Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
Issued by NWS Mt. Holly, NJ
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975 FXUS61 KPHI 051726 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 126 PM EDT Wed Jun 5 2024 .SYNOPSIS... An area of low pressure approaches from the northwest late today with a warm front moving through the region this evening. A cold front follows tomorrow crossing through the region on Thursday into Thursday night. Heading into the weekend unsettled weather looks to persist into early next week as several shortwaves pivot around the upper low over southern Canada. && .NEAR TERM /THROUGH TONIGHT/... Warm front lies just southwest of the forecast area and will continue to lift north this afternoon and into tonight and should be north of the area by Thursday morning. The front will be accompanied by some shortwave energy aloft which will increase the forcing of ascent across the region. As a result, an initial batch of showers and thunderstorms are expected to develop and approach from the southwest and overspread the rest of the region this evening. For most of the overnight period, light to moderate rain (with embedded thunder) is expected, giving way to just some spotty showers/storms by early Thursday morning as depicted by most of the hi-res guidance. Although mostly cloudy to overcast skies will encompass much of the region today, a very moist airmass will be in place. Thus, there is a fairly high chance for some thunderstorms this afternoon into tonight. Despite limited surface heating, a narrow corridor of SBCAPE in excess of 1000 J/kg this afternoon will be in place across the Delmarva which will lie in close proximity to the warm front. However, mid-level lapse rates are weak (only near 6.5C/km) which will likely hinder development of strong updrafts. As a result, the Storm Prediction Center has upgraded the Eastern Shore of Maryland into a Marginal Risk (Level 1/5) for severe weather today. The rest of the area lies in just a general thunderstorm risk. The main threat in the highlighted area will be damaging winds. With backed SE surface winds near the warm front, model soundings due show some curved hodographs in the lowest 0-3km. So while there is a non-zero chance of a tornado, the greater potential looks to lie outside of our area. PWATs will also be near/in excess of 2.0 inches later this afternoon into tonight, so heavy downpours are likely, especially in any thunderstorm that occurs. Currently, WPC has the western half of our forecast area highlighted within a Marginal Risk (Level 1/4) risk for excessive rainfall. However, flash flooding does not appear to be a threat as ground soils are relatively dry and the storm motion is quite quick. QPF values through tonight are forecast to be around 0.5-1.0 inches, locally higher in thunderstorms. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... A deep upper trough will be accompanied by a nearly vertically stacked low pressure system which will be meandering around southern Canada and the northern Great Lakes during the period. This will bring a cold front through by Thursday into Thursday evening. Guidance continues to highlight the likelihood of a concentrated set of showers and thunderstorms moving through the region Thursday afternoon into the evening. CSU-MLP guidance still indicates a 5-14% chance of severe weather on Thursday with the most likely threat being hazardous wind. Showers and thunderstorms will cease on Thursday night as the cold front moves offshore. Highs will be in low/mid 80s on Thursday dependent on the amount of clearing. Thursday night lows will be cooler in the upper 50s to mid 60s. && .LONG TERM /SATURDAY THROUGH TUESDAY/... The long term period is forecast to be generally unsettled through early next week. The aforementioned upper trough and low will meander across southern Canada and the northern Great Lakes through the weekend. As it does so, multiple shortwaves will round through the upper trough resulting in several rounds of showers and occasional thunderstorms through the weekend into next week. While no singular day appears to be a washout, there will be quite a bit of showers around, more likely north and west with drier conditions south and east. The highest probability of precipitation will be during the afternoon hours as diurnal heating allows instability to be maximized. Temperatures during this period will remain quite seasonable for early June with a mix of 70s/80s during the day and 50s/60s at night. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...Some lingering MVFR CIGs becoming VFR by 19Z. Another round of lowering CIGs down to MVFR are expected later in the day as rain showers and isolated thunderstorms move into the region. South-southeast winds around 5-10 kt. Moderate confidence. Tonight...All terminals should encounter lowering CIGs and decreasing VSBYs as heavier rain moves in this evening. Heaviest of rain should continue through about 06-08Z, before lifting north and east of the region. Still anticipate lower CIGs/VSBYs to persist after rain exits. South-southwest winds around 5-10 kt. Low confidence. Outlook... Thursday through Thursday night...Sub-VFR conditions probable with showers and thunderstorms. Friday through Saturday...Primarily VFR expected with sub-VFR conditions possible. A chance of a shower or thunderstorm each afternoon. && .MARINE... No marine headlines are expected through tonight. Fair weather this morning will give way to showers and thunderstorms later this afternoon into tonight. South-southeast winds around 10-15 kt today increasing up to 15-20 kt tonight. Localize higher gusts up to 22-23 kt possible. Seas of 2-3 feet increasing to 3-4 feet. Outlook... Thursday and Thursday night...Sub SCA expected, however winds may gust around 20+ kt on Wednesday night into Thursday. Seas around 3-4 feet. Showers likely with a chance of thunderstorms. Thursday night through Saturday...No marine headlines expected. Winds generally around 10-15 kt with seas of 2-4 feet. Slight chance of a shower or thunderstorm each afternoon. Rip Currents... A LOW risk for the development of rip currents is in place for both New Jersey and Delaware beaches for today. Winds will be on onshore from the SSE, but only around 10-15 mph with 1-2 foot waves and a 9 second period. For Thursday, SSW winds around 10-15 mph will parallel the shoreline for NJ and offshore for DE beaches. With breaking waves of 2-3 feet, a medium period swell, and a new moon, the risk for rip current development is MODERATE for New Jersey beaches and LOW for Delaware beaches. Rip currents occur often in the vicinities of jetties and piers. Utilize any guarded beaches if venturing out into the water. For specific beach forecasts, visit weather.gov/beach/phi && .TIDES/COASTAL FLOODING... Went ahead and issued a Coastal Flood Advisory for southern NJ, southern DE, as well as the Delaware Bay counties and Delaware River counties for this high tide cycle tonight. The threat for widespread minor flooding increases as winds strengthen then turn and become shore parallel on Thursday, potentially trapping water along the coast. In addition, tide cycles will be elevated due to the New Moon on Thursday. Will continue to monitor upcoming high tides and make adjustments to the forecast accordingly. Additional Coastal Flood Advisories may be needed for the Thursday night high tide cycles. Overall, the threat for tidal flooding appears to be lower along the Chesapeake Bay than elsewhere in the region but by the early morning high tide Thursday, water levels may also approach spotty minor. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Coastal Flood Advisory from midnight tonight to 5 AM EDT Thursday for PAZ070-071-106. NJ...Coastal Flood Advisory from 9 PM to 11 PM EDT this evening for NJZ016. Coastal Flood Advisory from 7 PM this evening to 1 AM EDT Thursday for NJZ021>025. Coastal Flood Advisory from midnight tonight to 5 AM EDT Thursday for NJZ015-017>019. DE...Coastal Flood Advisory from 9 PM to 11 PM EDT this evening for DEZ001. Coastal Flood Advisory from 7 PM this evening to 1 AM EDT Thursday for DEZ002>004. MD...None. MARINE...None. && $$ SYNOPSIS...Deal NEAR TERM...DeSilva/MPS SHORT TERM...Deal/MPS LONG TERM...Deal/MPS AVIATION...Deal/DeSilva/MPS MARINE...Deal/DeSilva TIDES/COASTAL FLOODING...