Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 282237 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 637 PM EDT Sun May 28 2017 .SYNOPSIS...
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A low pressure system stalls over Ontario tomorrow. Two cold fronts associated with this low are expected to move through our region, one on Monday, and another late Tuesday or early Wednesday. High pressure will build in over the region on Thursday. Another low pressure system is expected to approach the region Saturday.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A weak short wave will move across the srn areas this evening and showers and perhaps an isolated tstm will accompany it. We will have high chc/low likely pops across Delmarva/SE PA/Srn NJ this evening for this shortwave. Later tonight, a more generalized area of showers will affect the area with mostly chc pops in the grids for this. Clouds will remain across the area all night, so low temperatures will not be that cool. Readings will only fall into the upper 50s (north) and low 60s elsewhere. Overall rainfall totals will be mostly 1/10th to 1/4 inch, but locally higher totals in isolated tstms. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... Monday, Memorial Day, looks to feature cloudy conditions across the area with some improvement later in the day. Showers will be across the N/E areas during the morning, but these will move away by afternoon. Temperatures will be cool early, but then jump once the clouds begin to thin. High temperatures will range from the low 70s north to the low 80s over Delmarva. winds will switch from onshore...to Wrly at 5 to 10 knots. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
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The main thing to watch through the long term period will be the mid and upper level low that is expected to mostly stall out over Ontario early this week. Monday night...added fog to the forecast...areas along the coast and patchy inland. It clears aloft, though some cirrus at times. That leaves Mondays stratus deck likely to settle to the sfc as fog...possibly dense in a light wind field with the weak sfc ridge overhead. Tuesday and Wednesday...A secondary cold front (the first one, a rather weak and dissipating one is expected tomorrow) is expected to move through the region either late Tuesday or early Wednesday at the same time a mid level short wave trough digs along the south side of the main low. Synoptic scale lift isn`t especially impressive through this time period, but there could be enough instability both days to support some thunderstorms. Despite the cold front, temperatures through this period should stay near or even slightly above normal, with highs generally in the 70s and 80s. Thursday...With a surface high building over the region, this looks to be the day with the best chance of dry weather of the week. It also looks like the coolest day of the work week, with temperatures slightly below normal. Friday through Sunday...As mentioned by the previous shift, the details in this period are uncertain at this time as it will be highly dependent on how the mid and upper level low evolves. At this point, there are rather large differences both between models and with run to run consistency. Therefore, stayed close to the previous forecast and a guidance consensus through this period.
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&& .AVIATION /00Z MONDAY THROUGH FRIDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. VFR conditions are across the area this afternoon as the onshore flow continues. When the daytime heating developed earlier, some BKN MVFR cigs formed across srn NJ and Delmarva. Conditions will lower this evening with little confid in the timing of the occurrence. Generally MVFR will develop around sunset and IFR will develop overnight. Scattered showers (isolated thunder) will be across the area as well. No enough of a chc for thunder to include in the tafs attm. Winds will be mostly E to SE around 10 knots this afternoon and 5 to 10 knots tonight. Monday...Low cigs should continue into the morning before improvement late. Outlook... Tuesday and Wednesday...Some possible fog or low clouds to start Tuesday, otherwise generally VFR through Wednesday. There is a chance for showers and thunderstorms each day which could also lead to conditions below VFR. Thursday...VFR is anticipated with dry conditions. Friday...Increasing shower and thunderstorm chances. If any affect the TAF sites, it may result in MVFR or lower conditions. && .MARINE... We will continue with the SCA flag for the northern NJ coastal waters as previously outlined. While conditions have been sub-SCA today, a gradual increase in seas is expected overnight with the continuing SE flow across the waters. Scattered showers are expected overnight. There is a chance for a thunderstorm too, mainly across Delaware Bay and possibly the Delaware ocean waters. Outlook... Tuesday through Friday...winds and seas are expected to stay below SCA criteria. However, seas may begin to build above 4 ft on Friday. RIP CURRENTS...Waves along the coast are forecast to be in the 2 to 3 foot range the rest of today with a period of 7 to 8 seconds. A southeast to east wind of 10-15 MPH should continue. It appears as though the risk for the development of dangerous rip current will be low for much of the day. However, it may begin to approach moderate toward evening as wind speeds gradually increase. The outlook for Monday is still a low risk for the development of dangerous rip currents. We expect a 2-3 foot east or southeast swell and a south or southwest wind to develop from southern NJ southward (Atlantic and Cape May Counties in Nj and Sussex County DE). A somewhat enhanced but still LOW risk for the formation of dangerous rip currents may develop for Monmouth county and possibly the beaches of northern Ocean County NJ where an east or northeast wind of 15 mph may persist through the entire day. && .TIDES/COASTAL FLOODING... Onshore flow continuing into the evening hours and the continued high astronomical tides should result in another round of minor coastal flooding tonight. As a result, the coastal flood advisory continues for the high tide cycle tonight. It covers the coastal counties of New Jersey and Delaware, as well as the counties along Delaware Bay and the lower Delaware River up to the area just below the Commodore Barry Bridge. Based on the guidance and on the fact that the astronomical tides are decreasing as we move away from the new moon, tonight`s Coastal Flood Advisory should be the last one for a while. && .CLIMATE...
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May rainfall as 2 PM today: ACY 7.11 inches ranked #2. record 8.80 1948. POR 1874. PHL 6.12 inches. ranked #11 record 9.46 1894. POR 1872. #10 is 6.65" just last year. ILG 5.70 inches. ranked #16. record 11.99 1894. POR 1894. May rainfall in central DE without todays amts...ie through the 27th Smyrna 7.33 Kenton 6.10 Dover 6.03 and 6.50 (two different DEOS reported sites) Townsend 5.61 Blackbird 5.63
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None. NJ...Coastal Flood Advisory until 3 AM EDT Monday for NJZ012>014- 020>027. Coastal Flood Advisory from midnight tonight to 4 AM EDT Monday for NJZ016. DE...Coastal Flood Advisory until 3 AM EDT Monday for DEZ002>004. Coastal Flood Advisory from midnight tonight to 4 AM EDT Monday for DEZ001. MD...None. MARINE...Small Craft Advisory from midnight tonight to noon EDT Monday for ANZ450>452.
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&& $$ Synopsis...Johnson Near Term...O`Hara Short Term...O`Hara Long Term...Drag/Johnson 636 Monday night Aviation...Johnson/O`Hara Marine...Johnson/O`Hara Tides/Coastal Flooding... Climate...Drag 636

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