Scientific Forecaster Discussion
fxus61 klwx 220149
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
949 PM EDT Wed Aug 21 2019
an upper level disturbance will cross the region this afternoon
and evening. A cold front will approach the region Thursday and
move southward crossing Thursday night, and likely stalling
nearby into Friday. Behind the front, high pressure will build
over the region for the weekend.
Near term /through Thursday/...
main thunderstorm activity from earlier today has dissipated or
moved away from our area, while a few isolated showers and
thunderstorms are still lingering at this moment. Conditions
should become drier in the next hours, with partly cloudy skies.
Patchy fog will be possible towards morning as temperatures
bottom out in the middle 60s to middle 70s.
Short term /Thursday night through Friday night/...
a surface cold front will then push southward towards the region
Thursday and should be located near the Mason Dixon line by
Thursday evening. At the same time, upper level shortwave energy
will traverse the region from west to east. Thus, additional
development of scattered showers and thunderstorms seems
probable during the afternoon and evening hours. A marginal risk
of severe thunderstorms appears warranted, and we will also
remain moist with mean flow parallel to the front, so heavy
rain resulting in isolated incidents of flooding will also be a
concern. Highs on Friday will again be hot, in the upper 80s to
The front shifts southward Thursday night into Friday, but
likely lingers close enough nearby to bring continued chances
for scattered showers/thunderstorms through Friday evening.
Temperatures will trend noticeably cooler on Friday on the
northern side of the front, with highs from 75-85f. A drying
trend should commence Friday night as the front sinks further
south into southern Virginia. Lows will likely fall into the
Long term /Saturday through Wednesday/...
cold front will continue to sag southward through Saturday morning,
before high pressure builds in from the north by Saturday
afternoon. This will result in showers, with an isolated rumble
of thunder, across central Virginia and maybe southern Maryland on Saturday
morning. The front likely clears our forecast area by Saturday
afternoon, taking rain chances with it. However, there is still
a bit of uncertainty as far as whether our southern most regions
escape the rain. So, keeping low end chance pops across parts
of central Virginia. Though the front should be far enough south on
Sunday to keep the entire area dry, can't completely rule out an
isolated shower wandering into southern parts of the forecast
area. Temperatures this weekend will be below average, with
highs near 80 or so, with significantly reduced humidity as
High pressure will push northeast early in the week, resulting in a
return southerly to southeasterly flow. This could bring showers and
thunderstorms back into the forecast, with muggier conditions
returning. Guidance shows a slight uptick in temperatures as well,
but only into the low to mid 80s by Tuesday. Will carry chance pops
Monday and Tuesday with some thunderstorms possible once again.
Aviation /02z Thursday through Monday/...
afternoon/evening scattered showers and storms can be expected
through Friday as a cold front slowly transits the area,
bringing brief periods of sub VFR conditions. Some of the
thunderstorms may become strong to locally severe with heavy
rain, gusty winds, and hail. Patchy fog could also yield
MVFR/IFR vis, mostly likely at mrb/cho.
VFR conditions expected through the long term period. The only
exception could be at cho on Saturday morning, where an isolated
thunderstorm cannot be ruled out.
winds have started to decrease below criteria and will monitor
for possibly canceling the Small Craft Advisory soon. Wind gusts are expected to
remain below Small Craft Advisory criteria Thursday and Friday. The front will
drift over the waters on Thursday, lingering nearby into Friday.
As such, afternoon and evening showers/storms can be expected,
some of which will deliver strong gusty winds.
Sub-Small Craft Advisory winds expected on Saturday, but a stiff easterly breeze is
expected Sunday afternoon, which could approach Small Craft Advisory criteria.
District of Columbia...none.
Marine...Small Craft Advisory until midnight EDT tonight for