Scientific Forecaster Discussion
fxus61 klwx 240004
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
804 PM EDT Fri Aug 23 2019
a cold front will move into the southern mid-Atlantic and
southeast states tonight into Saturday. Strong high pressure
will build north of the region tonight and settle over northern
New England and Atlantic Canada through early next week. A
tropical cyclone could form over the weekend and move near the
southeast coast and out to sea.
Near term /through Saturday/...
rain showers have ended across virtually all of the region,
though can't completely rule out a pop up shower in central
Virginia overnight closer to the stalling front (which is
hanging out near the North Carolina border).
Otherwise, gradual clearing is expected tonight with low
temperatures in the mid 50s to lower 60s. Patchy fog is possible
as well given recent rains, especially in areas where the sky
can go mostly clear later tonight.
Short term /Saturday night through Sunday night/...
high pressure will build north of the region on Saturday with
north to northeasterly flow continuing. Aloft an upper level
trough will rotate across the region. This will lead to a mix of
sun and clouds with more clouds south, but everywhere should at
least see a scattered cumulus deck. An isolated shower is also
possible, especially near the Chesapeake Bay where instability
will locally be higher due to warmer water temperatures.Highs
will range through the mid to upper 70s. Lows Saturday night in
The ridge will strengthen down the mid-Atlantic coastline on
Sunday with flow turning more easterly. A mix of sun and clouds
is expected again, although likely more clouds than Saturday. An
isolated shower remains possible again as well. Highs in the 70s
to near 80f. Lows Sunday night in the 50s/60s.
Long term /Monday through Friday/...
an upper-level ridge will build in over the region on Monday and
Tuesday. Meanwhile, at the surface, high pressure sets up across the
northeast, resulting in ridging along/east of the appalachains.
Generally expecting dry conditions on Monday, but can't rule out
some stray showers across the higher elevations, as 850-700mb flow
seems to be more easterly. This is in response to a low pressure
system riding along the NC coastline throughout the day. Rain
chances will be highest along/east of the Blue Ridge, but still not
all that high on Monday. Temperatures will remain below average,
with highs in the low 80s or so.
Monday night into Tuesday, rain chances increase, as low pressure
slides by to the southeast, high pressure still to the northeast.
This results in easterly low-mid level flow, and likely a higher
rain chance. Could even see some embedded thunderstorms, as
temperatures will be a bit warmer (highs around the mid 80s) and the
atmosphere will be more moist. Additionally, an upper trough will be
approaching from the west, lending some upper-level support as well.
A cold front, associated with a low moving from the Great Lakes into
Ontario, will push through the region on Wednesday, before possibly
stalling overhead into Thursday. Ahead of this front, southerly flow
returns, bringing highs into the mid-upper 80s as well as more
humidity. Showers and thunderstorms will again be possible on both
days, especially on Wednesday. Most of the upper-level support is
displaced far to the north, so not seeing an organized severe threat
at this time.
Aviation /00z Saturday through Wednesday/...
patchy MVFR or even IFR mainly near cho this evening, tough to
say exactly when it will lift but most guidance/trends suggest
late evening into the overnight. VFR expected everywhere after
daybreak Saturday into Sunday, though some patchy lower ceilings
are possible Saturday night and again Sunday night due to
ensuing onshore flow.
VFR expected for Monday and Tuesday for the majority of the time at
all terminals. However, an isolated shower or storm, or lower
ceilings due to onshore flow could bring restrictions at times.
Eastern terminals may also see some gusty winds (20-25 kts or
so) Monday into Tuesday, depending on how offshore low pressure
evolves (which is significantly uncertain at this time).
drying tonight as cold front pushes south, but additional
northerly flow will create Small Craft Advisory conditions later tonight into
Saturday. Additional scas may be needed for northeasterly winds
Sunday through Monday with strong gradient between high
pressure across New England low pressure near the southeastern
Uncertainty exists for winds/possible intermittent rain during
the middle of next week with low pressure moving just off the
District of Columbia...none.
Marine...Small Craft Advisory from 3 am to noon EDT Saturday for
Small Craft Advisory until 10 PM EDT this evening for anz534-
Small Craft Advisory from 6 PM Saturday to 6 am EDT Sunday for