National Weather Service (2024)

Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
See Also
-- Discussion containing changed information from previous version are highlighted. --739FXUS61 KPHI 272149AFDPHIArea Forecast DiscussionNational Weather Service Mount Holly NJ549 PM EDT Mon May 27 2024.SYNOPSIS...A cold front crosses through our region tonight into Tuesdaymorning. Weak high pressure builds through the region Tuesday.Low pressure passes through Wednesday and Wednesday night. Highpressure returns to close out the week.&&.NEAR TERM /THROUGH TUESDAY/...-- Changed Discussion --
Main change with the early evening update was to lower PoPs andcoverage of showers and thunderstorms through the evening hours.We`re not out of the woods yet in terms of severe risk as windsjust a few thousand feet aloft are above 40kt, but due to theearlier convection and cloud cover, it appears the more stableboundary layer is limiting the extent of evening thunderstorms.Very broken line of showers and storms continues to progresscloser to our region from central PA and central MD. The severethunderstorm watch continues through 9 PM EDT. That shouldcover the peak of the severe risk period, but may have stormsand showers linger a few hours later than that.As far as hazards, wind is becoming the primary hazard. Asmentioned above, we have stronger winds just above the surface,so it won`t take much to mix it down. Also have a concern forheavy rain and flooding especially in the Lehigh Valley, NW NJ,and southern Poconos where some areas have already receivednearly 2 inches from earlier stormsThe hail threat is decreasing as convection has been relativelylow topped, though can`t rule out hail around the severethreshold (1" in diameter). Low level winds are now nearlyunidirectional, which further decreases the threat of tornadoes.Can`t rule any one threat out, but in general our focus now isprimarily on the wind and heavy rain threat.The bulk of the activity should be east of the region aroundmidnight, just ahead of the initial cold front. A secondarycold front will pass through later in the day on Tuesday.Temperature gradient across either front isn`t significant, sotemperatures tomorrow may be close to what we are seeing today.However, the big change will be noticed in the humidity. Surfacedew points drop from the upper 60s/low 70s on Monday to theupper 50s/low 60s on Tuesday.We should have mostly dry conditions tomorrow, though isolatedstorms are possible in the southern Poconos as a lagging mid andupper level short wave trough slides just northwest of theregion.-- End Changed Discussion --&&.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...That upper trough will be over the Northeast/Great Lakes/OhioValley/Mid-Atlantic for the mid-week period. A short wave troughwill dive into the base of the trough Tuesday night, and surfacelow pressure develops over the Appalachians. This low will thepass through the region on Wednesday and Wednesday night.Showers will become likely along with scattered thunderstormsfor most of the area Wednesday. With highs generally in the midto upper 70s and dew points mainly in the mid to upper 50s, SBCAPE looks to be minimal, generally up around 500 J/kg andhighest 0-6 km Bulk Shear values will be 35-45 kt, mainly oversouthern New Jersey and Delmarva. So while thunderstorms arepossible, there does not look to be a widespread severe weatheroutbreak at this time. Showers taper off Wednesday night as lowpressure departs.Another shortwave trough is expected to cross on Thursday, butby then, moisture will be very limited, so only have a slightchance of showers and storms at this time.&&.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...The Long Term period should mostly be dry as surface highpressure builds over the area. Upper trough departs over theweekend and will be replaced by mid- level ridging. Conditionsshould remain dry into the weekend with the next systemapproaching early in the new week.Cooler Friday with below normal temperatures, and thentemperatures return to normal levels over the weekend.&&.AVIATION /22Z MONDAY THROUGH SATURDAY/...The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,KILG, KMIV, KACY and surrounding areas...Through Tonight...Expect periods of MVFR and even IFR duringthe direct impacts of the storms. The prime period for stormslooks to be between 22 and 03Z. Conditions improve to VFRthereafter. S winds around 10 kt, become W after 06Z. Moderateconfidence on the overall pattern, but low confidence ondetails.Tuesday...Mostly VFR. Westerly winds 10 to 15 kt. Moderateconfidence.Outlook...Wednesday...Sub-VFR conditions Wednesday inSHRA/scattered TSRA.Thursday through Saturday...VFR.&&.MARINE...-- Changed Discussion --
Small Craft Advisory for the NJ ocean waters for this afternoonand the first half of tonight for as winds will increase to 15to 20 kt with gusts up to 25 kt. For DE ocean waters and DE Bay,S winds will average 15 to 20 kt. Winds turn W around 10 ktlate tonight.Thunderstorms will impact the waters with potentially damagingwinds and large hail later today and tonight.Outlook...Tuesday through Saturday...Sub-SCA conditions expected throughthe week. VSBY restrictions in showers and scatteredthunderstorms expected on Wednesday.Rip Currents...For Tuesday, winds will shift to more of a W to SW flow. Therewill continue to be a MODERATE risk for dangerous rip currentsat NJ beaches and a LOW risk at DE beaches.For Wednesday, it appears that most of the region should see aLOW risk for rip currents. However, with the unique bathymetryof Altantic County, the risk there may be MODERATE.As always, rip currents can still develop, and often occur inthe vicinities of jetties and piers. Utilize any guarded beachesthis holiday weekend if venturing out into the water.-- End Changed Discussion --&&.PHI WATCHES/WARNINGS/ADVISORIES...PA...None.NJ...None.DE...None.MD...None.MARINE...Small Craft Advisory until 1 AM EDT Tuesday for ANZ450>453.&&$$SYNOPSIS...Johnson/MPSNEAR TERM...Johnson/MPSSHORT TERM...Johnson/MPSLONG TERM...Johnson/MPSAVIATION...Johnson/MPSMARINE...Johnson/MPS