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FXUS61 KLWX 230800

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Wed Oct 23 2019

High pressure building into the Tennessee Valley today will move 
northeastward across the Mid-Atlantic tonight and Thursday, then 
offshore of New England by early Friday. A cold front approaching 
from the Great Lakes will cross the region late Friday. Low pressure 
is expected to develop over the lower Mississippi River Valley 
Saturday, then track northeastward into the eastern Great Lakes late 
in the weekend bringing a frontal system through the region. Another 
system may approach early next week.


A cold front has moved offshore of the DelMarVa Peninsula as of 
early this morning, and will continue to push further offshore today 
as high pressure builds toward the region from the Tennessee Valley. 
Any fog should be a distant memory by mid morning, with sunny and 
dry weather expected today. Opted to lean on the warmer temperature 
guidance this afternoon with the sunny weather and northwest winds 
(which could gust to about 25 MPH at times), as this setup usually 
favors a warmer solution.

Flipped to the cooler side of guidance tonight, especially in the 
sheltered valleys west of the Blue Ridge into the central Virginia 
Piedmont as high pressure builds overhead. Patchy frost is possible, 
but mainly only for areas where the growing season has already 
ended. Therefore, no Frost/Freeze headlines are anticipated.


High pressure will move from the Mid-Atlantic to off the New England 
coast Thursday into Friday with continued dry weather and seasonable 
temperatures expected. Winds will be lighter with the high overhead, 
variable to start early Thursday then becoming light southerly.

GFS/GEFS has continued to trend to the rest of the model guidance 
which supports a dry cold front passage Friday. The front will drop 
southeastward from the Great Lakes through the day, then move 
southeastward overnight. Along the western end of this front over 
the lower Mississippi River Valley, low pressure is expected to 
develop by daybreak Saturday. Although no precipitation is expected 
(except perhaps a shower or two popping out over Allegheny Highlands 
Friday night), clouds will be on a slow but steady increase late 
Friday afternoon into Friday night.


A high amplitude upper level flow pattern continues to result in 
considerable model spread during the long term time frame. However, 
the GFS/GEFS are the more progressive outliers and will carry less 
weight in the forecast. On Saturday, a closed low in the southern 
plains will become absorbed back into the northern stream, lifting 
northwest of the area by early Sunday. The best moisture and ascent 
will be to our west through most of Saturday, with high pressure in 
New England retaining some influence. There could be some light rain 
later in the day or overnight, especially in western areas. Sunday 
appears to stand the highest chance of rain as a cold front trailing 
the associated surface low will cross the area.

The front will be losing steam though as it encounters strong 
ridging off the southeast US coast. Cold advection will be limited, 
and it's possible the front could get hung up near by. At the 
moment, Monday is favored to be drier. Tuesday will be more 
dependent on whether any moisture can ride northward on the western 
side of the ridge. However, the next (much stronger) cold front 
should hold off until later in the week.

With high heights due to the southeast ridge, temperatures will 
likely remain above normal through the extended period.


Fog is burning off early this morning, with mainly VFR then expected 
through Friday. W or NW winds could gust to around 20 kts 15-21Z 
today, before becoming calm tonight, then light southerly Thursday 
through Friday as high pressure builds overhead.

VFR conditions are likely Saturday as high pressure exits. A cold 
front could bring showers and sub-VFR conditions Saturday night into 


West or northwest winds are expected to gust to around 20 knots 
today, probably most widespread and frequent right around midday 
into early this afternoon. Winds are expected to diminish quickly 
late this afternoon into this evening, then remain light (southerly) 
Thursday into Friday as high pressure builds overhead.

High pressure over New England will likely keep winds light through 
Saturday. Southerly flow may increase Saturday night, then a cold 
front may result in west winds later Sunday. However, confidence in 
SCA conditions is low at this time due to large model spread.


Anomalies are gradually subsiding and thus will not be carrying any 
advisories past the current cycle. Sustained west winds will help 
the cause today. There is some uncertainty heading into tonight 
however. If the water can't evacuate the Bay completely, it could 
slosh back as winds become light. CBOFS and P-ETSS would place 
Straits Point and Annapolis near threshold. Guidance then holds 
anomalies low for the remainder of the week.


MD...Coastal Flood Advisory until 8 AM EDT this morning for MDZ508.
VA...Dense Fog Advisory until 6 AM EDT early this morning for 
MARINE...Small Craft Advisory from 10 AM this morning to 4 PM EDT this 
     afternoon for ANZ535-540.
     Small Craft Advisory until 4 PM EDT this afternoon for ANZ532-
     Small Craft Advisory until 4 PM EDT this afternoon for ANZ533-
     Small Craft Advisory from 10 AM this morning to 6 PM EDT this 
     evening for ANZ530-531-538-539.



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