Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 201959 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 359 PM EDT FRI MAY 20 2016 .SYNOPSIS...
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High pressure shifts off the mid Atlantic coast tonight, giving way to developing low pressure off the VA Capes late Saturday, which will progress northeastward well offshore Sunday morning. High pressure over the Mississippi Valley Monday slowly moves east and will cross our region by mid week. Low pressure moving through the Great Lakes Thursday is expected to lead to a cold frontal passage across our area Friday.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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Beautiful May day with seasonal temps, light winds, and lots of blue sky. It`s not going to last. Clouds will be on the increase tonight with the leading edge of the rain forecast to arrive across our southwestern zones right around daybreak. Overnight lows will drop into the mid 40s and mid 50s which is pretty much where we should be for this date. Overall, winds will be light out of the southeast.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
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The rain will push across the CWA from southwest to northeast tomorrow morning. By midday, just about everyone will have the opportunity to get wet. By midday, the coastal surface low will be developing well off the Virginia Capes and will push northeast out to sea the remainder of the afternoon. QPF amounts have increased the last 12 hours. Through the day tomorrow, the area could pick up as much as a 0.25 inch well north and west to between 1.00 and 1.50 across extreme southern NJ and across the Delmarva. With the rain forecast to be heavy at times, some poor drainage and nuisance flooding is possible. Temps will climb into the upper 50s to mid 60s. Winds will begin to pick up out of the east tomorrow morning across southern NJ and southern DE. The winds will back to the NE in the afternoon and could gust into the 25 to 30 mph range across the coastal plain. Strongest winds will be along the southern beaches.
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&& .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
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A Mid level trough will close off over the northeastern quarter of the U.S. and become our dominant weather maker in the Sunday thru Tuesday time frame. Brief ridging will follow in the wake of this feature Wed, after which the northern stream lifts well north into Canada, promoting a southwest flow aloft. Several southern stream shortwaves will eject out of a mean trough over the southwest US and affect our weather thru the end of the work week. Temperatures will be below normal thru Monday under the influence of the upper low, then trend above normal after Tue, as mid level heights rise. Saturday Night...Surface low is progged just southeast of the mouth of DE Bay around 00Z Sun, and will be progressive, moving northeast further offshore overnight. The heavier rainfall should be exiting the region by midnight, with some lingering scattered showers in the wake of the system. Sunday...Mid-level trough cuts off overhead, with cold air aloft, and ample moisture in the column. Expect considerable cloudiness, with scattered showers in the afternoon. Cannot rule out a rumble of thunder, and SPC does have points northwest of I-95 in general thunderstorms. While it`s cold aloft (-19C at 500 hPa), and there will be a weak surface trough setting up over the aforementioned area, mid-level lapse rates are weak and instability is meager. At this time, expect some low topped showers. Monday and Tuesday...The cutoff low is progged over Delmarva Mon and is anticipated to begin moving northeast toward Southern New England Tue. Ground fog is a possibility Mon morning given the weak gradient and abundant low-level moisture, but will be dependent on how much clearing takes place during the overnight. For now, have inserted patchy fog into the forecast. Otherwise, expect similar weather Mon and Tue compared to Sun. In addition to showers, there will be a better chance of isolated pulse-type convection both days, given better modeled instability. However, uncertainty regarding spatial extent leads to low confidence, so it`s not reflected in the current forecast. Overall, we have kept consistency with the previous forecast of the last few days, with at least some pops during the Sun thru Tue time frame. Due uncertainty regarding spatial extent, later shifts can adjust accordingly. Wednesday...Weatherwise, the pick of the week at this time. The mid level ridge crests over the region as surface high pressure moves offshore. Sunny skies to start with high clouds streaming in aloft as the day progresses. The flow will become southwest with temperatures rebounding to several degrees above normal. The gradient should be weak enough for a sea breeze to develop along the coast and DE Bay, which will allow for cooler temps. Thursday and Friday...Low pressure moving through the upper peninsula of Michigan will promote a pre-frontal trough Thu afternoon and a gradual cold frontal passage during the day Fri. The best chance for convection will be Thu, and possibly Fri, depending on the timing of the fropa. The models indicate sufficient moisture and instability, but with the upper jet displaced to the north, shear is lacking for more organized convection. Both days, 850 hPa temperatures approach 30C, so depending on the extent of mixing, high temperatures have the potential to reach well into the mid 80s along the I-95 corridor.
