Scientific Forecaster Discussion
fxus61 klwx 251428
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1028 am EDT sun Jun 25 2017
high pressure will build west of the area through the rest of
the weekend and into next week as a series of weak cold fronts
cross the region. The high will then cross the region Wednesday
and settle over the western Atlantic Ocean late in the week.
Near term /through tonight/...
a mix of sun and clouds expected today as a low pressure system
pushes from the eastern Great Lakes and into New England. High
clouds will depart by the afternoon, but expecting fair weather
cumulus to continue to develop and spread across the area. Westerly
winds will pick back up with gusts up to about 20-25 mph.
Temperatures will be within a couple degrees of normals, with
highs from the upper 70s to upper 80s. Partly to mostly clear
skies expected overnight with lows in the 50s/60s.
Short term /Monday through Tuesday night/...
another reinforcing shot of cooler air pushes south across the
area late Monday into Monday night. Forcing remains weak and
moisture remains limited so think precip will be hard to come
by. Clouds may be a bit more common though. Highs will slip down a
bit more with upper 70s to low 80s common. Dew points will slip into
the upper 40s during part of the day. Lows Monday night will drop
back into the 50s most spots, but still 60s in the warmest locales.
Strong upper trough will cross the region Tuesday with another
surface boundary. This trough is probably the most interesting
weather through the forecast period, with increased instability
associated with it. Some guidance is still dry with it (the
Canadian suite), but others, including the NAM and ECMWF, are
rather convective, so we could definitely see some scattered
showers and thunderstorms given the cold pool aloft and decent
positive vorticity advection. For now have kept probability of precipitation rather low east of the mountains,
but may need to be bumped if guidance comes into better
agreement. Highs Tuesday will be quite cool, with most places
failing to reach 80. Dew points will be slightly higher, with
most places staying in the 50s. Clearing Tuesday night behind
the trough, with lows into the 50s in most places, except near
60 in the cities and Bay Shore and 40s in the mountains.
Long term /Wednesday through Saturday/...
the upper level trough axis shifts east of the mid-Atlantic
Tuesday night per global guidance consensus. The trailing
surface low will then be overhead Wednesday before shifting
offshore later that day. The streak of below normal temperatures
end Thursday with the return southerly flow that begins
The high becomes centered over Bermuda with a return to Summer-
like conditions (max temps around 90f) Thursday into the
weekend. The jet stream and associated low pressure looks to
stay north of the central mid-Atlantic/over the Great Lakes
through the weekend with continued low chance probabilities for
Aviation /14z Sunday through Thursday/...
VFR through the period with sustained winds generally around 10
knots or less, gusting to around 20 knots each afternoon. Main
concern will be an isolated showers/thunderstorms on Tuesday.
Otherwise, no significant winds, precipitation, visibility or
ceiling limitations expected.
winds below Small Craft Advisory criteria currently, but with deeper mixing and
a weak system passing near/north of the region, expect some
gusts to reach up to around 20 knots later today and into this
evening. Thus Small Craft Advisory remains in effect from noon-10 PM.
There is concern again for marginal Small Craft Advisory on Monday with another
weak boundary and good mixing, but given marginal event
expected, did not raise headlines yet.
On Tuesday, a passing trough may cause spotty showers and
thunderstorms, and given dry environment overall, some gusty
winds could accompany them.
Tranquil and cool weather Wednesday under surface high
pressure. Return southerly flow begins Wednesday night as the
high shifts to Bermuda.
District of Columbia...none.
Marine...Small Craft Advisory until 10 PM EDT this evening for