Marine Weather and Tide Forecast for Choptank, MD

NEAR TERM /THROUGH SUNDAY/
935 PM update...
Virga is overspreading the region per radar, but ceilings are actually lifting where the virga has moved overhead, suggesting alot of dry air to overcome. Thus, no additional changes at this time.

650 PM update...
No big changes. Latest guidance has reduced potential snow coverage tonight, so trimmed POPs back a bit. However, guidance insists on plenty of cloud cover, so nudged low temperatures up a few degrees.

246 PM discussion...
A low level trough is situated just west of the region. This trough, combined with deep northwest flow, could result in isolated snow showers moving into areas north and west of the Fall line through late tonight. It is unlikely that any area in our region will see accumulating snow, thus, expect more flurries than anything else.

The center of the low will cross eastward overnight (staying well north of our region), and will be northeast of our region by daybreak on Sunday. As it does so, a weak warm front will lift through our region, ushering in a shift to southwesterly flow in the low levels and, consequently warm air and moisture advection. Temperatures on Sunday are expected to be 10 to 15 degrees higher than on Saturday.

This could set the stage for a very saturated boundary layer on Sunday night. That being said, expect increasing clouds ahead of the Monday system should preclude any widespread fog/freezing fog development on Sunday night. However, will be watching trends closely as the warm front arrives.

SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/
An active pattern begins as a strong upper-level trough moves across the Midwest and northern Plains Monday. This feature will then work its way slowly south and eastward. A plume of deepening moisture and forcing for ascent results in an area of rain from the Ohio Valley to the Gulf coast states Sunday night.
The moisture surge, with precipitable water values increasing to near an inch, and ascent arrives in our area during Monday with a period of rain. The onset of the rain looks delayed some and therefore initially slowed the PoP increase to start the morning. If some light precipitation arrives fast enough, some wet bulbing may result in a touch of light freezing rain in spots although this threat looks to be low and localized. The overall rainfall amounts with this system look to be on the lighter side especially as the system may be quick moving, however any precipitation is certainly needed across our region.
Amounts generally will be around a tenth to half an inch. The rain should quickly lift to our northeast during the afternoon with some showers potentially lingering Monday evening.
Temperatures on Monday should be a little cooler than Sunday given the cloud cover and some rain, and Monday will not be as cold given lingering cloud and an overall milder air mass in place.

As we go through Tuesday, an upper-level trough gradually shifts eastward and closer to the East Coast and this will maintain southerly flow south of a warm front. Low-level warm air advection ahead of an advancing cold front tied to low pressure near or north of the Great Lakes may support some showers, however with our area mainly being within the warm sector may keep a period of rain-free conditions through most of the day. As this system gets closer especially in the late afternoon/early evening into the overnight hours, some forcing for ascent begins to overspread our area from the west and therefore rain chances will quickly increase. Our region will continue to be within a milder regime and therefore no wintry precipitation is expected. Temperatures are forecast to be above average, with high temperatures well into the 50s to even some low 60s across the coastal plain and a bit cooler north and west of I-95.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
Summary...Much needed rain later Tuesday night and Wednesday followed by colder air to end the week, then some warming to start the weekend.

Synoptic Overview...As an upper-level trough shifts eastward from south-central Canada to the southern Plains Tuesday night, surface high pressure remains centered in the western Atlantic.
The upper- level trough may be slow to arrive into the East as it amplifies even more. Low pressure tracks north of the Great Lakes Tuesday night then toward northern New England during Wednesday. A strong cold front moves through later Wednesday, with an area of low pressure developing along it across the Mid- Atlantic. High pressure then starts to build in later Thursday and especially Friday into Saturday.

For Tuesday night through Wednesday night...An amplifying upper- level trough moves into the East during this time frame along with the passage of a strong cold front. Our sensible weather will be driven by the timing of the trough and the more organized forcing for ascent across our region. A milder air mass is forecast to advect into our area with this more pronounced across the coastal plain with high temperatures well into the 50s with even some low 60s possible Wednesday.
Temperatures may actually rise some Tuesday night for at least parts of the region. A period of rain arrives Tuesday night and much of Wednesday ahead of and with the strong cold front, and given strong south to southwest flow there will be a period of high shear values.

