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ANZ535 Tidal Potomac From Key Bridge To Indian Head- 1233 Pm Est Wed Dec 6 2023
.small craft advisory in effect until midnight est tonight...
This afternoon..NW winds 10 to 15 kt with gusts to 20 kt. Waves 1 ft. Scattered sprinkles.
Tonight..NW winds 5 to 10 kt. Waves 1 ft.
Thu..SW winds 5 to 10 kt. Waves 1 ft.
Thu night..SW winds around 5 kt. Waves 1 ft or less.
Fri..S winds around 5 kt. Waves 1 ft.
Fri night..S winds around 5 kt. Waves 1 ft.
Sat..S winds 10 to 15 kt. Waves 1 ft. A chance of rain after midnight.
Sun..S winds 15 to 20 kt...becoming sw. Waves 2 ft. Rain likely in the morning. Showers through the night, then a chance of showers after midnight.

ANZ500 1233 Pm Est Wed Dec 6 2023
Synopsis for the tidal potomac and md portion of the chesapeake bay..
high pressure will build over the region through Friday, then move offshore this weekend. A strong frontal system will likely impact the region on Sunday. Small craft advisories may be needed starting Saturday night, and are likely Sunday and Sunday night.

FXUS61 KLWX 061500 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1000 AM EST Wed Dec 6 2023

SYNOPSIS
High pressure will build over the region through Friday, then move offshore this weekend. A strong frontal system will likely impact the region on Sunday. High pressure will return Monday.

NEAR TERM /THROUGH TONIGHT/
The main trough axis was pivoting offshore as of 10am, with just enough moisture for spotty sprinkles in its wake (except flurries for the higher elevations (and NE MD) east of the Allegheny Front. Upslope snow continues along/west of the Allegheny Front, but continues to generally gradually taper off.

As the system moves offshore this afternoon, winds will increase out of the W/NW. A few gusts to 30 mph are possible, primarily in the mountains. Cloud cover will provide poor mixing this afternoon, so don't anticipate those gusts to get to the lower elevations. Could see gusts around 15 to 20 mph though, which will still make it feel quite brisk with highs in the 40s today.

Winds will become lighter tonight especially over sheltered valleys east of the Appalachians. With a mainly clear sky east of the mountains this evening, radiational cooling should allow temperatures to drop well into the 20s. Elsewhere, 30s are expected with high clouds increasing toward dawn. Along and west of the Allegheny Front, lingering flurries or a few snow showers are possible, especially this evening.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
The shortwave that is accompanying the aforementioned surface low will slide by to our north on Thursday. While the low levels look a mostly dry, there could be just enough lift for some sprinkles or flurries in northeast MD if there is a little bit of lingering moisture. Otherwise, dry and slightly milder/less breezy conditions are expected through Thursday night.

High pressure moves offshore and turns flow southerly on Friday, which will act to moderate temperatures considerably.
Highs will be back into the mid to upper 50s, with some spots in the Shenandoah Valley even breaking into the 60s.

LONG TERM /SATURDAY THROUGH TUESDAY/
On Saturday, upper level ridging will be moving off the East Coast as a trough digs into the Plains. Surface high pressure to our south continues advancing offshore with southerly flow behind it advecting moisture and above normal temperatures into the region. Dry conditions are expected most of Saturday with rain chances moving into our western periphery Saturday night as surface low pressure moves into the Ohio Valley.

Guidance remains in decent agreement synoptically with the next significant weather maker on Sunday, amplifying the upper trough as it moves into the Midwest with the base of the trough digging down into the Mississippi Valley. There are some notable timing differences, with the GFS jogging slightly ahead of the ECMWF and Canadian. The suite of guidance seems to have trended slightly slower overall though, the jet moving overhead later in the afternoon/early evening. Ensemble members continue to introduce some modest CAPE around this time, though the more favorable shear might be later in the evening/overnight. Probs for 24hr 1" rainfall have continued to increase as well.

This far out, there is significant uncertainty, but we will continue to monitor for the potential severe/heavy rain threat. Strong winds may also accompany this system. Timing will be key in whether these threats materialize. For now, our area can at least anticipate a soaking rain.

After the system exits, high pressure is expected to build in behind it Monday into Tuesday, with some possible upslope precipitation along the Alleghenies.

Temperatures are forecast to be well above normal over the weekend, approaching over 15 degrees above average by Sunday. As the cold front associated with the system moves through, temperatures drop sharply behind it Monday and Tuesday.

AVIATION /15Z WEDNESDAY THROUGH SUNDAY/
VFR conditions are expected through Friday as low pressure departs and high pressure begins to encroach on the region.
Winds today may gust to around 25 kts out of the W/NW.

VFR conditions are expected Saturday with high pressure exiting to the east. Winds out of the SE pick up overnight Saturday as a low pressure system approaches from the west. A soaking rain will move through the area Sunday with the passage of a cold front. We're continuing to monitor the severe potential for the system on Sunday, but there is the possibility for thunderstorms as well as strong winds, with gusts up to 25-30 kts possible. Behind the cold front Sunday, winds shift from the SE to W and likely remain gusty.

MARINE
Winds pick up out of the N/NW today, especially into the afternoon, in the wake of a departing low pressure system. Gusts to 20-30 kt are most likely during this timeframe.

Winds begin to taper a bit later tonight, especially over narrower waterways, but 20-25 kt gusts likely persist over the wider waters until at least daybreak on Thursday.

Thursday brings lighter westerly winds over the waters, with no marine hazards expected at this time. Sub-SCA level southerly winds are expected over the waters on Friday.

Southeasterly flow on Saturday will increase overnight ahead of the approaching cold front, and continue into Sunday. SCAs will likely be needed Saturday night and through Sunday as the front moves through. A few gale gusts are possible, but there is uncertainty regarding anomalously warm temperatures overrunning cooler waters. There is the potential for thunderstorms as well, which would aid in mixing down stronger gusts.

TIDES/COASTAL FLOODING
Anomalies likely decrease today as winds increase out of the NW.
Flow becomes southerly Thursday and persists through most of the weekend increasing tidal anomalies and likely bringing sensitive locations to action by the end of the week.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...None.
VA...Winter Weather Advisory until 1 PM EST this afternoon for VAZ503.
WV...Winter Weather Advisory until 1 PM EST this afternoon for WVZ501-505.
MARINE...Small Craft Advisory until midnight EST tonight for ANZ530>532- 535-536-538>540-542.
Small Craft Advisory until 7 AM EST Thursday for ANZ533-534- 537-541-543.

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