Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 170717 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 317 AM EDT Sun Mar 17 2024 .SYNOPSIS...
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A weak cold front passes through the region today, followed by a reinforcing cold front on Monday. 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 TONIGHT/...
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Low pressure passing north of the area today will cause a cold front to move thru the Middle Atlantic area this morning. A developing South to Southwest wind early this morning will bring slightly milder air to the region but very limited moisture. After the front passes, cooler air will arrive and drier air from the Great Lakes region arrives. The best dynamics with the system move north of the area today and with the limited moisture present, we will only have small chances for showers this morning and into the afternoon. The best chances for any rains are for the southern Poconos and north NJ. Slight chances exist further south. Any rain that does occur will be light. It will be mild again today with highs in the upper 50s/low 60s for the south/east areas and mostly 50s for the Lehigh Valley and north NJ. Gusty winds will make the air feel cooler today compared toe Saturday. Tonight, the front will have moved away, but a lingering upper trough remains over the area. We`ll carry a dry forecast for now, but a few sprinkles for the NW areas are possible. The air will continue to be quite dry, so this will limit any precip possibilities. Temperatures will be cooler than recent days with upper 20s to low 30s for the N/W areas and mid/upper 30s elsewhere. Winds will be mostly NW at 5 to 10 mph.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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A deep upper trough with strong shortwave energy will push a reinforcing cold front through the Northeast and Mid-Atlantic on Monday. Meanwhile surface high pressure will build over the Southern Plains and Gulf Coast states and will remain in place through the middle of the week. With the passage of that front, Lake Effect snow showers will develop upstream and some of those snow showers may make it down into the southern Poconos. Will carry slight chance PoPs for Monday afternoon for Carbon and Monroe counties. Gusty west winds will develop as the pressure gradient tightens over the area and will range from 15 to 20 mph with gusts up to 25 mph. With the upper trough over the area, strong cold air advection will be underway. Highs on Monday will be in the upper 40s to low 50s, and then highs on Tuesday will be in the 40s. Continued breezy with gusts as high as 25 to 30 mph. Another front approaches Tuesday night, touching off isolated snow showers in the southern Poconos once again. Lows at night will generally be in the 30s.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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Upper level trough remains in place on Wednesday and gradually moves offshore on Thursday. Weak cold front passes through Wednesday morning, touching off some isolated snow showers in the southern Poconos. Canadian high pressure builds down into the Great Lakes on Wednesday and moves into eastern Canada Thursday. Another shot of reinforcing cold and dry air builds south into the region on Thursday. A chilly airmass remains in place. Towards the end of the week, low pressure develops over the Gulf Coast states and may take a run at the mid-Atlantic. There are several inconsistencies among the models. The 00Z/17 ECMWF and the 00Z/CMC have high pressure over the Northeast, and this keeps the approaching low suppressed to the south and east. The 00Z/17 GFS has the high over eastern Canada, and low pressure rides along the coast. For now, will follow the NBM and carry chance PoPs.
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&& .AVIATION /07Z SUNDAY THROUGH THURSDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas... .thru dawn...Increasing S to SW winds as a cold front approaches. Increasing clouds. LLWS thru 09Z/10Z as SW winds around 40 to 45 kts develop around 2000 ft. VFR expected. A brief sprinkle far NW areas possible. High confid. .Today...VFR conditions expected today as a cold front crosses the area this morning. Some low clouds (040-050) and mid level clouds will be around for the morning then decrease during the afternoon. Winds will switch to West following the front and increase to 10 to 15 knots with frequent gusts to 25 kts during the daylight hours. Medium/high confid. .Tonight...VFR continues. Decreasing winds which will settle to mostly NW around 5 kts. High confid. Outlook... Monday through Thursday...In general, a VFR forecast. A few SHSN may briefly result in sub-VFR conditions Monday morning, then again Tuesday night and Wednesday. A prolonged period of W flow at 10 to 20 kt with 25 to 30 kt gusts. Moderate confidence.
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&& .MARINE...
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A cold front will cross the waters this morning. Increasing winds and seas ahead of the front will bring SCA winds/seas to the NJ coastal waters. The SCA flag in effect will continue into the morning. After that, winds and seas will diminish and sub- SCA conditions are expected for the afternoon and into tonight. Fair weather is expected for the most of the time. A brief sprinkle or shower is possible. Outlook... Monday through Thursday...SCA conditions from time to time during the week with W winds 15 to 20 kt with gusts as high as 30 kt. Sub-SCA conditions likely Tuesday night.
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&& .FIRE WEATHER...
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Isolated to scattered rain showers are possible across portions of the southern Poconos today. Isolated to scattered snow showers are then possible across portions of the southern Poconos Monday morning, then again Tuesday night through Wednesday morning. Aside from that, dry conditions on tap. Although most of the area is above normal for precipitation since March 1, it is now 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 30 percent, and a breezy westerly flow will develop over the area as well with winds generally 15 to 20 mph with 25 to 30 mph gusts. 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 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 concerns for the rapid spread of any fires that may develop.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 10 AM EDT this morning for ANZ450>453.
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&& $$ SYNOPSIS...MPS NEAR TERM...OHara SHORT TERM...MPS LONG TERM...MPS AVIATION...MPS/OHara MARINE...MPS/OHara FIRE WEATHER...MPS

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