Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 160106

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
906 PM EDT Mon May 15 2017

High pressure will build into the region through Tuesday,
setting up Bermuda high pressure through Thursday. A cold front
will pass through the region on Friday, then stall near the
Virginia/North Carolina border, before returning north as a warm
front Saturday. A cold front from the Ohio Valley will then
approach the region on Sunday.


The center of surface high pressure extends from Lake Huron to
eastern Ohio, and will slide directly overhead by Tuesday
morning. The mid and upper level ridge axis is located along the
Mississippi Valley and will reach the east coast by Wednesday.
Skies will be clear tonight except for a few cirrus skirting
western portions of the area. Winds have decoupled and will
remain light to calm the rest of the night. With favored
radiational cooling and dew points around 40, will be broadening
the range of temperatures tonight between the rural valleys and
urban centers. Downtown Baltimore/Washington likely will stay
in the mid-upper 50s while some of the western valleys will be
near 40.

A weak disturbance is expected to move across northern portions
of the region and mid- level clouds may move into the region in
the mid-late morning. Southerly flow is expected by Tuesday
afternoon and will be the beginning of warm conditions across
the region. Temps will climb into the upper 70s to lower 80s
Tuesday. With ridging moving in and a lack of sufficient
instability, precipitation is not expected.


High pressure moves off the east coast by Tuesday evening and
southerly flow continues across the region. Any convection will
diminish around sunset Tuesday evening. Mild conditions
expected into Wed morning with temps in the U50s/L60s.

Much warmer conditions expected Wednesday with temperatures topping
out near 90 deg Wed afternoon. Another day of southerly flow will
increase dewpts across the region and with warm temps instability
will be present. A cu field will likely form with iso showers and
thunderstorms mainly west of I-95. Convection will again
diminish near sunset Wed evening and dry conditions are
expected overnight.


High pressure will set up shop near Bermuda through the weekend.
This will keep the area in a generally warm and moist southwesterly
flow/summer-like pattern.

A pop up thunderstorm is possible Thursday afternoon with any
terrain circulation patterns that set up on the local scale, but
lack of forcing for ascent and a capping inversion around 700 mb
should preclude widespread convection.

A weakening cold front will drop into the area Friday resulting in a
more numerous showers and thunderstorms. Widespread severe looks
unlikely at the moment with the bulk of better shear displaced to
the north, but given the heat and humidity there will be enough
energy for the storms to feed off of Friday afternoon, so a few
stronger storms can`t be ruled out especially if a bit of a broken
cluster develops along the front.

The front will stall just south of the area during the first half of
the weekend, then return north as a warm front by Sunday. Models
begin to diverge on the timing of the next (stronger) cold
front/upper-level shortwave which would bring another chance of
showers and thunderstorms sometime Sunday into Monday.


Predominantly VFR expected through at least Wednesday night.
Expecting only some scattered high cirrus and possibly some
afternoon cumulus during the period. There may be an isolated
shower or thunderstorm Wednesday afternoon, but the chance of
one affecting any particular TAF site is very low. Winds will become
light and variable later tonight, and then turn to the
south/southwest for Tuesday/Wednesday around 10 knots or so.
Valley fog may affect MRB Wednesday morning.

Mainly VFR Thu w/ brief sub-VFR psbl Fri PM in sct`d
SH/TSRA. Winds SWLY 10-15 kts.


Extended the SCA until midnight on the southern MD waters, as
there were indications winds could resurge for a few hours once
air temperatures cool below water temperatures. However, if
current conditions continue (strong inversion and light winds),
will be able to cancel early. Winds will turn to the
south/southwest Tuesday as a warm front crosses the region with
winds less than 10 kt. SCA-criteria gusts may occur over
portions of the waters Wednesday night as a nocturnal low level
jet develops.

Southerly channeling may bring gusts into Small Craft
Advisory range Thursday into Friday ahead of an approaching cold
front. This front may also touch off a gusty thunderstorm or two
Friday afternoon and evening.


MARINE...Small Craft Advisory until midnight EDT tonight for ANZ533-534-


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