Scientific Forecaster Discussion
fxus61 klwx 212005
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
305 PM EST Thu Nov 21 2019
high pressure will move south and away from our area into
tonight. A cold front will move across on Friday. Low pressure
will move across late Saturday into Sunday. High pressure will
likely return early next week before another front impact our
area by mid week.
Near term /through tonight/...
high pressure will continue to move to our south as a cold
front approaches from the west with ridging aloft. Clouds will
continue to overspread over our area as flow becomes southerly.
This will allow low temperatures to be above normal tonight,
dropping into the 40s.
Short term /Friday morning through Saturday night/...
a cold front will be moving across our area on Friday morning into
the early afternoon with high temperatures occurring before that.
Rain showers associated with this front will start in the morning
hours west of the Blue Ridge and overspreading east into the
afternoon. Quantitative precipitation forecast Max values are along and west of the Allegheny Front
and near central Virginia into southern Maryland. Highest values
seems to be between two tenth and half an inch of rain. Sounding
profiles suggest snow may be seen over a few areas near the
Allegheny Front behind the front late Friday afternoon/evening.
A high pressure will build behind the front Friday night into early
Saturday bringing dry and cool air into our region. Low
temperatures Friday night will be in the upper 20s into the mid 30s.
A low pressure system with plenty of moisture will move from the
southwest into our region on Saturday as mid-level low pushes east
into our region from the Midwest. This system will be over or near
our area on Saturday night. Precipitation will overspread the region
from the southwest into the northeast, with rain over most of our
region, but wintry mix could occur near and over the ridge tops as
suggested by soundings.
Long term /Sunday through Thursday/...
wave of low pressure will be exiting stage right early Sunday, with
dry weather likely to prevail. Temperatures will remain a bit
below normal, but not by a large margin. High pressure will slide by
to the south Monday into Tuesday. While temperatures likely stay
fairly steady Monday, southerly flow as the high heads off the coast
Tuesday should allow temps to rise back to near or even a bit above
normal. Rain may infringe on the area by Tuesday night as another
wave of low pressure lifts northeastward to our west, followed by a
cold frontal passage during early Wednesday. Downslope flow with a
Pacific air mass may help Wednesday turn out on the mild side, even
warmer than Tuesday, but temps will cool as Canadian high pressure
slides south for Thursday.
Aviation /Thursday through Tuesday/...
overcast but VFR conditions are expected for the remainder of today
and into early Friday. A cold front will be moving across our region
Friday bringing rain showers over the terminals through the day
Friday with periods of sub-VFR conditions and gusty winds, up to 20
knots. Cloud cover will decrease in the evening hours, but some
gusty winds could still linger around, but should become light
overnight Saturday. VFR conditions expected Saturday before a
low pressure system that will move across our area late
Saturday. Rain will move into the terminals on Saturday bringing
sub-VFR conditions at times.
VFR should prevail Sunday and Monday with high pressure.
a Small Craft Advisory is in place for tonight. Another one may
be needed for Friday afternoon as cold front moves across. This
will be evaluated by the evening shift. Winds should diminish
Friday night into Saturday before a low pressure system impacts
US on Saturday night.
Small Craft Advisory can't be ruled out immediately behind the departing low
pressure Sunday, but by Monday sub-Small Craft Advisory conditions are expected.
southerly to southwesterly flow will increase a bit over the next 12
to 24 hours, resulting in increasing water levels. This may result
in near minor flooding at Annapolis tonight and tomorrow, though
etss and estofs are notably lower than cbofs and snap-ex mean. Split
the difference since southwesterly flow doesn't usually result in
quite as high water levels, thus with current forecast no headlines
are needed, but will require close monitoring the next day or
District of Columbia...none.
Marine...Small Craft Advisory from 8 PM this evening to 6 am EST Friday