Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
835 PM EDT Thursday Jul 30 2015
a cold front moves through this evening...with high pressure
building in the wake. A cold front may move through over the
weekend...with the high pressure returning to start the week
before the next cold front moves through the middle of next week.
Near term /through Friday night/...
cold front near the blurdg at this time...marked by a drop in dewpoints more than
temperatures /mid 70s balt-District of Columbia crrdr vs middle-upper 50s mrb-hgr-cbe as of 00z/.
Still a little bit of instability in advc of fnt...as noted by recurring
rain showers/thunderstorms and rain in central Virginia. However...recent hrrr runs take this activity
east-southeastward...which means it/ll be southeast of County warning forecast area by 02z. Have made forecast dry
for the rest of the night.
Since dewpoints will be slow to drop across central Virginia and grnd wet from
late day rafl...have entertained patchy fog in this area for the
overnight hours-- primarily found in sheltered valleys. Elsewhere...the slow
drop in dewpoints...not to mention a light /blo 10 knots/ northwesterly flow through
the night...will preclude fog formation. Kept temperatures close to lamp...
which is quite close to climatology.
High pressure builds in Friday...keeping the area dry then through Friday
night. Plenty of warming under mostly sunny skies and downsloping
from westerly flow on Friday could push temperatures into the upper 80s...touching
90 in the District of Columbia and Baltimore metropolitan areas. However...with the lower
dew points...heat advisory criteria is not expected to be reached.
Short term /Saturday through Sunday night/...
the middle Atlantic remains under a broad upper level trough and on
the western periphery of high pressure at the surface by Sat morning.
12 model suite now suggesting that a cold front will move through
sometime late Sat. However...any upper level forcing with shortwave
energy looks to still remain mainly north of the area. With a
fairly dry air mass in place...precipitable waters below 1.0 inches...expecting
the frontal passage to be mainly dry...with nothing more than a
wind shift. Have kept the low end slight chance probability of precipitation for just the far
west areas in case of terrain driven convection. Anything that
does form will be gone by Sat evening.
The high pushes east Sat night through Sun night...bringing dry and
quiet weather to the area. Highs hovering in the low to upper 80s with
overnight lows generally in the 60s.
Long term /Monday through Thursday/...
high press dominates conditions Sun night into Monday. Late Monday
into Tuesday southwesterly flow advects moisture over our region increasing
the chance of showers and thunderstorms. A cold front approaches Tuesday night into
Wednesday and stalls around our area through Thursday... bringing additional
chance of showers and thunderstorms for this period. Temperatures will near
normal sun and gradually increasing into he low 90s for Wednesday.
Aviation /00z Friday through Tuesday/...
thunderstorms have pushed east of the terminals. VFR conds should prevail for the
taf period. Winds already northwest at mrb...and should veer to the northwest elsewhere
between 02-04z as a cold front mvs through. West-northwest flow will continue through
VFR conditions Friday night into next Monday.
outside of thunderstorms and rain...winds were not reaching Small Craft Advisory criteria...so have
dropped advisory for all waters. Storms have mostly cleared the waters
as well...although recent recurrent activity in vicinity of ezf suggests scattered
rain showers/thunderstorms and rain still possible lower ptmc/Middle Bay until midngt or so.
Southerly flow will become northwesterly near/aftr midngt. There may be a brief
increase in wspd bhd fnt until about dawn...but based on model soundings do not
believe these winds will exceed Small Craft Advisory criteria. Have capped winds at 15
knots...mainly in gusts.
Sub-Small Craft Advisory conditions will remain in place for the rest of Friday...
through the weekend...and into Monday with high pressure.
District of Columbia...none.