Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia
320 PM EDT Tuesday Jun 2 2015

Synopsis...
a cold front will stall to our south tonight through Wednesday.
The boundary will return north toward our area as a warm front
Thursday before dissipating nearby on Friday. High pressure will
build north of the region during the weekend.

&&

Near term /through Wednesday/...
a cold front will stall out to the south tonight through
Wednesday while an upper-level low remains over the Tennessee
Valley. A southwest flow aloft around the upper-level low will
cause warm and moist air to overrun the surface cooler air behind
the front...resulting in plenty of clouds along with times of rain
and drizzle. Rainfall amounts across most areas should be
light...but a couple heavier showers and thunderstorms may develop
across the central Shenandoah Valley late this afternoon...closer
to the boundary where more instability may develop.

Temperatures this afternoon will hold in the 50s across northern
Maryland...with lower to middle 60s expected in the Washington
metropolitan area to the middle and upper 60s in central
Virginia. Min temperatures tonight will be in the 50s for most areas and
maximum temperatures Wednesday will remain well below normal thanks to the
clouds and precipitation...topping off in the lower to middle 60s
for most areas.

&&

Short term /Wednesday night through Thursday night/...
the upper-level low will slowly slide east into the Carolinas
Wednesday night...increasing the easterly component to the low-
level flow and also increasing low-level frontogentical forcing.
The increased forcing and moisture will lead to more widespread
rainfall...especially for locations near and east of the Blue
Ridge mountains overnight. There is still divergence among the
guidance as to how close the upper-level low gets which will have
an impact on rainfall rates. Should the low be close
enough...there can be a period of moderate to locally heavy
rainfall that occurs...and with already saturated soils this may
lead to an increased threat for flooding. Confidence in this
occurring at this time is low.

Upper low drifts east-northeast from NC to southeastern Virginia Thursday...before drifting
offshore through Friday. This will maintain northeasterly flow over the area
with much below normal temperatures.

Blended the warmer met with mav and previous forecast for continued
maximum temperatures in the upper 60s inland...low to middle 70s near shore and
lower southern Maryland.

Subtropical moisture flux continues into the area with convergence
expected over southern Maryland. 12z GFS suggests this area will have some
instability and some excessive rainfall is possible along this
convergence. This forecast has shifted over the past couple
days...so will need to continue to monitor for specific threats. For
now...thunder possible east from Interstate 95 and in the Allegheny
Highlands in the afternoon. Left a general mention in both sections
of the severe weather potential statement for flood potential. Cloudy across the area through this
period.

Min temperatures Thursday night cool with north-northeasterly flow streamlines stretching
back to the Gulf of Maine where the water temperature is currently
50f. Went with a mav/met/sref blend of middle/upper 50s west of the Blue
Ridge and upper 50s to low 60s east (mid 60s near shore).

Friday...continued north/NE flow with weak low offshore warmup should be
ongoing. However...with continued clouds limited maximum temperatures to middle
70s. Little in the way of rain...just some chances.

&&

Long term /Friday through Tuesday/...
low pressure will move off the East Coast Friday. There is a
chance that a couple of showers will linger. A cold front will sag
southeastward across the eastern Great Lakes and across the region
Friday night. Additional rain showers will develop and continue to
persist Saturday as the front slides into southeast Virginia.
Temperatures each period will be near normal.

High pressure will build over New England and wedge southward
along the East Coast Saturday night and Sunday. A few rain
showers could develop on the cool side of the front with some
upslope rain showers over the Potomac Highland. Temperatures will be
near normal.

The next cold front will drag across the Ohio Valley Sunday night
then push across the region Monday. Showers and perhaps a
thunderstorm could develop along and ahead of the front. Should most
of the rain activity increase in coverage during the middle afternoon
hours...then some thunderstorms could be strong to severe.
Temperatures will be above normal.

&&

Aviation /19z Tuesday through Sunday/...
a boundary will remain to our south through Wednesday night. Warm
and moist air will overrun the surface cooler air in
place...resulting in low clouds along with times of rain and
drizzle. IFR conditions are expected most of the time.
However...ceilings may mix out to MVFR levels for a period this
afternoon and again Wednesday afternoon.

Continued IFR/MVFR ceilings with northeasterly flow persisting Thursday into
Friday. Rain likely Thursday...less for Friday.

MVFR conditions possible Friday through Saturday with rain showers
scattered about the area.

&&

Marine...
a boundary will remain stalled to our south through Wednesday
night. A north to northeast flow is expected during this time. A
Small Craft Advisory is in effect through tonight for the Maryland
Chesapeake Bay and lower tidal Potomac River. The Small Craft
Advisory continues Wednesday for the middle portion of the Bay and
lower tidal Potomac River. Small craft advisories may need to be
extended through Wednesday night for portions of the waters.

Northeasterly flow 15 gust 20 knots with Small Craft Advisory expected Thursday as low pressure
shifts south of the area. Thunderstorms likely and possibly gusty...
particularly for southern Maryland waters. North flow around 10 knots then
Thursday night and Friday.

No marine hazards are expected Friday through the weekend.

&&

Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...Small Craft Advisory until 6 am EDT Wednesday for anz530-531-
536-538-539.
Small Craft Advisory until 6 PM EDT Wednesday for anz532>534-
537-540>543.

&&

$$
Synopsis...bjl
near term...bjl
short term...baj/bjl
long term...klw
aviation...baj/bjl/klw
marine...baj/bjl/klw

National Weather Service Glossary of Abbreviations