Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KRAH 260029
Area Forecast Discussion
National Weather Service Raleigh NC
829 PM EDT Tue Apr 25 2017
Low pressure will move slowly northeastward over eastern North
Carolina this afternoon, and then push off the Mid Atlantic coast
tonight. High pressure will extend from the Atlantic westward into
the Southeast states Wednesday through Thursday.
.NEAR TERM /through Tonight/...
As of 215 PM Tuesday...
Lingering high water on many area roads and in creeks necessitated
an areal flood warning through this evening for a large chunk of
central NC. However, the heavy rain threat is done, and water should
continue to recede on roads and in creeks. Flooding will
persist, though, on many mainstem rivers (see hydro section below).
The mid level low, stacked nearly atop the surface low, will move to
the NE over coastal areas of NC through early evening, before
passing off the Delmarva coast tonight. Confluent cyclonic low level
flow acting on residual moisture favors a lingering threat of
scattered showers on the W/SW side of the low into the evening as it
pulls away slowly. A storm or two also remains possible over the far
NE CWA, where observed mid level lapse rates are around 6-6.5 C/km,
low level lapse rates are nearing 7 C/km, and MUCAPE is 500-1000
J/kg, thanks to some sunshine. Vorticity lobes pivoting around the
low may also contribute to ascent. Will hold onto areas of chance
pops into early evening. Drier air eventually building in from the
WSW in the wake of the low overnight will lead to a clearing trend
from SW to NE, with NE sections the last to see the benefits of
downslope flow and falling dewpoints. Expect lows tonight in the
lower 50s west ranging to around 60 in the far E. -GIH
.SHORT TERM /Wednesday and Wednesday night/...
As of 305 PM Tuesday...
Mid level ridging will build gradually over the area from the SW
through Wed night, with a drying column and 850-700 mb
stabilization. Expect little more than scattered flat diurnal
cumulus clouds Wed afternoon. Thicknesses and good mixing up through
850 mb support highs of 79-84. Skies should be mostly clear Wed
night, although the light SW flow leading to increasing dewpoints
topped with strengthening warm advection just off the surface may
encourage formation of fog areas late Wed night. Lows 59-63. -GIH
.LONG TERM /THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --As of 330 PM Tuesday...
A fairly stout upper trough will lift out of the southern Plains
on Thursday, though the core of the upper forcing will pass
through the Ohio Valley. Limited moisture transport off the
GOMEX and lack of better forcing should result in a decreasing
chance of convection as the front attempts to cross the
mountains late Thursday. The front it self may nit actually make
it across the mountains, so just a few showers are possible as a
pre-frontal trough moves into the Piedmont. A sub-tropical ridge
will then expand across the Southeast through the weekend as an
upper low develops over the southwest US, resulting in
thicknesses nearing 1410m and near record heat peaking Saturday.
these thicknesses support highs climbing in the upper 80s and lower
90s, about 10-15 degrees above normal. Climatological convective
chances will be diurnally driven and focused in the higher terrain,
though GFS forecast soundings indicate rather strong instability by
Saturday, which is plausible given that the upper ridge is centered
to our south and the cap will be weaker to the north.
Height aloft then lower Sunday and Monday as the aforementioned
upper low lifts toward the Great Lakes, but the influence of
the upper ridge may still be felt over the east, leading to
highs more in the lower 80d west to upper 80d east. A stronger
cold front attendant to the upper low will is forecast to move
through Monday, bringing a better chance of showers and storms
and temps falling back toward normal by the middle of next week.
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.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --As of 825 PM Tuesday...
24 Hour TAF Period: Deep mid/upper level low will lift northeastward
and away from the area tonight. However, lingering low level
moisture will continue to lead to some sub-VFR conditions through
around 12-15Z Wednesday.
Patchy drizzle/rain will continue to lingering through around 02/03Z
across the area, before ending. This should lead to a mix of
generally MVFR/VFR cigs across the area. However, expect cigs will
generally lower to MVFR later this evening, with a few location even
dropping to IFR. Late tonight we may see some thinning/scattering of
the MVFR/IFR stratus. Given the recent rains and very wet soils, (if
we do scatter/clear) then we may see a period of very low stratus
(LIFR) and/or fog (IFR/LIFR).
Any sub-VFR cigs and/or visbys should dissipate/lift by 13-15Z or
so, with VFR conditions expected for the rest of the day as high
pressure at the surface and aloft builds/extend into the area.
Outlook: Shallow fog is possible early Thu morning within a light
moist flow from the SW, followed by a better chance of MVFR/IFR
fog/stratus each late-night through morning, Fri through Sun. A few
storms with sub-VFR conditions are possible Sat and Sun afternoon.
-- End Changed Discussion --
As of 300 PM Tuesday...
Rainfall across central NC over the past 48 hours ranged from 4
to as much as 8 inches across the Tar, Neuse, and Cape Fear
river basins, with the heaviest amounts tending to fall across
the upper and middle Neuse basin. Significant widespread
flooding has largely receded on smaller creeks and streams, and
most roads have been re- opened. However, ongoing high water on
some roads and on numerous creeks has prompted the extension of
an areal flood warning for much of central NC through early
This rain resulted in major river flooding on the Neuse river at
Clayton, while downstream, Smithfield is expected to reach major
flood stage this evening. Flooding at forecast points in the Tar
river basin will reach moderate flood stage, while only minor
flooding is expected at forecast points along the larger Cape Fear
See water.weather.gov/ahps2/index.php?wfo=rah for the latest
forecasts and for additional information.