around 11am and will be offshore around 2 PM.
Expecting surface-based instability values on the order of 500-1000 J/kg by around noon across much of the forecast area as dewpoints surge into the mid to upper 50s. Impressive low-level wind fields will develop amid the intensifying system with 850 mb winds of 50-60 kts and 925 mb winds of 40-50 kts, especially closer to the low pressure center. Deep layer bulk shear values look to be on the order of 60-70 kts along with 0-3 km shear values of around 40 kts.
All of this combined with the aforementioned rapidly deepening surface low and strong forcing aloft will result in an environment favorable for severe weather, especially across the southern half of the area, ahead of the cold front. Since the cold front itself will be the primary surface based forcing mechanism, convection in the wake of the morning pre-frontal trough convection should be confined to the cold front itself in the form of a squall line, as many of the CAMs indicate. Primary threat will be strong to damaging wind gusts. Poor mid-level lapse rates should preclude any large hail threat. Forecast hodographs are quite straight with surface winds southwesterly just ahead of the front; so the tornado potential will be low, but given the strong shear values, can't completely rule one out.
Sensible Weather: Some areas of fog are possible around daybreak, especially near the coast, and may linger for a couple hours before the low- level stable/marine layer mixes out. Initially southeasterly winds around 10 mph will increase to around 20 mph and switch southwesterly by late morning. As the cold front sweep across the forecast area, a line of showers and thunderstorms will develop along it as instability increases. This line will be characterized by a sharp increase in winds.
Winds just behind the front and convection will increase to around 25 mph with gusts up to around 50-55 mph, especially across the coastal plain where surface pressure rises are more drastic and pressure gradient is stronger. All models indicate a 3-4 hour period of westerly winds with gusts of 40-50 mph in the wake of the cold front. BUFKIT profiles show a mixed layer up to around the 800 mb level through the afternoon with mean boundary layer winds of around 40 kts (slightly higher across Delmarva and along the coast). A Wind Advisory has been issued to highlight this threat.
Winds should taper off into the evening as the boundary layer begins decoupling with lack of sufficient cold air advection. Cold air advection arrives after midnight Thursday night and will likely signal another surge in winds before daybreak Friday. Confidence is lower for the Thursday night and Friday periods at this time, however the Wind Advisory may need to be extended.
Temperatures ahead of the front will warm well into the 60s for most, then fall into the 50s behind the front.
Long Term - Thursday Night Through Sunday
No rest for the weary looking ahead. Biggest concern is the threat for advisory level wind gusts Friday as a strong sub 980 mb surface low continues to churn over central Maine before making its track into the Canadian Maritimes. An active weather pattern featuring a battle of the airmasses will take shape through the upcoming week as chilly air attempts to spill southward out of Canada, meeting warm and humid air as it builds out of the Gulf. Then again, hello Spring!
Windy day in store again Friday as a strong 160+ knot jet screams overhead behind the departing low to our north and east. Forecast sounding suggest advisory level winds are still possible to even likely with High pressure builds to our south across the Carolinas through the weekend as cyclogenesis gives birth to another surface low over the Plains Sunday. Generally quiet weather Saturday, though it will remain breezy with RH values dropping below 30 percent into the afternoon.
The low will trek up the Ohio River Valley Sunday night as a warm front lifts northward across the Mid-Atlantic. Rain should hold off Sunday at least until Sunday night as the low begins to further organize to our west. The GFS takes the low northward a little faster than the EC at this point, but a general consensus on the track appears to have been reached. By Monday afternoon, a new surface low will form somewhere along the coast as the parent low occludes over Ontario. A shortwave will zip through the amplifying long wave Tuesday, likely bringing another round of showers and maybe a thunderstorm or two to the region as a wave of surface low pressure races across the region.
High pressure makes another brief stint across the region Wednesday before another shortwave trucks on through the quasi-zonal flow pattern of mid-week. Highs staying seasonable all in in all in the upper 50s to lower 60s.
GALE WATCH NOW IN EFFECT FROM LATE THURSDAY AFTERNOON THROUGH FRIDAY EVENING.
Tonight...Sub-SCA (Small Craft Advisory) conditions on the waters. Some nearshore fog may develop along the NJ and DE coasts.
Thursday...SCA (Small Craft Advisory) conditions develop in the morning, quickly ramping up to gales in the afternoon. A Gale Warning is now in effect for Thursday afternoon for all waters. Strong thunderstorms with potentially damaging winds will affect the waters mainly from late morning through the early afternoon. Gales will subside into the evening.
Thursday night...Winds will increase overnight potentially up to gale force before daybreak Friday. The Gale Watch for Friday was extended earlier into Thursday night to highlight this threat.
Outlook... Friday...Westerly gale force winds reaching 40 knots or higher. Seas remain elevated from 4 to 6 feet.
Saturday...SCA (Small Craft Advisory) conditions through at least the first half of the day, from 15 to 20 knots and gusts to 25 knots. Seas lowering from 3 to 5 feet to 2 to 3 feet.
Sunday...Generally sub-SCA (Small Craft Advisory) conditions expected with southeasterly winds from 15 to 20 knots. A few advisory level gusts possible, especially across the southern three Atlantic zones.
Tides / Coastal Flooding
The coastal flood advisory has been expanded to include the shores of the Delaware Bay. A coastal flood advisory remains in effect for the southern shores of the Raritan Bay, the New Jersey shore, and the Delaware Beaches for the high tide cycle on Wednesday evening.
Astronomical high tides will be running high for the next few days associated with the full moon on April 7. We don't have much onshore flow through the next few days, but given the current astronomical high tides, even weak onshore flow could produce minor coastal flooding. Widespread minor flooding is expected with in the advisory area. There may be spotty minor flooding with the Thursday morning high tide, but after that, strong off shore flow will decrease water levels for subsequent high tide cycles.
On the tidal portions of the Delaware River, there could be spotty minor tidal flooding for the next few high tide cycles, but the chance for widespread minor flooding is low.
At this point, tidal flooding is not expected along the northeastern Chesapeake Bay.
NOAA Mount Holly NJ Office: Watches - Warnings - Advisories
PA...Wind Advisory from noon to 5pm EDT Thursday for PAZ054-055- 060>062-070-071-101>106. NJ...Wind Advisory from noon to 5pm EDT Thursday for NJZ001- 007>010-015>019. Wind Advisory from 1pm to 7pm EDT Thursday for NJZ012>014- 020>027. Coastal Flood Advisory until 2am EDT Thursday for NJZ021. Coastal Flood Advisory until 1am EDT Thursday for NJZ012>014- 020-022>027. DE...Wind Advisory from noon to 5pm EDT Thursday for DEZ001. Wind Advisory from 1pm to 7pm EDT Thursday for DEZ002>004. Coastal Flood Advisory until 2am EDT Thursday for DEZ002. Coastal Flood Advisory until 1am EDT Thursday for DEZ003-004. MD...Wind Advisory from noon to 5pm EDT Thursday for MDZ008-012. Wind Advisory from 1pm to 7pm EDT Thursday for MDZ015-019- 020. MARINE...Gale Watch from Thursday evening through Friday evening for ANZ430-431-450>455. Gale Warning from 2pm to 7pm EDT Thursday for ANZ430-431- 450>455.