Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 260757

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
357 AM EDT Sun Mar 26 2017


A cold front is dropping into the Mid Atlantic and will stall
over the area today. This will move back to the north as a warm
front Monday. Another cold front will cross the area late
Tuesday. High pressure will build over the region Thursday.



As of 3am, a 1036mb surface high pressure is centered over north-
central Quebec, 1027mb surface high pressure is centered over
Bermuda, and 1008mb surface low pressure is centered near the border
of IA/MO/IL. The low is weakening/filling under an upper trough over
eastern Canada. The Canadian high pressure will shift southeast
across Maine through today. Influence of the Canadian high is
already felt with a backdoor cold front moving through the area. It
has pushed through KCBE, KOKV, and KEZF in the past hour (and KLWX
radar depicts the front moving from Fauquier to Culpeper County).
South of this front is southerly flow and warmer air from the
Bermuda high.

The front is expected to cross all of the CWA today except maybe
southern Nelson County. Mid-level clouds currently across the area
will thicken, lower and eventually produce rain and drizzle. The 00Z
GFS depicts drizzle across the area before sunrise. Cloud ceilings
are starting to lower on the Eastern Shore with light showers
developing south of Atlantic City over the past hour. Maintained a
forecast of patchy drizzle starting at 10am east from the Blue
Ridge. PoPs remain low given the shallow saturated layer. However,
the occluded front from the Midwest low crosses the western half of
the CWA this afternoon, so likely rain is out there through this

Whether the occluded front will be enough to break the CAD wedge
tonight remains a key question. 00Z consensus shifts the wind to the
south across the area tonight. However, models often erode CAD
wedges too quickly, particularly overnight. So, there is low
confidence in temperatures Monday particularly in NErn zones/in the
Baltimore metro where low clouds may hold on well into the day.
Where wind does shift south, temperatures Monday look to rise well
into 70s.



A second low currently along the CO/NM border will reach the Midwest
late Monday before tracking across the northern Mid-Atlantic Tuesday
per 00Z ECMWF/GFS. Continued moist southwesterly flow warrants high
chance PoPs with slight chance for thunder for the LWX CWA Monday.
Better chance for thunderstorms looks to be Tuesday on the south
side of the low crossing the region.

The cold front trailing this low enters the area Tuesday night
bringing in a brief stretch of quiet weather under high



The first part of the forecast will be dominated by an induced
upper ridge over the Mid Atlantic in-between low pressure east
of Nova Scotia and a developing low across the central US. The
middle part of the week will be dry. Highs Wednesday in the 60s.
Lows Wednesday night 35-40. Thursday should see quite a bit of
sunshine with highs in the lower 60s.

Conditions will deteriorate Thursday night as the aforementioned
low tracks into Missouri to near Lake Erie Friday. The
attendant warm front will hang south of the Mid Atlantic through
Friday. This will bring cooler temperatures to the region,
cloudy skies, and likely PoPs.

Low pressure may develop along the Virginia coast Friday night
keeping the forecast area on the cloudy and wet side through



Onshore flow across the area generally 10 to 15 knots through
tonight. Drizzle and IFR conds expected to develop through the
daylight hours today with ceilings slow to lift tonight.

Southwesterly flow from low pressure to the west/north Monday and
Tuesday brings rain showers and thunderstorms to the DC metros
with the better thunder threat Tuesday afternoon.

VFR conditions Wedensday and Thursday. Clouds will thicken
Thursday nght.



Onshore flow 15 to 20 knots continues through tonight before
shifting south Monday.

Generally sub-SCA SWly flow prevails Monday and Tuesday with thunder
chances Tuesday. Cold front crosses the area Tuesday night with SCA
likely across the area in NWly flow.

High pressure will build into the waters for midweek. No
problems expected on the waters Wednesday/Thursday.


MARINE...Small Craft Advisory until 9 PM EDT this evening for
     Small Craft Advisory until 9 PM EDT this evening for ANZ533-


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