656
FXUS61 KLWX 031820
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
220 PM EDT Mon Jun 3 2024

.SYNOPSIS...
Spotty shower and thunderstorm chances will continue through Tuesday
as low pressure pushes offshore and weak high pressure builds back
into the region. More widespread shower and thunderstorm activity
arrives Wednesday and Thursday as a series of fronts cross the
region. Precipitation chances decrease in the wake of the front
Friday into Saturday before another front and series of disturbances
impact the area early next week.


&&

.NEAR TERM /THROUGH TONIGHT/...
Weak upper level ridging aloft combined with high pressure
offshore will lead to limited coverage for showers and
thunderstorms today through Tuesday. Even with that said, there
should be just enough low level moisture combined with a stalled
front and weak low pressure system passing to the south and
east to touch off a few showers and perhaps a thunderstorms
during the peak heating period. Coverage will mainly confined to
the mountains and in areas along and south of I-66/US-50 where
better lift along the stalled front can be found. Any
thunderstorms look to weaken after sunset with just a few
passing showers during the front half of the overnight period.
Patchy fog is possible in particularly across the river valleys
and right along the bay. Areas that do see the rain will also
see the potential for fog development.

Highs today will remain at or above normal in the upper 70s and low
to mid 80s. Lows tonight will fall back into the mid to upper 60s.
Mountain locations will remain in the 40s while metro centers/bay
locations sit around 70 degrees.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Tuesday`s forecast will be quite similar to Monday`s due in part to
weak upper ridging aloft and high pressure slowly pushing further
offshore. Meanwhile, the frontal boundary associated with the area
of low pressure from earlier in the week will stall somewhere
across central and southwest Virginia. This will yield more of a
southeasterly onshore flow around the high while continuing to
increase low level moisture across the region.

The front will eventually become parallel with fairly zonal upper
level flow aloft yielding additional scattered shower and
thunderstorm chances mainly in areas west of the Blue Ridge and
south of the I-64 corridor Tuesday afternoon and evening. Highs
Tuesday will warm into the mid to upper 80s with upper 70s and low
80s expected over the mountains. Lows Tuesday night will fall back
into the mid to upper 60s and low 70s as low level moisture
increases.

Heading into Wednesday, a potent upper level trough will gradually
dive south into the Upper Midwest and Great Lakes region with a
strong cold front cutting east through the Ohio River Valley and a
warm front lifting north into the Mid-Atlantic region. This will
yield numerous showers and thunderstorms across the region Wednesday
afternoon and evening. Some of these storms could be locally strong
to severe given CAPE values around 500-1000 j/kg per the latest
deterministic/ensemble guidance. 0-6km shear values will also run 30-
40 kts this time with the better increase in shear along the cold
front itself Thursday. Main threats with any thunderstorm activity
will be gusty winds and perhaps a little hail. Locally heavy
rainfall is also possible leading to isolated instances of flooding.
Widespread flooding is not expected given the recent antecedent dry
conditions, low streamflows, and wells across the region. Will
continue to monitor the severe threat which will depend on this
timing in relation to the favorable shear and daytime heating, or
lack thereof.

As for the cold frontal passage, it looks to occur late Wednesday
night into Thursday. Models continue to depict a faster solution
with a warm front late Tuesday into Wednesday followed by the cold
front for the tail end of the midweek. Some subtle timing
differences have yet to be resolved, so the risk of numerous showers
and thunderstorms will likely continue into Thursday.

Highs temperatures Wednesday will push back into the upper 70s and
low 80s given the added cloud cover and increased thunderstorm
activity. Lows Wednesday night will remain in the mid to upper 60s
and low 70s.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Overall an unsettled pattern is expected throughout the long-term
period. A potent upper low will dive southeastward across the region
Thursday into Friday, and potentially hang around for the weekend.
No day looks particularly like a washout at this point, but moreso a
chance for afternoon showers and storms each day. Temperatures look
to gradually cool off each day. Highs on Thursday reach the mid 80s,
but we are back down into the mid 70s potentially over the weekend.

