Overnight:
Patchy fog. Mostly cloudy, with a low around 68. East wind around 5 mph.

Tuesday:
Patchy fog before 8am, then a slight chance of rain showers between 10am and 11am, then a slight chance of showers and thunderstorms between 11am and noon, then showers and thunderstorms likely. Mostly cloudy, with a high near 88. Southeast wind 0 to 5 mph. Chance of precipitation is 60%. New rainfall amounts less than a tenth of an inch possible.

Tuesday Night:
A chance of showers and thunderstorms before 8pm, then a slight chance of showers and thunderstorms. Mostly cloudy, with a low around 72. South wind around 5 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch possible.

Wednesday:
A slight chance of rain showers before 8am, then a chance of showers and thunderstorms between 8am and 2pm, then a chance of showers and thunderstorms. Partly sunny, with a high near 89. South wind around 5 mph. Chance of precipitation is 50%. New rainfall amounts less than a tenth of an inch possible.

Wednesday Night:
A chance of showers and thunderstorms before 2am. Partly cloudy, with a low around 71. Southeast wind 0 to 5 mph. Chance of precipitation is 50%. New rainfall amounts less than a tenth of an inch possible.

Thursday:
A slight chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 91. Chance of precipitation is 20%.

Thursday Night:
A slight chance of showers and thunderstorms before 8pm. Partly cloudy, with a low around 71.

Friday:
A chance of showers and thunderstorms after 8am. Partly sunny, with a high near 88. Chance of precipitation is 40%.

Extended Forecast

Friday Night Chance Showers And Thunderstorms	Saturday Slight Chance Showers And Thunderstorms then Showers And Thunderstorms Likely	Saturday Night Showers And Thunderstorms Likely then Chance Showers And Thunderstorms	Sunday Slight Chance Showers And Thunderstorms then Chance Showers And Thunderstorms	Sunday Night Chance Showers And Thunderstorms	Monday Chance Showers And Thunderstorms
Lo 72 °F	Hi 90 °F	Lo 71 °F	Hi 89 °F	Lo 69 °F	Hi 87 °F
PoP 30%	PoP 60%	PoP 30%	PoP 40%	PoP 40%	PoP 40%

AREA FORECAST DISCUSSION
National Weather Service Mount Holly NJ
204 AM EDT Tue Jul 7 2020

Weather Synopsis:
A frontal boundary remains stalled over the region today but will progress north of the area on Tuesday. A summer-like pattern will then persist throughout the week with scattered showers and thunderstorms expected most days along with above average temperatures. A coastal storm will the region Friday through Saturday as it moves north from the Carolinas.

Near Term:
UNTIL 6 AM THIS MORNING - Scattered showers and isolated thunderstorms are now confined to Delmarva with a gradual southward push. These storms may continue to remain over our southernmost areas over the next several hours, with a weakening trend.

The main concern now shifts to fog development especially in locations where heavy rain has occurred earlier today. Dew point depressions are less than 5 F for most of the area, with the winds becoming light and more to the south/southeast. While winds were more to the southwest earlier, it may have been enough to help limit early fog development but satellite images are showing and area of fog/low clouds starting to develop and expect that to eventually overspread the region through the early morning hours. With uncertainty as to how much fog vs low cloud development there will be, kept just a patchy fog mention across the region.

Short Term:
6 AM THIS MORNING THROUGH 6 PM TODAY - Convection looks to continue into the daytime tomorrow, thankfully much more reduced than today. The remnant MCV/MCS from today`s convection will be highly influential in convective initiation tomorrow. The lack of a shortwave but rather weak mid-level ridging, this should preclude as widespread convection as today. Forecast CAPE values of, dare say, only 2000-3000 J/kg also indicate weaker convection. Flooding with PWAT values still around still between 1.5-2 inches, is possible, especially over areas that saw abundant rainfall today. Highs will be a bit cooler in the mid to upper 80s as the front from today remains situated further south.

