Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion...updated 
National Weather Service Baltimore Maryland/Washington District of Columbia
931 PM EDT Fri Oct 21 2016

an upper-level trough will pass through the area Saturday and
high pressure will build into the region for Sunday. A reinforcing
cold front will pass through the area Monday with high pressure
returning for the middle portion of next week.


Near term /until 6 am Saturday morning/...
scattered light showers are expected overnight as heights aloft
fall as upper level system moves across the area. This will
steepen lapse rates and allow for weak instability. Showers are
expected to decrease toward daybreak as subsidence increases
behind trof axis.

Wind fields will increase aloft, and appear sufficient for
advisory level winds at the higher elevations. Even at lower
elevations, gusts will increase toward 30 miles per hour. Temperatures will
continue to fall behind the front. At the highest elevations,
temperatures will be near freezing, and there may be some upslope
snow showers late tonight. Some accumulations less than one half
inch are possible above 3kft.


Short term /6 am Saturday morning through Sunday night/...
the main story for Saturday will be the winds. The peak may come
during the morning hours as mixing increases; however, winds will
remain strong through the day at 30-40 miles per hour. Will have to monitor
for advisory level winds across mainly northern portions of the
area. The existing advisory for higher elevations may need to be
extended into the evening, as low level wind fields are shown to
increase again.

There may be some showers across northern parts of the area (and
upslope) during the morning, but the atmosphere will be drying by
afternoon. Temperatures will be much cooler with highs remaining
in the 50s to around 60 in many locations.

Troughing moves to the east Saturday night and Sunday with high
pressure south of the area. A dry period is expected with slightly
higher temperatures. A reinforcing cold front will approach Sunday
night, with a small chance of showers in The Highlands.


Long term /Monday through Friday/...
a large sprawling area of high pressure will build into the region
from the Great Lakes region Monday into Monday night ushering in a
reinforcing shot of seasonably cool air. The high will persist
through the middle of next week leading to fair and dry conditions
with temperatures at or slightly below seasonable normals.

A cold front may approach the region by the end of next week.


Aviation /02z Saturday through Wednesday/...
the main story for tonight and especially Saturday will be strong
winds. Expect peak values Saturday morning, although 30 kt or
greater will be possible much of the day. Breezy conditions will
continue through Sunday, but at lower speeds.

Mainly VFR expected Monday-Tuesday with northwesterly
winds of 10 to 15 knots.


should see a steady increase in winds overnight and through the
day on Saturday. Gale Warning GOES into effect except for the
upper Potomac tonight and for all waters Saturday. Gales were
extended for the Main Channel of the Chesapeake Bay until 04z sun.

Cold air advection as high pressure builds in will likely
result in winds gusting to Small Craft Advisory levels Monday into


Tides/coastal flooding...
coasta flooding occurring at Annapolis and Straits Point. Blowout
tides expected overnight.


Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...coastal Flood Advisory until 6 am EDT Saturday for mdz014-017.
Virginia...Wind Advisory until noon EDT Saturday for vaz025>027-029-503-
WV...Wind Advisory until noon EDT Saturday for wvz055-501-502-505-
Marine...Gale Warning until 2 am EDT Sunday for anz531>534-539>541-543.
Gale Warning until 6 PM EDT Saturday for anz530-537-538-542.
Small Craft Advisory until 6 am EDT Saturday for anz535-536.
Gale Warning from 6 am to 6 PM EDT Saturday for anz535-536.


near term...lfr
long term...dfh
tides/coastal flooding...lfr

National Weather Service Glossary of Abbreviations