textproduct: State College

WHAT HAS CHANGED

* Uptick in wind speeds on Sunday; still sub-Advisory * Slight decrease in rainfall totals over the next 48 hours, with highest rainfall across Lancaster and Sullivan Counties.

KEY MESSAGES

1) Nor'easter continues to bring gusty winds and periods of rain to central Pennsylvania this weekend.

2) Tranquil conditions expected for the first half of next week with a slight warming trend emerging across the region.

DISCUSSION

KEY MESSAGE 1: Nor'easter continues to bring gusty winds and periods of rain to central Pennsylvania this weekend.

A strong Nor'easter (988 mb) off the coast of Delaware coupled with a broad area of high pressure stationed to the north will continue to bring gusty winds and periods of rain throughout the weekend across central Pennsylvania. So far across central Pennsylvania gusts have remained largely below 30 mph; however, there have been some gusts that have briefly gusted above that threshold such as Lancaster Airport (KLNS), where a 33 mph wind gust was observed this morning. In terms of precipitation, periods of rain likely continue across portions of eastern Pennsylvania, with a brief area of relatively dry conditions beginning to fill in behind this precipitation. Guidance continues to outline a general trend in continued periods of rain through the evening hours before a brief lull in precipitation is observed later this evening and ahead of sunrise on Sunday. Further west, low-level dry air continues to erode rainfall as it dived southwestward. This trend likely continues with recent observations at JST/AOO/HMZ outlining 30-40% RH values although slightly more saturation is projected based on all model guidance to occur this evening.

As the nor'easter tracks closer to the NJ Coast, an increase in winds is expected to occur across much of the forecast area, with widespread 25-30 mph gusts on Sunday. Some locations across eastern Pennsylvania, especially areas with more complex terrain will likely push closer to 35-40 mph with localized gusts pushing close to Wind Advisory criteria. In terms of Wind Advisories, there was some consideration on hoisting flags for Sullivan, Schuylkill, Lebanon, and Lancaster Counties; however, confidence remains too low at this time with NBM 24-hr Max Gusts only showing a 20-40% chance for exceeding criteria. That being said, with leaves remaining on trees across the region this time of year, cannot rule out some tree damage and isolated power outages on Sunday. Another aspect of the closer track of the storm will be more widespread rainfall; however, no flooding concerns are expected with the stratiform nature of this rain as storm-total rainfall approaches one inch across Sullivan and Lancaster Counties.

KEY MESSAGE 2: Tranquil conditions expected for the first half of next week with a slight warming trend emerging across the region.

As the aforementioned nor'easter shifts further north and east of the region, the bulk of precipitation is expected to end by Monday morning outside of some lingering showers across eastern Pennsylvania. Once these lingering showers begin to diminish, fairly high (~70-80%) confidence in dry conditions prevailing through Wednesday. All model guidance trends towards a warming trend in this timeframe, with above-average temperatures prevailing area wide by Tuesday. Unsettled pattern begins to emerge towards the end of the week with a return of rain chances; however, model differences bring low confidence to the forecast this far out in the game.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

It appears that dry conditions will prevail overnight for most, with the bulk of model guidance keeping ceilings above VFR. The main concern for the rest of tonight will be LLWS at eastern TAF sites as surface winds decrease to less than 10 knots while winds at 2000 feet remain around 40 knots.

Rainfall appears to be more widespread after 15Z with the the nor'easter closer to the NJ Coast. This will bring a higher potential for lower ceilings and visibilities across much of the region. Ceilings and visibility should deteriorate throughout the day, with IFR conditions possible at nearly every airfield by 00Z Monday. Any showers will be quite efficient and therefore could result in visibilities dropping below 3 statute miles (categorical IFR). There remains some uncertainty with how quickly ceilings will lower, but the combination of reduced visibility when showers are most numerous and lowering ceilings after showers weaken/dissipate give confidence in a lengthy period of restrictions Sunday afternoon through the overnight hours. The location of the Nor'easter will also lead to wind gusts exceeding 20-25kts across all of central Pennsylvania on Sunday; slightly stronger gusts are likely at KMDT and KLNS (up to 35kts possible).

Outlook...

Mon...MVFR restrictions persist in with lingering scattered showers.

Tue...Gradual improvement, MVFR lingers at higher elevations (BFD, JST) in a typical northwest flow pattern.

Wed...Sunshine returns, mostly VFR.

Thu...Chance of showers late PM, some restrictions possible.

CTP WATCHES/WARNINGS/ADVISORIES

None.