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&& .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. Tonight...VFR with light southeast winds becoming east toward daybreak. Saturday...VFR at sunrise will transition to MVFR and than to IFR around midday. LIFR is possible during the afternoon hours. NE winds will gust between 20-25 kt during the afternoon from the I95 terminals eastward. OUTLOOK... Sat night...Widespread MVFR, particularly I-95 terminals and points southeast, with IFR possible at ACY in MIV, mainly in low clouds and SHRA. Northeast winds could gust 20 to 25 knots early in the night I-95 terminals and points southeast, particularly ACY. Sun through Tue...Predominantly VFR, with a low probability of a short period of MVFR in widely scattered SHRA each afternoon. Wed...VFR.
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&& .MARINE...
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Great conditions on the water today. More of the same expected tonight. Things go downhill tomorrow with the coastal low tracking just east of our waters. Forecast soundings did not support a Gale Warning, so SCA`s were issued. They begin late morning. For the ocean, I have them going through Saturday night. For Delaware Bay, they`re up through the evening hours. Winds will gust from the east and seas will build to 4 to 6 ft on the ocean. OUTLOOK... Sat Night and Sun...SCA is in effect for DE Bay thru 02Z Sun and the Atlantic Waters thru 10Z Sun. The SCA may need to be extended for hazardous seas over the Atlantic waters into the day Sunday. Sun night thru Wed...Both winds and seas are expected to remain below SCA criteria. RIP CURRENTS: The Surf Zone Forecast began for the season Fri morning. The Surf Zone Forecast currently has a news headline on our homepage. It should also be accompanied by a probable debut of the Experimental National Beach Forecast page (if not Saturday morning, then certainly early next week). You will be able to click the beach located umbrella and comprehensive beach localized forecast information including beach specific forecasts, the surf zone forecast, ultraviolet index, rip current preparedness/safety information for beaches within our forecast area. DIX and DOX live radar will be posted on the right side as well as a Rip Current recognition video, and Lightning Safety tips. Comments on the page will be welcome. We expect that we will need to adjust the density of the beaches offered. All this was tied together in a social media announcement Friday afternoon. Ultimately for beach goers maximum enjoyment and safety...swimming within vision of lifeguards is a best practice. Rip currents come and go, tending to repeat only near jetties and piers, particularly the incident side of the swell. Rip currents may be a little stronger when the tide cycle is in the lower half of its cycle. Most rip current fatalities are male, under 40 and unguarded beaches. Water temperatures are currently a little below normal, mid 50s.
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&& .TIDES/COASTAL FLOODING...
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At this time, all available guidance indicates water levels for both the Saturday evening and Sunday evening high tides will remain below the threshold for minor flooding.
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&& .CLIMATE...
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As we near the conclusion of the 2016 meteorological spring, preliminary estimates indicate ABE on pace for a top ten driest, barring significant rainfall over the next 12 days. The average spring rainfall for ABE is 11.09 inches, with 5.58 inches as of 5/19. If less than 1.89 inches of rain falls for the remainder of May, ABE will be at least within the top ten. In terms of the May 2016 monthly climate (as of 5/19), all of the big four long term climate sites have experienced temperatures below normal and precipitation above normal. The following table lists: the normal average vs. May 2015 average and the resultant departure from normal for both temp and precip. SITE TEMPERATURE (F) PRECIPITATION (IN) ---- ------------------ --------------------- ACY 59.3 VS. 55.7 -3.6 1.96 VS 3.93 +1.97 PHL 62.1 VS. 57.8 -4.3 2.20 VS 2.96 +0.76 ILG 60.9 VS. 56.4 -4.5 2.35 VS 3.10 +0.75 ABE 58.0 VS. 55.2 -2.8 2.44 VS 2.83 +0.39 note: the above normals represent the month through May 19.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory from 11 AM Saturday to 6 AM EDT Sunday for ANZ450>455. Small Craft Advisory from 11 AM to 10 PM EDT Saturday for ANZ430-431.
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&& $$ Synopsis...Franck Near Term...Kruzdlo Short Term...Kruzdlo Long Term...Franck Aviation...Franck/Kruzdlo Marine...Franck/Kruzdlo Tides/Coastal Flooding...Franck Climate...Franck

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