Long Term:
TONIGHT THROUGH MONDAY - Summary: The extended forecast will feature continually active convective weather likely through next weekend, although the primary focus will be the influence of a departing coastal southern stream low Friday and Saturday.

Synoptic pattern: A fairly progressive pattern is expected, synoptically speaking, into this coming weekend. Tuesday will start with an upper trough departing eastward over the north Atlantic then as trough axis moves from the Great Lakes region east toward the Canadian maritimes by early Thursday. Ridging will follow briefly in the trough`s wake late Thursday into Friday, then the attention turns to the southern stream trough digging across the Midwest and eventually into the southeast by Saturday. This trough will be the driver of the next synoptically forced system to impact our region into the weekend. Thankfully, it appears that the medium range guidance is coming into better agreement with regard to timing and evolution of the synoptic pattern during this period.

Sensible weather: The main theme for the upcoming long term period is "unsettled." Basically every day will probably feature convection in some way, shape, or form, however the mesoscale details beyond Tuesday are essentially impossible to determine this far out.

Southerly surface flow will persist Tuesday and Wednesday pumping a continual stream of warm and humid air into the region from the south. So it`ll be quite warm and humid, but not excessively so. Expect maximum temperatures nearing 90 degrees and minimums around 70 both days along with dewpoints around 70 degrees along with scattered showers and thunderstorms mainly during the late afternoon and evening time frame.

Tuesday`s convection and severe weather environmental setup will be similar to today`s with the exception of a few things. Lapse rates will be lower (~6 C/km), so there won`t be nearly as much of a hail threat. Precipitable water values will be about the same (1.7-1.9"), but the steering flow will be roughly parallel to the main initiating boundary (oriented E-W across central NJ and eastern PA). So flash flooding could be more of a concern. MLCAPE will remain high (~3000 J/kg) south of the boundary with DCAPE locally over 1000 J/kg. Deep layer shear for organization will be considerably less and flow aloft for forcing is also much less than today, so coverage appears to be much lower. Nonetheless, we will need to watch for wet microburst potential and flash flooding threats with Tuesday`s convection.

Synoptically speaking, Thursday appears to be the driest day as a somewhat more prominent ridge passes to our north leading to more subsidence locally. With that said, could still see more isolated convective activity on Thursday. Surface flow will turn more southeasterly as a surface low takes shape across the coastal Carolinas. Still expecting highs right around 90 degrees and lows around 70.

Guidance has come into better agreement that the southern stream coastal low will lift north into the Mid-Atlantic Friday and depart Saturday. This system will bring precipitable water values nearing the "extreme" range for this latitude with values of 2.25-2.50" depicted by the GFS. The precipitation evolution of this system is still quite unclear at this time. I suspect there will be some sort of showery tropical band or bands of rain that lifts north across the eastern portion of the forecast area on Friday followed by more diurnally driven convection later in the day as instability builds. Both the GFS and ECMWF keep the highest QPF offshore, but with surface flow turning easterly with high moisture content, it`s difficult to believe that QPF amounts will remain low over land.

On Saturday, the surface low will be departing to the north, but the upper trough axis will remain to our west along with a very soupy airmass and diurnally driven instability. So will still expect to see widespread convection with heavy rain potential. The main takeaway is that there is a heavy rain and potentially flash flooding threat with this system. Thankfully the system will be moving quickly, but it`s something that will need to be watched closely.

Temperatures are a bit uncertain Friday and Saturday since cloud cover is a big question mark as of now, but with the tropical airmass that will be advected northward, I see no reason why we couldn`t still get highs around 90 degrees. As you may have guessed, dewpoints will rise into the mid 70s Friday and Saturday, so it`ll be quite uncomfortably humid regardless of the temperature. Long story short, expect Friday and Saturday to be very warm, wet, and humid.

Without any sort of strong cold front in the wake of this system, it`ll likely remain quite warm and humid into early next week.

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