Marine Weather and Tide Forecast for Greensboro, MD

NEAR TERM /THROUGH TONIGHT/
Forecast is generally on track. Some clouds have filtered in over the Poconos but otherwise generally expect clear skies across the region as WV imagery shows subsidence aloft. The mid level 700mb trough is tracking offshore as the 250mb jet has setup just to our south. With the left entrance region expected to pass over the region we should continue to expect generally sinking air aloft and little in the way of sensible weather through tonight. This leads to a very similar day today as Tuesday with temps generally sitting in the 20s to low 30s across the urban corridor. BUFKit soundings suggest the PBL should end up mixing during peak heating to between 875-900mb this afternoon leading to gusts on the order of 25mph or so.
Those gusts combine with chilly temps will result in wind chills across the region sitting in the teens to low 20s for most of the day before quickly starting to fall heading into the evening hours. Minimum wind chills tonight are forecast to fall into the single digits for most areas and below zero for the higher elevations of Carbon/Monroe in PA and Sussex in NJ.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
The late week period Thursday through Friday night will start out with continued below normal temperatures Thursday as a weak frontal boundary and shortwave trough approach from the northwest. This system is expected to bring potential for light accumulating snowfall to portions of the region. The system will move offshore Thursday night, then temperatures will finally moderate back toward normal values on Friday following cessation of cold advection and an upper ridge axis moving in throughout the day.

A bit of a change to Thursday's forecast with this update. Now that we're within range of higher resolution guidance, confidence has increased that the period of light snow showers could be a little more robust than originally forecast, although not particularly impactful. A potent, but positively tilted shortwave trough will approach quickly by midday. The dynamics aloft support weak to modest forcing for ascent right around the DGZ layer as the shortwave arrives, beginning into the afternoon across our east to southeast PA areas. The forcing then spreads ESE toward the Philly metro or so by late afternoon and early evening, then beginning shifting offshore between the 7-10 PM hours. The limiting factor with this system is a lack of any notable moisture advection ahead of it, and a rather dry airmass in place at the surface. So whatever snow does develop aloft will take some time to reach the ground, but once it does, temperatures in the upper 20s to low 30s will be cold enough to support some light dusting accumulations less than 1".

We have increased our PoPs to reflect the latest guidance consensus of the system evolution. This includes up to 40-50% for much of our Pennsylvania, New Jersey, and northern Delmarva areas. While QPF remains very light (less than 0.05"), the high snow to liquid ratios potentially as high as 20:1 or more should support a dusting less than 1" for areas that receive a more persistent, steady light snow. Some localized amounts around Berks County, Lehigh Valley, or southern Poconos where snow could persist longest could see around 1-2" at best. While there is some concern with the snow falling around the evening commute, the snow should be light and dry enough to not cause any significant travel issues, especially in light of the residual salt on many roads.

Following the system's departure Thursday night, temperatures will fall to the upper 10s to low 20s as skies clear out overnight.

Temperatures will rebound closer to normal values for Friday, with increasing heights aloft and an upper ridge axis passing across the region into the night. Highs should be mainly in the upper 30s to low 40s under mostly sunny skies. While not the warmest of winter days, it will definitely be the nicest day for any outdoor activities for the foreseeable future. Lows in the mid to upper 20s Friday night with increasing clouds.

LONG TERM /SATURDAY THROUGH TUESDAY/
For the long term period this weekend into next week, expecting a rebound of temperatures to near or even slightly above normal into the weekend thanks to increasing heights aloft. A warm front should lift north through the area on Saturday, with south to southwest flow and warm advection pushing temperatures into the low to mid 40s across much of the area. While the mild temperatures will provide brief reprieve from the prolonged frigid temperatures, the milder weather will be accompanied by periods of rain showers, mainly by Saturday afternoon. Any precipitation will diminish into late Saturday night.

A strong arctic front is expected to arrive sometime Sunday, with a much colder airmass advecting in behind it. Some guidance suggests potential for a coastal system late Sunday into early Monday, although some guidance remains much more suppressed with this, keeping the system well offshore at our latitude.
Have maintained chance PoPs at this time, but am skeptical this potential for light accumulating snowfall will pan out at this point. These details should become a bit more clear within the next day or two.

By Monday night into Tuesday, the coldest airmass so far this season is expected to be in place across a large portion of the CONUS from the Midwest eastward across much of the Northeast.
850 mb temperatures in the -20C to -25C range will likely spell temperatures upwards of 15 to 20 degrees below normal through he middle of next week. This would mean highs near 20 degrees and lows into the single digits. Wind chills potentially below zero at night and in the single digits during the daytime. A period of a few days of well below freezing temperatures could lead to some cold weather impacts to infrastructure, including freezing water pipes and high demand for heating energy.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Today...VFR with FEW/SCT afternoon clouds around 4000 ft. West- northwest winds around 10-20 kt with gusts 20 to 25 kt. High confidence.

Tonight...VFR. Winds decreasing around 5-10 kt. High confidence.

Outlook...

Thursday...Mainly VFR, however a period of light snow possible at all terminals between 18Z to 03Z with potential for MVFR conditions. Southwest winds 5-10 kts.

Friday...VFR. No significant weather expected. Winds 10 kts or less.

Saturday...Ceiling and visibility restrictions likely with periods of rain showers. LLWS possible.

Sunday...VFR. No significant weather aside from breezy winds.

MARINE
A Small Craft Advisory is in effect for all Atlantic coastal waters and the Delaware Bay through today. A Freezing Spray Advisory is in effect for all Atlantic coastal waters and the Delaware Bay through early Wednesday afternoon.

Northwest winds will generally be 15 to 20 kts with gusts up to 30 kt and seas of 4-6 feet.

Due to the combination of cold air/water temperatures, gusty winds, and enhanced seas, moderate freezing spray accretion is likely beginning tonight through early Wednesday afternoon.
While the winds should be slightly weaker Wednesday evening, freezing spray is possible again as water temps should be sufficiently colder thus allowing for more efficient ice accretion.

Outlook...

Thursday through Saturday...No marine hazards expected. Winds 10-15 kts with gusts up to 20 kts possible at times. Seas mostly 1-3 feet. Rain showers developing late Saturday, along with a period of wind gusts near 25 kts and seas near 5 feet possible.

PHI WATCHES/WARNINGS/ADVISORIES
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ430- 431-450>455.
Freezing Spray Advisory until 1 PM EST this afternoon for ANZ430-431-450>455.