Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 292341 AFDCTP Area Forecast Discussion National Weather Service State College PA 741 PM EDT SUN MAY 29 2016 .SYNOPSIS... An upper level trough will push across the region tonight and Monday. Tropical moisture lifting northward from the Mid Atlantic region will feed an increasing chance of showers and thunderstorms over southeast Pennsylvania overnight. A ridge of high pressure will build east into Pennsylvania for midweek. A slow moving cold front will likely push into the region from the Great Lakes by late in the week. && .NEAR TERM /UNTIL 7 AM MONDAY MORNING/... HRR spot on tonight with drying and stabilization happening on time. Much of the area will be dry/not-raining in less than an hour or two. It is barely raining in the SE despite the look on the radar/mosaics. Thunder looks like it is done. However, we will hold onto just a slight chc down in the far SE where the enhanced rainfall is expected overnight. So far, KDCA has received only 0.25 inches. Of course, the overnight rain will be formed by mostly tiny tropical droplets. Still, the inch or so of rain in Lancaster should not overflow any banks since everything is growing and waterways are slightly below average flows for Memorial Day weekend. Previous: Near term is panning out as upper ridge continues to slide east of the region as an upper trof swings towards the western GLAKS from the upper midwest. Deep plume of subtropical moisture off of the southeast Atlantic coast is being directed northward between now T.D. Bonnie (downgraded at 8:00 AM this morning) and aforementioned 5H ridge...which models pool from northern Virginia to the Chesapeake Bay and southeast piedmont region by late this afternoon. Isolated to scattered slow moving convection fired along the Allegheny plateau early this afternoon...with some local heavy rainers producing 1-2"+ in spots. The spine of the Allegenies and the Susq River Valley will the focii for locally heavy rainfall...the latter waiting until deeper subtropical moisture arrives this evening and late tonight. By late this evening expect two main areas of rainfall...the first associated with the upper trof approaching from the eastern GLAKS and OH Valley and the 2nd over the southeast...where PW surges over 2 inches along and south of the Mason Dixon line and slow moving 5h shear axis maintains lift overnight into Monday morning. Successive HRRR runs have shown a distinct back edge to the precip reaching towards the Lower Susq River Valley by 09z...and extrapolated further could mean that the balance of the day is mostly dry after this activity exits. Still expected isolated to sct coverage of diurnal activity in the heat of the day...but by and large the bulk of the rain should come tonight...and some areas will see well over an inch or rain along and east of I-81. && .SHORT TERM /7 AM MONDAY MORNING THROUGH 6 PM MONDAY/... After morning activity slides east of the Susq River Valley... most of Memorial Day is now appearing dry...although isold to sct coverage of diurnally driven shra/tsra is still expected. Guidance continues to indicate fair amount of mid/high cloudiness streaming north from remnants of td bonnie circulation over eastern PA...while increasing amounts of sun will be found rather west over PA. Highs should range from the upper 70s to the mid 80s. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... Looking at a nice break from the showers and storms from later Monday into Wed. Temperatures still a little above normal. Expect some showers and storms later Thursday into Friday with the next cold front. Some variation between the GFS and EC at times on the large scale by the time I got to Sunday...I adjusted the superblend pops a little...too much detail for that far out. Regardless of detail...trend is to a cooler and wetter pattern again. Other issue is hints that some remains of Bonnie stay behind under the upper level ridge until the next cold front moves in by Friday. Main change to the package was some minor adjustments. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... A trough of low pressure will push across the region late today into Monday. VFR coonds will prevail this morning. Increasing cirrus is expected central and western areas, as high-level moisture is drawn northward from TD Bonnie. Daytime heating/ destabilization will be enough to lead to isolated/scattered mainly afternoon convection confined mainly along the spine of the Alleghenies. Through much of the afternoon, reducing conditions should be contained to the western and poss central TAF sites. As impacts from approaching trough move eastward this evening and especially tonight, the eastern TAF sites will likely see periods of MVFR develop in a moderate rain with isolated TSRA as slight connection to tropical system develops. A chance of showers and isolated TSRA continues into Monday mainly in eastern third, followed by high pressure and more settled weather building into the region through midweek. OUTLOOK... Mon...Sct tsra impacts poss east. Tue-Thu...No sig wx. Fri...Chc of showers and thunderstorms with cold front. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir NEAR TERM...Dangelo/DeVoir SHORT TERM...DeVoir LONG TERM...Martin AVIATION...DeVoir/Martin/RXR is the U.S. government's official web portal to all federal, state and local government web resources and services.