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562
FXUS61 KLWX 241810
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
210 PM EDT Mon Jun 24 2024

.SYNOPSIS...
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High pressure will build back into the area through Tuesday
bringing a brief reprieve to the excessive heat and humidity.
High pressure pushes offshore Wednesday as another cold front
approaches from the Ohio River Valley. The front will cross the
area Wednesday afternoon into Thursday with the next chance for
showers and thunderstorms. High pressure briefly returns from
the north Friday before another series of fronts and increased
heat this weekend.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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An upper trough axis will pivot offshore through tonight, with
high pressure building at the surface. Humidity has really
fallen which will result in notably lower temperatures overnight
tonight compared to the last couple of nights. Breezy conditions
will subside this evening which will also aid in falling
temperatures overnight. Lows are expected to range from the mid
50s to mid 60s, except around 70 in the major urban centers and
right along major bodies of water.
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&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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High pressure will pivot over the area Tuesday, then move
offshore by Tuesday night. Humidity will remain low but
temperatures may end up a degree or two higher than Monday.

Warm air advection will cause an increase in clouds heading into
Tuesday night, with perhaps a few showers or a thunderstorm
approaching the Appalachians through the night.

A sharpening upper trough and associated strong surface cold
front will approach from the Ohio Valley Wednesday, then cross
the region Wednesday night. Return flow ahead of this system
will result in a surge of heat and humidity. Cloud cover as a
result of upstream convection draws into question just how hot
it gets, with some questions surrounding the quality of low-
level moisture return as well. This results in uncertainty
regarding the level of instability, although the potential is
rather high given the ambient airmass. In addition, deep layer
flow and shear will increase to 30 to 40 knots by Wednesday
evening. All of this combined with increased ascent lends to the
potential of strong to severe thunderstorms. This threat will
need to be fine-tuned in the coming days as finer scale details
come into focus, but a considerable severe weather episode is
possible if conditions come together.
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&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
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Heat and humidity return for the weekend along with additional
shower and thunderstorm chances as a series of fronts push through
the area.

Calmer conditions are expected for the late week period as a cold
front slowly exits south and east Thursday with high pressure
building in briefly from the north Friday. A few showers and
thunderstorms may linger along and east of the boundary (i.e east of
the Blue Ridge) Thursday morning into early Thursday afternoon. The
12z GFS and ECWMF advertise a few spotty showers and thunderstorms
mainly across central and eastern VA with high pressure building
south from the Great Lakes region. As for temperatures Thursday,
expect highs to drop back into the upper 80s and low 90s with
dewpoints in the low to mid 60s. Additional relief arrives Thursday
night as dewpoints fall into the 50s under light north to northwest
flow. Lows Thursday night will range from the 50s and low to mid 60s
west of US-15 to upper 60s and low 70s in the metros.

High pressure continues to push eastward into the New England states
Friday before pushing offshore Friday night into Saturday. This will
allow for a light onshore flow component to converge against the
Blue Ridge promoting a few showers and perhaps an isolated
thunderstorm over the central/southern Blue Ridge (Shenandoah
Valley/central VA Piedmont). Most locations will remain dry with
temperatures once again in the mid to upper 80s and low 90s.
Overnight lows Friday night will fall back into the upper 60s
and low 70s areawide with increasing moisture as the flow turns
toward the south.

By the weekend, temperatures look to increase as a series of fronts
push into the area. High pressure will continue off the New England
coast Saturday with a warm front lifting into our region from the
south. This front is in association with an area of low pressure
moving across the northern Great Lakes into eastern Canada. With the
warm front nearby, synoptic/ensemble guidance illustrates a few
showers and thunderstorms mainly tied to areas along and west of the
Blue Ridge. However, the highest probabilities of thunderstorms
appears to be on Sunday as the warm front kicks north and the
incumbent cold front follows from the Ohio River Valley. Some of
these thunderstorms could be on the strong side given the recent Day
6/7 probabilities from CSU machine learning. SPC also makes a
mention in their Day 4-8 discussion although confidence in how
strong the storms will become and placement remains uncertain.
Any rain that we do see will be beneficial at this point given
the flash drought conditions. Highs this weekend will get back
into the low to mid 90s with heat indices running close to or
just shy of Heat Advisory criteria.
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&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
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VFR conditions are forecast through Wednesday morning. Gusty NW
winds will persist until around 00Z before diminishing, then
become SW Tuesday into Wednesday. A strong cold front will
likely touch off some showers and thunderstorms Wednesday
especially late into the day and into the night.
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&&

.MARINE...
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Gusty NW winds will continue into tonight before diminishing
late. High pressure moves overhead tonight, then offshore
Tuesday. Southerly channeling is likely Tuesday night, with
gusty SW flow ahead of a strong cold front Wednesday. This front
will likely deliver strong thunderstorms.
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&&

.TIDES/COASTAL FLOODING...
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Tidal anomalies decrease through Tuesday with NW flow. A return
of southwest winds late Tuesday into Wednesday will bring
another increase in water levels, although no flooding is
forecast at this time.
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&&

.CLIMATE...
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Very hot temperatures are expected on Wednesday. Several
records could be in jeopardy. Below is a list of record high
temperatures for June 26th, the year the record was set, and
the current forecast high temperatures for that day. A plus sign
after the date signifies the record was set multiple times,
with the most recent year indicated below. RERs are only issued
for DCA, IAD, BWI, and MRB, but other sites are shown for
reference.

                                    Wednesday Jun 26th
Washington-National (DCA)    101F (1952)          98F
Washington-Dulles (IAD)       95F (1998)          97F
Baltimore (BWI)               99F (1954+)         98F
Martinsburg (MRB)            102F (1943)          93F
Charlottesville (CHO)         99F (1998)          97F
Annapolis (NAK)               98F (1952)          94F
Hagerstown (HGR)              98F (1954+)         93F
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&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 2 AM EDT Tuesday for ANZ530>534-
     537>541-543.
     Small Craft Advisory until 8 PM EDT this evening for ANZ535-
     536-542.

&&

$$

SYNOPSIS...EST
NEAR TERM...DHOF
SHORT TERM...ADS/DHOF
LONG TERM...EST
AVIATION...DHOF/EST
MARINE...DHOF/EST
TIDES/COASTAL FLOODING...LWX
CLIMATE...LWX