830
FXUS61 KLWX 270758
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
358 AM EDT Sat Jun 27 2026
.WHAT HAS CHANGED...
No major forecast changes were made. We continue to monitor
showers and thunderstorms tracking across the area.
&&
.KEY MESSAGES...
- (1) A weak frontal boundary will linger across the region
through Sunday, delivering waves of showers and
thunderstorms.
- (2) Excessive heat and humidity next week heading into the
Independence Day holiday.
&&
.DISCUSSION...
KEY MESSAGE 1...A weak frontal boundary will linger across the
region through Sunday, delivering waves of showers and
thunderstorms.
Mosaic radar imagery shows several areas of showers and
thunderstorms extending off to our west. One more concentrated
area of showers and a few thunderstorms is located from Central
Virginia northward into the Shenandoah Valley. Another larger
area of showers has largely stratified out over southern WV,
eastern KY, and far southern OH. Even further to the west
numerous showers and thunderstorms are present across southern
IN and central KY. With zonal flow in place through much of the
depth of the atmosphere, these various areas of showers and
thunderstorms will continue to progress off toward the east
today into tonight. As seen in the the 00z IAD and ILN
soundings, there`s deep moisture in place. Model guidance shows
PWAT values climbing to near 2 inches over the course of the
day. As a result, any storms will be capable of producing very
heavy rainfall. However, questions remain regarding how many
storms will ultimately form, with recent model guidance showing
showers over southern WV/eastern KY/southern OH moving overhead
and persisting on/off through much of the day. If this solution
were to play out, it may be difficult for destabilization to
occur, and we may largely just end up with cloudy skies and on/off
showers. The best chance for some breaks in the cloud cover to
occur this afternoon may actually be across northern MD, so
we`ll need to keep an eye on that area over the course of the
day. WPC currently has most of the forecast area outlooked in a
Marginal Risk for excessive rainfall. No threat for severe
thunderstorms is expected with the minimal instability and
saturated profiles (which should limit the strength of
downdrafts). With the ample cloud cover and shower activity,
temperatures will be cooler than preceding days, with highs in
the upper 70s and lower 80s for most.
Coverage of any storms should decrease through the evening, but
a few showers may linger through the overnight hours. In
addition to low clouds, patchy fog may be possible later
tonight. Overnight low temperatures will be in the mid 60s to
around 70.
Upper ridging will start to build to our west over the
Mississippi Valley and Great Lakes on Sunday. This will cause
flow to turn northwesterly aloft. A weak shortwave disturbance
is expected to dive southeastward from the Great Lakes and
approach the area from the northwest. Showers and thunderstorms
are forecast to develop once again ahead of this disturbance
Sunday afternoon. Coverage of showers and storms should be much
higher than Saturday with stronger daytime heating and large
scale ascent ahead of the approaching shortwave. Model soundings
show largely saturated profiles once again, with PWATs still
near 2 inches. However, instability is much greater, at around
1000-2000 J/kg of MLCAPE. With ample instability, high PWATS,
and deep warm cloud layers extending up to around 15kft, storms
should be capable of producing heavy rainfall. The most recent
runs of the HRRR and RRFS show localized maxima of 2-4"
scattered about the forecast area. As a result, there could be a
threat for flash flooding in urban areas. Outside of the urban
areas, the background drought conditions should help to limit
the threat for flooding. While flooding looks to be the greater
threat, there could also be a low-end threat for damaging winds,
with DCAPE values around 600-800 J/kg.
Upper ridging will continue to build in from the west on Monday.
Coverage of storms is expected to be lower on Monday, with most
of the activity likely remaining confined to the higher terrain
to the west of the Blue Ridge.
KEY MESSAGE 2...Excessive heat and humidity next week heading
into the Independence Day holiday.
Looking at a prolonged significant heat risk across the entire
region Tuesday through the Independence Day holiday/weekend.
Strong/broad subtropical high pressure and a building upper-level
ridge will allow temperatures and humidity values to climb
toward record levels by the middle and end of next week.
