Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 231012 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 512 AM EST Thu Feb 23 2017 .SYNOPSIS...
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A cold front moving through the Great Lakes today will stall just north of our region tonight into Friday, before lifting northward as a warm front Friday night. This will be followed by a strong cold frontal passage on Saturday evening. High pressure will traverse the middle Atlantic Sunday into Monday. A frontal boundary will setup near our region during the early to middle part of next week, and several waves of low pressure are expected move along it.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A light south to southwest surface flow continued to bring mild air and increasing low level moisture into our region during the night. Low clouds and fog have developed across parts of northeastern Maryland, Delaware, southeastern Pennsylvania, and central and southern New Jersey. The low clouds and fog are expected to expand northward. We have issued a Dense Fog Advisory for much of the central and southern parts of our forecast area. It is in effect until 10:00 AM. The original advisory was expanded to include Berks County in Pennsylvania and the New Jersey counties of Hunterdon, Somerset and Middlesex at 5:05 AM. The low clouds and fog are expected to lift and break gradually from mid morning until early afternoon. We are anticipating some sunshine during the afternoon hours. Temperatures are forecast to respond to the sunshine and the mild south to southwest flow. Highs should reach the 60s in much of eastern Pennsylvania and northern and central New Jersey. Maximum temperatures are expected to be near 70 in much of northeastern Maryland, Delaware and southern New Jersey. The exception will be locations near the coast which should not get above the 50s due to the chilly water temperatures. It looks as though we will set a new record high temperature at Georgetown, Delaware today based on the latest projection. Mount Pocono, Pennsylvania may get close, as well. Our other six primary climate sites (Philadelphia, Wilmington, Atlantic City, Trenton, Allentown and Reading) will likely fall short of their record highs for today.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
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Our region should be more solidly in the warm air for tonight. As a result, we may see more stratus than fog development except near the water. Nevertheless, we will continue to mention at least some patchy fog for late tonight. Scattered showers may spread across parts of eastern Pennsylvania and northern and central New Jersey. Rainfall amounts should be light, generally a few hundredths of an inch. The wind is forecast to be light for tonight and low temperatures should range from the middle 40s in the Poconos and far northern New Jersey to the lower 50s on the coastal plain.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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Active pattern in the Friday thru Wednesday period. Dense fog is possible Friday and Friday night. There is a marginal risk of severe thunderstorms on Saturday. There is also the potential for daily record high temperatures on Friday, especially Delmarva. Temperatures cool to seasonal levels on Sunday. A more zonal flow sets up in the Monday thru Wednesday time frame with additional chances of light precip along with a return to above average temperatures. There is a lot of uncertainty regarding coverage and timing of precip in the early to middle part of next week. Friday will feature a warm front just north of the area, with diffuse shortwave energy moving along it. This will promote the chance for scattered rain showers, mainly north of an I-195 to PA Turnpike line. Given the proximity of a warm front, which may briefly backdoor to the south, we anticipate considerable cloudiness across much of NJ and eastern PA. This is reflected in our temperature grids, and will likely limit record high potential across this area. Further south across Delmarva, we have maintained warmer temperatures (mid-70s), and thus there is a greater potential of setting records across this area. With the nearby frontal boundary, we expect fog through mid- morning Friday and again Friday night. The fog could be dense, and we have continued a mention of this in the HWO. Saturday and Sunday...A strong cold front moves through the region Saturday evening. The synoptic pattern is favorable for a squall/convective line to move through much of the area, and SPC has placed our entire region within a marginal risk of severe thunderstorms in their day 3 convective outlook. Thus, we maintain a chance of thunder in the forecast. Some heavier downpours are also likely, but amounts are expected to be less than one inch. High temperatures on Saturday are expected to fall just shy of daily records. Fair weather is expected for Sunday, with a return to near normal temperatures, and gusty west-northwest winds. Looking ahead to Monday thru Wednesday, several shortwaves will interact with a frontal boundary that sets up near our region, offering additional chances of light precipitation. Details in timing and coverage continues to be low, so the forecast shows a general slight chance of showers during this period. Snow showers are possible Monday and Tuesday nights. We expect temperatures to return to above average levels, generally around 5 to 10 degrees above normal.
