Forecast Discussion for Willowsford Farm and vicinity from the NWS in Sterling, Virginia

FXUS61 KLWX 160134

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
934 PM EDT Sat Jun 15 2019

High pressure will move offshore through tonight. A cold front
will approach the area from the north Sunday. The front will
stall out nearby on Monday and remain nearly stationary across
the area through the middle of next week.


A few isolated showers are moving over western MD, eastern WV.
Mid and high level clouds continue to move across the area
overnight, originating from convection in the Ohio Valley.
Current projections show that the decaying convection will
largely stay north of the area through the night. Expect a
milder night with lows in the 60s.


Convective outlook for Sunday is still rather uncertain pending
evolution of today`s activity to the west, and the approach of a
cold front from the north. There`s some potential for showers
during the morning due to a low level jet...or at the very
least, some clouds. If sun can be realized, a warmer and more
humid day will unfold as southerly flow continues. Potential
triggers for convection include the terrain, a lee trough, and
differential heating boundary from the clouds. There`s also
potential for a convective complex to develop upstream in
association with a shortwave and propagate into the area toward
evening. If heating/CAPE can be maximized, there will be
moderate shear to present a threat of locally severe storms.

Looks like there will be a lull in showers/storms late Sunday
night into Monday morning as the area resides between two
shortwaves. A muggier airmass will only allow lows in the mid
60s to lower 70s.

Fine scale details get muddier as the forecast progresses due to
uncertainty of the position of the southward sinking front and
timing of shortwave energy. Currently, a shortwave is projected
to approach the area Monday evening with an attendant low level
jet. As this interacts with the boundary, moderate instability,
and high precipitable water, there could be some potential for
slow moving and/or repetitive storms. While highest QPF
continues to be north/west of the area, 12Z guidance does
indicate a secondary enhancement across our forecast area that
will need to be monitored.


High pressure over the Western/central Atlantic will continue to
funnel warm and moist air into the region Tuesday through Thursday.
Meanwhile, the aforementioned frontal boundary remains stalled
near/north of the CWA. So south of that boundary, expecting very
warm and humid conditions, with highs into the mid 80s on Tuesday,
and cooling a bit on Wednesday into the low 80s. Both days will see
dew points in the upper 60s to low 70s, so it will be quite muggy.

As far as precipitation is concerned, it will be a very active
period. This is due to the presence of the stalled frontal boundary,
and multiple pieces of upper-level energy moving across the region.
Tuesday may be dry to start, but a piece of upper-level energy will
sweep across the region later Tuesday through early Wednesday,
bringing a surface low pressure system along with it. Showers and
thunderstorms will be likely during this time, with very heavy
rainfall possible.

A stronger area of low pressure will slide by to our north and west
throughout the day on Thursday, which should act to finally lift the
front north of the area. As a result, temperatures will increase
once again on Thursday, back into the mid 80s, with dew points
continuing to be oppressive in the upper 60s to low 70s. By Thursday
afternoon/evening, expect a round of thunderstorms to accompany the
passage of the cold from associated with the aforementioned low.

Friday looks to remain mostly dry, other than some showers and
storms in the higher elevations. Temperatures will see a slight dip
into the low to mid 80s, but it should be less humid.


VFR with Mid/high level cigs will continue overnight. Expect
VFR for most of Sunday, though some showers and thunderstorms
may develop by afternoon into the evening in an unstable
atmosphere. Gusty winds and brief heavy rain will be possible.
Likely a lull in precipitation late night into Monday morning,
but additional showers and storms are likely toward Monday
evening, with an additional heavy rain threat. There`s some
indication lower clouds could develop as this activity exits and
a front drops south into the area Monday night.

Thanks to the expected rainfall Monday evening/night, could see some
brief reductions in visibility early on Tuesday morning. Otherwise,
generally expecting VFR conditions to prevail throughout the
Tuesday/Wednesday timeframe. However, thunderstorms will be a
concern in the afternoon/evening hours both days, which could also
bring cig/vsby reductions, and perhaps even gusty winds.


Winds have receded below SCA criteria this evening and are
expected to increase Sunday morning reaching SCA conditions over
the waters. Isolated t-storms are possible Sun afternoon more
likely Sunday evening, which could warrant Special Marine
Warnings. Am not sure how long or over what area the SCA threat
will continue into Sunday evening, as this may depend on have not extended the advisory at this time. Current
indications are that winds will be a bit lighter on Monday,
though more storms are likely by late afternoon and evening.

Winds will generally remain below SCA criteria on Tuesday and
Wednesday. However, with thunderstorms expected each afternoon,
gusty winds can be expected as these cross the waters, so Special
Marine Warnings will probably be needed.


Southerly winds are leading to gradually increasing anomalies.
Don`t have any flooding forecast at this time, but it could come
close in a few places with the Sunday morning high tide.


MARINE...Small Craft Advisory until 6 PM EDT Sunday for ANZ530>534-
     Small Craft Advisory from 11 AM to 6 PM EDT Sunday for ANZ535-



NWS LWX Office Area Forecast Discussion