Marine Weather and Tide Forecast for Northfield, NJ

NEAR TERM /THROUGH SATURDAY/
Tranquil conditions continue tonight with light or calm winds and clear skies. The decent radiational cooling has commenced and temps have dropped into the teens and low 20s many areas with mid/upper 20s in the urbany areas. Temps will drop a bit more before mid/high clouds will stream in after midnight.

For Saturday, high pressure will shift offshore and settle within the vicinity of Bermuda. At the same time, a weak warm front will pass north of the Mid-Atlantic as a surface low tracks across southern Canada. This will cause surface flow to become more southwesterly aiding in a weak and brief WAA regime.
High temperatures as a result, will be noticeably warmer than those on Friday with highs in the upper 30s to upper 40s. Aside for clouds continuing to increase and thicken throughout the course of the day, the day looks to be relatively benign and dry
As some would say
"the calm before the storm".

SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/
Confidence continues to increase that a snow event that will impact the region Saturday night into Sunday morning. A clipper system will ride along the base of a closed upper low, moving across the Ohio River Valley during the day Saturday and into the Mid Atlantic states Saturday night before moving offshore Sunday. As this clipper system arrives across the region, the closed upper low will begin to reopen as an amplified trough, providing baroclinic forcing that will assist in the strengthening of a weak clipper system into more of a broad offshore low. As it strengthens, guidance shows a zone of strengthening 700-850mb frontogenesis (FGEN) developing across the southern half of the region as snow begins Saturday night into Sunday morning. Forecast soundings plentiful cold air through the column that is well saturated aloft with plentiful moisture within the dendritic growth region. All of this would point to a zone of potentially some increased snowfall intensity for a time early Sunday morning with snowfall rates potentially as high as 1" per hour at times. There still remains some potential on the southern fringe of the precipitation shield that the precipitation starts as some light rain or a mix of rain/snow before changing to all snow. Lows Saturday night will fall squarely into the 20s, supporting this all-snow event. The model consensus puts the axis of the maximum precipitation amounts very close to the I-95 corridor, favoring areas just south and east. Overall, a widespread 2-4 inches of snow are expected across the Highlands from northern NJ into southeastern PA, the I-95 corridor, and across the coastal plain into the central Delmarva Peninsula and the rest of southern NJ, including the Jersey Shore. Given the increasing potential for mesoscale FGEN snow bands, there is a potential for a concentrated are of 4-5 inches of snowfall somewhere near the I-95 corridor and immediately south and east with up to 20-30% chance for for a handful of reports over 5 inches in that specific area. At this time, we have issued a Winter Weather Advisory for much of the forecast area. Areas further north and west, including the Lehigh Valley, Poconos, and extreme northwestern NJ currently do not have an advisory as they are expecting around 1-2 inches when the criteria for an advisory is 3 inches or greater. Snowfall is expected to begin during the late evening hours Saturday night and continue overnight into Sunday morning, tapering off throughout the morning and moving offshore by the afternoon. The heaviest snowfall rates look to occur during the pre-dawn hours early Sunday morning through mid-morning.

In the wake of this system, a very cold airmass will arrive with gusty northwesterly winds. Highs Sunday afternoon will only nudge up a few degrees, topping off in the 20s to low 30s, though it will feel much colder with northwest winds gusting to 25-30 mph dropping wind chills into the teens with single digits in the higher elevations. Given the current forecast of total snowfall, the gusty winds will then result in some blowing snow.
Air temperatures drop into the teens Sunday night with some single digits possible in the Poconos. A brisk wind will drive wind chills well down into the single digits to near zero through Sunday night with some below zero values mostly in the Poconos. If the wind remains strong enough combined with even colder temperatures, some areas may be very close to Cold Weather Advisory criteria later Sunday night and early Monday morning.

High pressure will continue to build across the eastern US, keeping the forecast generally dry, but cold temperatures persist into Monday, with nearly all locations staying below freezing in the afternoon. A stiff WNW breeze will persist, keeping wind chills in the 20s with teens across the higher elevations.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
Summary...Arctic air/bitter cold starts to ease during mid- week, then it turns much milder Thursday, with a chance for showers Thursday into Thursday night with a cold frontal passage that will bring back cool weather for Friday.

