Sunrise 5:49 AM   Sunset 8:20 PM Moonrise 4:42 PM   Moonset 3:06 AM

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ANZ535 Tidal Potomac From Key Bridge To Indian Head- 435 Pm Edt Mon May 20 2024
Rest of this afternoon - SE winds 5 kt. Waves less than 1 ft. Tonight - S winds around 5 kt. Waves 1 ft. Tue - S winds 5 to 10 kt. Waves 1 ft. Patchy fog. Vsby 1 to 3 nm. Tue night - S winds around 5 kt. Waves 1 ft. Wed - S winds 5 kt. Waves less than 1 ft. Wed night - S winds 5 kt. Waves less than 1 ft. Thu - W winds around 5 kt. Waves 1 ft or less. A chance of showers and tstms. Fri - SW winds around 5 kt. Waves 1 ft. A chance of showers and tstms.
winds and waves higher and visibilities lower in and near tstms.

ANZ500 435 Pm Edt Mon May 20 2024
Synopsis for the tidal potomac and md portion of the chesapeake bay -
high pressure will build over the waters through Tuesday. A strong cold front will approach the waters Wednesday into Thursday. This frontal system will settle south of the area Friday before retreating back toward the waters this weekend. Small craft advisories may be needed for portions of the waters Wednesday.

FXUS61 KLWX 201827 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 227 PM EDT Mon May 20 2024

SYNOPSIS
Warmer temperatures and mostly dry conditions are expected through Wednesday as high pressure meanders overhead. A cold front will approach from the Ohio River Valley Wednesday night into Thursday bringing renewed chances for showers and thunderstorms. Additional shower and thunderstorm chances are likely Friday into the weekend as the front stalls nearby. Drier conditions return by the middle of next week.

NEAR TERM /THROUGH TONIGHT/
Low and mid level clouds continue to scatter out along and east of the Blue Ridge this afternoon with mostly clear skies further west as high pressure settles overhead. Once the low and mid level clouds break scattered to broken high based stratocumulus will be leftover during the afternoon and evening hours especially east of the Blue Ridge. An outside chance of a spotty shower remains over the higher ridges of the Appalachians, but overall most locations will remain dry. High temperatures today will range from the mid to upper 70s to around 80 along and west of US-15 with low to mid 70s further east where the cloud cover has held on the longest.

Mainly clear skies are expected this evening as subsidence under the surface high fully asserts itself across the region. This will allow for additional stratus migrating in from the east and areas of fog in the river valleys. The bulk of this fog and stratus should lift out early Tuesday morning after sunrise. Lows tonight will fall into the mid to upper 50s and low 60s.



SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
Sensible weather conditions are expected Tuesday and Wednesday as surface high pressure gradually pushes offshore. Upper level ridging will persists Tuesday squashing any convection that may form in the diurnal peak heating period. The exception to this will be over the mountains where a pop up shower or thunderstorm remains possible thanks to orographic lift. Tuesday will be much warmer than Monday with 850 mb values climbing to around +14 to +17 degrees across the region. This will yield high temperatures in the low to mid 80s with upper 70s across the mountains.

Strong low pressure over the upper Great Lakes region and it's associated cold front draped across the Upper Midwest/Ohio River Valley will gradually push east Wednesday as the upper level ridging breaks down. 12z guidance continues to slow the progress of the front eastward Wednesday afternoon/night with most of the guidance favoring Thursday into Thursday night. This is due in part to the placement of the departing surface high off the Mid-Atlantic coast and secondary surface high pressure over the southeastern U.S. Even with that said, a few showers and thunderstorms (some of which could be strong) remain possible in areas west of the Blue Ridge Wednesday afternoon and evening as an initial piece of shortwave energy pivoting around the upper level low passes through. Most locations will remain dry with increased south to southwesterly winds boosting temperatures into the mid to upper 80s to near 90 outside the mountains/bay.

Scattered shower and thunderstorm chances will continue especially west of the Blue Ridge Wednesday night into Thursday morning. This is in association with the cold frontal boundary and trough as it inches closer to the region. Cloud cover/convective debris that occurs from this activity could play into how much of severe threat we see going into Thursday afternoon. More in the extended below.



LONG TERM /THURSDAY THROUGH MONDAY/
We return to an active pattern on Thursday as a potent upper trough moves through southeastern Canada, carrying a slow moving cold front into the area Thursday into Friday. Timing remains uncertain yet critically important as it often is. Recent guidance has been more consistent, however, in having the cold front move through our area during peak heating, increasing confidence for severe potential.
With ample moisture and CAPE (+1500 J/kg) from previous persistent southerly flow, the area will be primed for thunderstorm development. The latest guidance has also placed us in the favorable right entrance region of a jet, with deterministic guidance having 30-50kt of bulk shear. If these parameters continue to be favorable, strong to severe thunderstorms will be possible Thursday, especially as the front moves through in the afternoon/evening. Setup would be less favorable if timing shifts forward or back, but could still see some strong storms given the instability. Will continue to monitor.

