Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 222021
Area Forecast Discussion
National Weather Service Wakefield VA
421 PM EDT Sat Apr 22 2017
A frontal boundary becomes nearly stationary across the Carolinas
tonight and Sunday. Low pressure will slowly track along the
southeast coast Sunday and Monday, then linger off the Mid Atlantic
coast through mid week. This system will bring periods of moderate
to heavy rainfall to the region.
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
FYI...Results from the storm survey in the Colonial Beach area
shows mainly straight line wind damage. Official statement to be
issued later today.
Latest MSAS has cold front draped across southern most Va zones
and is progged to slowly sag south into NC this evening before
stalling there overnight. Threat for strong to severe storms
will be along and south of this boundary into the evening mainly
west of I95. SVR WW Box 157 through 01Z. Fairly stable north of
it as high pressure to the NW prodives an in-situ wedge scenario
as rain continues to move in from the west. A decent feed of
moisture results in likely to cat pops this evening (locally
heavy downpours) then trailing off after midnight as the the
wave moves east. Overcast with areas of rain, drizzle and fog
overnight. Much cooler as the high to the NW provides the CAA.
Lows 45-50 NW, 50-55 SE.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
A cloudy and wet period ahead with periods of mdt to hvy rainfall.
QPF btwn 1.5 to 3.5 inches (highest across the Piedmont).
Models in general agreement that a cut-off upr level low tracks SE
across the lwr Mid Atlantic region tonight and Sunday. System then
takes on a neg tilt that spawns a coastal low off the se coast
Monday. This system get cut off from the main upr lvl flow which
allows it to spin over the warm Gulf Stream waters Monday and
Tuesday before slowly lifting NE Wednesday. Upshot will be for
mainly cloudy skies with periods of mdt to lclly hvy rainfall
through the period as copious amounts of deep Atlantic moisture gets
entrained and rotates around the system. Thus, confidence high
enough to go with likely to categorical pops each period. First shot
of mdt to hvy rainfall will be Sunday, second one Sunday night and
Monday and possible a third one Monday night. NAM more agressive
than GFS with thunder chcs as the NAM actually brings the system
inland thus allowing a warm sector to develop along the sern coastal
areas. GFS keeps the system offshore. Thus, kept high pops but low
chc thunder given the model differences.
Highs Sun in the mid 50s to lwr 60s. Lows Sun nite in the upr 40s-
mid 50s. Highs Mon in the mid 50s-mid 60s except 65-70 sern coastal
areas. Lows Mon nite in the upr 40s-lwr 60s. Highs Tue in the lwr
Hydro wise, no flood headlines anticipated attm with numerous breaks
in between bouts of rain expected. Do expect some healthy rises in
local river by early next week, especially if the heavy rainfall
falls over the headwaters. Given the forecasted QPF and after coord
with the RFC, expect minor flooding at Lawrenceville on the Meherrin
River by Tue. Again, this based on QPF so plenty of time to adjust
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Long term period will feature a trend towards drier and warmer
conditions. For Tue night, mid-level cutoff low and associated
sfc low start to progress offshore, with some pcpn psbl on the
backside of the systm. PoPs range from 20-40%. Warming trend
then commences for Wed as deep SWly flow develops across the
eastern seaboard, lasting through the end of the week with temps
in the 70s Wed reaching the 80s most areas Thu and Fri.
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
As of 18Z...A nearly stationary front is draped across southern
portions of the forecast area. This front should continue to slowly
drift south through the afternoon and evening hours. IFR ceilings,
currently impacting SBY/RIC/PHF, will continue to expand to the
south behind the boundary. Widespread IFR ceilings are expected
tonight and into tomorrow morning as the front moves south of the
region. Rain shower coverage is also expected to increase through
the afternoon and evening hours for much of the area with MVFR
visbilities possible in the heaviest showers. Winds turn to the NE
and will be gusty at times behind the front, occasionally gusting in
excess of 20 knots near coastal sites.
Outlook: Lower pressure will linger off the Carolina coast through
early next week. Unsettled conditions, widespread moderate to heavy
precipitation, and degraded aviation conditions are expected Sunday
through Tuesday. Drier conditions are expected on Wednesday and
-- Changed Discussion --Surface analysis and radar imagery depict the cold front south of
the Chesapeake Bay and approaching the VA/NC border at 330 PM EDT.
The front will continue moving to south of the waters this evening.
Winds north of the boundary were from the north and northeast.
Low pressure over the Tennessee Valley will slide eastward into the
Carolinas Sunday and deepen off the Carolina coast Sunday night and
Monday. Northeast winds will increase with seas increasing through
SCA is in effect for the Chesapeake Bay and Currituck Sound and the
coastal waters south of Parramore Island. The SCA expands into the
Lower James River and the coastal waters north of Parramore Island
at 10Z (6 AM EDT). The SCA expires late Sunday morning north of New
Low pressure lingers off the coast through Tuesday. Current
headlines run through Sunday night most of the area and especially
the coastal waters but will likely be needed into Tuesday or
Wednesday. Winds will generally run 20 to 25 knots with seas
building to at least 6 to 8 feet due to prolonged northeast
-- End Changed Discussion --
An extended period of onshore flow will result in increasing
tidal departures thru mid week. Tidal departures will reach +1
to 1.5 feet through Sunday night along the Atlantic coast and in
the lower Chesapeake Bay and James River. Northeast flow
increases Monday, with tidal departures of 1.5 to 2 feet. Minor
flooding is expected Monday night thru Tuesday during high tide.
Flow becomes offshore Wednesday.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ632-634-654-
Small Craft Advisory until 10 PM EDT Sunday for ANZ633.
Small Craft Advisory until 10 AM EDT Sunday for ANZ630-631.
Small Craft Advisory from 6 AM Sunday to 6 AM EDT Monday for