Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 271412 AAA
AFDLWX

Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
1012 AM EDT Tue Jun 27 2017

.SYNOPSIS...
A sharp upper level trough will move across the region late
today. High pressure builds over the area Wednesday before
moving offshore Thursday. Warm conditions expected towards the
end of the week and through the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Sharp trough axis will move across the area this afternoon and
help trigger scattered showers and t-storms. Moisture and CAPE
are limited, but plenty of large scale forcing to overcome these
negatives. Best coverage is expected along the I-95 corridor
where low-level moisture is higher due to proximity to the
water. Gusty winds will be primary threat due to inverted-V
soundings and large amounts of downdraft CAPE. Convection will
shift east quickly after 21Z with precip ending.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
The surface high pressure center crosses the LWX CWA Wednesday
morning. Return southerly flow develops Wednesday afternoon with a
gradual return to summerlike conditions. Pressure gradient looks
light enough for good radiational cooling Wednesday night.

Max temps around 90F on Thursday with dewpoints rising into the 60s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
High pressure will have moved well offshore by Friday. This
will allow warmth/humidity to stream into the Mid Atlantic.
Upper level ridge will not bring the east coast especially high
heights so expect to see highs around end-of-June climo norms
of near 90.

Low pressure is expected to spin over Ontario/Quebec this
weekend. This will allow a weak cold front/trough to be in the
vicinity of the Mid Atlantic which could provide a focus for
shower/thunderstorm activity, although by no means should the
weekend be a washout.

Looking out to the 4th of July - there are differences between
the Euro and GFS. One thing seems certain is that the possibility
of it being an extremely hot day does not look to be in the
cards. Euro shows east coast "in between short waves" while GFS
has a short wave approaching the Appalachians Tuesay night. We
have a chance of showers/thunderstorms in the forecast but we`ll
continue to monitor in the coming days.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
VFR prevails through the week as high pressure slowly builds from
the west. Passing shower/isolated thunderstorm both this morning and
later this afternoon across the DC metros ahead of a cold front.

High pressure overhead Wednesday with return southerly flow into the
weekend.

Majority of Friday/Saturday should be VFR. There will be
potential for showers/thunderstorms - especially Saturday, which
could drop conditions briefly below VFR.

&&

.MARINE...
Considering an SCA for today or MWS for later this afternoon and
tonight. SMWs may be required later this afternoon.

Return southerly flow begins Wednesday night as the
high shifts to Bermuda.

Winds expected to be below SCA values Friday/Saturday.
Showers/isolated thunderstoms will be possible on the waters
Saturday.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$
Update...LFR
Products...BAJ/WOODY!


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