Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
239 PM EST Wednesday Nov 25 2015
high pressure will remain in overall control of the weather
through Friday. A cold front will stall in the area Saturday then
dissipate in the area Sunday and Monday as high pressure builds in
from the north. A cold front will cross the area Tuesday.
Near term /through Thursday/...
as of 2 PM...strong high pressure was centered over New England
with a extension southwestward across our area towards northern
Georgia. This high will continue shifting east into the northwest
Atlantic through Thanksgiving day...but the extension
southwestward will remain in place over our region. A ridge will
be in place aloft this evening...but a weakening trough will move
overhead on Thanksgiving day. This will have the minor effect of
increasing high clouds over the region...which may keep high
temperatures a little cooler than they otherwise might be. With
the flow turning southeastward on the back side of the high...dew
points have been creeping upward...so tonight should not be a
chilly as last night with readings mostly near to slightly above
normal. Highs on Thursday will probably reach the lower 60s in
much of the area especially from I-95 south and east. If clouds
are thicker than forecast it could stay a little cooler...but if
clouds are thinner we could reach the middle 60s in much of the area.
Short term /Thursday night through Friday night/...
weak ridge aloft will settle over the area Thursday night...while
high pressure extension remains in place over the region. Winds
should be very light and additional moisture will be in place from
the southeast flow preceeding it...so the likelyhood of fog has
increased notably. Guidance is actually hitting it pretty
hard...but for now have gone with patchy fog and increased sky
cover a bit but nothing dramatic. If guidance is to
believed...there could be some pretty widespread dense fog for
early black Friday shoppers. Lows Thursday night will be several
degrees above normal overall and notably warmer than recent
Once any fog Burns off...temperatures should rebound nicely.
Depending on just when that happens...upper 60s are not out of
the question...but given the uncertainty of the fog...kept values
mostly in the low-middle 60s.
Front approaching from the northwest has slowed down and high
pressure extension will linger over the region longer...so reduced
probability of precipitation for Friday night. High clouds will thicken and wind speeds
should be a little faster than dead calm with the front
approaching...so do not expect fog to form again. Lows kept above
normal by clouds and the approaching front.
Long term /Saturday through Wednesday/...
models/ensembles continue to trend weaker with forcing along a
cold front dropping into the area from the north on Saturday. A
wave of low pressure will ride up the front Saturday night into
Sunday enhancing a chance of rain across the area.
Another area of low pressure looks to cut up the Ohio Valley into
the Great Lakes bringing another chance of rain early next week.
At this time temperatures look largely mild enough for all
rain...with only a very small window of opportunity for spotty
wintry precipitation in the higher elevations late in the weekend
into early next week.
Aviation /20z Wednesday through Monday/...
VFR conditions through the next 30 hours as high pressure
maintains control with light winds and primarily middle and high
clouds being the only ceilings around. No fog of significance
expected tonight or Thursday morning.
Southeast flow off the ocean thurday and light winds Thursday
night may result in IFR conditions with low clouds and fog at the
terminals later Thursday night and Friday morning. Clouds and fog
likely to burn off enough to bring it back to VFR by Friday
afternoon. Higher clouds moving in Friday night and increased flow
at the surface ahead of an approaching front should prevent fog
and low cloud formation Friday night.
Mainly VFR Sat. Periods of sub-VFR possible mainly sun-Monday in periods
of -ra. Winds generally southerly at or below 10 knots.
sub-Small Craft Advisory conditions expected through Friday night. Southeast winds may
pick up on the Bay this evening but should generally stay below
Small Craft Advisory...perhaps just barely. Otherwise winds should be generally 10
kts or less through Friday night.
With a front stalled near the area...the pressure gradient and
subsequently the winds look relatively light over the waters this
weekend into early next week. Guidance has weakened the front
approaching the region Saturday so gusts look to stay below Small Craft Advisory
a developing southeasterly flow may result in increasing water
levels along the Chesapeake Bay shore through the latter half of
the week. Full moon today is helping the cause by producing high
astro tides. Minor coastal flooding is still possible as early as
Thursday evening...though guidance is backing off a bit on the
water levels as the southeast flow looks lighter than it appeared
District of Columbia...none.