Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
241 PM EDT sun may 24 2015
high pressure located to the east over the western Atlantic will
promote warmer and more humid weather over the next several days.
An approaching cold front will increase the risk of showers and
thunderstorms starting Tuesday and continuing later this week.
Near term /through Monday/...
latest surface analysis shows high pressure along the coast of
Virginia...with a storm system well to the west in Colorado and
another well to the north in southeastern Canada. Aloft...a strong
ridge of high pressure is located over Florida with a ridge axis
extending northwest towards the western Great Lakes...and a closed
low to the west over The Rockies. A west-northwest flow aloft is
in place over our area.
Over the next 24 hours...the ridge aloft will shift slightly east
while the ridge axis will shift east faster...ending up over our
region by late Monday afternoon. The high pressure will shift a
bit further east but its influence will remain and the
southwesterly flow of moist and warm air on its western periphery
will continue over our area.
This will promote a continued trend of warmer and more humid
weather...with temperatures staying in the 50s and 60s tonight and
rising well into the 80s on Monday. Dew points which are in the
upper 40s to lower 50s currently will rise into the middle to upper
50s. Some cumulus buildups over the mountains this afternoon
should not produce any showers or thunderstorms but these clouds
will likely advect northeast into the metropolitan area this evening and
skies may cloud over for a time as a result.
The clouds should break up/advect northeast away from the area
later tonight and skies on Monday should be mostly sunny with high
cirrus and a few cumulus being the main features. The ridge aloft
should suppress any convection and keep the weather dry despite
the increased warmth and humidity. Winds will become more
noticeable as the pressure gradient increases...with gusts above
20 miles per hour likely across the area Monday afternoon.
Short term /Monday night through Wednesday/...
return flow continues Monday night as high pressure stays off the
East Coast. The upper level ridge will also move eastward which
will allow moisture to increase through the column. Showers are
possible in The Highlands early Tuesday morning as some
dissipating convection moves into the region. Scattered showers and
thunderstorms are expected Tuesday afternoon mainly along and west
of the Blue Ridge as the upper level ridge influences areas closer
to the East Coast. Storm motion is expected to be S-SW on the west
side of the ridge so showers and thunderstorms should stay near
and west of the Blue Ridge. As the ridge moves eastward Tuesday
night...some showers will be possible across northern Maryland. At this
time...instability and shear are weak and any thunderstorms should
stay sub-severe Tuesday.
Wednesday will be warmer and more humid than Tuesday as the upper
level ridge moves further off the East Coast. This will lead to
more widespread shower and thunderstorm activity Wednesday
afternoon. A disturbance is also expected to approach the region
Wednesday as a upper level jet moves across the eastern Great
Lakes. Instability and shear will increase by the afternoon and
some storms will have the potential to be severe. High precipitable waters will
also lead to heavy rainfall.
Long term /Wednesday night through Sunday/...
a cold front at the surface will approach the region from the
lower Great Lakes and eastern Ohio Valley Wednesday
night...allowing for a couple of showers and thunderstorms to
linger in parts of the region. Low temperatures will be about 10
to 15 degrees above average.
The cold front should push through the region Thursday.
Additional showers and thunderstorms will develop ahead of and
along the front in response to some daytime heating. High
temperatures will approach 90 degrees in most places with middle
80s expected farther to the west.
We expect the cold front to stall across the eastern half of the
region Thursday night and Friday...providing ample opportunity for
showers and thunderstorms to develop and produce heavy rainfall.
There will be plenty of moisture along the front as well as light
and variable winds in the middle and upper levels of the
atmosphere...hence any activity should be moving slowly from west
to east. Low temperatures Thursday night and high temperatures
Friday could still be 7 to 10 degrees above average.
The cold front is expected to briefly return northward as a warm
front Friday night before a second cold front...moderately-
strong... approaches the region Saturday. While shower activity
may be scattered Friday night...showers and thunderstorms will
develop Saturday along the cold front and could bring heavy
rainfall and gusty winds. Low temperatures Friday night and high
temperatures Saturday could be 10 degrees above normal...reaching
the upper 60s and near 90...respectively.
The cold front should slowly push through the region Saturday
night into Sunday. Showers and thunderstorms will still linger
along the cold front Saturday night into Sunday...but become more
isolated in the Potomac Highlands later in the weekend. Lows
Saturday night and highs Sunday will still be above average.
Aviation /18z Sunday through Friday/...
VFR ceilings and visible very likely through the next 36 hours as high
pressure remains in control. There will be some cumulus this afternoon
and evening...probably some on Monday but likely not as much. The
increasing southwesterly flow will likely prevent any fog
formation despite increasing humidity...while the ridge aloft
should suppress any potential showers or thunderstorms. Winds will
increase from the south and southwest on Monday afternoon with
gusts above 20 knots likely.
By Tuesday afternoon -shra/thunderstorms in the vicinity possible mainly at mrb/cho.
-Shra/thunderstorms and rain are likely at all the terminals Wednesday. Some storms
may produce gusty winds and heavy rainfall resulting in sub-VFR
MVFR to IFR conditions possible at all terminals Wednesday night
through Thursday with showers and thunderstorms. Winds generally
southwest 5 to 10 knots with a few higher gusts.
a few gusts to around 20 knots have occurred this afternoon so
have kept Small Craft Advisory in place. As high pressure continues its slow March
eastward into the Atlantic...the pressure gradient will begin to
increase as we get further from its center and the south-southwest
flow will increase. After possibly relaxing a bit
overnight...winds will increase to Small Craft Advisory levels across most waters
by Monday afternoon and have also not altered the Small Craft Advisory in this time
frame either. It may need to be extended across the remaining
waters if some of the predicted gusts materialize but not
confident yet. No precipitation is expected through Monday night.
Gusty S winds will continue on the waters Tuesday and Wednesday
and Small Craft Advisory may be needed or extended. Showers and thunderstorms
possible Wednesday and some may produce gusty winds and low visibilities
on the waters.
Small Craft Advisory conditions possible Wednesday night through
Thursday...primarily for the main Stem Chesapeake Bay.
District of Columbia...none.
Marine...Small Craft Advisory from noon Monday to 6 am EDT Tuesday for
Small Craft Advisory until 6 am EDT Tuesday for anz534-543.
Small Craft Advisory until 6 am EDT Monday for anz532-533-537-
Small Craft Advisory from noon Monday to 2 am EDT Tuesday for