Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 240036 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 836 PM EDT Fri Mar 23 2018 .SYNOPSIS... High pressure briefly affects the area Saturday while an area of low pressure passes to our south Saturday night. High pressure will then build across the northeast later Sunday, then across much of the east coast through early next week. A warm front will likely lift north of the area Wednesday. Then a weak cold front may move across the area later Wednesday or early Thursday, before a storm system moves toward the east coast late Thursday into Friday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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630 and 9 PM: Very little change expected. Mid afternoon water vapor satellite imagery shows a mid-level shortwave trough digging southeastward across central PA. There is a weak surface reflection of this disturbance marked by a subtle wind shift (from W-NW to NW) along a surface trough that was moving southward through our region. Mainly virga spreading se through our area given the very dry sub- cloud layer (large T-Td depressions of 15-25 degrees) that is backed up by a lack of obs reporting precip. Kept a mention of isolated showers and sprinkles (snow showers and flurries over the higher terrain). Clouds should diminish from west to east tonight as drier air works in. The pressure gradient remains tight enough to inhibit winds at most locations from decoupling tonight, except at the typical sheltered valleys in eastern PA and northern NJ as well as the NJ Pine Barrens. Consequentially, forecast low temperatures are approximately 3-6 degrees lower in these favored radiational cooling spots (mid 20s) vs the urban/coastal locales (near 30).
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... Saturday`s weather will be similar to today with no significant changes in the large-scale pattern over the next 24 hours. The region will be embedded in northwest flow around the backside of the low pressure to our north/west. A rather diffuse surface trough/cold front looks to progress southward through eastern PA and much of New Jersey during the afternoon. Following the passage of the mid-level shortwave trough this afternoon, the next one digs southward toward the area about 30 hours later. Clouds will start to filter in from the north late in the day, but with the deeper lift/moisture ahead of this next system not arriving until Saturday night, expect mostly sunny skies during the day, except perhaps transitioning to a partly sunny deck in the late afternoon across northeastern PA and northern NJ. Given the similarities in thermal profiles and mixing potential in the boundary layer tomorrow compared to today, a blend of the bias- corrected MAV/MET guidance was used for to populate temps for Saturday. Highs ranging from the mid 30s in the southern Poconos to the upper 40s along and south/east of the I-95 urban corridor equate to 5-10 degrees below climo. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Fairly quiet weather for much of the long term period, before unsettled weather returns for the end of next week. An area of low pressure will will pass far enough to our south Saturday night that our area avoids another major snow event. However, several short wave/vorticity impulse are forecast to move across the area Saturday night through Sunday, while some enhanced low-mid level moisture and low-mid level lapse rates increase during the day as well. This could lead to some isolated snow showers overnight Saturday into Sunday, although it is a small chance at this time. Any showers during the day may melt enough to fall as rain. Otherwise, a cool, breezy period is expected Saturday night through Sunday. The high pressure that builds across the northeast Sunday builds down the east coast Monday through Tuesday. This will keep dry conditions across the area Sunday night through Tuesday. Temperatures remain below normal Monday and Tuesday, but a warming trend begins by Tuesday. The potential for unsettled weather returns for the middle to end of next week. A warm front will likely lift north of the area Wednesday. As this happens, some light precipitation may fall across portions of the area, especially northeast Pennsylvania and northwest New Jersey. If the precipitation fall early enough, temperatures may be cold enough for a wintry mix to occur, possibly a brief period of freezing rain. A weak cold front may move across the area later Wednesday or early Thursday, keeping a slight chance of showers in the forecast into Thursday. However, this front may lift back northward into the area as an area of low pressure moves up the Appalachians and toward the area late Thursday into Friday. This storm system could bring a round of gusty winds and rainfall to the area late next week. Right now it looks like temperatures would be warm enough for all rain. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Through Tonight...VFR sct-bkn near 6000 ft. An isolated shower or sprinkle possible thru about 02Z but confidence/coverage too low to mention in 18Z TAFs. A slight wind shift is expected early this evening from about 290-310 degrees to 320-340 degrees with the passage of a surface trough. A few gusts of 15-20 kt this evening. Saturday...VFR. Though CIGs may start out around 3 kft AGL in the late morning/early afternoon, it should be FEW to SCT. CIGs increase to 3.5-5 kft AGL after 18Z and could become BKN near ABE-TTN in the late afternoon. NW winds around 10 kt. OUTLOOK... Saturday night-Sunday...Generally VFR. Slight chance of isolated snow showers which may temporarily lower conditions. North to northeast winds gusting 15 to 20 knots. Moderate confidence. Sunday night...Generally VFR. East winds gusting 15-20 knots. High confidence. Monday-Tuesday night...Generally VFR. High confidence. Wednesday...Generally VFR. Slight chance of showers. Gusty south winds 15-20 knots. Moderate confidence. && .MARINE...
