Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
840 PM EST Sat Mar 8 2014
a cold front will pass through the area tonight then high
pressure will return Sunday. High pressure will move offshore
Monday. A cold front will move into the area Tuesday. A low
pressure system is expected to impact the area during the middle
portion of next week.
Near term /through Sunday/...
cold front was located near the Mason Dixon line early this
evening. This front will slip southward through the County Warning Area
tonight...initiating a wind shift to the northwest.
We already have a deck of high clouds over the County Warning Area for mostly
cloudy skies early this evening. Expect ceilings to lower tonight
as a middle-level shortwave/vorticity maximum moves eastward and across the
County Warning Area. This vorticity maximum may also produce some showers overnight. Much
of the showers would be rain showers...but as colder air moves in
behind the surface boundary...rain showers would change to snow
showers over the western slopes and if colder air moves in soon enough
a mix with snow showers could occur near the Mason Dixon line. No
accumulation would be expected with the latter...but over the
western slopes a light accumulation under 1 inch is possible.
High pressure moves into the region from the west Sunday. Gusty
northwest winds are expected with temperatures reach the middle 40s in northern Maryland to
the middle to upper 50s in the Piedmont.
Short term /Sunday night through Tuesday/...
high pressure over the area Sunday evening will slide to the
southeast...and off the coast near the Outer Banks by Monday
morning. Clipper system will pass to the north of the forecast
area...but the only affect here is likely to be middle-level cloud
cover across northern Virginia and Maryland. Less cloud cover further south
will promote better radiational cooling...and the end result is a
fairly uniform low temperature profile across the region. Lows
mostly in the upper 20s to around 30 expected...with temperatures a few
degrees higher in urban Baltimore/Washington.
Another weak boundary moves through Monday...with middle-level cloud
cover expected over most of the forecast area by afternoon.
Otherwise region will be in a return flow regime around high
pressure over the Atlantic. This will support above normal high
temperatures...generally in the upper 50s across northern Maryland to middle 60s
across the Virginia Piedmont.
A cold front is expected to drop down from the north Monday night
and stall across the region Tuesday. The front itself is expected to
be mostly dry...except possibly for upslope precipitation late
Monday night through Tuesday morning in the Potomac Highlands. Warm
advection and cloud cover is likely to keep low temperatures in this
area above freezing...so any precipitation is likely to be liquid.
Otherwise only affect from the front through Tuesday should be cloud
cover and a wind shift to the northwest behind the front. In spite of cloud
cover...wind shift will support downsloping during the afternoon
with highs slightly warmer than Monday.
Long term /Tuesday night through Saturday/...
an upper-level trough and associated deepening surface low will
approach the area from the west Tuesday night. Rain will likely
overspread the area from west to east after midnight and through the
Wednesday morning commute. Warm temperatures ahead of the low should
keep precipitation all rain across the entire County Warning Area.
Temperatures will struggle to climb much during the day Wednesday
with widespread clouds and rain likely. By evening...colder air will
begin to filter in from the north and west as the low deepens along
the middle-Atlantic coast. Depending on how quickly the cold air moves
into the region...any remaining precipitation may end as a brief
period of snow or a rain/snow mix. The best chance for any wintry
precipitation at the moment appears to be well north and west of the
I-95 corridor...generally in the Potomac Highlands.
Another anomalously cold airmass will move over the region late
Wednesday night into Thursday as the storm departs to the
east...with high temperatures Thursday in the upper 30s and lower
40s /about 10 degrees below normal for this time of year/. Clearing
conditions and lighter winds will likely allow temperatures to fall
into the 20s Thursday night...before the airmass quickly modifies
and temperatures return to near or even slightly above normal for
the end of the week into next weekend.
Aviation /01z Sunday through Thursday/...
VFR conditions expected tonight. A cold front will move across
the terminals resulting in a wind shift to the northwest...mainly 03z-
06z. Middle-level shortwave will allow ceilings to fall to around 5k feet
overnight. -Ra is possible for mrb-dca-BWI...but chance not quite
high enough to mention as prevailing in the taf. Northwest winds may gust
near 20 during peak mixing Sunday.
Sunday night...VFR. SW winds around 5kt.
Monday...VFR. SW winds 5-10kt.
Monday night...primarily VFR. Possible fog late. Winds west-SW 5kt.
Tuesday...fog possible early. Otherwise VFR. Winds west-northwest 5-8kt.
Sub-VFR conditions are likely in rain spreading from west to east
after midnight Tuesday night and lasting through the day Wednesday.
A brief mix with or changeover to snow is possible Wednesday
evening...mainly for terminals well north and west of the
District of Columbia/Baltimore metropolitan. Northeasterly winds at or below 10 knots Tuesday
night into Wednesday will become northwest and increase to 10 to 20
knots Wednesday night into Thursday.
cold front moves to the south tonight...promoting a wind shift to
the northwest. Winds increase Sunday morning...and Small Craft Advisory continues
into the afternoon for the waters.
Sub-Small Craft Advisory conditions likely Sunday night through Tuesday. Generally SW
winds Sunday night through Monday night 10kt or less...becoming west-northwest
Sub-Small Craft Advisory conditions are expected in a weak pressure gradient regime
as low pressure passes near or over the area Tuesday night into
Wednesday. Behind the low...winds increase out of the northwest with
Small Craft Advisory winds likely on all waters Wednesday night into Thursday.
water levels increased today...and anomalies were running 1-1.3 feet
above normal early this evening. But given relatively low
astronomical tides...these anomalies are not expected to be
significant enough to promote minor tidal flooding. In
addition...as winds shift to the northwest overnight anomalies
should be on the decrease through Sunday.
District of Columbia...none.
Marine...Small Craft Advisory from 10 am to 6 PM EDT Sunday for