Marine Weather and Tide Forecast for Tolchester, MD

NEAR TERM /THROUGH TONIGHT/
Dangerous cold continues through tonight. No changes made to the cold weather headlines. A Cold Weather Advisory is in place for a large majority of the region. The exception being the Pocono Plateau, where an Extreme Cold Warning is in place. All headlines are in place through noon Wednesday.

Clouds continue to overspread the region this morning. Temperatures range from the low teens to negative single digits with wind chills generally around 0 to -15. Other than that, a quiet morning overall.

For today, clouds increase due to an approaching mid-level trough and strengthening upper-level jet over the region. Arctic high pressure remains over the region though, resulting in a dry day overall. Cold airmass remains relatively unchanged, though winds will be lighter today. Highs will only get into the mid to upper teens/low 20s.

Another bitterly cold night expected. High pressure weakens, with an area of low pressure passing by to the south and east. The precipitation shield should get up into lower Delmarva and South Jersey, resulting in a brief period of snow showers down that way.
Accumulations up to half an inch are possible, but not much to write home about. A rather tricky low temperature forecast given the timing of skies clearing out remains uncertain. Winds will be light and a faster transition to clear skies will result in colder temperatures with an ideal radiational cooling setting up. If cloud cover is slow to move out, temperatures will remain a touch warmer. Regardless, it will be dangerously cold. Single digit lows are expected, with some spots in the northern Lehigh Valley, Poconos, and northern New Jersey falling below zero.
Wind chills of -5 to 5 are expected, with values as low as -10 to -15 expected in the Pocono Plateau.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
Bitterly cold conditions continuing through Wednesday night, then not as harsh Thursday afternoon. Cold Weather Advisory/Warning remain in effect through Wednesday morning.

Arctic air remains firmly entreched across the region through Wednesday night. While the wind will not be all that strong, it will not take much wind given the extent of the cold to drive down the wind chill values. As a result, wind chills early Wednesday morning are forecast to range from about 0F to minus 15F and then in the teens to single digits in the afternoon. Given this extended stretch of bitterly cold conditions (cumulative impacts), the Cold Weather Advisory remains in effect for the entire area through Noon on Wednesday (Extreme Cold Warning for the southern Poconos, with wind chills as low as minus 20F at times especially across the Pocono plateau).

The passage of an upper-level trough axis early Wednesday morning results in the flow aloft turning more zonal for a time. This then may back more to the southwest later Wednesday night into Thursday as an upper-level trough starts to approach from the west during Thursday. The airmass will modify some ahead of this trough and therefore temperatures, after starting out very cold early Thursday morning, climb into the lower to mid 30s for parts of the coastal plain and 20s elsewhere. In association with the aforementioned trough axis exiting to start Wednesday, an offshore system moves farther away with the western extent of a snow shield also to our south and east. Surface high pressure then crests over our area Wednesday before shifting offshore into Thursday.

Ahead of the the next upper-level trough, which looks to have a positive tilt, approaches Thursday night. A weak cold front should approach our region from the northwest Thursday night, however higher pressures linger across our area overall. Some guidance though hinting at a quick but mainly small system spinning up off the Mid-Atlantic coast initially focused along an inverted trough.
This feature overall should remain offshore, however will have to monitor this in the event that some snow showers brush some of the coastal areas.

LONG TERM /FRIDAY THROUGH MONDAY/
Summary...The cold eases with temperatures forecast to get to about average Sunday and Monday. A few systems should move through as the air mass continues to transition out of the bitter cold.

Synoptic Overview...An upper-level trough is forecast to be sliding eastward across eastern Canada to the Great Lakes Friday with a stronger shortwave extending this trough across the Gulf Coast states. These features look to quickly shift off the East Coast Friday night into Saturday. The next upper-level trough across central Canada shifts south, however it may amplify southward some from the Midwest and central Plains over the weekend. This trough then moves eastward into early next week, however its positive tilt would suggest stronger energy hangs back longer and this may develop a wave of low pressure along a cold front that initially moves into or crosses our area late Sunday and Monday.

For Friday and Saturday...An upper-level trough shifting eastward across eastern Canada Friday may remain somewhat separated from a strong tailend trough across the Ohio and Tennessee valley's to the Gulf Coast. A surface cold front may arrive into our area later Friday associated with the northern part of this larger trough, however this front looks to be on the weak side with limited moisture. The upper-level trough looks to be progressive and as a surface low develops off the Southeast U.S. coast, it should tend to track out to sea. While temperatures will not be as harsh as earlier in the week, at least some guidance has trended a bit colder and the 01z NBM has reflected this. Some areas especially across the coastal plain are forecast to get to or a few degrees above freezing Friday afternoon, and then this expands a bit more Saturday afternoon. Low temperatures Friday night drop into the teens to single digits, then teens to low 20s Saturday night.

For Sunday and Monday...The upper-level flow looks to be split as northern energy continues to cruise across Canada and into the northern tier of the U.S. Meanwhile, southern stream energy slides out of the four corners region during the second half of the weekend. This all results in a system tracking well to our north with a trailing cold front arriving into our area later Sunday. This front however may tend to stall in our vicinity as the southern stream energy results in a surface low developing on the tailend of the front in the vicinity of the southern Plains. This feature may then may make a run at our area early next week, however the track, timing and strength of it remains uncertain. This is especially the case as the positioning of the troughs themselves will likely change over the coming days. This changing of the pattern looks to result in temperatures across our area getting back to right around average.
Regarding the chance for precipitation, given the uncertainty opted to keep the PoPs on the lower side which is pretty much with the NBM output suggests.

AVIATION /08Z TUESDAY THROUGH SATURDAY/
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Through 12z...VFR. West/northwest winds gradually diminishing to around 5 kt. High confidence.

Today...VFR with increasing clouds. West-northwest winds around 5-10 kt. High confidence.

Tonight...VFR. Northwest winds around 5 kt. A few snow showers possible at KACY-KMIV, but only 20% chance. High confidence.

Outlook...

Wednesday through Saturday...VFR with no significant weather anticipated.

MARINE
A Small Craft Advisory is in effect for all ocean zones through 6 AM with a Freezing Spray Advisory in through today. Buoys have reported ice accretion, so caution is advised when navigating the waters.

For today and tonight once the SCA expires, sub-Small Craft Advisory conditions are expected with west/northwest winds around 10-20 kt and seas 2 to 3 feet.

Outlook...

Wednesday...Some wind gusts up to 25 knots possible Wednesday morning, otherwise the conditions are anticipated to be below Small Craft Advisory criteria. Areas of freezing spray may linger at times.

Thursday through Saturday...The conditions should be below Small Craft Advisory criteria.

PHI WATCHES/WARNINGS/ADVISORIES
PA...Cold Weather Advisory until noon EST Wednesday for PAZ060>062- 070-071-101>106.
Extreme Cold Warning until noon EST Wednesday for PAZ054-055.
NJ...Cold Weather Advisory until noon EST Wednesday for NJZ001- 007>010-012>027.
DE...Cold Weather Advisory until noon EST Wednesday for DEZ001>004.
MD...Cold Weather Advisory until noon EST Wednesday for MDZ012-015- 019-020.
MARINE...Freezing Spray Advisory until 6 PM EST this evening for ANZ430- 431-450>455.
Small Craft Advisory until 6 AM EST early this morning for ANZ450>455.