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Through tonight...NW winds 5-15 kt gusting to 20 kt through the remainder of the afternoon and tonight. However, issuing short fuse-duration SCA for ANZ450-51 for gusts to 25 kt through 05z. Seas 2-4 ft in coastal waters and 1-2 ft in the DE Bay. Saturday...NW 5-15 kt. Seas 2-3 ft in coastal waters and 1-2 ft in the DE Bay. OUTLOOK... Saturday night...Conditions expected to be below advisory levels. Sunday-Sunday night...Small Craft Advisory conditions possible. Monday-Wednesday...Winds expected to be below advisory levels, but seas likely to remain well above advisory levels on the Atlantic waters. Its early, so we`re not sure, but there is a chance that a developing strong ocean storm in the western Atlantic could send 8 to 10 foot 15 second period swells west into our coastal waters Tuesday or Wednesday.
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&& .CLIMATE... NJ NEW state record for March snowfall established per the NJ State Climatologists office-Dr David Robinson #1 Jefferson Township - Morris County 44.3" so far. 2018 #2 Rockaway Township - Morris County 43.9" so far 2018 #3 Canistear Reservoir (Sussex County) 43.0 -1958 the previous record til yesterday. Cooperative observer reports are no longer taken at Canistear Reservoir for a direct comparison. Below based on cooperative observer reports past century. Statewide 1913-1914 22.7 1957-1958 19.4 1955-1956 18.8 2017-2018 16.6 Ranked 4th snowiest March statewide All regions below are top 10! Northern NJ (Sussex,Passaic,Bergen,Warren,Morris,Essex,Hudson) 2017-2018 26.4 NEW record 1915-1916 25.6 Central NJ (Union,Middlesex,Hunterdon,Mercer,Monmouth,Somerset) 1955-1956 21.4 1913-1914 19.5 1966-1967 18.6 1957-1958 18.2 2017-2018 17.4 Southern NJ (Burlington,Atlc,Cumberland,Salem,Camden,Gloucester,Ocean Cape May) 1913-1914 25.8 2017-2018 ranked #9 with 10.9" The four climate sites in our Mount Holly Forecast area with snowfall data are now in their top 5 snowiest March`s on record. Snowiest March`s on Record... Philadelphia - Currently tied for second. 1) 17.7" in 1941 2) 15.2" in 2018 2) 15.2" in 1914 4) 13.4" in 1958 5) 12.4" in 1993 Allentown - Currently at fourth. 1) 30.5" in 1958 2) 21.6" in 1993 3) 21.3" in 1960 4) 20.7" in 2018 5) 18.3" in 2017 Wilmington - Currently at second. 1) 20.3" in 1958 2) 14.2" in 2018 3) 13.9" in 1993 4) 13.4" in 1960 5) 13.3" in 1914 Atlantic City - Currently at fifth. 1) 17.6" in 1969 2) 15.6" in 2014 3) 13.4" in 1960 4) 12.7" in 1956 5) 9.6" in 2018 1-Day Snowfall Records in March... Atlantic City, 5.7 inches on 3/21/18 is the 7th highest. Wilmington, 6.7 inches on 3/21/18 is the 6th highest (2-day total of 8.1 inches is tied for the 7th highest). Allentown, 13.2 inches on 3/21/18 is the 4th highest behind 16.7 inches on 3/13/93, 16.5 inches on 3/20/58 and 13.8 inches on 3/3/60. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Robertson Near Term...Drag/Klein 836 Short Term...Drag/Klein Long Term...Robertson Aviation...Drag/Klein/Robertson Marine...Drag/Klein/Robertson 836 Climate... is the U.S. government's official web portal to all federal, state and local government web resources and services.