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Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia
928 am EDT Thursday Mar 26 2015

Synopsis...
high pressure will continue to move off the coast overnight. A
warm front will pass through the area Thursday morning followed by
a cold front that will move through Thursday night. An upper-
level disturbance will pass through the area later Friday through
Saturday. High pressure will return for Sunday and continue into Monday.

&&

Near term /through tonight/...
high pressure remains off the coast this morning and a warm front
is draped across West Virginia south into southern Virginia
before it extends northeast into extreme southern Maryland.
Atlantic moisture has gotten wrapped into this system...resulting
in showers and even a couple thunderstorms across central Virginia
into the Washington metropolitan area. This activity will spread
northeast into the Baltimore metropolitan area late this morning
before eventually moving away from the area this afternoon. The
warm front will pass through our area late this morning and early
afternoon.

There should be a lull in precipitation for several hours behind
the warm front this afternoon. Southerly winds and some sunshine
will result in unusually warm conditions for this time of year.

A potent cold front looks like it will cross the area between 22
and 04z. High resolution guidance is coming into range and almost
all solutions depict a narrow convective line along the front.
Have maintained chance thunder wording...as MUCAPE appears it will
only be around 500 j/kg or less. Gusty winds can be expected with
the showers...although severe level gusts seem to be a low
probability due to the low level wind fields.

Upper level jet streak interacts with front aloft to provide
additional precipitation overnight. As temperatures fall...snow will become likely
in the upslope regions. Not out of the question there could be some
mix farther east...but confidence too low to include in forecast for
now. Lows outside of the mountains generally in upper 30s and 40s.

&&

Short term /Friday/...
showers will exit east portions Friday morning. Moisture profiles
suggest threat of upslope precipitation in western mountains will diminish to smaller
chances. Friday will be marked by cold air advection but a downslope component will
allow for good mixing and highs in the middle 40s to lower 50s.

&&

Long term /Friday night through Wednesday/...
strong cold advection at low levels continues as the core of
unseasonably cold air moves out of the Great Lakes region and into
the northeast...brushing the northern mid-Atlantic. 850 hpa temperatures
prognosticated in the -9c to -13c range Saturday. Examination of upper air
records shows only about a dozen times has 850 temperatures fallen to -10c
or lower from Mar 27 into April. With decent cold air advection on Saturday...
should be enough moisture for strato-cumulus deck. Where clouds hold...
temperatures will struggle into the 40s east of the Blue Ridge and
low/middle 40s east of the Blue Ridge. However...if the deck gets wiped
out due to lack of moisture and/or downsloping then the relative
warmth of late March sun could cause temperatures to overcome cold air advection and rise
a Cat or two higher then forecast. Still...unseasonably cold and
brisk on Saturday.

Sun-Thu...high pressure moves overhead on Sunday...chilly start to the
day with temperatures well below normal...even middle/upper teens in far Western
Mountain area. By Monday...temperatures rebound back to to near seasonable norms
based upon HPC guidance as high pressure moves off southeast US.
Another cold front will pass through Monday night or early Tuesday. Some
differences in models on timing of this front. Not much moisture
associated with it. Wednesday...high pressure again returns to the
region. On Thursday...moderation in temperatures continues as return SW flow
around departing high Ushers in mild air across the region.&&

Aviation /08z Thursday through Monday/...
ceilings and visibilities will lower this morning as a warm front moves
through...but should be mainly VFR. Showers possible mainly along
and east of I-95. Conditions improve by midday/early afternoon but
southerly winds will become gusty. A cold front sweeps eastward
during the early evening hours with wind shift to northwest. Line of
showers and possible embedded thunderstorms along front...with Post-frontal
precipitation and lowered flight conditions possible overnight. Expect
improvement by Friday with northwest winds.

On Sat...expect VFR conditions...except some isolated MVFR in snow showers
with northwest winds 10-20 kts. High pressure moves overhead on Sunday and
continues into moderate...with VFR conditions expected.

&&

Aviation /13z Thursday through Monday/...
showers will impact the eastern terminals late this morning. IFR
conditions are possible during this time. Ceilings will improve behind
a warm front this afternoon and southerly winds will increase with
gusts around 25 to 30 knots expected. A cold front will pass
through during the evening hours with a wind shift to northwest. Line of
showers and possible embedded thunderstorms along front...with Post-
frontal precipitation and lowered flight conditions possible overnight.
Expect improvement by Friday with northwest winds.

On Sat...expect VFR conditions...except some isolated MVFR in snow showers
with northwest winds 10-20 kts. High pressure moves overhead on Sunday and
continues into moderate...with VFR conditions expected.

&&

Marine...
light winds ahead of a warm front this morning. Expect southerly
winds to increase 20-30 knots as warm front passes this morning.
Showers and perhaps thunderstorms are possible through early afternoon.
Cold front crosses this evening with wind shift to northwest and more
showers and embedded storms. Winds continue to gust behind the
front. Extended Small Craft Advisory through until Friday afternoon...as mixing may
continue to allow higher gusts to reach the surface.

Friday night into Sat expect Small Craft Advisory conditions in cold advection and northwest winds.
High press builds over the waters on Sunday and continues into Monday with
winds falling below Small Craft Advisory levels early Sunday morning.

&&

Tides/coastal flooding...
southerly flow will increase ahead of a cold front today causing
an rise in water levels. Tidal anomalies may be high enough for
minor flooding during the tide cycle this evening and overnight.
However...confidence is low because a wind shift to the northwest
will be taking place at that time and it is also the lower of the
two astronomical norms.

Northwest winds will continue overnight and Friday...causing
anomalies to decrease.

&&

Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...Small Craft Advisory until 5 PM EDT Friday for anz530>543.

&&

$$
Synopsis...ads/smz
near term...bjl/ads
short term...ads
long term...smz
aviation...bjl/ads/smz
marine...bjl/ads/smz
tides/coastal flooding...bjl

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