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ANZ538 Patapsco River Including Baltimore Harbor- 933 Pm Est Sat Dec 2 2023
Rest of tonight..NE winds around 5 kt. Waves 1 ft or less. Showers. Areas of fog with vsby 1 nm or less.
Sun..NE winds 5 to 10 kt...becoming nw late. Waves 1 ft. Showers. Areas of dense fog. Vsby 1 nm or less.
Sun night..W winds 5 kt. Waves less than 1 ft.
Mon..W winds 5 to 10 kt. Waves 1 ft.
Mon night..NW winds 5 to 10 kt. Waves 1 ft.
Tue..W winds 5 to 10 kt. Waves 1 ft.
Tue night..N winds around 5 kt. Waves 1 ft or less. A chance of rain.
Wed..NW winds 5 to 10 kt. Waves 1 ft. A chance of rain in the morning.
Thu..W winds 5 to 10 kt. Waves 1 ft.

ANZ500 933 Pm Est Sat Dec 2 2023
Synopsis for the tidal potomac and md portion of the chesapeake bay..
low pressure will slide by to the north today. A stronger frontal system looks to cross the waters Sunday into Monday. Another area of low pressure may impact the area Tuesday into Wednesday. High pressure returns to the waters by late next week. Small craft advisories may be needed early next week.

FXUS61 KCTP 030339 AFDCTP

Area Forecast Discussion National Weather Service State College PA 1039 PM EST Sat Dec 2 2023

SYNOPSIS
A mild Saturday afternoon is in store, followed by a period of rain tonight into early Sunday. Cooler conditions will arrive Sunday night into Monday, with a weak clipper system impacting the by midweek. Temperatures should moderate by the end of next week.

NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
815 pm update... Areas of light rain are knocking on the door along the Mason-Dixon line this evening. We still expect that steadier rain will overspread most of central PA from SW-NE through the night, as better forced lift ahead of an approaching southern stream shortwave encroaches on the region.

Another item of concern overnight is the potential for locally dense fog, particularly for areas near and south of I-80.
Although there are isolated patches of thicker fog this evening over parts of south-central and southeastern PA, most of the dense fog is still down over the Delmarva region. However, with the approach of the above mentioned upper wave and associated surface low, a S-SE low-level jet may transport some of this very moist, foggy boundary layer environment into parts of the region. For now, we've added the mention of fog in the grids overnight, and we'll monitor for widespread development of dense fog, which could necessitate the need for an advisory.

Temperatures will not move a great deal overnight, and should generally stay in the 45-50 degree range.

SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/
830 pm update... We're still anticipating steadier rain on Sunday to mainly occur during the morning and midday hours, with more spotty coverage of showers in the afternoon, as a dry slot aloft rotates across the Commonwealth.

One thing we did do was add in the mention of isolated thunder in the afternoon, mostly across our western/Allegheny Highland zones. Several convection-allowing models are now depicting the development of some instability Sunday afternoon (MLCAPE of 100-300 j/kg) in this area, just ahead of an approaching surface occlusion.

Otherwise, for the Sunday night-Tuesday timeframe, please refer to the below earlier discussion for pertinent details.

Previous discussion... Rain will continue into Sunday morning before gradually pulling away from the area as the day progresses. A solid half an inch (or more) of rain is expected across all but far NW PA. This will be a beneficial rainfall, especially across south-central PA where we are still running notable year-to-date rainfall deficits.

As low pressure pushes up the Saint Lawrence Valley Sunday night, it will drag a cold front across the area and usher a chillier airmass for early next week. Scattered rain and snow will continue across the western highlands into Monday before briefly tapering off Monday night.

By Tuesday, eyes turn to a clipper-system approaching from the Lower Great Lakes. It looks like this system will be weakening and rather moisture-starved as it slides just to our south, but it should be enough to produce some light rain and snow. We could see some light snow accumulation across the western highlands, likely focused on the Laurel Highlands if the system does pass just to our south.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
Clipper system diving southeast from the Great Lakes across southwest PA Tuesday PM remains key focus early in the period with increasing potential/confidence for accumulating snow | particularly at higher elevations | Tuesday night into Wednesday. We continued to take POPs higher over the Laurel Highlands given favorable low track and enhanced orographic lift. The upper trough is slow to depart which will likely linger snow/snow showers into Wednesday before sfc ridge axis arrives Wednesday night. Northerly flow behind the departing clipper will continue colder temp trend (near to below climo)
through the middle of next week.

