Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 231453 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1053 AM EDT Tue May 23 2017 .SYNOPSIS... A low pressure system will pass to the south and east of our area tonight, followed by weak high pressure for Wednesday. Another system develops over the Ohio Valley affecting the mid Atlantic states late Wednesday through early Friday. Weak high pressure returns for Saturday with yet another low pressure forecast to affect the region for Sunday or Monday. && .NEAR TERM /THROUGH TONIGHT/... 1037AM update: withdrew shower threat for much of the area today except Delmarva. Lowered temps several degrees today based on more cloud cover. Plenty of virga southern part of our forecast area this afternoon. Confidence on whether it will rain beyond a trace for our area late today is below average. Our climate section has some information of use. A briefing package is being considered for 3 PM to highlight tidal inundation potential for the Wed-Thu evening high tide cycles on the Atlantic coasts of DE and NJ, and also less confidently, a possible QLCS svr wx event late Thursday. This afternoon...lots of clouds. A brief period of lower clouds this morning is advecting swwd but its predominantly high cloud today. How far north the rain late today? Uncertainty but enough confidence to lower the POPs. Tonight: Low pressure off the mid Atlantic coast will continue to slide northeast, with showers possible, especially through the evening hours for a part of the Delmarva and se NJ coast.. A mid level short wave ridge is expected to build over the ridge beginning late tonight though. The associated subsidence should help to bring a quick end to the precipitation after midnight. && .SHORT TERM /WEDNESDAY/... Wednesday...the coastal low remains to the south and east of our area and pushes to the northeast fairly quickly. We dry out through Wednesday and rain looks to hold off for much of the day as weak high pressure crosses the area. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Wednesday night and Thursday...Low pressure over the Ohio Valley will move northeast on Thursday. Another low forms along the cold frontal boundary as it nears our area, and will cross our area later Thursday. Rain will start to overspread the region late Wednesday night and continue through much of Thursday. Marginal instability is noted and we continue to mention the chance for convection across the area. With PWAT`s once again rising up around 1.5-1.7 inches, we have the potential for moderate to heavy rain. With the wet period we have had of late, we will need to continue to monitor any heavy rain threat. Friday...Some showers possible Friday, mainly early and across the northern half of our forecast area. Overall, it should start to clear out across our area. Although, a slight cool down can be expected in the westerly flow. Saturday...High pressure will build in for Saturday and it should be a great start to the holiday weekend. A shortwave moves through the mid levels and across our area Saturday afternoon/evening. This may spark off a few light showers, mainly across the northern areas. Sunday and Monday...The rest of the holiday weekend looks unsettled as another low pressure system develops and heads towards the Mid- Atlantic. A chance for some showers and/or thunderstorms will be possible. A cooler day on Sunday with highs only into the low to mid- 70s but warming is expected for Monday, with highs into the upper 70s to lower 80s. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...A band of MVFR cigs lasting an hour or two was moving swwd and soon should be a non-factor in the TAFS. Otrw VFR CIGS, mostly abv 10000 ft. Northeast Wind may gust 15 kt. Tonight...VFR lowering CIGS with potential MVFR Conds in showers KACY/KMIV late at night. Northeast wind, may gust 20 kt ACY. Wednesday...VFR. MVFR/IFR conditions early, mainly at KMIV/KACY. Easterly winds around 10 knots or less except gusty 15-20 kt at KACY. Outlook... Wednesday night and Thursday...Deteriorating conditions as rain moves into the area. VFR conditions with periods of MVFR/IFR in showers/thunderstorms. Easterly winds around 10 to 15 knots becoming south to southeast around 10 knots or less late. Friday...Improving conditions with a return to VFR expected. Showers possible early. West winds around 10 to 15 knots. Saturday...Mainly VFR conditions expected. West to southwest winds. && .MARINE... No marine headline today in a general ne flow. SCA was issued at 1027AM for the DE Atlantic coastal waters ANZ454-455) tonight into Wednesday. Outlook... Thursday and Friday...Seas are expected to build in the prolonged easterly flow. Small Craft Advisory will likely be needed. Improving conditions on the waters through Friday as seas start to subside and winds diminish. Saturday...Both winds and waves are expected to stay below SCA criteria. && .HYDROLOGY... After rain amounts over 3 inches in some places across south Jersey yesterday, levels for many creek and rivers on the coastal Plains were slowing their rises or receding. At this time, all remain below bankfull and flood stages, but we continue to monitor this area. Models have trended further southeast and later with heavy rain today. Thus, though these areas will likely see additional rain late today, we are expecting generally light rain amounts (near or below one quarter inch). A wet pattern looks to continue for much of the week. The next period of heavy rain could come as early as Wednesday night into Thursday. && .TIDES/COASTAL FLOODING... The plan is to probably issue a briefing package around 3 PM this afternoon for multi high tide cycle advisory potential, beginning Wed evening through Thursday evening, including possible Watch- moderate potential for the Sandy Hook related tides Thursday evening. Some of the highest astronomical tides of the year are occuring late this week. The new moon cycle on Thursday, combined with a possible prolonged easterly flow, we will probably see some of our coastal sites exceed minor tidal flooding levels during the Wednesday and Thursday evening tide cycles. There is also a small chance that we could reach moderate levels in a few spots. && .CLIMATE... ACY is #6 wettest May on record with its 6.07. The record there for May is 8.80 set in 1948....POR back to 1874. Monthly avg temps should end up within .7 degrees of where they are now, possibly edging on the warmer side of the current departures as seen in our climate data ending the 22nd. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory from midnight tonight to noon EDT Wednesday for ANZ454-455. && $$ Synopsis...Meola Near Term...Drag 1053 Short Term...Drag/Johnson Long Term...Meola Aviation...Drag/Johnson/Meola 1053 Marine...Drag/Johnson/Meola 1053 Hydrology...1053 Tides/Coastal Flooding...1053 Climate...1053

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