Synoptic Overview...An upper-level trough and its associated cyclonic flow will continue to shift east Monday night into Tuesday. Flow will then become more zonal aloft Wednesday. The flow aloft then looks to back more Thursday ahead of a potentially strengthening upper-level trough across the Great Lakes region, though significant model discrepancies exist regarding the evolution of the upper-air pattern at this range.
The center of arctic high pressure will slide just to our south Tuesday before shifting offshore. A warm front may slide by to our north during Wednesday as low pressure gradually pivots across the upper Great Lakes region and into portions of Ontario and Quebec. A trailing cold front looks to pass through the region Thursday night into Friday.

For Monday night into Tuesday...An upper-level trough and its associated cyclonic flow is expected to remain in place during this time frame. It could be enhanced for a brief time Monday night or Tuesday as a stronger shortwave dives southeastward out of the Great Lakes and across our area. It is not out of the question that a few snow showers could accompany this shortwave, with the best chances being across the northern half or so of the area. The NBM features PoPs Monday night around 20%, which seems reasonable so have opted not to make any changes. High pressure centered to our south Tuesday will begin to shift offshore, though its axis will extend northward over our area.
This will result in much less wind on Tuesday. It will still be rather cold, however the harsh conditions will start to ease slowly.

For Wednesday through Friday...A pattern change should result in a surge of much milder air across our area as we get into Thursday. As surface high pressure becomes more anchored in the western Atlantic and we lose the upper-level trough, warm air advection will be underway. This should increase more as a warm front slides by to our north during Wednesday. An upper-trough across the Great Lakes looks to slide to our north Thursday into Friday, though there is disagreement amongst the models as to its exact evolution and the degree of amplification. For now, the expectation is that a surface low will shift northeastward from the Great Lakes region Thursday and into Quebec by Friday, with a trailing cold front passing through the region by Friday.
Southwesterly flow well ahead of this will boost the warm air advection, with much of our area currently forecast to get into the 50s on Thursday. Showers (rain for most, some snow in the Poconos) will be possible with the passage of the cold front, with PoPs right now in the 40-50% range areawide Thursday night.
Temperatures look to return to near normal for Friday.

AVIATION /01Z SATURDAY THROUGH WEDNESDAY/
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Tonight...VFR. Clear skies attm, with increasing mid and high level clouds after midnight. Light and variable winds generally 3 kt or less. High confidence.

Saturday...VFR. A few scattered low clouds in the morning, otherwise mostly cloudy. South-southwest winds around 10 kt with occasional gusts up to 15-20 kt in the afternoon. Moderate-high confidence.

Outlook...

Saturday night and Sunday...A period of MVFR/IFR conditions with snow from about late Saturday evening through mid Sunday morning. The conditions improve to VFR thereafter. West- northwest winds increase during Sunday with gusts up to 30 knots.

Monday...VFR. West-northwest wind gusts up to 30 knots.

Monday night...Primarily VFR. Slight chance for snow showers (around 20%) for the Lehigh Valley terminals.

Tuesday through Wednesday...VFR. No significant weather.

MARINE
No marine headlines are in effect through Saturday.

West-northwest winds around 15-20 kt this afternoon will diminish tonight while becoming west-southwest around 5-15 kt.
Southwest winds will then increase on Saturday around 10-20 kt with a few gusts up to 23 kt possible in the afternoon. Seas of 1-3 feet. Fair weather.

Outlook...

Saturday night...The conditions are anticipated to be below Small Craft Advisory criteria.

Sunday...Small Craft Advisory conditions developing during the morning, then Gale force wind gusts probable late Sunday afternoon and especially Sunday night. Areas of freezing spray possible Sunday night.

Monday...Gale force wind gusts possible in the morning, otherwise Small Craft Advisory conditions probable. Areas of freezing spray possible during the morning.

Monday night...Small Craft Advisory conditions could linger into the night with westerly wind 15-20 kt and gusts perhaps near 25 kt. Seas 2-4 feet.

Tuesday through Tuesday night...No marine headlines are currently anticipated with winds remaining below 25 kt and seas below 5 feet.

Wednesday...Small Craft Advisory conditions possible with southwesterly wind 15-25 kt. Seas 2-4 feet.

PHI WATCHES/WARNINGS/ADVISORIES
PA...Winter Weather Advisory from 7 PM Saturday to 1 PM EST Sunday for PAZ070-071-101>106.
NJ...Winter Weather Advisory from 7 PM Saturday to 1 PM EST Sunday for NJZ009-010-012>027.
DE...Winter Weather Advisory from 7 PM Saturday to 1 PM EST Sunday for DEZ001-002.
MD...Winter Weather Advisory from 7 PM Saturday to 1 PM EST Sunday for MDZ012-015-019-020.
MARINE...Gale Watch from Sunday afternoon through Monday morning for ANZ430-431-450>455.