A more zonal flow pattern aloft likely resumes after this (mid- week upper trough) system exits the East Coast. In response, temps should bottom Wed/Thu and rebound to above climo levels by next Friday/Saturday. Will have to keep an eye on the potential for some light precip along a warm front Thursday or Thursday night, if temps are cold enough that could result in some light mixed precip. Otherwise, rising 500mb heights ahead of organized storm over the west- central U.S. should also keep mild conditions into next weekend. GFS/ECMWF displaying their usual fast/slow bias with this system with CMC a middle ground with round of precip for later Sunday/Sunday night (very low confidence on timing).

AVIATION /04Z SUNDAY THROUGH THURSDAY/
A wide range of conditions are occurring with VFR currently being observed as of 23Z at JST, AOO, and UNV, and MVFR to IFR elsewhere. Similar to last night, there is high confidence in widespread IFR/LIFR ceilings and visibilities developing overnight with the HRRR showing an 80-100% chance of IFR or lower conditions for most of Central Pennsylvania. Periods of rain will occur throughout the early morning and into the afternoon as low pressure approaches from the west. IFR conditions will persist through most of the day tomorrow, though it is possible that areas in the southwest see improvement to MVFR after 21Z.

While most of the area will see rain come to an end tomorrow afternoon, an approaching cold front will likely bring some more showers to the northwest part of the area into the evening.
A few rumbles of thunder cannot be ruled out with these showers as at least marginal destabilization occurs ahead of the front, but confidence is too low to mention any thunder in the TAF at this point.

A strengthening low level jet will move in from the southwest towards the end of the 00Z TAF period and will lead to the development of LLWS for JST and AOO. The threat for LLWS will continue to expand eastward after 00Z as the low level jet continues to move into the area.

Outlook...

Mon...MVFR/IFR western 1/3 with snow showers.

Tue-Wed...Light rain/snow with sub-VFR likely.

Thu...Chance of rain or snow.

CLIMATE
Williamsport Monthly (November) and Seasonal (Fall) Climate Summary: ------------------------------------------------------------- The average temperature for November was of 41.3F or -0.6F below the 30yr mean. The average maximum temperature was 51.4F or +0.8F above normal while the average minimum temperature was 31.3F or -1.9F below normal. The most notable callout last month was the -1.74" departure from normal in precipitation with only 1.51" (24th driest). For the Fall/Autumn season spanning the 3-month period from September to November, it was a rather mild and dry ranking as T-20th warmest (54.9F mean temp) and 23rd driest (7.15" total precip or -4.56" below normal).

Harrisburg Monthly (November) and Seasonal (Fall) Climate Summary: -------------------------------------------------------------- The average temperature for November was of 44.7F or -0.2F below the 30yr mean (T-50th warmest). The average maximum temperature was 55.0F or +1.1F above normal (T-30th warmest)
while the average minimum temperature was 34.4F or -1.4F below normal. The total precipitation last month was 2.49" or -0.48" below normal. For the Fall/Autumn season spanning the 3-month period from September to November, it was a quite mild ranking as 15th warmest (57.6F mean temp). The total precip was 9.39" or -2.22" below normal.

CTP WATCHES/WARNINGS/ADVISORIES
None.

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Middle Branch
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Sat -- 05:37 AM EST     0.25 feet Low Tide
Sat -- 07:07 AM EST     Sunrise
Sat -- 10:11 AM EST     0.69 feet High Tide
Sat -- 11:42 AM EST     Moonset
Sat -- 03:58 PM EST     0.00 feet Low Tide
Sat -- 04:43 PM EST     Sunset
Sat -- 09:36 PM EST     Moonrise
Sat -- 10:59 PM EST     1.18 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Middle Branch, Baltimore Harbor, Maryland, Tide feet

Baltimore (Fort McHenry)
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Sat -- 05:09 AM EST     0.27 feet Low Tide
Sat -- 07:07 AM EST     Sunrise
Sat -- 09:45 AM EST     0.77 feet High Tide
Sat -- 11:42 AM EST     Moonset
Sat -- 03:30 PM EST     0.00 feet Low Tide
Sat -- 04:43 PM EST     Sunset
Sat -- 09:36 PM EST     Moonrise
Sat -- 10:33 PM EST     1.31 feet High Tide
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Baltimore (Fort McHenry), Maryland, Tide feet

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