Marine Weather and Tide Forecast for Chester Hill, PA

NEAR TERM /UNTIL 8 AM WEDNESDAY MORNING/
Cold front now into the far NW with clear wind shift and seriously lowering dewpoints behind it. There are showers and storms along it, but most look tame. Gusts into the 30s are common with the front, even outside the cells. The stable sfc layer and lack of solar heating/mixing should keep worries for SVR low with this line. But, we'll continue to monitor it as the shear remains high. CLE has recently issued a couple of warnings. Cluster of storms moving into nrn WV should stay mainly south of the CWA, but will likely clip areas along and S of the Turnpike between midnight and 2 AM. Expect partial clearing for most of the area after the front clears things out.
It will take much of the night for the front to push thru Lancaster Co. Temps will get into the m30s in Warren Co, but hold up in the 60s in the Lower Susq.

SHORT TERM /8 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/
Latest guidance supports warm and dry weather Wednesday, as the cold front stalls out south of the Mason-Dixon Line and high pressure noses into PA from the Grt Lks. However, the boundary will remain close enough to justify low POPs across the southwest part of the forecast area. For most, it should be another perfect spring day with a refreshing northwest breeze, low humidity, and abundant sunshine. Good day to mow the grass with more widespread rainfall expected Thursday into Saturday.
RH does get into the 20s for much of the area. Wind not especially gusty, but without much rain in the SE, fire weather concerns are not out of mind.

LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/
Changes with the late evening update to the long range forecast are very minor. Still a great deal of uncertainty with the possible development of an upper low over the OH Valley over the weekend (ECMWF) vs. a progressive trough swinging thru to clear things out for the latter half of the weekend and almost all of next week (GFS). So, the forecast from the NBM is basically a wash of the two camps. Don't see a lot of reasons to have a closed low form, esp in early May. But, the low chc PoPs that now permeate the extended are an expression of the forecast uncertainty, and this solution is not (entirely) out of the question.

Prev...
Efficient radiational cooling will support a frost risk across the northeast zones/Endless Mtns late Wed night into early Thursday morning with fcst min temperatures in the mid to upper 30s. The growing season for this area does not activate until 5/11, so no frost headlines will be issued. Meanwhile, more clouds and higher dewpoints keep lows near 50F along the PA/MD border.

Quasi-stationary front will pivot and lift northward as a warm front across CPA on Thursday as a sfc low tracks from near Chicago into Lake Huron by 02/12Z. Expect shower activity to ramp up particularly in the western/northwestern portions of the CWA through Thursday night in association with strongest 850mb moisture flux and IVT. Thursday night looks very mild for the first night of May 2025 with min temps 55-65F or +15 to +25 degrees above climo.

Scattered convection is likely to accompany the trailing cold front on Friday with daytime highs ranging from 65-70F in the NW mtns and 75-85F in the south central/southeastern ridges and valleys. Severe storm potential remains limited based on the D4 discussion from SPC. However, WPC excessive rainfall outlooks carry a marginal risk Thu/Fri with an emerging trend toward more rain (wetter on the margin) on Saturday tied to a frontal wave.
POPs were increased vs. NBM to start the first weekend of May.

What appeared to be firm drying trend and nice stretch of wx dominated by high pressure from Sunday into early next week has now faded away -- as medium range models and ensembles show a more blocky pattern over the Lower 48 and potential cutoff low developing somewhere over the Eastern U.S. This spread keeps confidence much lower than average on sensible wx details due to very uncertain upper level flow details.

AVIATION /03Z WEDNESDAY THROUGH SUNDAY/
A line of severe thunderstorms continues to race across the forecast area and is quickly approaching IPT. These storms have a history of producing wind gusts in excess of 50 knots and radar trends indicate that this threat will likely continue through IPT. Additional thunderstorms are developing south of this line and may approach MDT and LNS, but there is less confidence on impacts for those two airfields.

Light rain will continue for an hour or two behind the line but will come to an end by 04-06Z. A few lighting strikes will also be possible through that timeframe. MVFR ceilings will likely develop overnight at BFD with only around a 30% chance of any other sites seeing ceilings dip below 3500 feet. Clouds clear out during the morning as high pressure builds in leading to widespread VFR conditions with northwest winds around 10 knots.

Thu...Showers/t-storms return areawide, restrictions possible.

Fri...Showers with restrictions possible.

Sat...Showers early. Improving late.

Sun...Mainly VFR with a few showers possible.

CTP WATCHES/WARNINGS/ADVISORIES
None.