Unsettled weather continues through the weekend as the cold front stalls to our south. A series of minor disturbances are expected to move through the area in this time as well, resulting in continued shower activity in the vicinity of the front each day. Temperatures in the mid/upper 80s on Thursday will cool a bit into the upper 70s to low 80s and moderate around there through the weekend.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Any leftover stratus should scatter out across the corridor terminals after 18z/2pm. Terminals west of the corridor will continue to see SKC conditions with high based stratocumulus passing through during the diurnal peak heating period. VFR conditions should prevail for the remainder of the afternoon and evening as high pressure settles overhead.

Mainly clear skies are expected tonight with additional low clouds and patchy fog tonight especially within the river valleys and terminals closest to the bay. Any low clouds/fog should form between 8-14z/4am-10am. Fog and low clouds will quickly burn off starting at the mountain terminals before working east toward the corridor around daybreak. Outside of the early morning MVFR/IFR fog/low cloud restrictions, VFR conditions should prevail at all terminals Tuesday and Wednesday afternoon. The exception to this will be in areas west of KMRB where a spotty shower or thunderstorm could pop up in advance of the front Wednesday afternoon.

Sub-VFR conditions are possible at times Thursday and through the weekend. A cold front moves through Thursday, bringing strong and possibly severe storms to the area. Timing is still coming into focus, but currently best chance for shower and thunderstorms will be in the afternoon and early evening hours. Any precipitation moving over the terminals could bring restrictions. Additionally, the front is expected to stall to our south through the weekend, likely keeping shower activity in the area for the duration.



MARINE
Light south to southeast winds are expected through Wednesday although some channeling/river or bay breeze enhancement is possible during the afternoon and evening hours. Winds should stay sub-SCA level through Tuesday morning with high pressure overhead. Marginal to sporadic SCA gusts are possible over the open waters Tuesday afternoon and evening. Confidence is low for SCAs given the short time window these conditions may occur. Some SCA level southerly channeling is possible Wednesday into Wednesday night ahead of an approaching cold front from the Ohio River Valley.

SCAs are not expected Thursday or Friday. However, as a cold front moves through, showers and thunderstorms are expected on Thursday.
Special Marine Warnings may be required for the stronger storms.
Unsettled conditions continue through the weekend as the front stalls nearby. Winds shift to west-northwest behind the front Friday as it stalls south of the waters.

TIDES/COASTAL FLOODING
Elevated water levels are expected to persist through Wednesday with persistent light onshore (S/SE) flow. Minor flooding is likely along vulnerable shoreline particularly during the overnight/early morning high tide cycles (the higher of the two astronomically). The higher end of the guidance envelope approaches moderate flooding at Straits Point and Annapolis, but this seems unlikely given the light flow. Coastal Flood Advisories are in effect for these two locations along with DC Waterfront for the upcoming high tide cycle.

Winds turn offshore behind a cold front Thursday, which will cause a subsequent decrease in water levels.

LWX WATCHES/WARNINGS/ADVISORIES
DC...Coastal Flood Advisory until 9 AM EDT Tuesday for DCZ001.
MD...Coastal Flood Advisory from midnight tonight to 9 AM EDT Tuesday for MDZ014.
Coastal Flood Advisory until 3 AM EDT Tuesday for MDZ017.
VA...None.
WV...None.
MARINE...None.

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Washington
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Mon -- 12:48 AM EDT     0.55 feet Low Tide
Mon -- 04:05 AM EDT     Moonset
Mon -- 05:51 AM EDT     Sunrise
Mon -- 06:42 AM EDT     3.18 feet High Tide
Mon -- 01:45 PM EDT     0.54 feet Low Tide
Mon -- 05:41 PM EDT     Moonrise
Mon -- 07:09 PM EDT     2.73 feet High Tide
Mon -- 08:18 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION

Washington, D.C., Tide feet

Fort Washington
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Mon -- 12:16 AM EDT     0.48 feet Low Tide
Mon -- 04:05 AM EDT     Moonset
Mon -- 05:51 AM EDT     Sunrise
Mon -- 06:35 AM EDT     2.79 feet High Tide
Mon -- 01:13 PM EDT     0.47 feet Low Tide
Mon -- 05:41 PM EDT     Moonrise
Mon -- 07:02 PM EDT     2.40 feet High Tide
Mon -- 08:18 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION

Fort Washington, Maryland, Tide feet

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