Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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129 FXUS61 KPHI 240813 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 413 AM EDT SUN JUL 24 2016 .SYNOPSIS...
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High pressure will remain in control over the area until a weak cold front approaches the from the northwest by late tonight. This front will push across the area Monday. High pressure will return for the middle part of the week. Another front may affect the area Thursday into next weekend.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A frontal boundary will continue to sink just to our south early today, with drier air moving into the region from the north as high pressure north of the area weakens as it tries to move across the area. Temperatures today will continue to be hot with most places reaching the low to mid 90s. With the lower humidity, even with the high temperatures, the heat index values will not reach much more than the actual air temperature, except across the far south where the humidity will be the highest. The Excessive Heat Warning for the Philadelphia metro areas will remain in effect as heat index values will hover near criteria today and certainly get there tomorrow. We should be precipitation free today as drier air moves in behind the frontal boundary an no short wave/vorticity impulses are expected through the daytime hours.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
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The evening will start off precipitation free, but as we go through the night, the frontal boundary to our south will begin lifting northward, while a short wave/vorticity impulse approaches from the west. This short wave is expected to interact with the lifting frontal boundary and create isolated/scattered showers or thunderstorms during the overnight hours. The best chance for any precipitation overnight looks to be the northern two-thirds of the area. There could also be some patchy fog north of the lifting warm frontal boundary overnight with a warm and moistening airmass moving northward.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/...
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The main impact will be the heat and humidity for the early part of the week. Expect high temperatures in the mid to upper 90s across the area Monday. This, combined with a very humid airmass will push heat index values above 100 degrees for most of the area. A weak cold front will push across the region late Monday and Monday night. This will spark off the next round of showers and thunderstorms with the potential for some to become severe. This cold front will slide to our south by Tuesday, bringing some slight moderation in temperatures and humidity levels. Still expect temperatures in the lower to mid 90s with heat indexes that approach 100. Much of the area should stay dry Tuesday and Wednesday, with just extreme southern New Jersey and the Delmarva with the threat of thunder due to the proximity to the stalled frontal boundary lingering across the mid-Atlantic. The slight downward trend of heat and humidity levels will continue on Wednesday with temperatures generally staying in the lower 90s. The front starts to approach back from the south as a warm front by Wednesday night into Thursday. A couple of weak waves of low pressure may develop and then ride up along this boundary giving us a couple of chances for shower and thunderstorm development for the latter part of the week. There does not look to be much in the way of a pattern chance into next weekend, so expect the warm, humid and unsettled weather to continue through the end of the week and next weekend.
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&& .AVIATION /08Z SUNDAY THROUGH THURSDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. There is some patchy light fog this morning, mainly at MIV and other rural areas, but this will lift and burn off around/shortly after sunrise. The rest of the day will be VFR. It is possible that some patchy fog could develop again overnight tonight into Monday morning. Also, there is a chance for isolated/scattered showers or thunderstorms overnight tonight. Winds are light and variable at many locations this morning, but where they have a direction, they are more northwest and will likely become north to northeast later this morning. Winds are expected to become more south to southwest during by midday as high pressure weakens as it tries to move across the area. outlook... VFR much of the time. Scattered (mostly) late afternoon and evening showers and thunderstorms may limit cigs/vsbys at times through the period. The best chance for this will be Monday afternoon and evening and then again on Thursday.
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&& .MARINE...
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Sub-small craft advisory conditions will continue today and tonight across the area. There is a chance of showers or thunderstorms late tonight into Monday morning. outlook... Mostly a period of sub-sca conditions expected. Scattered showers and thunderstorms will create locally higher winds and seas through the period. Best chance for this will be Monday afternoon and evening and Thursday.
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&& .CLIMATE...
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Record high temperatures today through Thursday are below. Site 24th 25th 26th 27th 28th ---- ---- ---- ---- ---- ---- PHL... 98-2011 96-1899 101-1892 101-1940 100-1941 ABE... 95-1999 95-1999 98-1940 98-1955 97-1949 ACY... 100-2011 99-2010 96-2011 99-2005 98-1999 ILG... 98-2011 96-1987 99-1894 100-1894 101-1894 TTN... 98-1910 97-1999 99-1892 100-1894 101-1894 GED... 99-2011 99-2010 97-2012 98-2005 99-1949 RDG... 96-2010 96-1999 99-1940 98-1955 99-1941 MPO... 91-1914 90-1999 89-1949 91-1955 93-1949
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...Heat Advisory from 11 AM to 6 PM EDT Monday for PAZ060>062-101- 103-105. Excessive Heat Warning until 6 PM EDT Monday for PAZ070-071- 102-104-106. NJ...Heat Advisory from 11 AM to 6 PM EDT Monday for NJZ001-007>010- 012>014-016-020>027. Excessive Heat Warning until 6 PM EDT Monday for NJZ015- 017>019. DE...Heat Advisory from 11 AM to 6 PM EDT Monday for DEZ002>004. Excessive Heat Warning until 6 PM EDT Monday for DEZ001. MD...Heat Advisory from 11 AM to 6 PM EDT Monday for MDZ008-012-015- 019-020. MARINE...None.
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&& $$ Synopsis...JK Near Term...Robertson Short Term...Robertson Long Term...JK Aviation...Robertson/JK Marine...Robertson/JK Climate...Staff

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