Marine Weather and Tide Forecast for Grasonville, MD

NEAR TERM /THROUGH FRIDAY/
935 PM update...
Dense fog is now encroaching on our central coastal zones from Atlantic City northward, so have issued initial dense fog advisory for coastal Atlantic and all of Ocean/Monmouth counties for the time being where fog is already breaking out. This will likely need to be expanded westward as we head through the night.

905 PM update...
Cams guidance has not improved on giving us more concrete timing on MCS convection early Friday, so have low POPs overnight ramping up to likely/categorical through the morning before declining back to chance during mid afternoon. Otherwise, main concern overnight into early Friday remains potential for widespread dense fog. No advisories issued yet, but have areas of fog in forecast into the morning. Timing of convection may determine when it dissipates.

552 PM update...
No actual changes at this moment, just noting we have resumed local operations following the AWIPS update.

439 PM update...
The low clouds and fog from this morning continue to mix out and improve this afternoon. With the mid level trough axis remaining in the vicinity and the weak surface low nearby as well, diurnal instability has resulted in some isolated to scattered showers/storms this afternoon.

PoPs were increased slightly across the board for this afternoon. With PWats around 1.25-1.50", heavy downpours will be possible as well as gusty winds and small hail. PoPs are generally around 40-60%, but those that see something could see some urban and poor drainage flooding. A Marginal ERO (1/4)
remains across most of the area given potentially slow storm motion and a saturated surface with some areas seeing 2-3" yesterday. Severe thunderstorms are unlikely as shear is pretty weak, but can't rule it out completely. High temperatures will be mainly in the 70s and a bit muggy.

A brief period of quiet weather comes tonight as a brief period of ridging moves overhead. Marine stratus is expected to push inland again tonight. Could see some areas of fog yet again, though not expecting it to be as widespread or as dense as this morning. Mainly dry through tonight following the diminishing diurnal convection, but still mild and humid, with lows in the upper 50s/low 60s.

For Friday, a decaying MCS from upstream across the Midwest this evening is anticipated to impact the region. The threat of severe hazards will be conditional based on the timing of the MCS. If it comes through very fast and early in the morning, the severe threat will likely be low. However, a slower propagation will yield increasing instability ahead of it, which would support strengthening. These systems do tend to trend faster and further south of what guidance suggests. If a slower evolution comes to fruition, all severe hazards would be possible, mainly focused on locally damaging wind gusts, but some hail or a brief tornado could be possible if all the stars align properly. Brief heavy downpours possible as well. This MCS and the environment ahead of it will need to be monitored closely overnight. The SPC has introduced a Slight Risk for portions of our area to highlight this threat.

Depending on how quickly the MCS passes offshore, we could potential for diurnally driven convection developing in the afternoon or early evening as well. A faster/earlier departure of the MCS will yield a greater threat for severe thunderstorms in the afternoon, but a slower/later departure will mean a much lower threat for severe thunderstorms in the afternoon/evening.
Something else to keep an eye on as well.

In summary, Friday's weather and forecast will be highly mesoscale driven and have low predictability beyond about 6 hours or so. High temperatures should be mostly in the mid 70s to mid 80s, and muggy with depends in the mid to upper 60s. It will be mostly cloudy with light south to southwest winds.
Remain alert for additional forecast updates regarding the potential convective threats.

SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/
Forcing strengthens with an incoming potent shortwave digging from the Great Lakes Friday night into Saturday. At the surface, an area of low pressure slides by to the north Saturday into Saturday Night, with a cold front advancing towards and eventually through the region.

Another decaying MCS may impact the area again Friday night or early Saturday. Any convection Friday night and Saturday could be impacted by this system.

Temperatures will climb into the 80s and it will feel quite muggy ahead of the front. Instability looks to be on the order of around 1000 J/kg with relatively favorable shear. Thinking any showers and thunderstorms will come in the afternoon and evening as the front arrives. Main concern would be damaging wind gusts and heavy downpours, but still a good amount of uncertainty being a couple days out, especially given the potential for another early MCS. Coverage in showers and thunderstorms diminishes into the night with the loss of daytime heating and passage of the front.

LONG TERM /SUNDAY THROUGH THURSDAY/
Sunday through about Tuesday actually looks pretty nice for now. With the front coming through, it should result in dry conditions and seasonable temperatures to close out the weekend and start next week. Perhaps a little gusty on Sunday, with wind gusts near 30 MPH possible, but nothing significant.

Next chance for rain comes in the middle of the week with longer range guidance hinting at a potential coastal storm.
Still widespread timing and track differences but another spring rainmaker could potentially be on the horizon. Stuck close to NBM given the uncertainty in the ensembles and deterministic guidance.

AVIATION /02Z FRIDAY THROUGH TUESDAY/
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Tonight...VFR to start, but restrictions likely return overnight with low clouds and areas of fog. Low confidence on timing and details. Winds light and variable to calm.

Friday...Restrictions likely to start, then improvement to VFR expected between 15-18Z. A complex of SHRA/TSRA is anticipated to impact the area in morning, but confidence on timing and details is low. Opted for SHRA for now. Details should become more clear in future updates overnight. Winds mainly 5 kts or less, settling out of the SW by 18Z. Additional SHRA/TSRA possible by 21Z. Low confidence overall.

Outlook...

Conditions expected improve for Friday night and Saturday with prevailing VFR likely during the daytime, aside from any showers and thunderstorms move in. VFR conditions look to come Saturday Night and beyond. A few gusts out of the west/northwest 20-25 kt possible but other than that, no significant weather beyond Saturday Night.

MARINE
For tonight, winds and seas remain below advisory criteria.
However, areas of fog will remain and some locally dense fog is likely. Have issued dense fog advisory for marine zones from Atlantic County northward for the time being, and this may need expansion further southwest overnight.

Outlook...

Sub-SCA conditions expected Friday through Monday. However, showers and spotty thunderstorms may continue to be a risk through Saturday, especially during the afternoon and evening hours.

TIDES/COASTAL FLOODING
A Coastal Flood Advisory was issued for the upper portions of the tidal Delaware River for minor flooding forecast at Burlington. Philadelphia should stay just shy of minor flood thresholds through the remainder of the week.

Minor coastal flooding is forecast with the early morning high tides through Sunday morning as well, especially along the upper reaches of the tidal Delaware River. Additional advisories may be needed.

PHI WATCHES/WARNINGS/ADVISORIES
PA...Coastal Flood Advisory from 2 AM to 8 AM EDT Friday for PAZ106.
NJ...Dense Fog Advisory until 11 AM EDT Friday for NJZ013-014-020- 025-026.
Coastal Flood Advisory from 2 AM to 8 AM EDT Friday for NJZ019.
DE...None.
MD...None.
MARINE...Dense Fog Advisory until noon EDT Friday for ANZ450>452.