Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 300045 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 845 PM EDT FRI JUL 29 2016 .SYNOPSIS... Scattered showers and thunderstorms with locally heavy rainfall will re-develop Saturday afternoon and linger into Monday with low pressure and a frontal boundary hung up across the mid Atlantic States. High pressure will then bring mainly dry and less humid weather for the remainder of the next work week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 830 PM ESTF: had to hourly update southward the advance of showers toward Trenton and eventually Philadelphia. There is instability and weak low lvl convergence, especially near the Delaware River eastward. Then dry overnight (after midnight). Winds will be light. This, combined with the recent heavy rainfall across portions of the region means we could see patchy fog, especially across the axis of heaviest precip in northern Delmarva, the Pine Barrens and parts of the area along and north of I-78. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... The upper level trough becomes more defined as it moves closer to the region. As a result, should see an area of precipitation move into the region (exact timing is uncertain by the higher chances look to be in the afternoon). As far as hazards, the primary hazard appears to be heavy rain. Precipitable water values are well above normal, and storm motions look to be quite slow (<15 kts) as the flow is weak. However, with limited focus for surface convergence (at least over our immediate area), not confident that there will be a widespread flooding threat. Thus, not planning to issue a flash flood watch at this time. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Highlights... * Scattered showers and thunderstorms Saturday night/Sunday with the potential for heavy rainfall and a very localized flood threat * Scattered showers/thunderstorms linger Monday, otherwise much of the next work week will be dry and less humid Details... Saturday night and Sunday... A couple of additional shortwaves will move across our region along with a frontal boundary in the vicinity. The result will be periods of scattered showers and thunderstorms Saturday night into Sunday. Specific timing is uncertain at this point, but Pwats of 2+ inches will bring the potential for locally heavy rainfall. While any flood threat looks very localized, weak low level wind fields may result in slow movement and back building of any thunderstorms, so that will need to be watched. Weak wind fields will also result in a low overall risk for severe weather, but a few strong storms can not be ruled out. Monday... Guidance has trended a bit slower over the past 24 hours. Frontal boundary will still be across our region along with another piece of shortwave energy moving in on Monday. The result will be the continued chance for scattered showers and thunderstorms. Tuesday Through Friday... Large high pressure will be building across the mid Atlantic States. While we can not rule out a few lingering showers Tuesday, mainly dry and less humid weather is expected through Friday. High temps will mainly be in the 80s for much of the next work week. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...VFR with sct clouds aoa 6000 ft. Showers lingering longer than expected and these may not dissipate until reaching the vicinity of Philadelphia around 1130 pm or midnight. Light wind becoming calm with a chance of patchy fog nw NJ and in the seabreezed areas of coastal NJ and coastal DE. Saturday...cirrus ceilings lower to sct-bkn aoa 3500 ft during the afternoon with showers and isolated tstms with heavy rain spreading newd. showers could begin to move into the western TAF sites (KABE, KRDG) after 15Z and Delaware Valley TAF sites (KPHL, KPNE, KILG, and KTTN) after 18Z. east or southeast wind. Outlook... Saturday night through Monday...Moderate to high confidence. VFR dominates but periods of lower conditions expected in scattered showers and thunderstorms. Tuesday and Wednesday...Moderate to high confidence in mainly VFR conditions. && .MARINE... Winds and seas should remain below SCA criteria tonight and tomorrow. Outlook...Saturday night through Wednesday...A wave of low pressure may result in a brief period of marginal small craft advisory seas across our northern waters Sunday afternoon/early evening. Otherwise, weak pressure gradient should keep winds/seas mainly below small craft advisory thresholds through Wednesday. Main concern for mariners will be the threat of scattered thunderstorms Saturday night through Monday. Rip Currents...The probability for the development of dangerous rip currents on Saturday is low. Sunday may become a moderate risk along parts of the central and northern NJ shore, dependent on the strength of the onshore flow. A longer period 2 to 3 foot se swell may develop around Wednesday August 3. && .CLIMATE... PHL: heading for top 8 warmest July on record. July avg temp for PHL will be about 80.9 or 81.0F, 8th warmest July in the period of record since 1874. if its 81.1...it would be tied for 7th. ACY: 8.77 inches as of 5 PM ranks 6th wettest July on record with its monthly record of 13.09 set in 1959. The por is back to 1874. 1959 13.09 1969 12.64 1958 10.92 1945 10.22 1903 10.14 2016 8.77 July normal 3.72 Still opportunity to rise in the monthly ranking, though WPC has only about .75 for the rest of the month. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Drag/99 845 Near Term...Drag 845 Short Term...Johnson 845 Long Term...99 Aviation...Drag/99 845 Marine...Drag/99 845 Climate...845

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