Chillum, Maryland 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

390
FXUS61 KLWX 200128
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
928 PM EDT Mon May 19 2025

.SYNOPSIS...
High pressure will settle to the north through Tuesday. A
strong area of low pressure will likely move across the region
Wednesday into Thursday, then move offshore at the end of the
week. A weak area of high pressure approaches the region by the
weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
Late afternoon clouds have mostly dissipated, with just mostly
clear skies expected through late this evening. No changes made
to the forecast as conditions remain dry tonight with a steady
north wind. High-level cirrus builds in after midnight. The
added cloud cover will prevent any sheltered valleys that
decouple from having frost. Chilly tonight as lows settle in the
40s west of I-95, and the low 50s along/east of I-95. Some
spots in the Alleghenies likely drop to the upper 30s.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Quiet conditions are likely for the first half of Tuesday before
the next weather maker impacts the area. While rainfall does not
arrive until later in the day, high clouds are expected to
increase from west to east. Through early Tuesday evening, initial
shower activity will largely be confined to areas west of the
Blue Ridge. Eventually all of this activity overspreads
locations to the east through overnight hours. High temperatures
on Tuesday should largely range from the upper 60s to mid 70s,
slightly cooler in the mountains. The added cloud cover and
rainfall will hold nighttime temperatures in the 50s.

The evolving pattern remains somewhat complex as a slew of
separate shortwaves and closed lows track eastward toward the
local area. As a pair of disturbances eject out of the Great
Plains, some interaction with a northern stream upper low
peeling southward from Quebec is likely. In the net, this
pattern will favor several periods of rainfall, particularly on
Wednesday as the better fetch of Gulf moisture sweeps northward
into the region. While most locations remain in drought, there
are some quite vulnerable to flooding concerns given last
Tuesday`s (May 13) hydrologic event. Most notably, this would
include western Maryland down into Mineral County, West
Virginia, as well as portions of the Blue Ridge Mountains.

Looking more closely at the rainfall forecast, a broad inch is
possible, with higher amounts west of U.S. 15 in Maryland and
portions of the West Virginia panhandle. While the main frontal
zone should be anchored closer to the Virginia/North Carolina
border, an occlusion will extend northward to the primary low in
eastern Ohio. This is the focus of some locally heavier rainfall
which may have some convective elements attached to it. As a
result, forecast amounts of around 2 inches are noted over
Garrett and Allegany, perhaps higher if some of the more robust
guidance verifies. Consequently, this area will need to be
monitored for potential flooding on Wednesday.

After spending the day wedged in with high temperatures in the
upper 50s to 60s, expect diurnal ranges to stay low into
Wednesday night with lows in the upper 40s to 50s (slightly
cooler in the mountains). Some breaks in the rain are possible
as an area of low pressure materializes off the southeastern Virginia
coast.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
A very active upper-level pattern will continue into early next week
as a very slow-moving and broad upper-low remains centered over
eastern Canada into the Great Lakes/Northeast CONUS regions. Several
loves of shortwave energy rotating around the parent upper-low will
likely result in multiple round of precipitation throughout this
timeframe. The exact timing for each of these features beyond
Thursday is somewhat uncertain, but at this point none of them
really seem to have any sort of signal for any significant impacts
at this point. Rain is likely Thursday into early Friday as one of
the stronger lobes of energy rotates through the region. Beyond
that, things just become a bit too uncertain. There will be more
waves of energy, but will there be much moisture to go with them?
That is the biggest question at this point.

At any rate, cooler than average temperatures can be expected during
this time with highs in the 50s and 60s each day. Portions of the I-
95 corridor will reach the low 70s Saturday and Sunday, though still
remaining below normal. Overnight low temperatures will be in the
40s and 50s each night.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Expect VFR conditions to continue through Tuesday evening as
high pressure remains situated to the north over Ontario. Winds
have diminished this evening, though a few gusts to around 20
knots possible through midnight.

Clouds increase through the day on Tuesday ahead of the next
weather maker. However, any rainfall should hold off until
Tuesday evening into the night. This likely starts a lengthy
period of restrictions across the area terminals.

For Wednesday, a cold air damming signature is evident which
will keep conditions cool and cloudy, with widespread rain
expected. IFR conditions will likely persist with a breezy
easterly wind gusting to around 15 to 20 knots. This pattern
holds into Wednesday night with further restrictions expected.

Chances for rain continue through the end of the week, and
potentially even into this weekend. Sub-VFR conditions are likely
Thursday into Friday, but become a bit less likely from late Friday
onward into the weekend due to lots of uncertainty regarding the
exact evolution of the upper-level pattern.

&&

.MARINE...
Small Craft Advisories remain in place across all waters through
midnight. Overnight the strongest winds will focus in the main
channel of the Chesapeake Bay as northerly channeling takes hold.
The Small Craft Advisories in place for the main channel of the
bay continue through Tuesday morning. Some residual winds
possible early Tuesday morning.

For much of Tuesday, expect quieter conditions across the marine
waters. However, a ramp up in easterly flow will support another
round of Small Craft Advisories for Tuesday night into
Wednesday. Easterly gusts of 20 to 25 knots are currently in the
forecast.

Low pressure takes shape off the coast which shifts winds to
northwesterly on Thursday. SCA criteria winds are expected in the
southern portions of the waters both Thursday and Friday afternoon.
Northwest winds gust 15 to 20 both days.

&&

.TIDES/COASTAL FLOODING...
By late Tuesday, the combination of strong high pressure to the
north over Ontario with low pressure passing through to the
south, winds will shift to easterly while strengthening in time.
During a 36-hour period stretching from Tuesday night through
Thursday morning, there will be an increasing threat for Minor
tidal flooding at the more sensitive locations. In particular,
this would include Annapolis where the Steven`s ensembles show
an outside chance of Moderate flooding. Water levels eventually
drop off on Thursday as winds shift to northwesterly.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 2 AM EDT Tuesday for ANZ530-531.
     Small Craft Advisory until 6 AM EDT Tuesday for ANZ532>534-537-
     543.
     Small Craft Advisory until 10 PM EDT this evening for ANZ535-
     536-538>542.

&&

$$

SYNOPSIS...BRO
NEAR TERM...KRR
SHORT TERM...BRO
LONG TERM...CJL
AVIATION...BRO/CJL/KRR
MARINE...BRO/CJL/KRR
TIDES/COASTAL FLOODING...LWX