365 FXUS61 KLWX 151417 AAA AFDLWXArea Forecast Discussion...UPDATED National Weather Service Baltimore MD/Washington DC 1017 AM EDT Mon Sep 15 2025
.SYNOPSIS... High pressure will build south from Ontario through early Tuesday maintaining the dry weather pattern. A coastal low pressure will approach the area from the south midweek bringing beneficial rainfall. A strong cold front will cross the area next weekend.
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.NEAR TERM /THROUGH TONIGHT/...
Increasing high clouds today, but remaining dry for one more day. Rain is still expected to arrive late tonight across St. Mary`s County and spread northwestward to areas south of the Capital Beltway by daybreak Tue. Highs today will be a little cooler than yesterday in the mid 80s.
Previous afd...
High pressure over southern Ontario will track across New England today, then offshore tonight. This is going to keep conditions dry for one more day though it won`t be as warm as it was this past weekend. Tightening pressure gradient over the Mid-Atlantic will produce increasing northeast to east winds this afternoon, with more abundant cloud cover quickly developing. A coastal low off the Carolinas slowly meanders toward Outer Banks. Highs this afternoon reach the upper 70s to low 80s. Some showers begin to move into central VA and southern MD tonight, though it will take some time to erode the dry airmass at the surface so most of the area remains dry. Overnight lows in the upper 50s to 60s with a steady easterly breeze.
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.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... The coastal low moves inland into far eastern NC, then slowly drifts back offshore through the middle of the week. Most of the model guidance keeps the low well to our south, meaning we likely won`t see much in the way of heavier showers or strong wind gusts. Still, we will see passing showers move in Tuesday morning, with the bulk of the activity expected Tuesday afternoon into Wednesday morning. Rainfall totals between a quarter to half an inch are possible west of I-95, with three quarters to an inch of rain east of I-95. Breezy conditions for Tuesday with gusts around 20-25 mph and up to 30 mph along the immediate western shore of the Chesapeake Bay. Rain cooled conditions and cloudy skies keep highs well below normal in the upper 60s to lower 70s.
Much of the same is expected on Wednesday, though rain chances will be lower as the coastal low weakens and pressure gradient slackens. Highs really struggle to reach the upper 60s to 70F, with drizzly and cloudy conditions expected all day. As the low pulls away northwesterly winds and drier air move into the area, with rain chances ending from west to east through the night.
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.LONG TERM /THURSDAY THROUGH SUNDAY/... On Thursday morning, a slow moving upper low will be in the process of accelerating away from the Mid-Atlantic region. This is in response to a broad upper trough pulling eastward from the central U.S. The influence of this system on the local weather does not materialize until over the weekend.
Some residual showers are possible during the f3irst half of Thursday. The coverage and timing of this activity will be driven by the position of the slow moving coastal low center. However, it does appear any such showers will largely focus east of I-95 and be confined to the morning hours. In the wake, expect mostly sunny skies and temperatures to warm back into the upper 70s to low 80s.
The warmest day of the period is likely to be Friday as heights build ahead of the next system. The latest forecast package calls for widespread mid 80s, with some spotty upper 80s. Across the mountains, 70s are more likely. As an upper trough sweeps across New England, another cold front tracks through early Saturday. While this should be a dry frontal passage, some added moisture from the central U.S. system will introduce a chance of showers for this weekend. At this point, any rain chances are largely in the 15 to 35 percent range. Temperatures fall through the weekend with low/mid 70s expected by Sunday.
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.AVIATION /14Z MONDAY THROUGH FRIDAY/... VFR conditions continue through tonight as winds become east to northeast this afternoon. An area of low pressure of the Southeast coast will approach the Mid-Atlantic Tuesday into Wednesday. Northeast to east winds will strengthen as showers overspread the area. Sub-VFR conditions are likely at some point Tuesday due to low ceilings. These restrictions could continue through most of Wednesday and Wednesday night.
Behind the slow moving coastal low, a few showers are possible Thursday morning. This could lead to a few residual restrictions for the Baltimore terminals. Otherwise, a return to VFR conditions is expected through Friday with dry weather. Multiple winds shifts are expected on Thursday into Friday. Initial northerly winds shift to southwesterly late Thursday before turning more north to northeasterly thereafter.
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.MARINE... The pressure gradient over the Mid-Atlantic is expected to tighten through the day in response to the interaction of high pressure to the north and a developing coastal low off the Carolinas. As this low makes its closest approach winds will increase tonight and remain elevated through Tuesday night. Northeast to east winds gust around 25-30 knots for most of the waters, with gusts close to gale- force possible in the middle Chesapeake Bay south of the Bay Bridge.
Winds start to decrease Wednesday, but SCA conditions are likely to continue through Wednesday night.
Overall gradients remain on the weaker side which should keep marine wind gusts below Small Craft Advisory levels. Gusts up to around 5 to 10 knots are expected, possibly up to 15 knots at times across the southern waters.
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.TIDES/COASTAL FLOODING... Onshore winds increase through the middle of the week as high pressure builds to the north and low pressure develops off the Southeast coast. Depending on the strength of the onshore winds, there is the potential for tidal flooding by the middle of the week. The trend for stronger winds continues, with winds peaking Tuesday morning into Tuesday afternoon. Minor coastal flooding seems more likely beginning early Tuesday and continue through Thursday.
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.LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Small Craft Advisory from 2 AM Tuesday to 6 AM EDT Wednesday for MDZ008. VA...None. WV...None. MARINE...Small Craft Advisory from 2 AM Tuesday to 6 AM EDT Wednesday for ANZ530>532-535-536-538>540. Small Craft Advisory from 4 PM this afternoon to 2 AM EDT Tuesday for ANZ533-541-542. Gale Watch from late tonight through late Tuesday night for ANZ533-534-537-541>543. Small Craft Advisory until 2 AM EDT Tuesday for ANZ534-537-543.
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SYNOPSIS...KRR NEAR TERM...LFR SHORT TERM...KRR LONG TERM...BRO AVIATION...LFR/BRO MARINE...LFR/BRO TIDES/COASTAL FLOODING...
NWS LWX Office Area Forecast Discussion