Area Forecast Discussion
Issued by NWS Sterling, VA-- Remove Highlighting --
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FXUS61 KLWX 240056
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
856 PM EDT Sat Jul 23 2016
A weak cold front will dissipate as it drops south into the area
tonight. High pressure will be in control of the area`s weather
Sunday before another front enters the area Monday into Tuesday.
This front may stall across the region during the middle of next
.NEAR TERM /THROUGH SUNDAY/...
No high temperature records were broken (or tied) Saturday. Close
though at IAD.
Temperatures remain in the lower 90s over much of the forecast
area with heat indices around 100. Where storms are able to
develop there is a large amount of CAPE available. Any storms
which form should exit the SE corner of the CWA near or shortly
Lows will range from the upper 60s west to 80 in the cities and
along the Bay.
Ridging will build into the area on Sunday, which should help
suppress most thunderstorm development, although an isolated
storm will be possible in the higher terrain. Temperatures will
probably be quite similar to today, but maybe a degree or two
cooler with little thermal chance. However, the decaying front
will have introduced lower dewpoints to at least the northern half
of the area, so heat indices will be closer to 100 or a little
below. Central VA (i.e. Charlottesville area) will have to be
monitored, because dew points there may be similar if not higher
than today and could result in heat indices close to advisory
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
Sunday evening and night will have to be monitored as a weak
impulse may be riding the ridge across the Great Lakes into PA, in
addition to low level theta-e advection. Have maintained low POPs
across the north through the night to account for any showers or
storms which may propagate into the area. Otherwise still muggy.
Monday still has the potential to be one of the more impactful
days of the next few in terms of heat and thunderstorms although
much uncertainty remains. Have made little change to the going
forecast. A front will be approaching from the northwest late,
although the best forcing and shear will remain north of the area.
Some storms may propagate into the area from the NW, but scattered
storms could also develop in the hot and humid airmass, especially
with north and westward extent. A Marginal Risk for severe weather
is in place. Air temperatures will be in the mid to upper 90s,
with heat indices potentially exceeding 105. The chance of storms
will linger into Monday night.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Temperatures and humidity will remain quite elevated with no real
relief in sight. In addition, a stalled front draped over the area
will serve as a focus for waves of scattered showers and
thunderstorms. Any upper-level disturbances riding by in the flow
aloft could enhance this threat, but are difficult to pinpoint from
a timing perspective this far out.
It is especially important to remember heat safety during
particularly prolonged heat events such as the one currently getting
underway. Also, this type of heat and humidity do not usually go
quietly, so stay tuned to later forecast updates for any strong
thunderstorm potential during the upcoming week.
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
VFR conditions overnight.
Few concerns for Sunday-Sunday night with high pressure. A front
will approach late Monday and could bring some scattered
Generally westerly flow at or below 10 knots is expected
Tuesday, becoming increasingly erratic as a stalled front sets up
over the area. Sub-VFR is possible in any showers or thunderstorms
A few storms may cross the waters this evening which could
contain strong wind gusts. Light and variable flow expected again
Sunday and Sunday night. Brief surge of SW winds possible on the
wider waters during the evening.
Gradient winds will likely increase Monday ahead of a cold front. Do
not have high confidence on reaching Small Craft conditions, but its
within the realm of possibilities. Will continue to leave the
wording in the synopsis. Thunderstorm chances increase Monday as
well, which may have a greater risk of locally high winds.
Not much of a pressure gradient is expected over the waters
into the middle portion of the week, which should keep winds below
Small Craft Advisory thresholds.
Record highs and max lows...
DCA...101 in 2010...84 in 2011
BWI...101 in 2010...82 in 2010
IAD... 99 in 2010...78 in 2010
DCA...100 in 1930...79 in 1965
BWI...100 in 2010...77 in 1887
IAD... 98 in 2010...76 in 1965
DCA...103 in 1930...79 in 1987
BWI...101 in 1940...80 in 1940
IAD....98 in 2012...76 in 2005