Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 241347
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
947 AM EDT TUE MAY 24 2016

.SYNOPSIS...
Low pressure off the Mid-Atlantic coast this morning will move
northeastward towards New England today and then toward the
Canadian Maritimes tonight. High pressure over the southern
Appalachians this morning will settle off the southeastern coast
by Wednesday and generally persist through the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Upper low continuing to slowly pull away from the region with
drier northwest flow working into the area. Expecting mostly sunny
skies across the region today with a few cirrus as well as some
instability cumulus developing this afternoon. Can`t rule out an
isolated sprinkle or light shower either but the vast majority of
the region should remain dry. Sky may also appear slightly hazy
with wildfire smoke lofted high in the atmosphere. Highs around 80
degrees pretty much area-wide with a northwest breeze gusting
15-20 mph.

Previous discussion...
Tonight high pressure shifts east but ridge with weak flow sits
overhead. This will again promote patchy fog development.
Otherwise...seasonal to a bit mild with lows in the 50s...60s in
the urban core.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Wednesday high pressure will dominate with continued warming.
Highs will reach the low to mid 80s. Southwest flow will continue
milder pattern Wednesday night...but an approaching weak system
will bring increased clouds and maybe even a stray shower late in
the mountains. This threat will spread east during the day
Thursday as weakening shortwave moves into the area. Have best
POPs west given some terrain influence likely...but advection will
likely carry activity east towards the metro. This will wane but
not completely end overnight as the shortwave drifts overhead.
Highs on Thursday will reach well into the 80s while lows Thursday
night stay well into the 60s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
An upper level northern stream ridge will persist over the eastern
CONUS Friday into Monday/Memorial Day. A southern stream low is
expected to develop off the southeastern CONUS coast per 00Z global
guidance consensus. Whether this low comes ashore or persists in the
gulf stream is yet to be determined.

Friday looks to be unstable with light sly flow and mainly terrain
driven diurnal thunderstorms.

Onshore flow and rain are possible at some point sunday into next
week from the coastal low. The 00Z GFS and ECMWF both feature
Memorial Day Monday into Tuesday as rainy. This would be a fitting
end to a rainy month.

Instability would be low in onshore flow Monday/Tuesday with
showers the expected precip.

Temperatures may be on steady cooling trend Friday into next week
due to this coastal low. Friday may yet have 90F temperatures in the
Balt-Wash metro where cloud cover should be less than farther west.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
Predominantly VFR through at least Thursday night. Some fog may
bring some reductions late tonight, early Wednesday morning, but
have left VFR for now as coverage will be patchy. Will also be
some scattered showers and thunderstorms around on Thursday which
may bring some brief reductions.

Light sly flow and diurnal thunderstorms Friday. ifr conds expected
in heaviest activity.

Forecast confidence drops this weekend through Memorial Day with a
coastal low likely on SErn CONUS. Onshore flow and rain chances
increase Sunday through Tuesday.

&&

.MARINE...
Marginal SCA in effect for gusts up to 20 knots through this
afternoon. Lighter winds return tonight and through Thursday but
shower/storm threat returns Thursday.

Light sly flow continues Friday. Flow looks to become onshore over
the weekend and persist into Tuesday.

&&

.TIDES/COASTAL FLOODING...
Water levels a half foot above normal early this morning. NWly
flow should keep any rises limited. No coastal flooding is
expected today.

&&

.CLIMATE...
We put together some records (preliminary) of how this month compares
to rainy Mays on record for our area.

Washington, DC (records since 1871)
Most days in May with at least a trace: 25 (in 1952
and 1943) So far in 2016 (through 2AM EST on the 24th): 20

Most days in May with at least 0.01": 20 (in 2003)
So far in 2016 (through 2AM EST on the 24th): 18

Highest May monthly rainfall: 10.69" (in 1953 and 1889)
So far in 2016 (through 2AM EST on the 24th): 5.22"

Baltimore, MD (records since 1870)
Most days in May with at least a trace: 25 (in 2003)
So far in 2016 (through 2AM EST on the 24th): 20

Most days in May with at least 0.01": 21 (in 1882)
So far in 2016 (through 2AM EST on the 24th): 16

Highest May monthly rainfall: 8.71" (in 1989)
So far in 2016 (through 2AM EST on the 24th): 4.92"

Dulles, VA
Most days in May with at least a trace: 23 (in 2003)
So far in 2016 (through 2AM EST on the 24th): 21

Most days in May with at least 0.01": 21 (in 2003)
So far in 2016 (through 2AM EST on the 24th): 17

Highest May monthly rainfall: 10.26" (in 2009 and 1988)
So far in 2016 (through 2AM EST on the 24th): 6.07"

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for
     ANZ530>543.

&&

$$
SYNOPSIS...RCM
NEAR TERM...MM/RCM
SHORT TERM...RCM
LONG TERM...BAJ
AVIATION...BAJ/MM/RCM
MARINE...BAJ/MM/RCM
TIDES/COASTAL FLOODING...RCM
CLIMATE...DFH



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