543
FXUS61 KLWX 310108
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
908 PM EDT Sun Aug 30 2026
.WHAT HAS CHANGED...
Earlier showers and thunderstorms have mostly weakened.
&&
.KEY MESSAGES...
- 1) Dwindling showers this evening, then dry with high clouds
overnight.
- 2) Near-record early September heat expected.
- 3) Thunderstorm chances increase this week, but timing
remains highly uncertain.
&&
.DISCUSSION...
KEY MESSAGE 1...Dwindling showers this evening, then dry with
high clouds overnight.
Some showers linger as of about 9PM EDT from just east of
Washington DC southwestward toward Nelson County VA. These
should continue to weaken and press eastward over the next hour
or two. To the north, a heavier shower near Baltimore MD will
drift northeast, as showers over southeast PA drift southeast. A
couple additional pop up showers are possible in the vicinity of
northeast MD until around midnight or so.
Otherwise, tonight will turn out precipitation-free for most
with passing high clouds and perhaps patchy river valley fog.
KEY MESSAGE 2...Near-record early September heat expected.
A strong mid-level ridge over the southern Plains will build toward
the Mid South during the early to middle part of the week. The
latest trend is for the ridge to build further east into the TN
Valley on Tuesday and Wednesday, then break down late in the week as
a strong trough digs down from southern Canada. Having the ridge
build to the east is going to keep hot and mostly dry conditions
over the region for longer.
Despite the uncertainties, it remains likely that high temperatures
will reach the lower to middle 90s for most of the area this week.
Latest guidance indicates potential for temperatures in the upper
90s to near 100 by mid week, so long as it is not disrupted by cloud
cover or convection. Depending on smaller scale details, dew points
could end up a little higher or lower than currently progged which
will ultimately affect how high heat index values get. Values
approaching Heat Advisory criteria (100-104 west of the Blue Ridge,
105-109 east of the Blue Ridge) are possible Tuesday through
Thursday. Similar heat and humidity could persist into Friday, but
there is a lot of uncertainty for the late week temperature forecast
due to possible convective systems moving through the area.
Temperatures may begin to moderate by next weekend as a cold front
crosses the region.
KEY MESSAGE 3...Thunderstorm chances increase this week, but timing
remains highly uncertain.
Disturbances rounding a ridge to the south and west in NW flow aloft
will introduce shower and thunderstorm chances at times this week.
Given the latest trend bringing the ridge further east during the
middle of the week, that should keep most of the convective systems
over NY/PA and the Northeast Tuesday and Wednesday. That does not
mean we are completely in the clear those days; if anything, the
highest chance of seeing thunderstorms will be in northeast Maryland
during the late afternoon to evening as storms move south from PA.
By Thursday, a strong upper trough digs south from Canada which will
rapidly break down the ridge overhead. As this occurs, our area is
going to be in a much more favorable location for upstream
shortwaves to pass overhead.
The enhanced lift and shear traversing the region besieged by
several days of hot and humid conditions will introduce the
potential for some significant severe weather. AI/ML guidance has
broad elevated probabilities of severe weather much of this week,
particularly Wednesday and Thursday. It should be noted that there
is a conditional potential for one or more organized clusters of
strong to severe storms at some point this week. The most likely
time currently appears to be either Wednesday or Thursday, but
changes are likely given uncertainty at this range. It is quite
possible given latest trends that the threat is highest Thursday and
Friday as the upper ridge breaks down more readily.
Storm chances may linger into next weekend as a cold front crosses
the region on Saturday.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
VFR through Thursday for the most part. Timing, coverage, and
location will be the uncertainty each day and evening for
scattered strong to perhaps severe thunderstorms. Any storms
will bring brief MVFR to IFR conditions in terms of downpours.
Winds generally south to southwest 5 to 15 knots but very gusty
in strong thunderstorms.
&&
.MARINE...
Southerly flow will subside overnight, with mostly sub-SCA flow
expected this upcoming weak, though intermittent channeling at
least to marginal SCA levels can`t be ruled out each afternoon
and evening.
Chances of thunderstorms increase throughout the week, so
Special Marine Warnings may be needed.
&&
.CLIMATE...
Near-record heat is possible, peaking Tuesday through Thursday.
Below is a list of record warm temperatures for September 1, 2, and 3.
(A `+` indicates the record also occurred in previous years).
The period of record for most sites dates back to the late 1800s,
except for Sterling-Dulles Airport which dates back to 1960.
====================================================================
SEPTEMBER 1
====================================================================
Site Record Daily High Record Daily Warm Low
Baltimore (BWI) MD 99 (1962) 78 (1932+)
Washington DC 99 (1980+) 77 (1980)
Sterling-Dulles Airport VA 98 (1980) 73 (2000)
Baltimore (Downtown) MD 99 (1973) 80 (2012)
Annapolis MD 95 (1962) 78 (2018+)
Hagerstown MD 101 (1902) 72 (2018+)
Martinsburg WV 103 (1932) 73 (2000+)
Charlottesville VA 105 (1932) 78 (1932)
====================================================================
SEPTEMBER 2
====================================================================
Site Record Daily High Record Daily Warm Low
Baltimore (BWI) MD 99 (1953) 75 (1932+)
Washington DC 101 (1980) 78 (1980)
Sterling-Dulles Airport VA 99 (1980) 72 (2020+)
Baltimore (Downtown) MD 98 (1980+) 80 (1980)
Annapolis MD 97 (1998) 79 (2018+)
Hagerstown MD 100 (1953) 73 (2018+)
Martinsburg WV 103 (1932) 72 (2000+)
Charlottesville VA 105 (1953) 80 (1930)
====================================================================
SEPTEMBER 3
====================================================================
Site Record Daily High Record Daily Warm Low
Baltimore (BWI) MD 98 (2023) 79 (1993)
Washington DC 98 (1953) 79 (1993)
Sterling-Dulles Airport VA 99 (2023) 77 (1993)
Baltimore (Downtown) MD 98 (2023) 82 (1993)
Annapolis MD 99 (1993) 79 (2018)
Hagerstown MD 100 (1953) 72 (2018+)
Martinsburg WV 102 (1953) 71 (1957)
Charlottesville VA 104 (1953) 75 (1930)
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 2 AM EDT Monday for ANZ531>534-537-
543.
&&
$$
DISCUSSION...LFR/KLW/DHOF/KRR
AVIATION...LFR/KLW/DHOF/KRR
MARINE...LFR/KLW/DHOF/KRR
CLIMATE...DHOF
NWS LWX Office Area Forecast Discussion