Some guidance hinting at some weak instability developing ahead of the front, however as of now this looks weak enough to keep lightning production at bay. A robust shortwave rounding the base of the trough may result in the trough taking on a negative tilt for a time. If this occurs, a zone of stronger forcing for ascent could develop especially with the cold front which would result in a narrow line of heavier showers/rain embedded within the rain shield. This will need to be watched given the strength of the wind field and shear that is forecast, although lapse rates look to be on the weak side. Precipitable water values may get as high as 1.50 inches ahead of the front, and therefore areas of heavier rainfall will certainly be possible. The rain may be enhanced some by a weak surface low that develops along the front as it is crossing our area. The rain will be beneficial though given the ongoing severe to extreme drought.

As the front shifts toward and off the coast later Wednesday into Wednesday night, a quick increase in the cold air advection will bring in much colder air. This may result in temperatures falling during the afternoon from west to east. Depending on the timing of this cold air advection, some rain changing to snow is possible Wednesday night before ending, mostly for the Pocono region. The chance of this occurring stills looks to be on the low side as some guidance tends to hold to much more moisture back into the cold air with these types of synoptic setups.

For Thursday...A strong upper-level trough across most of eastern Canada and extending down across the Great Lakes, Northeast and Mid- Atlantic regions will gradually lift northeastward through Thursday night. As deepening low pressure moves toward the Canadian Maritimes, strong high pressure is forecast to be building into the Ohio Vally and lower Mid- Atlantic. This will provide for a tightened pressure gradient across our region, with west to northwest winds rather gusty. It will be notably colder as well along with a much drier air mass moving in. There will be cyclonic flow aloft in place and with just enough moisture lingering, areas of stratocumulus may be in place for a time before clearing out at night. Strong high pressure builds closer at night and therefore the winds should diminish quickly. High temperatures will be below average.

For Friday and Saturday...The upper-level trough is forecast to lift farther away from our area Friday with even some mid level ridging arriving Friday night into Saturday. This will support strong surface high pressure building right over our area Friday with much less wind but still cold air. The next upper-level trough looks to be sliding across the Midwest to central Plains into Saturday, with surface high pressure starting to become more centered to our northeast. A warm front may organize and lift into the eastern Great Lakes Friday night into Saturday, with some warm air advection starting to get into our area. As a result, high temperatures are forecast to be a bit milder on Saturday compared to Friday.

AVIATION /03Z SUNDAY THROUGH THURSDAY/
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Tonight...VFR. Winds will favor westerly, but start to shift to more southwesterly through the overnight. Wind speeds around 10 to 15 kt.

Sunday...VFR expected. SW or W winds 10 to 15 kt with gusts up to 25 kt, especially for KABE and KRDG.

Outlook...

Monday.. MVFR/IFR conditions develop by afternoon along with a period of rain. The conditions may start to improve some at night as the rain ends.

Tuesday...Area of MVFR ceilings with a few showers possible, then conditions lower at night with some rain arriving.

Wednesday...Sub-VFR conditions with periods of rain. Conditions should improve at night as the rain ends. Gusty southerly winds possible during the day for some areas, then these turn westerly behind a strong cold front. A period of low-level wind shear possible.

Thursday...VFR. Westerly winds 10-15 knots with gusts to around 25 knots.

MARINE
Winds are in a temporary lull below 25 kt. Winds should increase again late this evening, reaching Small Craft Advisory near or after 10 PM. SCA conditions are expected to continue through Sunday afternoon.

Winds should diminish late Sunday afternoon and stay below SCA criteria through the remainder of Sunday night.

Outlook...

Monday and Tuesday...A few gusts close to 25 knots possible Monday, the Small Craft Advisory conditions may start to develop later Tuesday night.

Wednesday...Small Craft Advisory conditions probable, with gale force wind gusts possible at night.

Thursday...Mostly Small Craft Advisory conditions probable.

PHI WATCHES/WARNINGS/ADVISORIES
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 10 AM EST Sunday for ANZ430-431.
Small Craft Advisory until 4 PM EST Sunday for ANZ450>455.