NEAR TERM /THROUGH SUNDAY/

Cool night ahead under building high pressure. Still enough gradient overnight to keep winds up a bit and preventing temps from tanking.

Previous afd...

The cooler and drier airmass associated with high pressure building in behind the front will result in below normal temperatures tonight. Winds should go light enough over portions of western Pendleton and western Highland Counties to result in the formation of frost. Elsewhere, low temperatures will be mainly in the 40s, except low to mid 50s east of US-15 and south of I-70.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/
Large surface high pressure will build across the Ohio River Valley and Mid-Atlantic Sunday into Monday. Dry conditions are expected with ample sunshine. Fall-like temperatures are expected Sunday (in the lower 70s), with upper 70s Monday.

As the high settles overhead Sunday night into Monday morning, we likely see the coldest temperatures of the fall season so far.
Lows will drop to the low to mid 40s across most of the area, with 30s in the mountains. There is a chance a few spots at the highest elevations approach freezing as dew points are forecast to be in the low 30s. High elevation valleys will likely be the coldest spots and would be the locations most susceptible to dipping to or even a little below freezing. Frost is possible in some of the sheltered elevated valleys near and west of I-81.
Lows moderate Monday night into the 50s for most.

See the Climate Section below for a list of daily record low temperatures for September 8-9. Charlottesville, Martinsburg, and Hagerstown are the most likely to approach their daily record lows.

LONG TERM /TUESDAY THROUGH SATURDAY/
The long term period will be largely dominated by surface high pressure located overhead. Aloft, an upper-level trough pivots off the East Coast as zonal flow moves over the Mid-Atlantic. Dry conditions and slightly above normal temperatures are expected each day. Northwesterly winds on Tuesday shift to southerly on Wednesday.
By Thursday, winds shift to southeasterly leading to increased cloud cover as moisture increases.

High temperatures each day will be in the low to mid 80s for most of the area with higher elevations staying in the mid to upper 70s.
Overnight lows will be in the mid 50s to upper 60s each night.

AVIATION /01Z SUNDAY THROUGH THURSDAY/
Winds and gusts subside a bit overnight, with a few gusts possible Sunday especially from mid morning through early afternoon as mixing increases and before high pressure moves more directly overhead. VFR is expected through the TAF period, and is likely through Monday night under the influence of high pressure. Northwest to west winds prevail during this time.

VFR conditions are expected Tuesday and Wednesday as high pressure remains overhead. Light winds out of the northwest Tuesday shift to southeasterly on Wednesday.

MARINE
Gusts of 25-30 kts are expected tonight over the wider waterways/main channel of the Chesapeake Bay, with gusts of 15-20 kts anticipated over the narrower waterways/tidal rivers.

SCA level gusts should subside by Sunday afternoon with northwest winds then remaining light through Monday night as high pressure builds overhead.

Dry conditions are expected Tuesday and Wednesday as surface high pressure builds over the Mid-Atlantic. Winds remain light, staying below SCA criteria.

CLIMATE
Below is a list of daily record lows for September 8-9, and the forecast low temperatures for each day.

Climate Site Sep 8 Forecast Low Washington-National (DCA) 52F (1988) 54F Washington-Dulles (IAD) 43F (1984) 48F Baltimore (BWI) 46F (1962) 51F Martinsburg (MRB) 42F (1988) 44F Annapolis (NAK) 47F (1962) 53F Hagerstown (HGR) 43F (1988) 44F Charlottesville (CHO) 43F (1988) 46F

Climate Site Sep 9 Forecast Low Washington-National (DCA) 48F (1901) 52F Washington-Dulles (IAD) 40F (1986) 45F Baltimore (BWI) 44F (1986) 48F Martinsburg (MRB) 40F (1986) 40F Annapolis (NAK) 43F (1986) 53F Hagerstown (HGR) 38F (1986) 43F Charlottesville (CHO) 43F (1918) 44F

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Small Craft Advisory until 11 AM EDT Sunday for MDZ008.
VA...Frost Advisory from 2 AM to 9 AM EDT Sunday for VAZ503.
WV...Frost Advisory from 2 AM to 9 AM EDT Sunday for WVZ505.
MARINE...Small Craft Advisory until 11 AM EDT Sunday for ANZ530>533- 538>542.
Small Craft Advisory until 2 PM EDT Sunday for ANZ534-537-543.
Small Craft Advisory until 4 AM EDT Sunday for ANZ535.
Small Craft Advisory until 8 AM EDT Sunday for ANZ536.