Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 301951 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 351 PM EDT SAT JUL 30 2016 .SYNOPSIS... A weak frontal boundary remains near our area into early next week. A few weak low pressure systems will track along the boundary, bringing periods of showers and thunderstorms. High pressure will build across our area Tuesday into at least early Thursday before moving off shore as a cold front approaches the region the end of the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A warm frontal boundary and a mid-level shortwave have led to the development of showers and thunderstorms across most of Eastern PA and northern NJ. These features will be slow to move tonight. This means that the focus of the highest rain chances tonight are across the same regions. Later tonight, showers and thunderstorms over Eastern PA and MD will likely move east. However, potential exists for convection to decrease in coverage overall as shown the last few HRRR runs. PW values are rather high, near 2 inches currently with a lot of moisture streaming northward into the region. This will promote a heavy rain and localized flooding threat with some of the showers and thunderstorms. Currently, the threat looks too localized for the issuance of a flash flood watch. With plenty of clouds around and a southerly flow, temperatures will stay warm overnight with lows in the 70s for most. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... The frontal system will still be over the region through Sunday with the main cold front moving southeast toward the region late in the day. This will result in another round or two of scattered showers and storms. The highest chances of showers and storms will be across the northern portions of area, closer to the warm front. The initial shortwave will be east of the area on Sunday, pulling in some slightly drier air to the region. However, a lot of moisture will remain in place leading to a threat of heavy rain with any thunderstorms. Where more sun comes out across the southern half of the region, highs have a good shot of reaching 90. Further north with more clouds and thunderstorms, highs will be closer to 80. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Medium range models are fairly consistent bringing the mid level trough across the region Sunday night through Monday night. Expect enough instability, moisture, and lift associated with the broad trough and embedded shortwaves for a continuation of the unsettled weather. Pwats should still be in the 1.5-2 inch range at this point so any storms could contain heavy rainfall. Expect residual lingering boundaries to be the primary focus for any thunderstorm development. As the trough moves east Tuesday, northwest flow overspreads the region. A surface cold front will bring cooler temps, mainly in the 80s, as well as drier air which will linger into at least Thursday. Model solutions begin to diverge at the end of the work week, with the gfs showing a small but potent shortwave moving across the forecast area. Despite the differences, multiple models show a cold front moving across the region Friday night into Saturday. Due to uncertainty in timing will include only low chance pops for now. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Showers and thunderstorms will occasionally impact KRDG, KABE and KTTN through the remainder of the afternoon. These storms will likely create MVFR or IFR ceiling and visibility restrictions for short intervals. Thunderstorms may form at TAF sites further southeast including KPHL, KPNE, KACY, KILG and KMIV late this afternoon and early evening. The loss of daytime heating will reduce the thunder threat during the evening. A few more rounds of showers will likely occur throughout the night. Ceilings will likely lower throughout the night as well with MVFR ceilings and visibilities currently expected toward or just after midnight. Outside of thunderstorms, winds will generally be 10 knots or less. On Sunday, Additional scattered showers and thunderstorms are possibile. However, a break or a period of lesser coverage is possible in the late morning hours. Have kept the TAFS dry beyond 15z Sunday given the uncertainty. Lower ceilings should lift by late morning to VFR. Outlook... Sunday night through Monday night...Potential for MVFR ceilings Monday morning, otherwise VFR with scattered to broken cloud cover. Some showers and thunderstorms will be around especially Sunday and this will lead to mainly local and brief restrictions. Tuesday and Thursday...VFR overall as high pressure builds in. && .MARINE... Waveheights tonight will be around two feet with southeast winds from 10-15 knots. Waveheights will increase some tomorrow pushing four feet on the New Jersey coastal waters and around three feet further south. Outlook... Sunday night through Thursday...An onshore flow Sunday should increase some especially across the northern coastal waters, with gusts to about 20 knots. It appears at this point that conditions remain below advisory criteria. Otherwise, a weak pressure gradient should keep winds and seas mainly below Small Craft Advisory criteria through Thursday. Main concern will be the threat of some thunderstorms Sunday and Monday, however the greatest concentration of storms may be inland. Rip Currents... The rip current risk for the remainder of the day is low. However, with an increase in seas and winds on Sunday, a moderate risk is currently possibile on the New Jersey coastline with a low risk remaining in place further south where the increase will be less with the seas. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Runyan Near Term...Gaines Short Term...Gaines Long Term...Runyan Aviation...Gaines Marine...Gaines

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