Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
929 PM EDT Thursday may 28 2015
high pressure over Lake Ontario will shift southeast and
reinforce high pressure offshore through Friday. Southerly winds
will continue to bring warm and humid conditions to the middle-
Atlantic through Saturday. A cold front will arrive Sunday and
stall over the area through Monday.
Near term /through Friday/...
as of 01z...1025mb surface high across Lake Ontario with weak
convergence apparent in infrared imagery along the eastern Seaboard.
Radar is quieting down though remnant boundaries could continue to
bring isolated showers and thunderstorms.
Another warm overnight on tap for the area west/ lows in the 60s...l70s
in the cities.
Short term /Friday night through 6 PM Friday/...
high pressure shifts southeast off the middle-Atlantic coast Friday
morning. This reinforcing high will further aid southerly flow. Could
see more morning precipitation activity west of the Blue Ridge. Maximum
Long term /Friday night through Thursday/...
the overall synoptic pattern changes very little through Friday
night and Saturday. The region will remain under the influence of a
ridge of high pressure which will be centered offshore during this
time period. The nearest shortwave trough will be passing through
Ontario and Quebec...but it will not influence the height field over
the middle-Atlantic until Sunday. The associated cold front pushing
into the Great Lakes will tighten the pressure gradient...which may
tick up the breeze a little Saturday.
In terms of precipitation chances...any convection from Friday afternoon
should wane diurnally. The ridge will still be strong Saturday.
Slightly drier air (per precipitable water values) may advect into the southeast third of
the County Warning Area...and a cap may be in place as well. Have thus trimmed probability of precipitation
back a bit...and locations east of the Blue Ridge may very well be
dry as convection will largely be terrain driven. Any uncertainty
would hinge in a disturbance riding the edge of the ridge in west-southwest
flow aloft...and precipitable water and cape do remain higher over the Potomac
Highlands. Highs Saturday will rise a few degrees...especially in
locations which see more sun. Middle 80s to near 90 expected. Lows both
Friday night and Saturday night only fall into the 60s to around 70.
A cold front will slowly push southeastward across the region
Sunday into Sunday night. Showers and thunderstorms will form ahead
of and along the front. Temperatures will be about 3 to 5 degrees
above normal. Of course...the more cloud cover and convection that
we see associated with the front could knock those highs down a
High pressure over the northeast and the eastern Canadian Maritimes
will wedge itself southward along the East Coast Monday through
Wednesday. This high will usher in cooler air. A passing middle level
disturbance across the lower Great Lakes and smaller shortwaves
moving across the eastern Ohio Valley will bring another round of
showers and thunderstorms along and just on the cool side of a cold
front Monday. Although there still lingers a chance of rain showers
Monday night through Tuesday night...drier air will prevail into
Wednesday. Temperatures may only top out in the upper 60s to lower
70s Monday through Wednesday with lows in the middle 50s.
High pressure will move to the coast Thursday that will allow a
milder return flow of air and help to bring high temperatures back
up into the lower 80s Thursday.
Aviation /01z Friday through Tuesday/...
patchy fog possible aftr mdngt for valleys and Piedmont including
Sub-VFR visibility possible Saturday morning in br...with the highest
chances at mrb and cho. As of now...mrb has the best chance of being
affected by a stray thunderstorm on Saturday afternoon/evening.
MVFR or IFR conditions possible Sunday through Monday with
showers and thunderstorms in parts of the area.
south flow channels this evening to around 15 knots. Still the
potential for a gusty shower or thunderstorm rest of the evening
inspite of a mostly quiet afternoon/early evening.
Southerly flow 10 to 15 knots Friday as high pressure is reinforced off the
Southerly flow increases Saturday into Saturday night between high
pressure offshore and a cold front over the Great Lakes. Small Craft Advisory
conditions could be achieved...especially over the Bay. Any
thunderstorm activity from Friday night through Saturday night will
Cold front stalls across the central middle-Atlantic Sunday and
Monday. Gusty showers and thunderstorms...along with smws
possible Sunday into Tuesday.
District of Columbia...none.