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&& .AVIATION /10Z THURSDAY THROUGH MONDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Abundant low level moisture will continue to result in the development of low clouds and fog in our region early this morning. We are forecasting widespread IFR conditions. A gradual improvement is anticipated from mid morning through early afternoon with most locations rising into the VFR category by 1800Z or 1900Z. VFR conditions are anticipated from mid afternoon into this evening. However, a return of low clouds and fog is possible late tonight. Also, there may be scattered light rain showers around KRDG and KABE tonight. A light and variable wind early this morning should settle into the southwest and south around 5 to 10 knots for this afternoon. The wind is anticipated to become light and variable again for tonight. OUTLOOK.. Friday through Saturday...There is the potential for MVFR/IFR at times, especially Friday night, and again on Saturday with showers and potential thunderstorms ahead of a cold front. Winds out of the south on Saturday could gust up to around 20 knots. Saturday night and Sunday...Becoming VFR Saturday night with gusty west-northwest winds anticipated into Sunday, 25 to 30 knots at times.
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&& .MARINE...
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A southwest to south flow will continue on the coastal waters of Delaware and New Jersey for today and tonight. Sustained wind speeds should remain less than 15 knots with no gusts in excess of 20 knots. Wave heights on our ocean waters should range from 2 to 4 feet. Waves on Delaware Bay will likely be 2 feet or less. Mild air will continue to advect over the chilly water. Dew point readings will increase further above the water temperatures resulting in widespread fog. We have issued a Dense Fog Advisory over the water until noon for the time being. We may need to extend the advisory, especially on our waters north of Atlantic City. OUTLOOK... Sub-SCA conditions are forecast Friday. SCA possible Friday night thru Monday, with period of gales possible on Sunday. Sub- SCA conditions are forecast Tuesday.
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&& .CLIMATE...
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For those who refer to the RTPPHI: it hasn`t run correctly on its 715 AM/PM cron since the 20th but we were able to produce a version around 8 PM tonight. Not all the trace amounts of rain are in there. This will have to suffice until an improved fix hopefully is implemented Thursday evening. Thank you. For reference, here are the high temperature records for Thursday, Friday and Saturday. Location Thursday 2/23 Friday 2/24 Saturday 2/25 ACY 72-1985 75-1985 77-1930 PHL 75-1874 74-1985 79-1930 ILG 72-1985 78-1985 78-1930 ABE 71-1985 76-1985 74-1930 TTN 74-1874 74-1985 76-1930 GED 67-1985/1990 72-1961 76-1975 RDG 72/1932/1922 77-1985 77-1930 MPO 60-1977 60-1984 70-1930 The following monthly and seasonal expectations were recalculated with todays max/min and then the official 330 PM Mount Holly forecast. It is virtually certain that the numbers below will stand and that our forecast area is experiencing a record warm, or at least a 2nd warmest January on record and a top 10 warmest winter. Records date back to the late 19th century. Details below. These values are probably on the lower side of the solutions. February: PHL 43.3. #1 Normal 35.7 Record 42.2-1925 POR 1874 ABE 37.6 #2 Normal 30.7 Record 38.6-1998 POR 1922 There is a pretty good chance ABE will end up warmer, very very close to the record. ACY 42.2 #1 Normal 35.3 Record 41.6-1890 POR 1874 ILG 42.3 #1 tie Normal 35.1 Record 42.3-1903 POR 1895 Winter (DJF) PHL 40.1 #7 ABE 35.4 #5 ACY 39.6 #10 ILG 39.1 #6 tie Past two years of monthly average temperatures through February 2017, a summary of above normal months listed below: For ABE: 23 consecutive months of above normal temps! FOR PHL: 22 of the past 23 months have been above normal. For ACY: 19 of the past 23 months have been above normal. For ILG: 17 of the past 23 months have been above normal. (Jan Feb March 2015 was the last time we had significant and persistent below normal monthly temps.) Snow: February least on record: Atlantic City should/could end up tied for 5th.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...Dense Fog Advisory until 10 AM EST this morning for PAZ060-070- 071-101>106. NJ...Dense Fog Advisory until 10 AM EST this morning for NJZ009-010- 012>027. DE...Dense Fog Advisory until 10 AM EST this morning for DEZ001-002. MD...Dense Fog Advisory until 10 AM EST this morning for MDZ008-012- 015-020. MARINE...Dense Fog Advisory until noon EST today for ANZ430-431-450>455.
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&& $$ Synopsis...Franck Near Term...Iovino Short Term...Iovino Long Term...Franck Aviation...Franck/Iovino Marine...Franck/Iovino Climate...Drag

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