Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 181034 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 634 AM EDT WED MAY 18 2016 .SYNOPSIS...
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An area of low pressure will track to our south and east through Thursday and strengthen as it moves offshore away from the region. High pressure will build in from the midwest later Thursday and Friday. Another low pressure system is forecast to arrive on Saturday before moving away on Sunday. Unsettled weather may remain into early next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Low pressure off the coast and high pressure over the Great Lakes will result in a northeasterly surface flow in our region for this morning. The wind may veer a bit toward the east for this afternoon. Speeds should favor the 5 to 10 mph range. Even with an onshore component to the surface wind, the flow is expected to bring dry air into our region in the low levels of the atmosphere. Meanwhile, a westerly flow aloft is forecast to bring additional mid and high level clouds overhead. As a result, we are anticipating a mostly cloudy day. The overrunning pattern will result in scattered light rain showers affecting parts of southeastern Pennsylvania this morning and perhaps parts of the upper Delmarva as we go through the day. The low level dry air will cause the showers to weaken and dissipate as they enter our region. The cloud cover may be a bit thinner over our northern counties than over the south. The warmest temperatures in our region may occur in our counties in northern New Jersey where highs are forecast to be in the upper 60s. Maximum temperatures should favor the lower and middle 60s elsewhere.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
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The clouds are expected to linger into most of the tonight period. The cloud bases may lower a bit into the upper end of the stratocumulus range. Relatively dry air in the lowest levels of the atmosphere should preclude the development of any fog or rain showers at that time. We are anticipating a light wind for tonight and its direction should favor the north to east quadrant. Minimum temperatures are anticipated to range from the middle 40s to the lower 50s.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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High pres begins to build into the region from the midwest on Thu, with strengthening low pres well off the cst. Additionally, there is an upr low over nrn new eng and sern can. The GFS and NAM/WRF develop more precip assocd with the upr low than the ECMWF, with the highest pops n and w. For now, will keep some low pops n and w. The high pres moves further e Thu night and Fri and expect dry conds Thu night and beautiful wx on Fri, something that has been lacking this May. Low pres will then develop nr the Glfmex cst and move newd on Fri. The aforementioned high pres will mve ewd. The low will reach a posn nr the NC or VA cst and move offshore. It will then continue its track out to sea. However, it will bring ample rain to the area beginning on Sat and continuing into at least erly Sun, with the most likely time for rain Sat into Sat night. The rain could be hvy at times durg this time frame and quite honestly, Sat looks rather miserable, especially over srn and ern areas. The low will move by to the ne by Sun mrng and precip shud taper off. The guid differs how quickly precip ends. The GFS ends all precip by 22/12z. The ECMWF keeps some precip thru the mrng, especially over nrn and ern areas. The CMC is similar to the ECMWF. Then, more showers are expected later on Sat as the upr low moves around. There is still some disagreement in the mdls as to the handling of the upr low, so the confidence in the fcst for later Sun and for erly next week is lower than average. The GFS basically keeps things unsettled with at least some precip chcs thru Tue as the low just rotates from new Eng swd acrs the Carolinas and back to New Eng. The ECMWF is wkr with the low. It is more of an open trof and therefore, more progressive. After Sun, it is basically dry, except for some showers Mon night. It does develop another low Mon night into Tue but it is well off the cst, as it is more progressive with the upr low. This is a big difference from its prev soln, which brought the low wwd around Tue. The CMC soln is closer to the GFS. Upper lows, while pesky, are often not as wet as guid suggests. For now will maintain some low pops after sat. After the rain sat, temps will moderate and return to closer to nrml values for the remainder of the extendd pd.
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&& .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Conditions are forecast to be mainly VFR until the end of the TAF period. The sky should remain mostly cloudy. However, ceilings are expected to favor the 5,000 to 10,000 foot range. A northeast wind around 5 to 10 knots is expected to develop for this morning. The wind direction may veer toward the east for this afternoon before returning to the northeast tonight. OUTLOOK... Thu through Fri...VFR conds under high pres. High confidence Sat through Sun...MVFR/IFR conds in ra. The wettest pd looks to be Sat into sat night, when the ra could be hvy. Ra will taper off on sun, though there is some disagreement as to how quickly it ends on Sun. There cud end up being a break for a portion of the morning and then more ra later in the day. Moderate confidence.
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&& .MARINE...
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Low pressure off the coast and high pressure over the Great Lakes will result in a northeasterly wind on our coastal waters for today and tonight. Speeds are forecast to increase to 10 to 15 knots. Wave heights on our ocean waters will build into the 2 to 3 foot range. Wave heights should be 2 feet or less on Delaware Bay. OUTLOOK... Thu through Fri...High pres will be the dominant wx feature over the area and no marine headlines are anticipated. Sat through Sun...Low pres moves acrs the sern states then off the Carolina cst before movg newd on Sat thru Sun. Nely wind will increase which will cause rising seas. sca conds are expected sat aftn into later sun.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Nierenberg Near Term...Iovino Short Term...Iovino Long Term...Nierenberg Aviation...Iovino/Nierenberg Marine...Iovino/Nierenberg

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