Temperatures start to climb Tuesday as the upper-level ridge
expands eastward from the Ohio River Valley. Look for highs in
the 90s with heat indices running between 95-100 degrees.
Wednesday through Friday will be the peak of the heat with
highs for most in the upper 90s and lower 100s. Heat indices
each afternoon with run between 102-107 degrees with a few
readings around 110 along the immediate I-95 metro corridor and
down across the VA Piedmont region. Minimal relief is expected
across the mountains with highs in the mid 80s to low 90s and
heat indices in the mid to upper 90s as the heat peaks mid to
late week. No relief at night either with widespread lows in the
upper 60s to mid 70s (upper 70s-80 urban areas) Wednesday
through Saturday. More at weather.gov/lwx/heat.
Even with that said, there still remains some spread in temperature
data mid to late next week. Some of this is due top the
placement and positioning of the ridge along with any t-storm
chances that may develop late next week.
Right now, any convection looks to be tied to the mountains
Wednesday and Thursday due in part to the terrain influence. With
excessive heat and humidity there will be plenty of instability to
work with. You combine this with any potential ripples of low
pressure moving around the ridge or a bay/river breeze to get
convective development. This is illustrated by both the CSU/CIPS
outlooks along with Google WxNext AI model which suggest the risk
for severe weather during the Friday July 3rd and Saturday July 4
timeframe. Something we`ll continue to monitor in subsequent
forecast shifts. Historically, near record summer heat often
ends with widespread strong thunderstorm activity, and latest
guidance starts to break down the heat next weekend (July 4).
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Conditions are currently VFR at most terminals. MVFR ceilings
are forecast to move in toward daybreak and then persist through
today and tonight. On and off showers and thunderstorms will
be possible through the day. The greatest chance for
thunderstorms during the afternoon/evening hours has been
highlighted in the TAFs with PROB30 groups. Patchy fog appears
possible overnight, and ceilings could briefly approach IFR near
daybreak. Gradual improvement back to VFR ceilings is expected
through the day Sunday. Additional showers and thunderstorms may
develop Sunday afternoon. Patchy fog and lower ceilings may be
possible once again Sunday night. Winds will be light out of the
southwest today, and then light out of the east to northeast on
Sunday.
Prevailing VFR conditions are likely Monday through Thursday
next week. Light easterly winds will become southerly Tuesday
and Wednesday before turning southwesterly late week.
&&
.MARINE...
Light and variable winds are expected over the waters today.
Winds turn light out of the east to northeast on Sunday. Showers
and thunderstorms are expected on and off over the course of
the weekend, with SMWs possible.
Sub-SCA level east to southeast flow is expected Monday as high
pressure builds in the region. Winds will become more southerly
Tuesday before turning southwesterly mid to late weekend. SCA
conditions will be tied to channeling mainly over the Chesapeake
Bay Tuesday afternoon and evening, and again Wednesday afternoon
and evening. This is especially true over the middle and open
waters where brief SCA conditions are possible during this time.
&&
.CLIMATE...
There is a significant heat risk next week. The numbers below
aren`t a forecast, but rather a reference for historical context
for comparison. Latest forecast: weather.gov/lwx.
