Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KRAH 220802
Area Forecast Discussion
National Weather Service Raleigh NC
400 AM EDT Sat Apr 22 2017
A cold front will settle south through VA this morning and into
central NC this afternoon through tonight. The front will stall over
southeastern NC by Sunday, in advance of a slow-moving area of low
pressure that will track along the coast of the Carolinas through
.NEAR TERM /THROUGH TONIGHT/...
As of 935 PM Friday...
Highest threat for scattered showers and isolated thunderstorms into
the overnight expected to occur across the Piedmont into the far
northern coastal plain. Air mass across the region fairly moist with
precip water values hovering around 1.25 inches. At the sfc a weak
sfc trough extended from the foothills of western NC newd into VA.
The main sfc cold front stretched from western PA southwest into
middle TN. Aloft a weak perturbation was traversing eastward,
entering the western sections of central NC. This feature aloft
interacting with available moisture and weak convergence along the
sfc trough will maintain a threat for scattered showers, primarily
prior to midnight across the western Piedmont, and into the
overnight across the northeast Piedmont and the far northern coastal
plain. Severe storm parameters barely register across our region
while the better shear and instability reside well to our west and
Plan to maintain broken-overcast skies across the north half, and
variably cloudy skies across the south. Temperatures should be
fairly uniform in the 60-65 degree range.
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
-- Changed Discussion --As of 400 AM Saturday...
This long duration rain event on tap through the short term forecast
has the potential to produce widespread 2-3 inches of rain. This
will ultimately be beneficial in alleviating the abnormally dry to
moderate drought conditions which have been gradually developing
through the late winter/spring across central NC. The heavier rain
focus shifts from the west initilly Sunday to the east on Monday,
which will help mitigate the potential for widespread flooding, but
some flooding is possible on creeks and streams, and even our larger
rivers may have some minor flooding from Sunday night into early
As mentioned earlier, the initial focus for heavier rain will be in
the western Piedmont on Sunday as low level isentropic lift will be
focused on the frontal/CAD zone. Rain will ramp up over the
remainder of the forecast area later in the day and peak Sunday
night over the Piedmont as low level flow backs southeasterly as the
surface low pressure system moves slowly east across South Carolina.
The heavier rain then shifts east as the digging cutoff low phases
with the surface system Monday morning and begins to lift slowly up
the coast through Tuesday. Categorical PoPs through the period with
QPF amounts ranging from slightly >3 inches across the north to 2.5
inches in the southeast. CAD-flavored high temperatures in the Triad
will struggle into the mid and upper 50s Sunday and Monday with the
southeast reaching low 70s. Scattered non-elevated thunderstorms
will be possible around the periphery of the wedge, with lesser
potential for elevated convection heading into the deeper cool air
north and northwest.
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.LONG TERM /TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --As of 400 AM EDT Saturday...
Precip chances diminish rapidly Tuesday, with only slight chances in
the northeast by late afternoon. Shortwave ridging is expected in
the wake of the upper wave on Wednesday with dry conditions and a
warming trend through Saturday as an upper level ridge builds over
the southeast CONUS. Highs Tuesday will reach 70 to 75, with a
return to mid and upper 80s for Friday and Saturday.
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.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
As of 215 AM Saturday...
A series of disturbances in WSW flow aloft will interact with an
outflow boundary (from earlier and ongoing convection) that remains
draped from SW to NE across central NC from near CLT to JNX to EDE.
A continued threat of showers and associated sub-VFR visibility
restrictions will result along and north of the boundary,
particularly at Piedmont sites through daybreak. In addition, there
is a small chance of scattered to broken IFR-MVFR range stratus, and
fog, on the north/cool side of that boundary, also at Piedmont
sites, through 12Z. VFR conditions and a warm and breezy SW wind
will otherwise result until another round of showers and storms fire
along both the aforementioned outflow boundary and a cold front that
will settle south from VA late this afternoon and evening. MVFR
ceilings, patchy light rain, and gusty post-frontal NEly winds will
develop behind, and with the passage of, the front this evening.
Outlook: A prolonged period of rain/showers and sub-VFR ceilings and
visibilities --in springtime cold air damming-- can be expected
later tonight through Tue night, as an area of low pressure tracks
east along the aforementioned front, then slowly up the coast of the
Carolinas. Conditions will be slow to improve as the coastal low
drifts only slowly away from our region, with a return to VFR on