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FXUS61 KLWX 290837 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 337 AM EST Wed Nov 29 2023

SYNOPSIS
Chilly temperatures and less wind are expected today as high pressure builds over the region. Temperatures will start to warm Thursday as high pressure slides offshore. Rain chances return to the region Friday as an area of low pressure and it's associated cold front push east from the Ohio River Valley. Additional precipitation chances are expected through the weekend into early next week.

NEAR TERM /THROUGH TONIGHT/
It's another chilly day ahead with less wind as broad high pressure builds to the south of the region. Westerly winds this morning will cut off any residual upslope snow showers/flurries over the mountains while clearing residual patchy high cloud cover east of the Blue Ridge. Overall flow will transition to the southwest later this morning and into the afternoon as the center of the high meanders toward the VA/NC coast. This will allow for a slight boost in temperatures today after a bitterly cold start in the teens and 20s. Highs today will get back into the low 40s for many locations east of the Blue Ridge while mountain locations push back toward freezing. There will also be less wind which will allow wind chills to improve from the single digits and teens this morning to upper 20s and low 30s this afternoon. Southwest winds will remain sustained between 5 to 10 mph with gusts up to 20 mph heading into mid to late afternoon.

Dry conditions will continue overnight as high pressure shifts offshore. Elevated southwesterly flow will lead to widespread lows in the mid to upper 20s. The higher ridges could be slightly warmer with temperatures right around freezing while sheltered valley locations bottom out in the teens and 20s heading into Thursday morning. Wind chill factors will fall back into the upper teens and low to mid 20s.



SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
High pressure continues to push off the southeastern U.S coast Thursday allowing for increased southwesterly flow. Dry conditions will continue to prevail while temperatures warm back into the upper 40s and low to mid 50s. Cloud cover will increase as a result of the uptick in moisture with any precipitation likely to hold off until late week.

Synoptically, we are looking at a zonal upper level flow pattern with several embedded weak waves of shortwave energy to round out the workweek. The first wave comes in the form of an area of low pressure and it's associated front set to approach from the Ohio River Valley late Thursday night into Friday. Dry conditions are likely to persists Thursday with the residual antecedent dry airmass in play while precipitation chances increase with consistency amongst the latest 00z guidance. Most of the precipitation will fall in the form of rain and should be generally light with QPF amounts less than a quarter of an inch. Still monitoring the potential for a brief mix of snow and sleet over the cooler pockets of the Alleghenies late Thursday night into early Friday morning pending how quickly precipitation can arrive. Any wintry precipitation should remain fairly light with little to no accumulation expected.
Friday temperatures will start in the low to mid 30s west of the Blue Ridge with upper 30s further east. High temperatures Friday afternoon will warm back into the upper 40s and low 50s with increased southwesterly flow. Breezy conditions will alsO return with south to southwesterly winds at 10 to 15 mph gusting up to 25 mph at times Friday afternoon and evening.

By Friday night, best isentropic lift is forecast well north of the of the region with the best instability passing south along the Gulf Coast. This puts our area in a bit of a dry slot heading into the start of the weekend. Rain chances fall back into the slight chance range with a focus west of the Allegheny Front and south east toward the Delmarva/eastern VA. Overnight lows Friday night will fall back into the upper 30s and low to mid 40s.



LONG TERM /SATURDAY THROUGH TUESDAY/
A series of shortwave troughs in NW flow will carve out a longwave trough over the East early next week bringing a return to more seasonable temperatures. One weak area of low pressure is expected to move across the area Saturday bringing light rain to the Alleghenies and southern MD. A second stronger area of low pressure is expected to develop over the area Monday afternoon bringing another round of rain showers to lower elevations and a significant threat of snow showers/squalls to the mountains Monday through Wednesday which may eventually require winter headlines and/or snow squall warnings. Conditions begin to improve during the second half of next week, but remaining on the chilly side.

AVIATION /09Z WEDNESDAY THROUGH SUNDAY/
VFR conditions are expected with broad high pressure building south of the region today before sliding offshore Thursday. Winds will shift from the west this morning to the south-southwest this afternoon with gusts between 15 to 20 kts. South to southwesterly winds gradually lighten to around 10 kts or less tonight into Thursday.

Mid and high level cloud cover will start to increase Thursday afternoon into Thursday night. (SCT-BKN) VFR cigs are expected during this time with any MVFR restrictions holding off until Friday as an area of low pressure approaches from the Ohio River Valley.

MVFR conditions Friday into Friday night with light rain bringing reduced VSBYs and lower CIGs. Winds will increase from the south at 10 to 15 knots with gusts up to 20 knots Friday and Friday night.
Additional periods of sub-VFR conditions are likely Saturday through Monday as weak pieces of energy pass through.

MARINE
Marine conditions look to gradually improve this morning as winds briefly drop below SCA levels. SCA level winds return this afternoon and evening due to southerly channeling from increasing southwesterly flow. Winds drop back below sub-SCA levels Thursday morning with additional SCAS needed for southerly channeling Thursday afternoon and evening.

SCAs will be possible Friday and Friday night with southwest winds at 10 to 20 knots. Winds are expected to remain below SCA level Saturday. Winds could approach SCA levels Sunday amidst NW/NNW flow.

SCA conditions likely on Monday with potential for gales Monday night.

CLIMATE
The coldest air of the season is set to arrive tonight. This will result in near-record lows at IAD and MRB for Wednesday morning (November 29).

Below is a list of daily record lows for November 28-29

Climate Site Nov 28 Nov 29 Washington-National (DCA) 15F (1930) 14F (1930)
Washington-Dulles (IAD) 19F (1996) 17F (1967)
Baltimore (BWI) 15F (1951) 13F (1955)
Martinsburg (MRB) 12F (1938) 6F (1930)
Annapolis (NAK)* 17F (1930) 13F (1930)
Hagerstown (HGR)* 7F (1938) 1F (1930)
Charlottesville (CHO)* 13F (1930) 12F (1930)

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 9 AM EST this morning for ANZ530>534-537-539>541-543.
Small Craft Advisory from 1 PM this afternoon to 1 AM EST Thursday for ANZ530>543.

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