Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1051 am EST Thursday Nov 27 2014
an upper-level disturbance will pass through the area today and
high pressure will build overhead Friday. The high will move off
the coast during the weekend. A cold front is expected to move
Near term /through tonight/...
update to cancel the dense fog advisory. Any leftover patchy dense
fog in the Shenandoah Valley will burn off by noon.
An upper-level disturbance will pass by to our south late this
morning and a reinforcing cold front is expected to pass through
the region this afternoon. These systems may bring a few showers
to the area today...but precipitation amounts will be light. For
this morning...the best chance for showers will be across southern
Maryland and the Virginia Piedmont...closer to the track of the
upper-level disturbance. The cold front may trigger a couple rain
or snow showers this afternoon...but precipitation amounts will be
light and little or no snow accumulation is expected. The one
exception will be for locations along and west of the Allegheny
Front...where snow showers will be more widespread. Even across
these areas preciiptation amounts will be light so little snowfall
accumulation is expected. Maximum temperatures will range from the upper 20s
and lower 30s in the mountains to the lower and middle 40s near
Washington and Baltimore.
Surface high pressure will build toward the region tonight behind
the cold front...but another upper-level disturbance will swing
through the area during this time. A pressure surge will cause
blustery conditions and it will be cold due to a northwest flow.
An upslope northwesterly flow will bring accumulating snow to
locations along and west of the Allegheny Front. A few snow
showers may spill east of the mountains across northern
Maryland...extreme northern Virginia and eastern West
Virginia...but little or no snow acccumulation is expected. Forecast
min temperatures will range from the low 20s in the mountains to the low 30s
near the cities.
Short term /Friday through Saturday/...
still may have a few upslope snow showers ongoing to start Friday
otherwise surface high builds in from the west for dry
conditions/some sunshine but below normal temperatures.
Surface high shifts offshore Friday night. Shortwave in 500 mb flow
will bring increasing clouds Friday night into early Saturday. Much
of the County Warning Area should be dry although there will be a slight chance of
snow showers over the Allegheny/Potomac Highlands. Temperatures
start to moderate a little for Saturday.
Long term /Saturday night through Wednesday/...
return flow around high pressure located offshore will moderate
temperatures more Saturday night into Sunday. A warm front will
likely push north for Sunday. There will be some clouds but chance
of precipitation appears minimal.
Above normal temperatures are likely to persist into Monday. A cold
front will move across the area with a chance of rain showers.
Colder air is then expected to move in behind the front for the
Aviation /16z Thursday through Monday/...
MVFR/IFR conditions at kmrb and kcho will improve to VFR levels by
this afternoon. VFR conditions will persist through tonight.
High pressure builds in for Friday then moves offshore for the
weekend. No significant weather is expected.
weak low pressure will move south of the waters today leading to
northwest winds 10-15kts. Nearly winds behind the low will increase and
Small Craft Advisory conditions are expected tonight for portions of the waters
Northwest winds behind a shortwave should be able to mix down for
Small Craft Advisory conditions on Friday. High pressure builds in for less wind
Friday night. Return flow on Saturday could then increase into Small Craft Advisory
District of Columbia...none.
Marine...Small Craft Advisory from 7 PM this evening to 6 PM EST Friday
Small Craft Advisory from 8 am to 6 PM EST Friday for anz535-