Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
339 am EST Thursday Nov 26 2015
high pressure will remain in control of the weather through
Friday. A cold front will move into the area Saturday and stall
out nearby Saturday night through Sunday before building farther
south Sunday night and Monday. A stronger cold front will cross
the area late Tuesday into Wednesday.
Near term /through tonight/...
middle-upper level ridge extending from the Gulf Coast to
the northeast will maintain mild weather through Friday while strong surface
high near Nova Scotia maintains a weak srly flow over the area with
the potential for low clouds/fog this morning and again tonight.
Latest GOES-east cloud and fog products Show Low clouds covering areas
from Nelson County northeast to Warrenton and east to Fredericksburg
and into St. Marys County. There is also a band of high clouds
covering areas along and west of the Blue Ridge. Maxt today will
climb to near 60f after the low clouds mix out. Skies clear this
afternoon and with higher dewpoints tonight will have a better
chance of fog developing mainly over the I-95 corridor and northeast
Maryland east of Frederick County. For areas west of the Blue
Ridge...dense high clouds moving in again late tonight may inhibit
fog development in that area.
Short term /Friday through Friday night/...
fog/low clouds will dissipate in the morning giving way to a very
nice day with maxt in the middle 60s as 850 mb temperatures climb to near
10c. High clouds will move into the western part of the forecast area late
in the day but not early enough to have a sig impact on
A cold front will approach the area from the north and west Friday
night. Clouds will continue to increase ahead of the cold front
and a light west to southwest flow ahead of the boundary will
allow for mild conditions. A few showers are possible
overnight...especially across northern Maryland into the Potomac
Highlands. Min temperatures will be in the lower to middle 40s for most
areas. Despite the increasing clouds...patchy fog is still
possible due to increasing amounts of low-level moisture.
Long term /Saturday through Wednesday/...
a cold front will move into the area Saturday and it will stall
out nearby for Saturday night through Sunday. Weak upper-level
disturbances in the zonal flow aloft will ride along the
boundary...bringing the chance for rain across our area.
The boundary will likely push a bit farther south south Sunday
night into Monday as high pressure strengthens over New
England...but it may remain close enough for more unsettled
Timing of the cold front Saturday and its exact location Sunday
through Monday are still highly uncertain...and this will have a
significant impact on our forecast. If the boundary remains
overhead then rain and unsettled conditions are more likely.
However...if the boundary is farther south like some of the
guidance suggests then much of the time may end up dry. Leaned
toward the ensemble fields...which lines up well with continuity
in bringing chance probability of precipitation most of the time. Guidance does appear to
be converging on a solution for most of Saturday where any rain
that does fall will be light...and confined mostly toward northern
Maryland into the Potomac Highlands/Shenandoah Valley. The
highest degree of uncertainy is late Saturday through Monday.
Potent low pressure will develop over the plains later Monday and
it will move off into the Great Lakes Tuesday. This will allow for
warm and moist air to overrun the surface cooler air in
place...bringing more chances for rain. The cold front associated
with the low will pass through our region late Tuesday into
Wednesday...again bringing the chance for unsettled conditions.
Aviation /08z Thursday through Monday/...
it will likely remain VFR through 12z this morning at
all taf sites except perhaps at kcho. Potential for fog and/or low
clouds to affect the three main airports late tonight. Will likely
include at least MVFR ceilings/visibilities in 12z tafs.
A cold front will approach the terminals Friday night and it will
stall out nearby Saturday into Sunday. A few showers are
possible...especially later Saturday into Sunday. Uncertainty in
the forecast remains high but appears that patchy fog is possible
Friday night...and MVFR ceilings are possible Saturday through Sunday.
The cold front may push a bit farther south Sunday night into
Monday. Drier air will attempt to work its way in from the
north...but how far south the drier air makes it is still
uncertain at this time. Subvfr ceilings and showers are still
light and variable winds 5 knots or less through Friday. Fog
development possible tonight on the Potomac and upper Chesapeake
Patchy fog is possible Friday night. A cold front will stall out
near the waters Saturday through Sunday. The boundary will push a
bit farther south Sunday night into Monday before a stronger cold
front moves through late Tuesday into Wednesday.
Wind gusts near Small Craft Advisory criteria are possible Saturday and again
Monday into Tuesday. Have capped gusts around 15 knots for now due
to the low degree of certainty and a weaker pressure gradient.
a light onshore flow will cause tidal anomalies to increase a bit
today. However...the flow should be light enough to prevent minor
tidal flooding. A light south to southwest flow will continue
Friday and elevated water levels are expected...but again with the
flow being light minor flooding is not expected. Latest guidance
also shows water levels below minor flooding thresholds over the
next couple days. Will have to watch tidal anomalies this
afternoon through tonight.
District of Columbia...none.