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765
FXUS61 KLWX 241854
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
254 PM EDT Fri May 24 2024

.SYNOPSIS...
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A frontal boundary will dissipate near the Mason-Dixon Line
today. Another boundary settles to the north and remains there
through the holiday weekend. Eventually a much stronger cold
front pushes through the region Monday into Monday night. A
secondary cold front moves in by mid-week before high pressure
builds in late next week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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A weakly defined frontal zone near the Mason-Dixon Line has
dissipated through the day. However, the early afternoon
observations do indicate a notable moisture gradient with dew
points in the low 50s to the north and mainly 60s across the
local area. Isolated showers and thunderstorms continue to fire
up along the leading edge of this gradient. Multi-hour radar
trends focus this activity along the I-81 corridor down through
central Virginia into far southern Maryland. Showers have been
rather disorganized and slow moving owing to light winds in the
vertical profile. Aside from these isolated showers, most can
expect a dry day across the region. For those north of D.C. and
Baltimore, skies have cleared out with only some shallow fair
weather cumulus evident on recent visible satellite imagery.

For the remainder of the day, afternoon temperatures should top
out in the 80 to 85 degree range, locally cooler where showers
are occurring and over the higher terrain. These spotty showers
and thunderstorms are likely to persist until dusk before waning
given the loss of surface heating. The forecast has been
trending drier for the overnight period. Nighttime lows will a
tad cooler than previous nights given a slightly less humid air
mass in place. Expect mainly upper 50s to low 60s across the
area, with mid 60s more likely along the bayshore and over D.C.
and Baltimore.
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&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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While the frontal zone near the local area will have dissipated,
another boundary settles over Pennsylvania into New York. The
guidance is decent agreement in keeping this system north of the
area which would favor a steady period of warm advection. Very
weak gradients will make for rather weak wind fields for most of
the weekend. The highest winds are likely to be around 5 to 10
mph, although any shower/thunderstorm could easily produce
locally stronger gusts.

The synoptic pattern favors slight height rises through the
weekend. Given these gradual building of heights, daily
convection will need to be driven by local terrain circulations
and mesoscale boundaries. The guidance does break out some
isolated mountain convection early Saturday afternoon. It
remains to be seen how far east the activity can make it before
dissipating. The guidance is not terribly bullish with the
activity given the weak support aloft. Sunday`s convective
threats look similar as well while still under the influence of
shortwave ridging. Daily high temperatures during the holiday
weekend will be in the low/mid 80s, with 70s across mountain
locales. Expect increasingly mild nights ahead as south to
southeasterly flow persists.

Models continue to hint at upstream severe weather from the Ohio
Valley making its way toward the Alleghenies on Sunday night. It
is difficult to say if there would be any lingering severe
threat, but a remnant squall line could impact the Mid-Atlantic
region overnight. What remains of this system will also impact
how the Monday/Memorial Day event unfolds.
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&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
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A strong cold front will push across the CWA Monday into Monday
evening. Heavy rainfall, damaging winds and large hail could
accompany strong to severe thunderstorms. This adverse weather
could lead to travel disruptions on this holiday timeframe. The
severity of the thunderstorms on Monday into Monday evening
could be determine by the limited or widespread coverage of any
showers and thunderstorms that develop Sunday night. Highs
should top out in the lower to middle 80s. With dewpoint
temperatures punching well up into the 60s and perhaps the lower
70s, the warmth and humidity will make for a sticky holiday.
The relief should come from the expected showers and
thunderstorms.

Weak high pressure will build into the region Tuesday and Wednesday.
This high will bring dry and less humid conditions to much of the
area. There could be a few pop-up showers or a thunderstorm each
afternoon as we see a few weaker upper-level disturbances pivot
southeastward across the Great Lakes. Highs near 80 on Tuesday.
Highs middle to upper 70s on Wednesday.

The unsettled and uncertain conditions may linger into the day on
Thursday. A shower or two could develop mainly across the northern
half of the region. Highs will be cooler in the lower 70s.
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&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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The primary convective threat through the afternoon hours will
be across KCHO where showers are currently tracking toward the
south. Terminals to the north should stay dry today while being
on the dry side of a moisture gradient. Winds are rather light
and variable today, accompanied by VFR conditions. Expect much
of the same through tonight.

For the weekend, isolated to widely scattered showers and
thunderstormd can be expected each afternoon to evening.
However, a weak ridge building aloft should limit the intensity
of these showers. VFR conditions are expected otherwise with
light south to southeasterly winds. By Sunday night, strong to
severe thunderstorms may cross the Allegheny Front. If this were
to occur, some restrictions are possible across downstream
terminals.

Sub-VFR conditions Memorial Day into the evening with frequent
showers and strong to severe thunderstorms. A reduction in ceilings
are more probable, but a brief reduction in visibility is also
possible if the shower and thunderstorm activity is heavy. Winds
south to southwest 5 to 10 knots Memorial Day with gusts over 35
knots possible in gusty or damaging thunderstorms. These type of
gusts possible into Monday evening. Winds becoming northwest 5 to 10
knots Tuesday and Tuesday night.
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&&

.MARINE...
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Wind fields remain on the light side which keeps marine winds
below Small Craft Advisory levels. The main threats each day for
the holiday weekend will be diurnal shower/thunderstorm
activity. The upper pattern is not very ripe for organized
convection, but frequent lightning could occur with any stronger
storm. Additionally, cannot rule a Special Marine Warning or
two depending on how these events set up. There is a threat for
nocturnal thunderstorms late Sunday night. It remains to be seen
how far east these will track as they evolve out of the Ohio
Valley on Sunday evening.

No marine hazards expected Monday through Tuesday night. Special
Marine Warnings may be warranted Memorial Day into Monday evening as
strong to severe thunderstorm could rumble across the CWA from west
to east. Winds southeast 10 knots gusts 15 knots Monday and Monday
night. Winds shifting south to northwest 10 knots Tuesday and
Tuesday night.
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&&

.TIDES/COASTAL FLOODING...
Water levels are expected to gradually rise into the weekend
given south to southeasterly warm advection. Many tidal sites
see their higher of the two high tides reach Action stage.
Further increases are likely into Monday/Memorial Day which
could lead to some coastal flooding.

&&

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

&&

$$

SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...KLW
AVIATION...BRO/KLW
MARINE...BRO/KLW
TIDES/COASTAL FLOODING...BRO