Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia
1028 PM EDT Monday Sep 1 2014

Synopsis...
a Bermuda high will persist through Tuesday. A cold front will
cross the area Tuesday night...followed by high pressure through
the rest of the week.

&&

Near term /through Tuesday/...
surface high pressure persists offshore. Water vapor imagery
indicates an upper disturbance moving across WV. Shower activity has
become very isolated. One shower near Warm Springs Virginia may brush
the southern tier of the forecast area in the next couple of
hours...and other spotty areas of light rain are approaching the
Shenandoah Valley. Hrrr has depicted this pretty well...and
indicates some additional shower activity will be possible as the
disturbance moves across the County Warning Area over the next several hours. Kept
mention of thunder across the Potomac Highlands. Although it
should be isolated...cloud tops on the shower near Warm Springs
are at -36c...indicating enough instability for a few lightning
strikes.

Will have potential for fog tonight with moist airmass in
place...but it may be inhibited in some spots with approaching
clouds from the disturbance to our west.

Lows generally in the upper 60s to low 70s tonight...and slightly
cooler in elevated areas.

&&

Short term /Tuesday night through Thursday/...
cold front will still be located across the Ohio Valley at 12z Tuesday.
But front will March eastward through the day...making it to the
Potomac Highlands by late afternoon. Pre-frontal environment will be
warm and moist...but convection likely waits until the front gets
closer to the County Warning Area and have probability of precipitation expanding eastward with time highest
in the evening across the Interstate 95 corridor.

There is the risk for a few storms to become severe /damaging wind
gusts/ Tuesday...especially before dark due to the combination of
instability and increased shear. Confidence is lower further
downstream once the sun sets. Front moves through at night. Probability of precipitation
lower from west to east.

Drier air moves in for Wednesday with the return of sunshine. While
dewpoints are lower...downsloping will support above normal
temperatures which still may be near 90. Same type of scenario on
Thursday.

&&

Long term /Thursday night through Monday/...
weak surface trough...moisture and weak positive vorticity advection may be enough to supply
a slight chance of showers/thunderstorms Friday. Increased moisture
and the passage of cold front will support development of stronger
activity over the weekend and into Monday.

&&

Aviation /03z Tuesday through Saturday/...
primarily VFR conditions expected this evening into the overnight
hours...although a brief shower is possible at all terminals
outside of BWI/mtn. Fog may develop late tonight with a moist airmass
in place.

Thunderstorms and rain possible again Tuesday afternoon/evening ahead of a cold
front.

No significant weather expected middle to late week.

&&

Marine...
earlier gusts on the waters near Tangier Sound have diminished.
Winds generally from the south 10kt or less tonight.

Approaching cold front will likely produce scattered thunderstorms
late Tuesday afternoon and evening...with gusty winds possible.
Front moves through Tuesday night with high pressure building in
for Wednesday.

Southerly channelling/Small Craft Advisory conditions could be possible late
Friday. Cold front expected to move through over the weekend.

&&

Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...none.

&&

$$
Synopsis...cem/bpp
near term...bpp/kcs
short term...bpp
long term...cem
aviation...cem/bpp/kcs
marine...cem/bpp/kcs

National Weather Service Glossary of Abbreviations