-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 111404
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1004 AM EDT Sat Sep 11 2021

.SYNOPSIS...
High pressure will move offshore today, then remain there through
early next week. A cold front may approach the area from the
northwest by the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...

-- Changed Discussion --
Patchy dense fog along the Allegheny front has mixed out this
morning. An area of high level clouds are moving into our region
this morning and are expected to persist eastward throughout
the day. I have adjusted cloud grids to account for these clouds
but overall quiet and dry weather expected today.

.Previous discussion



Last GeoColor image of the day yesterday
and NESDIS smoke analysis showed a layer of thin smoke aloft
over northern MD. Latest HRRR Vertically Integrated Smoke output
shows areas of generally thin smoke affecting the region today,
but denser smoke reaching the Appalachian region during the
afternoon. Otherwise, high pressure overhead this morning will
shift offshore during the afternoon with winds shifting from the
south leading to a warming trend. Mostly sunny much of the day
except for some high clouds and thin smoke. Warmer tonight under
a light srly flow with lows around 60F.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Heights will rise quickly tonight into Monday as mid-upper level
high pressure over the OH/TN valley builds over the Mid-
Atlantic. This will result in a significant warming trend with
high temperatures exceeding 90F. Humidity will be also on the
increase with sfc dewpoints potentially reaching 70F on Monday.
It will remain dry through Mon due to strong subsidence,
however, a backdoor front pushing south across Pennsylvania
Monday evening may result in some convective activity that could
reach northeast MD Monday night. Any activity should remain
north of I-70. For now, just painting those areas with a 20%
PoP for Monday night.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
On the large scale, medium range guidance is in good agreement with
Bermuda high pressure anchored offshore for the middle to latter
part of next week. But, as usual, the devil is in the details.

Uncertainty surrounds the timing and strength of a cold front
approaching from the Great Lakes during the middle part of the week.
By late week, although the 00Z deterministic GFS/CMC/ECMWF all
loosely agree on low pressure and tropical moisture moving up the
coast from the Carolinas, ensemble spread remains quite large. Broad
low probabilities for precipitation accompany both of these features
in the latest forecast package, in line with the latest iteration of
the NBM.

In terms of temperatures, summer-like heat and humidity is likely
much of next week given persistent southerly flow around the
aforementioned Bermuda high pressure offshore.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
High pressure will support fair weather conditions through 12Z
Tue. A slight chance of showers/t-storms Monday night mainly at
KMTN.

There is a low probability of a pop up afternoon or evening shower
or thunderstorm or early morning patchy fog Tuesday and Wednesday,
mainly west of Blue Ridge Mountains.

&&

.MARINE...
Strengthening srly winds tonight into Sun with SCA conditions
expected. SCA has been expanded to include all of the
Chesapeake Bay and extended through Sunday.

Episodes of southerly channeling around Bermuda high pressure
offshore may yield several instances of gusts approaching Small
Craft Advisory criteria during the middle of next week.

&&

.TIDES/COASTAL FLOODING...
Strengthening southerly winds tonight could result in minor
coastal flooding at Annapolis and Baltimore tonight into
Sunday.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 4 PM this afternoon to 6 PM EDT
     Sunday for ANZ530>534-537-539>541-543.

&&

$$
SYNOPSIS...DHOF
NEAR TERM...LFR/JMG
SHORT TERM...LFR
LONG TERM...DHOF
AVIATION...LFR/DHOF
MARINE...LFR/DHOF
TIDES/COASTAL FLOODING...