Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 180509 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 109 AM EDT Mon Mar 18 2024 .SYNOPSIS...
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A cold front moves across our area later today. Several upper level disturbances will pass through the region this week as surface high pressure builds to the west. Developing low pressure approaches for the end of the week and weekend.
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&& .NEAR TERM /THROUGH TODAY/...
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Few changes needed with the update. Adjustments to temps and sky cover mostly. An upper-level trough from the Midwest and Great Lakes to adjacent Canada will slowly shift eastward through tonight. This trough then settles more over our region by later Monday. With boundary layer mixing decreasing with the loss of daytime heating, winds have largely dropped off into the 5-10 mph range where they are expected to remain through the overnight hours. This has set the stage for a chillier night as temperatures drop into the 30s overnight (even some upper 20s in the Poconos). Some mid and higher level clouds have moved in, and should be around through the overnight hours given strong mid to high level flow ahead of the trough. As we go through Monday, as mentioned above the upper-level trough axis starts to settle over our area by later in the day. This will deliver colder air with daytime high temperatures being much closer to average. Stronger flow remains and with deepening mixing occurring, a brisk west-northwest wind will once again develop during the course of the day. As the trough axis arrives, a secondary cold front will move through and this will deliver even drier low-level air as dew points drop into the teens for much of the area. There could also be some flurries or a snow shower mainly in the Pocono region. It will definitely feel colder as temperatures step down some more and with the breeze added in. Some stratocumulus is also expected to be around.
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&& .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... Weak reinforcing cold front and potent upper trough axis will cross the region Monday evening. Some CAMs suggest there could be some flurries or snow showers with it, particularly across northern New Jersey and the Poconos, but other guidance is dry, so for now maintain a dry forecast. We`ll be watching this potential closely. Otherwise, breezy and chilly conditions will prevail with temperatures running slightly below normal, but notably colder than recent days, with wind chills down in the 20s for most and teens in the Poconos. Lows mostly near or below freezing. Breezy and chilly conditions continue Tuesday, with the cold advection behind the front pushing temps several degrees lower than Monday. This looks like the first day with high temperatures notably below normal for weeks, with most areas staying in the 40s. While sunshine may start day, another passing upper trough likely helps instigate more cloud cover as the day wears on, but right now the chance of any precip looks minimal. A weak warm front will then try to lift into the region Tuesday night. This will keep clouds around and could help instigate a few flurries or snow showers i, though it looks majority rain, but tn the Poconos. Lows should stay a little milder, generally above freezing except in the Poconos. Modest warm surge develops ahead of another approaching cold front on Wednesday. This should help elevate temps back to near normal, with 50s more widespread, but by later in the day, a few showers may develop as the front approaches and then passes. These could be snow in the Poconos, but look more likely to be rain elsewhere. With the front approaching and then passing westerly wind could get pretty gusty, with peak gusts possibly 30-40 mph. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Cold advection is fairly quick behind the front Wednesday evening. Temps will likely drop below freezing again across the area, with upper teens possible in the Poconos. With winds still possibly gusting above 30 mph at least in the evening, wind chills may be in the teens at times across much of the area, perhaps even single digits in the Poconos. High pressure is finally building in on Thursday, but the winds will stay elevated at least through midday, and this may keep wind chills quite low in the morning. By afternoon, the pressure gradient relaxes and winds should start to drop off towards evening. The airmass Thursday looks slightly colder than Tuesday, making Thursday likely the coldest day of the week and quite possibly the coldest day of March this year. High pressure slides across the region Thursday night, and we should see lighter winds with at least partially clear skies. This should allow decent radiational cooling, so we could also make a run at the coldest night of the month as well, though this will be competing against March 1st which was quite chilly in outlying areas. Another wave of low pressure then quickly approaches for Friday, with a chilly morning with increasing clouds followed by a chance of showers by late day and at night. If there is enough cool, dry air remaining, its possible precip could being with some mixed precip or snow, but still highly uncertain, and it looks likely as the system passes at night into early Saturday that enough warm air will be drawn northward for most areas to go over to rain. Still, in a season with below normal wintry precip, any frozen precip coming down this late in the year will feel unusual, even though it isn`t particularly. After that, uncertainty presides over the weekend as a low pressure appears likely to develop across the southeastern US coast. A track northward is possible at some point, but timing that track and its exact direction is quite uncertain. Thus, while precipitation odds aren`t great over the weekend they certainly aren`t zero. Will need to watch this potential system. && .AVIATION /05Z MONDAY THROUGH FRIDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas... Tonight...VFR. West-northwest winds diminishing to around 5 knots then increasing to around 5-10 knots in the pre-dawn hours, particularly for the less sheltered I-95 terminals. High confidence. Monday...VFR. West-northwest winds 5-10 knots increasing to around 15 knots with gusts to around 25 knots. Moderate confidence. Outlook... Tuesday through Friday...VFR overall. Could be a few showers Wednesday afternoon and then Friday afternoon which could lower cats. Otherwise, the main concern through the week will just be persistent gusty west to northwest winds, which could gust up to 35 kts at times Wednesday. && .MARINE... Offshore flow will continue through Monday, however the better mixing looks to occur over land especially during the daytime hours. While the winds are expected to increase some through Monday, the conditions are anticipated to be below Small Craft Advisory criteria overall. Outlook... SCA conditions likely Tuesday through Thursday with persistent northwesterly winds. Could touch Gales at times, most likely sometime Wednesday or Wednesday night. Conditions probably subside below SCA levels Friday. && .FIRE WEATHER... A few rain/snow showers or sprinkles/flurries possible across the Poconos through the next several days. Aside from that, dry conditions. Although most of the area is above normal for precipitation since March 1, it has been a week since the last significant rainfall, and no significant rainfall is expected this week. Min RH values this week will generally range from 25 to 35 percent, and stronger westerly flow occurs over the area as well with winds generally 15 to 20 mph with gusts 25 to 30 mph. The day of highest concern looks to be Thursday, where surface dew points drop into the upper single digits to low teens. Min RH values may be as low as 20 to 25 percent, and west to northwest winds could gust as high as 30 to 35 mph. By then, it will be almost 2 weeks since the last significant rainfall. Depending on how fast and how efficiently fine fuels dry out will add to possible concerns for the rapid spread of any fires that may develop. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ SYNOPSIS...RCM NEAR TERM...AKL/Gorse/po SHORT TERM...RCM LONG TERM...RCM AVIATION...AKL/Gorse/RCM MARINE...Gorse/RCM FIRE WEATHER...

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