Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 270721 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 321 AM EDT Thu Jun 27 2019 .SYNOPSIS... As high pressure across the southern states expands northward across the Mid-Atlantic region through Friday, a weak front settles into our area. Low pressure tracking to our north Saturday will pull a cold front across our area later Saturday before settling to our south Sunday. High pressure builds in for Monday, then a weak cold front arrives late Tuesday into Wednesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A broad area of high pressure will influence much of the country east of the Mississippi River for today. We are expecting mostly sunny and warm conditions. Maximum temperatures are forecast to be slightly higher than those on Tuesday. Dew point readings are expected to be around 60 in the afternoon, so heat index values should be near of slightly below the actual air temperatures. A light northwest to west wind is anticipated. However, the sea breeze front should make some progress inland during the afternoon. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... High pressure will continue to bring a mainly clear sky to our region for tonight. The wind is forecast to be light and variable with low temperatures favoring the range from the middle 60s to the lower 70s. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Summary...Hot and becoming more humid through Saturday, then some temporary cooling and lower dew points Monday. The heat and humidity should build again during the first half of next week. Some showers and thunderstorms over the weekend, then again Tuesday into Wednesday with a weak cold front. Synoptic Overview...A strong ridge across the southern states builds northward across the Plains and into south-central Canada Friday into Saturday. Meanwhile, a closed low centered near Hudson Bay Friday is forecast to shift southeastward and across the Northeast during the weekend. Prior to the troughs arrival in the Northeast, a hot airmass continues for our region and dew points will be on the rise especially for Saturday. The trough should push a weak cold front across our area by later Saturday, which will result in cooler and less humid air on Monday. The heat and humidity then should build Tuesday and Wednesday. For Friday...Our area will remain on the southern edge of the westerlies. A closed low centered near Hudson Bay Canada will gradually amplify/spread southeastward. A short wave on the south side of this closed low will be responsibly for some convection across the Great Lakes region. Nearly all of this activity looks to remain to our northwest. A few isolated showers/thunderstorms though may develop to our west during peak heating and mainly tied to terrain influences (lee-side trough). We therefore bring in some slight chance PoPs mainly in the evening across the far northern zones and parts of eastern Maryland. It will be another hot day for the majority of the region, with temperatures topping out in the upper 80`s to low 90`s. A southwesterly flow looks light and therefore a sea breeze front should develop starting around midday. This will keep the coastal locales cooler. While the surface dew points will be a little higher than Thursday, enough drier air above the surface should help to keep the dew points low enough during daytime heating. As a result, the maximum heat indices are not expected to be much higher than the air temperatures. For Saturday and Sunday...As an upper-level trough overspreads the Northeast, surface low pressure tracks to our north Saturday with an associated weak cold front crossing our region by later in the day. This front is forecast to be clearing our southern areas early Sunday morning. On Saturday, temperatures should be at or a little above Friday`s however dew points will be near 70F in advance of the front. Assuming convection holds off long enough, the combination of the hot temperatures and higher dew points should result in peak heat indices Saturday afternoon approaching 100 degrees in Delmarva and along the urban I-95 corridor. Some showers and thunderstorms are anticipated to accompany the cold front, however coverage is less certain. Strong northwest flow aloft along with ample instability may result in some robust convection Saturday with locally strong wind gusts possible especially if enough organization can occur. Some strong convection may occur Sunday as well given the passage of the trough axis and a strong shortwave. This will be refined as we get closer and resolve the timing and forcing mechanisms better. Despite the cold front clearing our area to start Sunday, the passage of a strong shortwave with the upper- level trough axis should result in some additional showers and thunderstorms. For Monday and Tuesday...A strong trough is forecast to be moving away from the Northeast Monday with weak high pressure building in. Temperatures should be seasonably warm Monday as the trough and associated cold pool pull away. High pressure to our south Tuesday should result in a more south to southwest flow, allowing warmer air to once again overspread the area. As a result, some areas will make a run at 90 degrees Tuesday afternoon. A trough sliding across New England should send a weak cold front across our area Tuesday night with the potential for some convection. For Wednesday...Our region remains within nearly northwest flow aloft with a ridge axis to our south and west. Some mid level shortwaves embedded within the northwest flow aloft may still trigger some convection despite a weak cold front settling to our south. There does not look to be much of an airmass change, therefore more hot weather is anticipated. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...VFR with few clouds. Northwest to west wind 4 to 8 knots. The sea breeze front will likely reach KACY early in the afternoon resulting in a wind shift to the southeast at that location. Tonight...VFR with few clouds. Variable wind 6 knots or less. Outlook... Friday...VFR. Light and variable winds becoming southwesterly around 5 knots, however becoming south or southeast at ACY due to an anticipated sea breeze. Saturday and Sunday...Some showers and thunderstorms around especially each afternoon and evening, which will result in local and brief MVFR/IFR conditions. Southwest winds Saturday around 10 knots becoming west to west-northwest and then continuing Sunday. Monday...VFR. Northerly winds 5-10 knots, potentially becoming light and variable by late afternoon. && .MARINE... A westerly wind less than 10 knots this morning should become variable toward midday, then southerly in the afternoon. The wind is forecast to go back to the west tonight. Waves on our ocean waters and on Delaware Bay will be 2 feet or less. Outlook... Friday and Saturday...The conditions are anticipated to be below Small Craft Advisory, despite a southerly wind increasing some which then becomes west to west-northwest late Saturday. Some showers and thunderstorms are anticipated on Saturday afternoon and evening. Sunday and Monday...West to northwest winds Sunday becoming north Monday, however the conditions are anticipated to be below Small Craft Advisory criteria. Rip Currents... The wind direction is forecast to be westerly this morning, becoming onshore for this afternoon. Speeds are expected to be 10 MPH or less. Breaking waves should be 2 feet or less. As a result, there is a low risk for the development of dangerous rip currents for today. For Friday, a low risk for the development of dangerous rip currents is anticipated with southerly winds around 10 mph and waves (6-9 second period) in the surf zone of 1-2 feet. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Gorse Near Term...Iovino Short Term...Iovino Long Term...Gorse Aviation...Gorse/Iovino Marine...Gorse/Iovino

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