Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 221311 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 911 AM EDT SUN MAY 22 2016 .SYNOPSIS... Low pressure well off the New Jersey coast this morning will continue to track out to sea today. It will be followed by another low Monday and Monday night. A ridge will build over our region for Tuesday and Wednesday. The ridge will remain to the east of the area into the weekend while a few weak disturbances will affect the Middle Atlantic region. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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An upper air analysis placed a trough across the east with its axis just to our west this morning. Several short waves were analyzed within this trough and will play the main role in our weather for today. The forecast challenge is how much can the cloud cover erode during the course of the day and also shower chances. Lingering areas of rain early this morning continue to ease off to the east and gradually weaken as an initial short wave departs. The model guidance continues to highlight areas just to our west and south with the best chance for shower activity during the course of the day. This is due to the presence of the trough axis and lower heights along with steepening mid level lapse rates. The main short wave that will allow the trough to become closed off by late in the day is forecast to track to our south. As this occurs, some drying may try to work in from the north. This all spells for a tricky forecast regarding the details as our western and southern zones may be very close to the pop gradient. We used a model blend to try and capture this a bit better, which results in the highest pops around the edges of the CWA during the day. Recent radar trends have shown some of showers moving eastward toward Philadelphia and the Delmarva, so at least into the early afternoon we will cary higher chance pops for these regions as well. If enough breaks in the cloud cover can develop then perhaps some low topped convection can occur. This looks more of a chance to our west and south. Therefore we will continue with no thunder mention. As low pressure offshore continues to move farther away today, the pressure gradient will continue to relax. This in combination with the upper-level trough overhead should result in a decreasing wind field through much of the column today. This may result in any showers becoming slow movers with localized downpours possible. Overall, today looks more showery as we transition from the more stable and stratiform setup. As for the high temperatures, we used a MOS blend overall. The warmer temperatures are across the northern areas where a better chance of some heating and developing drier conditions may occur.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... The persistent upper-level trough becomes more closed off as the synoptic pattern is of an omega block. The closed off portion of this trough is forecast to track to our south tonight. This should take the bulk of the forcing with it with lingering showers across the western and then the far southern areas waning during the evening hours. We are still expecting a decent amount of cloud cover although the ceilings may rise some from north to south. The extent of any clearing though will determine if some fog can develop given the moist ground and light winds. As of now, any fog that may form overnight looks to be localized and therefore a mention was not included at this time. As for the low temperatures, we used mainly a MOS/continuity blend. The temperatures may be slow to fall especially where cloud cover is more notable for awhile. && .LONG TERM /MONDAY THROUGH SATURDAY/... The H5 heights across the east will be at their lowest at the beginning of the long term with a cut-off low across the VA cape region. The first sfc low from the near term will have moved off into the Atlantic while a second low will be deepening well offshore and moving northward well east of the area. The continuation of low level moisture and cooler temps aloft will keep the area unsettled with sct showers and afternoon tstms for mon and into tue. pops are generally in the chc range. temperatures will be below normal Monday and close to normal Tuesday. There will likely be more sunshine on Tue with dryer air beginning to arrive across the area. The Tue night thru Thu period will be mostly dry with sfc and upper high pressure affecting the area. We have continued with a small chc for an afternoon TSTM across the far n/w areas Thu afternoon. Temperatures will be above normal thru the period with highs reaching the low 80s in many areas Wed and then low and mid 80s for Thu. Humidity levels will be mostly comfortable thru the period...however a trend toward higher dew points will be under way. It could be muggy across the Delmarva by Thu afternoon. The mild temperatures will continue for the end of the ween and into the weekend. Highs will mostly be in the 80s each day except across the Srn. Poconos and along the shore. Chc for showers and Tstms exist for both Fri and Sat...although the activity will be sct and will be more of the typical summer-time variety. && .AVIATION /13Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today: Areas of MVFR ceilings this morning should lift to VFR ceilings this afternoon. Some IFR ceilings early this morning mostly at KACY/KMIV are expected to improve through midday. Some showers early this morning will send the local visibility into the MVFR range, then mainly scattered showers are anticipated through the afternoon with the best chance west and south of KPHL. Northerly winds 5-10 knots, becoming light northwest to southwest this afternoon and even light and variable. Tonight...VFR ceilings overall. Some showers around mainly in the evening can locally reduce the visibility for a time, then there is a chance of local MVFR due to fog late. Winds mostly light and variable. Outlook... Monday thru Tuesday...vfr or mvfr with sct showers/tstms mostly during the afternoons. fog possible mon night. Tue night thru Thu...Mostly vfr. Sct tstms n/w thu afternoon. some fog possible during the overnight periods. && .MARINE... Low pressure will continue to move farther out to sea today, allowing the pressure gradient to relax. The winds have already diminished across much of the area already. As the wind diminishes through the day the direction will become variable across the waters. The seas however remain elevated across much of the Atlantic coastal waters, however they continue to be slow in building passed 3 feet across the far north. We will continue the Small Craft Advisory as is (through at least tonight) mainly for elevated seas. The conditions are expected to remain below advisory criteria on Delaware Bay through tonight. RIP CURRENTS...There is a moderate risk of rip currents today. Northerly winds will be less and also become variable this afternoon, however a higher swell height into most beaches should lead to an elevated risk for the formation of dangerous rip currents. outlook...The last of the SCA conditions across the srn coastal waters Monday. near SCA seas possible Tue across the ocean with the second low out to sea. Mostly sub-sca Tue night-Thu. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 PM EDT Monday for ANZ452>455. Small Craft Advisory until 6 AM EDT Monday for ANZ450-451. && $$ Synopsis...O`Hara Near Term...Gaines/Gorse Short Term...Gorse Long Term...O`Hara Aviation...Gorse/O`Hara Marine...Gorse/O`Hara is the U.S. government's official web portal to all federal, state and local government web resources and services.