461
FXUS61 KLWX 060717
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
317 AM EDT Sat Jun 6 2026

.WHAT HAS CHANGED...
Most guidance has highest precipitation chances this evening,
though a few models indicate potential for storms north of
I-66/US-50 a few hours earlier. Wind gusts are expected to reach
Small Craft Advisory criteria over the upper waters from late
morning through early evening. Heat indices may briefly approach
95 degrees between 3 and 6pm in a few spots.

&&

.KEY MESSAGES...
- 1) A strong to severe thunderstorm threat glances northern
  portions of the region late this afternoon into this evening.

- 2) Early summer heat continues through the weekend.

- 3) Temperatures briefly drop early next week before increasing
  late in the week.

&&

.DISCUSSION...
KEY MESSAGE 1...A strong to severe thunderstorm threat glances
northern portions of the region late this afternoon into this
evening.

Early morning analysis shows a stout upper-level trough pivoting
across the Great Lakes. High pressure is shifting offshore of
the Carolinas as surface low pressure attendant to the upper
trough quickly moves northeast from Lake Huron toward James Bay.
A cold front trailing from the surface low over the Great Lakes
this morning was headed steadily southeastward. Locally, a weak
surface trough stretched roughly down the US-15 corridor.

The heart of the upper trough will pivot northeast then eastward
into northern New England through tonight, with low pressure at
the surface following suit. The trailing cold front will slowly
but surely drop southeastward, though its progress likely slows
as the parent trough/low pull away to the northeast and high
pressure ridging to the south/southeast only slowly erodes.

Surface dew points were mainly in the upper 50s to around 60
early this morning, slightly higher along the immediate shore of
the Chesapeake Bay. Last night`s 00Z KIAD RAOB showed abundant
dry air aloft through the entire troposphere, and this will be
slow to erode. An axis of low-to-mid-level moisture will advect
eastward ahead of the approaching cold front this afternoon and
evening, offset somewhat due to downsloping effects in westerly
low-level flow. This draws questions into just how much CAPE
develops later today, with the areas most likely to become at
least modestly unstable north of I-66/US-50 closer to the axis
of the incoming theta-e plume.

Mid-level (i.e. 700-500 hPa) flow increases to 30-40 knots this
afternoon into this evening near the Mason-Dixon line as the
upper trough to the northwest encroaches on ridging to the
southeast. Low- and mid-level lapse rates steepen accordingly
with the height falls aloft and robust diurnal heating. RAP
forecast soundings indicate pre-convective lapse rates around 7
deg C/km, steepest in the mid-levels in the I-70 corridor and
steepest in the low-level south of I-66/US-50. This is favorable
for gusty to damaging downburst winds in any storms that manage
to develop, with storm coverage and timing still somewhat in
question given a lack of stronger ascent locally.

Most guidance indicates the highest chances of convection this
evening. However, some members (i.e. WRF-ARW, RAP) have
convection developing a few hours earlier, perhaps out of
activity currently over Ohio which most other guidance
dissipates. If convection develops a bit earlier (mid afternoon)
near the Appalachians, it would move eastward during or just
after peak heating. This would increase the damaging wind threat
conditionally, though overall forcing will be rather weak.
Forcing increases a bit this evening, but the loss of diurnal
heating may cause storms and their wind threat to trend down,
should the later timing pan out.

All in all, this result in a risk of a few strong to locally
severe storms mainly in the I-68/I-70 corridor of northern and
western MD, perhaps down into the eastern WV panhandle, far
northern VA, and the Baltimore metro. Damaging wind gusts appear
to be the main threat, though lapse rates/shear aloft lend to a
conditional risk of some hail particularly in stronger, more
isolated updrafts/marginal supercell structures, should they
form and impact our area. The chance of rain drops off rather
significantly further south (i.e. south of I-66/US-50) due to
forcing being displaced to the north through peak heating.

A few showers may linger as the front nears the area from the
north tonight, but the threat for severe weather or even thunder
looks rather low beyond late evening, barring any greater-than-
expected upstream organization.

