Area Forecast Discussion
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FXUS62 KRAH 241103
Area Forecast Discussion
National Weather Service Raleigh NC
702 AM EDT Mon Apr 24 2017
An upper level low and attendant low pressure system will track
southeast from the Deep South to the Southeast coast this afternoon,
then lift slowly northeast along the Carolina and Mid-Atlantic coast
tonight and Tuesday.
.NEAR TERM /Today and Tonight/...
As of 345 AM Monday...
Overview: An upper level low centered over northern AL at 06Z will
track SE/ESE to the Southeast coast this afternoon and evening. An
attendant surface low will track eastward to the GA/SC coast this
evening, then lift slowly northeast along the North Carolina coast
Precipitation: With the upper level low /attendant surface low/
expected to track E/SE across GA/SC and an established CAD wedge in
place over central NC, the narrow warm sector in southern GA/SC is
expected to shift N/E through eastern SC to coastal NC this aft/eve.
As such, convection should remain elevated in nature over central
NC. A N-S oriented band of elevated convection over western NC will
shift eastward into central NC today and assume a NW-SE orientation
this afternoon as the upper level low progresses SE from northern AL
to eastern GA and low-level flow strengthens/backs to the Southeast
off the Atlantic. In close vicinity to the warm front (southern
Cumberland and Sampson counties), a narrow window for sfc-based
convection (and an attendant severe weather potential) cannot be
ruled out this afternoon. Otherwise, any threat for severe weather
should remain along/east of Hwy 17 near the Carolina coast. The
primary band of elevated convection will assume a W-E orientation
tonight as the upper low passes to the south and low-level flow over
central/eastern NC backs to an easterly direction. The heaviest rain
will fall where the band of elevated convection pivots as it
transitions from a N-S orientation to a W-E orientation this
afternoon into tonight.
Temperatures: With regard to temperatures, a pronounced CAD wedge is
expected to remain in place across the N/NW Piedmont through
tonight, with little variation in temperature (upper 40s to lower
50s). From the Triangle south and east, the modified CAD wedge
should vary little through the day (except perhaps in the far SE
Coastal Plain for a few hours this afternoon), though temperatures
will likely rise from east to west overnight as surface winds
strengthen from the east and advect a higher theta-e airmass inland
from the coast. -Vincent
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 330 AM Monday...
The vertically stacked/mature low pressure system will track slowly
north across eastern NC Tuesday and Tuesday night and then off the
Delmarva coast on Wednesday.
With the mid-level dry slot encompassing the area Tuesday morning,
there could be a lull/minimum in precip/pops across central NC to
start the day. However, diurnal heating and resultant weak
destabilization(at least across the eastern and possibly central
zones) as the wrap-around moisture band pivots NE through the area,
is expected to lead to convective re-development Tuesday afternoon
and evening. The threat for severe storms will be muted by the lack
of greater instability but given the presence of an occluded front
draped somewhere across eastern/east-central NC, cannot rule out an
isolated severe threat. Additionally, with the potential for slow-
moving/training convection with the wrap-around band, isolated
flooding, especially in low-lying or poor drainage areas will be
Highs Tuesday afternoon will be challenging, complicated by multiple
boundaries draped across the area. Expect one sharp temperature
gradient invof of where the aforementioned occluded front sets up
across eastern NC, with another tight temp gradient along the
lingering CAD airmass across the western Piedmont. Highs ranging
from upper 50s NW to mid/upper 70s east.
Rain chances will slowly taper off from SW to NE Tuesday night,
finally coming to an end across the NE zones early Wednesday morning
as the mature cyclone lifts away from the area. Lows Tuesday night
in the mid to upper 50s Tuesday night.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 330 AM EDT Monday...
In the wake of the low lifting up the Mid-Atlantic coast, low-level
swly flow and short wave ridging aloft will mark the return of
sunshine and warming temperatures. Highs in the upper 70s to lower
80s Wednesday, warming into the lower and mid 80s by Thursday.
On the southern periphery of dampening short wave energy lifting
through the MS and Ohio Valleys NE into the Great Lakes, we could
see isolated/slight chance of showers and storms Thursday night and
Friday. Otherwise, it will remain mostly dry with the main weather
headlines being the hot temperatures associated with the dominate
subtropical ridge building across the SE US.
Highs Saturday and Sunday in the upper 80s to lower 90s.
.AVIATION /12Z Monday through Friday/...
As of 700 AM Monday...
24-hr TAF Period: Adverse aviation conditions in the form of
IFR/LIFR ceilings and rain are expected through the TAF period as a
potent upper level low and attendant surface low track southeast
from the Deep South to the Southeast coast. Elevated showers and
thunderstorms /heavy rainfall/ are expected at all terminals this
morning through the afternoon/evening. Northeast winds initially at
5-10 kt will increase to 10-15 knots with gusts to ~20 knots after
sunrise. The FAY terminal could see light/variable or southeast
winds along with improved ceilings (MVFR or possibly VFR) for
several hours this afternoon, depending on the precise track of the
aforementioned surface low as it progresses toward the Southeast
Looking Ahead: Adverse conditions are likely to persist in
association with a lingering CAD wedge over the area Tue/Tue night.
Ceilings are gradually expected to lift/scatter out to VFR during
the day Wednesday as the upper level low lifts northeast along the
Mid-Atlantic coast. -Vincent
As of 330 AM Monday...
...Flood Watch remains in effect through 12Z Tuesday...
Widespread heavy rain is expected to develop over central NC today
into tonight. Storm total rainfall amounts of 3-5" are expected,
with locally heavier amounts possible where the primary band of
elevated convection pivots /persists the longest/. Flooding of local
creeks and streams can be expected. Main stem rivers will experience
significant rises in water levels this afternoon into tonight,
particularly the Yadkin, Haw, Neuse, Tar, Roanoke, and Cape Fear.
Flood Watch through Tuesday morning for NCZ007>011-021>028-038>043-