==================================================================
*** ALL-TIME RECORD HIGHS ***
==================================================================
Baltimore 107 (set on Jul 10, 1936)
Washington 106 (set on Jul 20, 1930 + Aug 06, 1918)
Sterling-Dulles Airport 105 (set on Jul 22, 2011)
Baltimore Downtown 108 (set on Jul 07, 2012 + Jul 22, 2011)
Annapolis 106 (set on Aug 06, 1918)
Hagerstown 105 (set on Jul 14, 1954)
Martinsburg 112 (set on Jul 11, 1936)
Charlottesville 107 (set on Sep 07, 1954 + 3 other times)
==================================================================
*** ALL-TIME RECORD WARM LOWS ***
==================================================================
Baltimore 83 (set on Aug 05, 1930 + 2 other times)
Washington 84 (set on Jul 24, 2011 + 2 other times)
Sterling-Dulles Airport 79 (set on Aug 08, 2007)
Baltimore Downtown 88 (set on Jul 02, 2011 and Jul 10, 1993)
Annapolis 92 (set on Jul 07, 1994)
Hagerstown 86 (set on Jun 15, 1899)
Martinsburg 86 (set on Jul 21, 1930)
Charlottesville 85 (set on Aug 07, 1918)
==================================================================
*** JULY MONTHLY RECORD HIGHS ***
==================================================================
Baltimore 107 (set on Jul 10, 1936)
Washington 106 (set on Jul 20, 1930)
Sterling-Dulles Airport 105 (set on Jul 22, 2011)
Baltimore Downtown 108 (set on Jul 07, 2012 + Jul 22, 2011)
Annapolis 105 (set on Jul 21, 1930 + Jul 02, 1901)
Hagerstown 105 (set on Jul 14, 1954)
Martinsburg 112 (set on Jul 11, 1936)
Charlottesville 107 (set on Jul 10, 1936 + Jul 20, 1930)
==================================================================
*** JULY MONTHLY RECORD WARM LOWS ***
==================================================================
Baltimore 83 (set on Jul 21, 1930)
Washington 84 (set on Jul 24, 2011 + 2 other times)
Sterling-Dulles Airport 78 (set on Jul 24, 2010 + Jul 08, 2010)
Baltimore Downtown 88 (set on Jul 22, 2011 + Jul 10, 1993)
Annapolis 92 (set on Jul 07, 1994)
Hagerstown 83 (set on Jul 24, 2010)
Martinsburg 86 (set on Jul 21, 1930)
Charlottesville 84 (set on Jul 22, 1930)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: Jul 01
==================================================================
Baltimore 103 (1901) | 80 (1933 + 1901)
Washington 102 (1901) | 79 (1977)
Sterling-Dulles Airport 96 (2012) | 72 (2017 + 3)
Baltimore Downtown 101 (2012) | 82 (2012)
Annapolis 103 (1901) | 79 (1945 + 1901)
Hagerstown 100 (1901) | 74 (2017 + 1977)
Martinsburg 102 (1933) | 74 (1933)
Charlottesville 101 (2012 + 1945) | 78 (1901)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: Jul 02
==================================================================
Baltimore 103 (1901) | 80 (1901)
Washington 101 (1898) | 79 (2012 + 1872)
Sterling-Dulles Airport 98 (1966) | 75 (2022)
Baltimore Downtown 102 (1966) | 84 (2002)
Annapolis 105 (1901) | 80 (1901)
Hagerstown 100 (1966) | 74 (2018 + 1901)
Martinsburg 102 (1933 + 1931) | 75 (1933 + 1901)
Charlottesville 100 (1954) | 76 (1910)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: Jul 03
==================================================================
Baltimore 104 (1898) | 80 (1898)
Washington 101 (1966 + 2) | 80 (2018)
Sterling-Dulles Airport 103 (1966) | 73 (2018 + 2)
Baltimore Downtown 102 (1997) | 82 (2018 + 1983)
Annapolis 100 (1901) | 84 (1896)
Hagerstown 102 (1966) | 76 (2002)
Martinsburg 102 (1941 + 1911) | 74 (1980)
Charlottesville 100 (1966 + 1954) | 79 (1911)
Period of Record (POR) context...
Area (obs site) Records since
------------------------------------------------------------------
Baltimore (BWI) Jan 1872
Washington (DCA) Jul 1872
Sterling-Dulles Airport (IAD) Jan 1960
Baltimore Downtown (DMH) Jul 1950
Annapolis (NAK) Jan 1894
Hagerstown (HGR) Jan 1899
Martinsburg (MRB) Jan 1891
Charlottesville (CHO) Jan 1893
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.
&&
$$
DISCUSSION...KJP/EST
AVIATION...KJP/EST
MARINE...KJP/EST
CLIMATE...DHOF
NWS LWX Office Area Forecast Discussion