Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 181839
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
239 PM EDT Wed Oct 18 2017

.SYNOPSIS...
High pressure will remain across the Mid Atlantic through the
rest of the week and this weekend. A low pressure system may
affect the region early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Surface high pressure will continue sliding southward through
the remainder of the day and tonight as a weak system pushes
through the Great Lakes. At the same time a weak upper level
trough will cross the area overnight into early Thursday
morning. All this means for us is that there will likely be some
cirrus clouds tonight and a light southerly flow. In addition,
dew points are 5-10 degrees higher than at this time yesterday.
Therefore, while temperatures will be seasonably chilly, they
are not expected to be quite as cool as previous nights, with
lows from the mid/upper 30s in the cooler locations to around
50F in the urban centers and along the Chesapeake and tidal
Potomac. There may be some patchy frost in those coolest
locations, but where the growing season remains, it is not
expected to be widespread enough for any advisories.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Surface high pressure center will remain generally to our south
and southwest Thursday into Thursday night as the tail end of a
decaying cold front/low level trough over New England clips the
area Thursday night. This will bring little more than a few
clouds and a wind shift to the northwest. The upper level
pattern will amplify (west coast trough/east coast ridge) Friday
into Friday night, with the surface high expanding back to the
north and east.

Temperatures will continue to warm through the period, with
highs Thursday in the low 70s, and low to mid 70s on Friday.
Lows will be generally in the 40s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
High pressure system centered to our northeast on Saturday will
keep dry conditions and light winds over our area. This system
will slowly move offshore into Sunday as flow becomes more
southerly over our area. High temperatures will be in the mid to
upper 70s for most areas.

A cold front approaches from the west on Monday with a wave of low
pressure tracking northeast along it. Guidance suggest that
precipitation associated with the cold front could start
sometime on Monday but there is still uncertainty on how early.
Afterward, guidance is in agreement with an upper level trough
amplifying behind the front over the eastern CONUS Tuesday into
Wednesday bringing some upslope precipitation to areas west.

High temperatures on Monday will be between the low to mid 70s
decreasing into the upper 50s on Wednesday.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
High pressure will remain in control through the end of the
weekend. Predominantly VFR expected, but can`t rule out a brief
period of fog/br at MRB/CHO the next few mornings. Otherwise
only passing cirrus is expected with winds less than 10 kt.

A frontal system will approach the region on Monday, and
precipitation could bring sub-VFR conditions at times beginning
late Monday.

&&

.MARINE...
High pressure will remain nearby through Thursday with light
southerly winds developing. A weak front will pass by to the
north Thursday night, which will turn winds to the northwest.
Potential for Small Craft Advisory conditions will be dependent
on mixing, so the greater chance would be over the more open
waters. Winds will subside during the day on Friday as high
pressure moves back overhead, which will then generally persist
through the weekend. Southerly flow will begin to increase on
Monday ahead of the next frontal system.

&&

.TIDES/COASTAL FLOODING...
Anomalies remain around one-half to three quarters of a foot
above normal. This should keep water levels below minor flood
thresholds but it will be close for the sensitive sites of
Straits Point, Annapolis, and Washington DC. Water levels will
need to be monitored.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$
SYNOPSIS...MM
NEAR TERM...MM
SHORT TERM...MM
LONG TERM...IMR
AVIATION...MM/IMR
MARINE...MM/IMR
TIDES/COASTAL FLOODING...MM



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