Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
252 PM EDT Thursday may 28 2015
High pressure will remain offshore through Friday. Southerly winds will
bring warm humid conditions to the middle-Atlantic through Saturday.
Showers and thunderstorms will be possible each afternoon and
evening as a series of cold fronts approach and weaken. A
stronger front will arrive Sunday and slide south through the
region during the early part of next week.
Near term /tonight/...
Radar operator will be keeping eyes on cells developing over the mountains that
will be tracking to the east-northeast through the evening hours. From morning sndg it
appears that brief heavy downpours will be the most likely concern.
Another warm overnight on tap for the area west/ lows in the 60s...l70s
in the cities. Ches Bay has also warmed quite a bit in the past
few wks...hence the "cooler temperatures along the bay" no longer applies to
the temperature forecast.
Short term /Friday/...
And a relativily similar forecast continues for Friday. Highs in the 85-90 range
west/ chances for afternoon cnvctn.
Long term /Friday night through Wednesday/...
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 /18z Thursday through Tuesday/...
VFR conds tonight/Friday outside of possible brief periods in tstms/rw. Light fog
possible aftr mdngt at mrb/cho/iad.
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.
Thunderstorms near the Bay could result in 1 or 2 smw's through middle evening.
Otherwise winds below Small Craft Advisory values tonight and Friday.
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
No marine hazards Sunday through Monday.
District of Columbia...none.