National Weather Service Mount Holly NJ
258pm EDT Monday July 29 2024
Synopsis
A cut-off low across southern New England this afternoon will gradually track northward through tonight. Another low pressure system will pass eastward to our north Tuesday into Wednesday, with several weak fronts passing through the area through the end of the week.
Near Term - Through Tuesday
A closed low across southern New England will lift northward through tonight and weaken some. Some shortwaves rotating around this closed low will move across our region through this evening. The combination of surface-based instability (SBCAPE) up to 2500 J/kg, bulk effective shear of 25-35 knots and enough lift from the shortwaves is expected to support isolated to scattered convection through this evening. While the model guidance varies on the location and especially the coverage, there is enough of a signal that New Jersey has a greater chance for some convection. Once the convection initiates some may try to develop into a small cluster within the moist southerly flow. This can result in a very localized heavy rain/flash flooding risk. In addition, stronger convective cores will be capable of localized damaging downburst wind gusts given some dry mid level air and some steeper low-level lapse rates. Also, some hail cannot be ruled out with a stronger convective core. Much of the convection should dissipate by late evening, although a few lingering showers cannot be ruled out overnight. Otherwise, some cloudiness around tonight along with humid conditions. Patchy fog is possible.
As the aforementioned closed low moves farther away from our area, another upper-level trough approaches from the west overnight. This second upper-level trough is forecast to get closer during the day Tuesday, although its axis remains to our west during the daytime hours. Some increasing forcing for ascent along with building instability should result in some increase in showers and thunderstorms especially in the afternoon. Higher moisture content air along with stronger convection will result in some spots of heavy rain and therefore a localized flash flooding risk. The more organized showers/thunderstorms may be across eastern Pennsylvania into northwest New Jersey closer to the incoming upper-level trough and this is where the highest Probability of Precipitation are placed.
Otherwise, it will be more humid Tuesday with dew points into the lower 70s for much of the area. The day may start out with areas of stratus, then at least some sunshine is expected although there should be more clouds than sun. This will hold temperatures down some, therefore despite the higher dew points the heat indices are not forecast to excessive heat (criteria) levels.
Short Term - Tuesday Night Through Wednesday Night
Multiple shortwaves will be pushing into the region from the west Tuesday through Wednesday, and combined with the ample atmospheric moisture present, we'll have scattered to numerous showers and t-storms through the period. Right now odds of severe look low, but not zero, while localized heavy rain could be more of a concern (or perhaps blessing for those who have been abnormally dry of late).
Initial shortwave moves in from the southwest early on Tuesday, but given limited instability and weakness of the feature, think just scattered showers or maybe an isolated t-storm will result. Stronger shortwave moves in later in the day and at night, and this one now looks to bring the bulk of the precipitation to our region, with fairly widespread coverage of showers and storms Tuesday night. With plenty of clouds, think highs stay relatively modest on Tuesday, mostly low-mid 80s, but the clouds, showers/storms and high dews keep lows near 70 for most Tuesday night.
Wednesday, we now looks a bit drier, though not completely dry. The stronger shortwave will be passing east, so we'll have some subsidence in its wake, so now looking fairly quiet in the morning before a trailing weaker shortwave moves in during the afternoon/evening. However, don't think we'll have as great storm coverage as we expect late Tuesday/Tuesday night, even though CAPE may be greater with some sun and warmer temps leading into it. Highs rise into the upper 80s to around 90, with heat indices approaching 100 in spots.
Wednesday night quiets down pretty quick, but remains warm and sultry with lows fairly close to 70 in much of the area.
Long Term - Thursday Through Monday
Upper ridge builds in from the southwest on Thursday, and the trend this day continues in the direction of drier and warmer. Now only retain some slight chance POPs near the higher terrain with sub-slight chance most of the area on Thursday, along with temps reaching the low-mid 90s and heat indices around 100. A weak shortwave passing at night may bring as stray shower or storm, but coverage looks meager with lows near 70.
Stronger shortwave then approaches Friday before crossing the area Friday night, with better odds of showers and storms during the afternoon and at night after another hot day with 90s for highs and heat indices again near 100.
This trough then starts to lift out on Saturday instead of crossing the area directly, which will only slightly reduce the heat while keeping a chance of showers and storms around. Not the quiet and pleasant Saturday we just had, that's for sure.
By Sunday, the trough lifts out but a much broader westerly flow develops aloft. This should both diminish the heat a little more while also decreasing storm chances... so right now, Sunday looks like the better day of the weekend.
Marine
Southerly winds are forecast to increase for a time into tonight and then again during Tuesday. There still looks to be times of wind gusts right near 25 knots and seas building to about 5 feet. As a result, all of our New Jersey and Delaware Atlantic coastal waters is in a Small Craft Advisory through the day Tuesday. The conditions should remain below Small Craft Advisory criteria on Delaware Bay. A few thunderstorms are possible through this evening, then again especially later Tuesday afternoon.
Outlook... Seas and winds start to drop Wednesday and should be generally below SCA (Small Craft Advisory) levels the remainder of the week. However, some showers and thunderstorms may make for hazardous conditions as well Tuesday night through Wednesday night, then again on Friday.
Rip Currents... Today...Winds will strengthen out of the south to 10 to 15 knots with waves in the surf zone increasing to 2 to 3 feet. There will also be the introduction of new swell groups. For this reason, there is a MODERATE risk for the development of dangerous rip currents for the Jersey Shore but will continue with a LOW risk for the Delaware Beaches.
Tuesday...Winds out of the south/south-southeast 10 to 15 knots with waves in the surf zone 2 to 3 feet. With similar swell to Monday, there is a MODERATE risk for the development of dangerous rip currents for the Jersey Shore but will continue with a LOW risk for the Delaware Beaches.
For specific beach forecasts, visit weather.gov/beach/phi
NOAA Mount Holly NJ Office: Watches - Warnings - Advisories
PA...None. NJ...None. DE...None. MD...None.
Marine
Small Craft Advisory until 8am EDT Tuesday for ANZ450>454.
