Forecast Discussion
502
FXUS61 KLWX 051414
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1014 AM EDT Sun May 5 2024
.SYNOPSIS...
An active pattern will continue through mid-week as multiple
disturbances pass through the area. A cold front will move through
toward the end of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
A cold-air wedge remains in place to the east of the
Appalachians. Warm/moist advection riding over this wedge is
allowing for precipitation over most of our CWA. During the past
hour, precipitation over Northeast MD and the northern
Chesapeake Bay has been diminishing, while the precipitation
over central MD and eastern WV has been holding its own as it
moves toward central PA. There has been additional development
of heavier showers over north-central and central West Virginia
during this same time stamp as this is the area of better
instability. As time goes on into the afternoon, we expect north
to northeast winds to become southeasterly at light to modest
speeds. Also, our temperatures should climb into the middle to
upper 60s by late afternoon depending on how much clearing. To
the west of the Blue Ridge, temperatures should climb into the
lower to middle 70s. Should we get some clearing and additional
low level warmth and moisture this afternoon, then we could see
additional showers and perhaps a couple of thunderstorms east
of the Blue Ridge. The greatest chance for a thunderstorm during
the mid- late afternoon hours looks to be between the Allegheny
Front and I- 81.
Conditions should dry out overnight, but skies should remain
mostly cloudy. If any breaks in the cloud cover are able to
develop, fog may develop overnight, given weak low-level flow
and ample moisture in place at low-levels following ongoing
rainfall. Temperatures will remain mild overnight, with lows in
the upper 50s to mid 60s.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Previous discussion...
A largely convectively generated disturbance (by ongoing storms
across the Southern Plains) will drift through the
Tennessee/Ohio Valleys toward the area on Monday. The day should
start out dry, but mostly cloudy for most. As the disturbance
drifts toward the area, low-level moisture will be drawn
northward into the area in southerly flow as greater mid-upper
level moisture simultaneously advects into the area aloft.
Daytime heating will allow temperatures to climb into the upper
70s and lower 80s, which when coupled with the increasing
moisture will lead to the development of some surface based
instability. Showers and thunderstorms appear possible Monday
afternoon, with the greatest coverage expected to be across the
Central Shenandoah Valley into Central Virginia, where low-
level convergence is expected to be maximized. Model soundings
show around 1000 J/kg of MLCAPE, along with relatively moist
profiles and weak flow through the lower half of the
troposphere. Such an environment could lead to slow moving,
heavy rainfall producing storms, especially from the Shenandoah
Valley into Central Virginia. 00z CAMs show isolated areas of
2-5 inches of rainfall across those locations Monday afternoon,
which potentially raises concerns for flash flooding. With the
disturbance forcing the precipitation being largely convectively
generated, that makes predictability a bit lower than normal at
this time range, so things could potentially change. However,
we`ll continue to keep an eye on the potential for heavy
rainfall Monday afternoon.
Additional showers and thunderstorms appear possible again on
Tuesday as a disturbance tracks into the Great Lakes. Much like
Monday, high temperatures are expected to reach into the upper
70s and lower 80s. Soundings again show relatively saturated
profiles along with some surface based instability, so storms
may once again be heavy rainfall producers.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Rain and thunderstorm chances will continue by Wednesday, with
an approaching cold front from the west. The precip chances will
increase from west to east later in the day on Wednesday with
highs in the mid to upper 80s for the lower elevations and 70s
for the mountains. Winds out of the west will be gusting to 15
to 20 knots throughout the afternoon. Precipitation chances
increase overnight Wednesday and through the day on Thursday as
the front continues to approach the area. Given the increasing
instability ahead of the front, a few isolated strong to severe
thunderstorms may be possible with the frontal passage on
Thursday. Additionally, some isolated instances of flooding will
be possible with the continuous prolonged batches of
precipitation over just a few days. Still a lot of uncertainty
pertaining to timing, intensity and antecedent conditions. Highs
on Thursday will climb into the upper 70s to low 80s for most
areas.
Behind the front on Friday, precipitation will likely linger around
with highs in the 70s for the lower elevations and 60s in the
mountains. Northwest winds will remain elevated with gusts getting
into the 15 to 25 knots range, with the higher amounts along the
higher elevations. Lingering light showers may persist into the
weekend with highs in the mid to upper 60s for most areas with 50s
in the mountains.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
IFR to LIFR conditions with rain showers at the terminals this
morning with more rain showers filling in during this afternoon.
Thunderstorms could develop across western MD and the eastern
WV Panhandle this afternoon, potentially impacting MRB. IFR
ceiling are expected to persist through much if not all of the
day, although some locations could go MVFR for a few hours this
afternoon. Winds this afternoon will steer away from a north to
northeast direction to a southeast direction. IFR ceilings and
fog look to build back in tonight.
Gradual improvement back to VFR conditions is expected on Monday. An
afternoon or evening shower or thunderstorm may be possible at any
of the terminals, with CHO standing the greatest chance to see
impacts. Winds will be light and somewhat variable Monday.
Prevailing VFR conditions continue into Tuesday, with afternoon
showers and thunderstorms possible once again. Winds will turn
southerly on Tuesday, but remain relatively light.
Mainly VFR conditions for the terminals on Wednesday with increasing
chances of sub-VFR ceilings by Wednesday night into Thursday as
precipitation begins to track across the area. Winds out of the west
will continue to gust out of the west.
&&
.MARINE...
Winds will remain northeasterly in the northern Bay waters,
while staying southeasterly in the central and southern Bay
water through the rest of this morning. Expect winds in all
waters to turn southeasterly by mid to late afternoon. SCAs
remain in effect for the wider waters this afternoon. SCAs may
potentially need to be extended a bit into the overnight hours
in channeled southerly flow. Thereafter, sub-SCA magnitude is
expected on both Monday and Tuesday. Thunderstorms will be
possible both Monday and Tuesday. Any storms that move over the
waters could lead to the issuance of SMWs.
SCA conditions are possible Wednesday and Thursday with increasing
pressure gradient over the waters. Additionally, an SMW may be
needed for any stronger thunderstorms that cross the waters Thursday
afternoon and evening.
&&
.TIDES/COASTAL FLOODING...
Onshore flow will continue to usher in minor to moderate tidal
flooding at the more sensitive locations along the Chesapeake Bay
through Monday morning. Winds will begin to turn more out of the
southwest on Monday with slow improvements in coastal flooding
through midweek. Additional periods of coastal flooding are possible
into Wednesday.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory until 3 PM EDT this afternoon for
MDZ017.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 3 PM EDT this afternoon for ANZ531-
532-538>540-542.
Small Craft Advisory until 6 PM EDT this evening for ANZ533-
534-537-543.
&&
$$
SYNOPSIS...KJP
NEAR TERM...KLW/KJP
SHORT TERM...KJP
LONG TERM...ADM
AVIATION...KLW/ADM
MARINE...KLW/ADM
TIDES/COASTAL FLOODING...KLW
