Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 292159 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 559 PM EDT Sat Apr 29 2017 .SYNOPSIS...
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A weak cold front will cross the area tonight before dissipating south of the region Sunday night. A ridge of high pressure will build across the area Sunday before low pressure and its associated fronts move toward the Middle Atlantic states later Monday and Monday night. High pressure will build in for the middle of next week. Another low will affect our area towards the end of next week.
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&& .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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630 PM ESTF sent 545PM: withdrew thunder and showers se pa/s nj and a portion of the Delmarva. Too dry (few cu) and main sfc convergence now favoring s DE. Have increased wind gusts late this aftn north of PHL with the dry air advection and gusts 25-30 kt. These should subside quickly this evening. Otherwise, a wind shift to the north and northeast will move from north to south overnight as part two of the cold front works southward. This will drive some drier air southward as a result and the forecast soundings are not really robust with low clouds/fog developing as a result. There should at least be some stratocumulus development especially as the northeast low- level flow gets going. Low temperatures are mostly a MOS/continuity blend. Max temps for ACY PHL may be occuring at 1 am Sunday.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... The weather will be rather different Sunday compared to today (Saturday) in the wake of a cold front. This front is expected to clear our entire area before stalling in a west to east orientation. An upper-level ridge axis should be moving across our area, allowing surface high pressure to build to our north and east. This will allow for a northeast low-level flow which should become east and then southeast with time. This will allow for a much cooler airmass to be over our area, enhanced by the flow off the colder ocean waters. While there may be areas of stratocumulus, the cloud bases may lower especially in the afternoon as the flow turns more east and southeast resulting in some increase in the moisture. Overall though, there should be a fair amount of cloudiness across the region during the day. As of now other than some slight chance PoPs early across parts of Delaware and Maryland, opted to go with a dry forecast as there is no real clear forcing with the southward/stalling front. Any remaining instability in the southern areas should be more elevated given the onshore low-level flow. High temperatures were a MOS/continuity blend, then some tweaks were made mostly along the coast. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... A weak ridge of high pressure will be across the area during the start of the long range. It will remain in place through Monday before moving to the east. Dry weather is expected Sunday night, then clouds will increase Monday along with the chances for a few showers across the N/W areas Monday afternoon. Temperatures will be above normal with highs Monday in the low 80s over srn NJ and Delmarva while highs will be in the mid/upper 70s across the N/W areas. A low pressure system across the upper Great Lakes Monday morning will move NE across southern Canada through Wednesday. A strong cold front will move across the Middle Atlantic Mon night and into early Tue. There appears to be a decent chc for showers and tstms with this front, so only small changes to the already high pops were made today. We have categorical pops N/W and high Likely S/E. It could be a 1/4 to 1/2 inch rain producer, higher in tstms. On Tuesday, the front will be east of the area, but the lingering upper low aloft will lead us to keep the chc for some showers into the early afternoon. High temps Tue will still be a little above normal S/E but by Wed, readings will be close to normal for early May. A short period for far weather Wed/Wed night with an area of high pressure across the area. Another low will approach Thu and will again bring decent chc for showers and sct tstms (Delmarva) for the end of next week. We have some likely pops for many areas Thu/Thu night and chc pops for Fri/Sat. Temperatures will be near or below normal towards the end of the week. && .AVIATION /22Z SATURDAY THROUGH THURSDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...VFR with a few clouds near 5000 feet and cirrus on top. VCTS was dropped at about 515 PM and the primary thunder threat through midnight should be s DE after 00z/30. Winds turning northwest with evenings gusts to 20 kt, then shifting northeast after 06z/30. Please see TAFS for the details. Tonight...A few showers or thunderstorms possible mainly in the evening especially near and southwest through east of PHL with locally reduced ceilings/visibilities, otherwise any ceilings should remain VFR. Northwest winds mostly 10 knots or less, becoming north and then northeast. Sunday...VFR ceilings may lower to MVFR through the day, however confidence is on the lower side. Northeast winds around 10 knots, becoming east and southeast in the afternoon. OUTLOOK... Sun night thru Mon Afternoon...Mostly VFR expected. Mon night thru Tue...Restrictions with showers especially Mon night. Tue night thru Wed night...Mostly VFR. Patchy morning fog psbl. Thu...Restrictions possible with showers.
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&& .MARINE...
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MWS issued for dry air advection momentum transfer wind gusts to 25 or 30 kt at the coast-water interface...making it difficult to navigate the final into and out of the bays and harbors. Expires around 630 PM. Winds will subside thereafter. A cold front will cross the area this evening, resulting in a wind shift to the northwest and north then to the northeast through the night. There could be a northeast to east wind surge Sunday especially across the northern coastal waters zones, however held gusts below 25 knots. The duration of this does not look long enough and therefore kept seas 4 feet or less. OUTLOOK... Sun night thru Mon morning...Sub-SCA conditions with Fair weather. Mon afternoon thru Tue night...SCA expected. Showers with sct tstms. Tue night...SCA on the ocean and sub-SCA across Del Bay. Fair. Wed thru Thu...Sub-SCA. Fair thru Wed night then sct showers Thu.
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&& .CLIMATE... We have already issued a RER product for a new record high temperature at Georgetown, DE...91 at 241PM. Atlantic City was 1 shy as of 330 PM (91) and think that might be it. Atlantic city doesn`t normally reach 90 until June 11 although the statistical database may be skewed to cooler temperatures closer to the coast. The earliest 90 degree day at Atlantic City occurred April 7, 2010. **Record or number 2 warmest April on record** Presuming our forecast temps these last 36 hrs of April are accurate, we are assured of a top 2 warmest April on record in much of our forecast area. Sunday is probably the critical day for determining record or not. Below: April projected within the top April average temps, the normal for April and the period of record (POR). This includes todays (29th) high and low temperatures through 4 PM. Sundays max temps may occur at 1 am and the min temps Sunday evening. PHL normal 54.0 POR 1874 59.5 2017 Projected warmest ever: still could slip .2 degrees. 59.4 1994 58.5 1921 58.4 2010 57.9 1941 ABE normal 49.9 POR 1922 56.8 projecting record and almost cant miss a record. 56.4 1941 54.7 1994 ACY normal 51.7 POR 1874 57.6 projecting record and almost cant miss. 56.3 2010 56.1 2011 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...O`Hara Near Term...Drag/Gorse 6P Short Term...Gorse Long Term...O`Hara Aviation...Drag/Gorse/O`Hara 6P Marine...Drag/Gorse/O`Hara 6P Climate...

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