If there is one day that stands out, Thursday may be it. Still a
decent amount of shear around, along with highs in the mid 80s and
low to mid 60s dewpoints. That could lead to a fair amount of
instability to pair with some modest shear.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Prevailing VFR conditions are expected through Tuesday with weak
upper level ridging overhead. Spotty to scattered showers and
thunderstorms are possible each afternoon mainly across terminals
along and west of the Blue Ridge as well as south of the I-66/US-50
corridor. This is where a weak frontal boundary remains acting as a
trigger point for convection during the diurnal peak heating period.
Any terminals that do see showers and thunderstorms will likely
see brief reductions in cigs and vsbys during the aforementioned
time.

Shower and thunderstorm activity will quickly diminish with the loss
of heating overnight into Tuesday morning. Patchy MVFR to IFR vsbys
are possible at KCHO, KMRB, KIAD, and KBWI where skies look to clear
fairly well. Any fog will develop between 08-14z/4am-10am Tuesday
before quickly mixing out Tuesday afternoon. Winds will remain
light and variable today before switching to the south tonight
and southeast Tuesday.

Weak upper level ridging will continue to reduce precipitation
chances across the terminals Tuesday afternoon although coverage
will increase for terminals mainly west of KIAD as a warm front
slowly lifts toward the region. Higher chances for more widespread
restrictions from shower and thunderstorm activity are possible
during the afternoon and evening hours Wednesday as a warm front
lifts through. Some storms Wednesday afternoon and evening could be
locally strong with gusty winds, hail, and heavy rainfall as the
predominant threats. This will lead to brief or temporary reductions
below VFR Wednesday afternoon and evening.

Some stronger storms are possible on Thursday afternoon/evening,
some of which could impact the terminals. As is typical in the
summer, nailing the location of storms at this time range is very
difficult, but should a storm move over any of the terminals, would
likely see some VSBY restrictions. Slight chance for storms
again Friday afternoon as an area of low pressure moves
overhead. Lots of model uncertainty in regards to Friday
specifically, so definitely check the latest forecast as we get
closer in time.



&&

.MARINE...
Sub-SCA level winds are expected through Tuesday as high pressure
remains nearby. Light and variable winds today will switch to
the southeast Tuesday with gusts under 15kts. Spotty showers and
thunderstorms cannot be ruled out due to a weak front stalled
just south of the waters. Cannot completely rule out the need
for a Special Marine Warning for any strong storms later
today/Tuesday, but the magnitude and intensity should be below
severe thunderstorm warning criteria.

SCA level winds return Wednesday afternoon and evening as a warm
front lifts into the area. Winds will increase out of the south and
southeast as the front passes through. Additional showers and
thunderstorms will also accompany this boundary heading into the
afternoon and evening hours. Once again cannot completely rule out
the need for a Special Marine Warning for any strong storms
Wednesday afternoon and evening.

Scattered showers and thunderstorms are forecast Thursday afternoon
and evening across all the waters. Any stronger storm could be
capable of producing wind gusts of 35 knots, in addition to
lightning strikes. Some thunderstorm chances continue into
Friday.

&&

.TIDES/COASTAL FLOODING...
Tidal anomalies will gradually rise throughout the week due to a
developing onshore flow by Tuesday, followed by a persistent
southerly flow through around Thursday. Expect minor tidal flooding
at the typical sensitive areas (Annapolis, Straits Point, DC SW
Waterfront).

A weak cold front crosses the area early Thursday, and the resulting
west winds are likely to cause anomalies to drop.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...EST
NEAR TERM...EST
SHORT TERM...EST
LONG TERM...CJL
AVIATION...CJL/EST
MARINE...CJL/EST
TIDES/COASTAL FLOODING...CJL