For Sunday, the cold front may remain near enough to trigger a
few showers and thunderstorms south of I-66/US-50. Moderate deep
layer flow and steepening lapse rates will again lend to a risk
of a few strong to damaging thunderstorm gusts, though lapse
rates aloft won`t be quite as steep so the hail threat is lower.


KEY MESSAGE 2...Early summer heat continues through the weekend.

Despite some high clouds and gradually falling heights with the
approach of a cold front, well above normal temperatures will
persist through the weekend as any appreciable cold advection
lags and rain remains relatively spotty and brief.

High temperatures are expected to reach the upper 80s and lower
to middle 90s across much of the region this afternoon, with 70s
over the higher elevations. Dew points in the upper 50s to lower
60s should keep heat index values near the air temperature, but
a few readings around 95 are possible mid to late afternoon.

The drier nature of the airmass allows temperatures to fall into
the 60s to lower 70s tonight before rebounding into the upper
80s to lower 90s (70s mountains) on Sunday. Again, dew points in
the upper 50s to lower 60s will hold heat index values close to
the ambient air temperatures.

Low temperatures will likely fall into the 60s (50s mountains)
Sunday night as a cold front presses further south.


KEY MESSAGE 3...Temperatures briefly drop early next week before
increasing late in the week.

An upper-level trough and low-level onshore flow behind a
surface cold front will bring cooler temperatures Monday into
Tue (widespread 80s/cooler in mountains). Overnight lows will be
in the 50s and 60s.

Upper-level ridging builds in Wednesday onward with surface
temperatures increasing daily. Temperatures look to rebound to
the 90s by Thursday into next weekend. Moisture returns with
the increase in temperatures resulting in an uptick in
humidity. Diurnally driven showers and thunderstorms look to
impact the area daily Thursday onward, with perhaps a higher
chance Friday with an upper-level disturbance approaching.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions are likely at the TAF sites through this
afternoon as high pressure gradually departs off the Atlantic
coast. Winds will be generally SW, with a more S component east
of a surface trough and a more W component to the west. Metro
TAF sites such as KBWI/KMTN/KDCA would be most likely to see a
bit more S component. Given decent vertical mixing, gusts up to
20 knots are possible, especially during the afternoon hours
(slightly lower at KCHO). Shower and thunderstorm chances
increase this evening, with KMRB to KMTN seeing the highest chance
for restrictions. Further south, high-resolution models depict
a weakening trend into the night. Although the consensus has
TS probs peaking in the evening, a few members indicate CI a few
hours earlier. Will monitor for possible AMDs. Any restrictions
or gusty winds in/near storms should be brief (sub-hourly).

Winds shift to northwesterly behind the front midday Sunday with
any convective chances mainly near KCHO. High pressure building
to the north will yield mainly north to northeasterly winds into
Sunday into Monday with continued VFR conditions. Some low CIGs
can`t be ruled out Monday night in onshore flow.

VFR is expected to prevail Tuesday into Wednesday with S winds
possibly gusting 15-20 kts each afternoon.

&&

.MARINE...
Generally S/SW flow is expected today, becoming more W/NW by
late tonight. Although the highest likelihood of gusts to around
20 kts is mid to late afternoon, forecast soundings indicate
potential for deep enough mixing to result in gustiness as early
as late morning, with a modest increase in low-level flow
heading into early evening ahead of an approaching cold front.
Have therefore issued SCAs for the upper waters covering 11am to
8pm. A few gusty showers and thunderstorms may approach the
waters late afternoon into this evening, with a few SMWs
possible (again mainly to the north).

Winds turn NW Sunday, N Sunday night, then NE to E Monday. Gusts
could again approach SCA levels briefly Sunday afternoon. More
widespread gustiness is probable Monday in onshore flow. Winds shift
to southerly Tuesday into Wednesday with additional SCAs possible.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 11 AM this morning to 8 PM EDT this
     evening for ANZ530-531-535-538.

&&

$$

DISCUSSION...AVS/BRO/DHOF
AVIATION...AVS/BRO/DHOF
MARINE...AVS/BRO/DHOF

NWS LWX Office Area Forecast Discussion