Forecast Discussion for Willowsford Farm and vicinity from the NWS in Sterling, Virginia

FXUS61 KLWX 180214

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
914 PM EST Sat Nov 17 2018

High pressure over the Ohio Valley will remain overhead through
tonight before moving offshore on Sunday. Several waves of low
pressure will then pass near the region, the first on Sunday
night, and the second on Monday night. A stronger cold front
will then approach the region from the northwest Wednesday.


High pressure will remain overhead late tonight while low
pressure moves northeast into the Midwest. A southwest flow will
develop aloft, and this will cause relatively warmer and more
moist air to overrun the surface cold air in place. Therefore,
clouds are expected to increase, especially north/west of the
I-95 corridor. Did tweak temps down a bit in rural areas for
radiational cooling, but temps may hold steady or even rise if
the clouds do develop overnight.

The 18znam continues to show the possibility of drizzle/freezing
drizzle toward morning, but most other guidance remains dry.
Will continue with the dry forecast for now since the low-levels
below 2kft are progged to be dry, but still cannot completely
rule out drizzle. Patchy fog is also possible. Lows will range
from the mid to upper 20s in the colder valleys and rural areas,
to the mid and upper 30s in downtown Washington and Baltimore.


Southerly flow will develop on Sunday as the weak area of low
pressure moves into the Ohio Valley. Mostly cloudy skies are
expected, but conditions should remain dry for just about
everywhere. Highs from the mid 40s to low 50s.

The wave of low pressure will pass by near or just to the north
Sunday night. Some light showers are possible overnight, mainly
near the PA border and across eastern WV and western MD.
Forecast temperature profiles suggest any precipitation should
be in the form of rain. Lows in the mid 30s to near 40F.

The first area of low pressure will pass eastward on Monday,
while a second low is progged to develop near or west of the
area by Monday afternoon along a frontal boundary. Thus, chances
for rain showers will be on the upward trend Monday, although
at this point, highest probabilities appear west of I-95 and the
metros during the day. The low will move near the region Monday
night and offshore Tuesday morning with the highest chances of
precipitation during this time. Most locations likely to see
rain showers, but a change to snow showers over the higher
terrain appears likely as cold air advection occurs behind the
system Monday night into early Tuesday. A light accumulation of
snow is possible. Highs Monday in the upper 40s to mid 50s with
lows Monday night in the 30s to around 40F.


On Tuesday, expecting high pressure to return to the region behind a
passing cold front, bringing dry weather for most of the
region. However, some upslope snow showers are possible along
the Allegany Front throughout the day, but not expecting much,
if anything, east of there. Cooler air following the frontal
passage will bring continued below average temperatures to the
region, with highs only expected to reach the mid to upper 40s.

On Wednesday, high pressure builds into the region, with dry
conditions expected across the entire area. Temperatures will again
be below average, with temps in the mid 40s. Another cold front will
drop through the region on Wednesday night or early Thursday
morning. This front does not have much moisture or upper forcing to
support precipitation. However, it will bring in much colder air.
High temperatures may struggle to reach 40 on Thursday. With high
pressure building in though, expect it to be a dry day at least.

High pressure continues to build into the region on Friday, bringing
continued dry conditions. Temperatures may rebound slightly, but
remain below average.


VFR expected through late this evening. Low level stratus
clouds are expected to form late tonight and especially Sunday
morning, and MVFR is likely for MRB and CHO, and possible at
IAD. Lesser chances for MVFR exist eastward to BWI/MTN. Its also
not out of the realm of possibilities that some patchy
fog/drizzle occur at MRB/CHO.

Potential for MVFR stratus continues Sunday night into Monday,
with the highest chances continuing at MRB.

VFR is expected through the long term period. Main issues will
just be periods of gusty winds with passing cold fronts, which
look mostly dry at this point.


As high pressure builds into the region through Sunday, winds
will trend lighter and sub SCA conditions are expected through
the weekend. Gradient will also remain weak over the waters
Monday and Monday night as weak low pressure approaches from the
west with sub-SCA conditions forecast.

SCA conditions will be possible Tuesday as a cold front departs the
region. Winds probably diminish Wednesday.


Here are the current rankings for wettest year on record
(through November 15th):

Washington DC area (DCA)
1. 61.33 inches (1889)
2. 60.83 inches (2003)
3. 60.09 inches (1878)
4. 58.58 inches (2018)
5. 58.17 inches (1886)
Weather records for the Washington DC area have been kept at
what is now Ronald Reagan Washington National Airport (DCA)
since 1945. Precipitation records observed downtown extend the
period of record back to 1871.

Baltimore MD area (BWI)
1. 63.18 inches (2018)
2. 62.66 inches (2003)
3. 62.35 inches (1889)
4. 58.98 inches (1979)
Weather records for the Baltimore MD area have been kept at
what is now Baltimore-Washington International Thurgood Marshall
Airport (BWI) since 1950. Precipitation records observed
downtown extend the period of record back to 1871.

Dulles VA area (IAD)
1. 65.67 inches (2003)
2. 59.17 inches (2018)
3. 59.05 inches (1972)
4. 58.09 inches (1996)
5. 55.43 inches (1979)
Weather records have been kept at what is now Washington Dulles
International Airport (IAD) since 1960.

NOTE: All climate data are considered preliminary until
reviewed by the National Centers for Environmental Information





NWS LWX Office Area Forecast Discussion