Scientific Forecaster Discussion
fxus61 klwx 231404
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1004 am EDT Fri Aug 23 2019
a cold front will cross the area today and move
into the southern mid-Atlantic and southeast states this
weekend. Strong high pressure will build north of the region
tonight and settle over northern New England and Atlantic Canada
through early next week. A tropical depression could form over
the weekend as it moves near the southeast coast.
Near term /through tonight/...
initial wind shift has crossed through the region, although
based on temperature/dew point analysis, cold front is still
slowly progressing southward and is located roughly from near
Luray eastward to Warrenton, then northeastward to near
Annapolis. Slow movement southward is expected to continue
through the day today. A surface wave is positioned along the
boundary across central WV and this will move eastward along the
front into the afternoon hours and be positioned near the
southern Delmarva by this evening. Widespread rain showers are
expected across the region, and some heavier rain is possible
just to the north of the surface low this afternoon as is
currently being observed across central West Virginia. Ahead of
the front and surface low, enough instability will likely still
be present this afternoon for some scattered thunderstorms, and
an isolated severe thunderstorm is possible. The risk for this
mainly exists across Nelson and Albemarle counties, possibly as
far north as Spotsylvania and St. Mary's counties.
Temperatures will be considerably cooler, with mainly locations
north of the front already reaching their highs for the day
overnight. Afternoon temperatures likely holding form the upper
60s to the mid 70s in and northwest of the metros, with low 80s
Rain showers will end from northwest to southeast late today and this evening
with drier air filtering in overnight. Lows tonight in the
Short term /Saturday through Sunday night/...
high pressure will build north of the region tonight and hold
strong through early next week. It should be pleasant and mainly
dry, but areas along the lower Chesapeake Bay may still have a
slight risk of a shower or two due to onshore flow.
Long term /Monday through Thursday/...
for the most part, high pressure will be in control of the weather
and provide dry and slightly cooler conditions Monday through
Tuesday. An onshore flow from the western Atlantic could spawn a few
showers or a thunderstorm, mainly Tuesday and across the Potomac
The high pressure will move to the northeast Tuesday night and
Wednesday. A cold front will approach the region from the west.
Ahead of the front, the warmth and humidity will return due to a
developing and persistent southerly flow. A chance for additional
showers and thunderstorms will be present, especially Wednesday
afternoon and evening.
The cold front is expected to push to the southeast and move
offshore the East Coast Thursday. A cooler dome of high pressure
will build behind the front from the upper Midwest and Great Lakes
region. Cooler and drier air will ensue with this high.
Aviation /14z Friday through Tuesday/...
MVFR cigs with showers expected for a majority of the day across
the taf sites. Localized heavier rain with reduced visibilities
are also likely. A few stronger thunderstorms are possible near
cho this afternoon. Conditions will improve tonight.
VFR conditions for all terminals Monday through Tuesday night. Any
isolated shower or thunderstorm could briefly bring conditions to
MVFR and probably would be mainly near mrb or cho Tuesday.
Winds northeast 5 to 10 knots Monday, then variable Monday night.
Winds southeast around 5 knots Tuesday and Tuesday night.
northerly winds will increase as a front moves southward across
the waters and a Small Craft Advisory is in effect across portions of the lower
tidal Potomac and Chesapeake Bay through this evening. In
addition, some smws may be required for the far southern waters
this afternoon as scattered thunderstorms are possible.
Improving weather tonight as cold front pushes south, but
additional northerly flow will create Small Craft Advisory conditions later
tonight into Saturday. Will also need to monitor northerly
channeling and potential tc passing offshore early or mid next
week for increasing winds and possible scas.
No marine hazards expected Monday through Tuesday night. Winds
northeast 10 knots Monday, then light and variable Monday night.
Winds becoming southeast 10 knots Tuesday and Tuesday night.
District of Columbia...none.
Marine...Small Craft Advisory until 1 PM EDT this afternoon for anz530-
Small Craft Advisory from 3 am to 6 am EDT Saturday for
Small Craft Advisory from 1 PM this afternoon to 10 PM EDT
this evening for anz534-537-542-543.
Small Craft Advisory until 6 PM EDT this evening for anz532-