732 FXUS61 KCTP 250954 AFDCTP Area Forecast Discussion National Weather Service State College PA 454 AM EST Thu Jan 25 2024 .SYNOPSIS... Weak troughing at the surface will provide a pathway for moisture to flow over the region for today and tonight. Low pressure passing to our north should drag a front through and end the steady rain on Friday. High pressure will briefly build into the region late Friday into early Saturday. Then, a southern stream trough and associated surface low will likely track just south of the state during the second half of next weekend. This storm will produce another widespread rainfall for the region and some wintry mix across the north. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A shield of steady light rain is sliding across the CWA this morning. The back edge to the rain appears to be moving into wrn PA, here at 09Z. The shortwave forcing the precip is likely just to the rear/west of this batch of precip (over ern OH). Will leave pOps over a good part of the region for the next couple of hours, mainly in the S. But, the shortwave could linger it longer. A drying trend is likely, though for the late morning and aftn. The nrn tier may have some patchy DZ/--RA linger, but they will have the best opportunity to be dry for a short time today and early tonight. Temps are running above near term guidance on the whole. CAD setup continues with UNV/RVL/IPT the coolest locations and the SE only a deg or two milder. Will continue to keep them above guid for the day, but we should see them get more homogeneous thru the day. Maxes in the L50s will be common. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... Deep layer moisture will increase into tonight, with PW over 1.5" nosing into the Lower Susq River Valley. Strong LLJ combined with anomalous deep layer moisture will bring a soaking rainfall this evening into much of Thu night, with precip around 1/2-3/4". Concerns for snowmelt adding to the runoff are being watched closely, but for now we aren't seeing quite enough QPF to tip the scale into Watch territory. A few river points reach into caution and just below minor given current QPE and snowmelt estimates. Current river stages are running a little below guidance. Latest ensemble river guidance shows very few sites going into caution stages, and none going into flood category at this point. The Yough at Confluence may get close to or just above to flood stage, due more to input from the Casselman R and Laurel Hill Cr than from the Yough, which is well controlled by the big dam just a couple miles upstream. The sfc low passes to our N on Friday, which usually brings in colder air. But, the occluded front trailing to the south of the low is followed by mild air. Temps should be into the 50s and even L60s in the aftn. The bust potential there is how much cloud cover remains in the wake of the front. Still, the current (10Z Thurs) temps in the west are already at 50F, so these values for Friday don't look bad. We'll keep very close to prior fcsts. Fri night and Saturday will hold a welcome but brief respite from the train of waves and rainfall, but a Miller-B storm approaches late in the day/Sat night that will present more water/winter challenges for Sunday. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Medium range guidance has converged on a solution that tracks a potent southern stream shortwave trough and associated surface low just south of PA the second half of next weekend, bringing a period of widespread stratiform precip to central PA Sat PM into Sunday. Recent model trends favor sufficient cold air to produce at least a period of accumulating snowfall, with the highest probabilities of 1 inch or more across the northern tier of Central PA (60-75%) through Monday morning. The storm track and developing coastal low will be favorable for snow in the northeast, but will be contingent on the amount of cold air in place prior to precipitation onset. Fair and seasonably colder conditions are likely to return early next week, as the low exits the east coast and high pressure builds southeast from James Bay into New England. A majority of ensemble members keep lows generally in the 20s across the Commonwealth early next week, but a few members bring temperatures in the single digits to teens and this outcome bears watching. A few additional shortwaves diving southeast embedded within cyclonic flow aloft should reinforce the cold air and bring terrain enhance snow/snow showers into the middle of next week. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... At 09z, widespread IFR/LIFR/VLIFR conds persist across the area thanks to low clouds, light rain, and patchy dense fog. Only marginal improvement is expected after sunrise, with most locations holding on to IFR conds through much (or all of) the day. There should be a break in the rain across at least northern PA today, but another round of steady rain is expected to return from south to north this evening into tonight. In addition to the return of a steadier rain, we could see marginal LLWS return tonight as well. Outlook... Fri...Drying out with gradual improvement. Sat...Predominantly VFR. Sat night-Sun...MVFR/IFR likely in rain/snow. Mon...Drying out with gradual improvement. && .HYDROLOGY... Combination of .5 to 1.5 inches of rain over the next 48 hours and steady snowmelt will result in a few to several foot rises on small streams, creeks, and rivers across central PA. A few points are forecast to exceed action stage and approach minor flood stage by Friday. Initial focus may be the Youghiogheny River at Confluence with latest OHRFC fcst crest just under 12ft minor flood stage. Snow-water equivalent values of 2-4" per NOHRSC over the Laurel Highlands and melting rate/high dewpoints will likely be a significant factor in waterway response over southwest PA. && .CTP WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until 10 AM EST this morning for PAZ004>006- 010>012-017-018-024-033-037-041-042. Dense Fog Advisory until 9 AM EST this morning for PAZ058. && $$ SYNOPSIS...DeVoir/Dangelo/Colbert NEAR TERM...Dangelo SHORT TERM...Dangelo/Colbert LONG TERM...Fitzgerald/Banghoff AVIATION...Evanego HYDROLOGY...Steinbugl