Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KRAH 250552
Area Forecast Discussion
National Weather Service Raleigh NC
152 AM EDT THU AUG 25 2016
-- Changed Discussion --High pressure will extend across the region through the rest of
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.NEAR TERM /THROUGH TONIGHT/...
As of 855 PM Wednesday...
High pressure continues to dominate the pattern and keep conditions
dry overnight although some low level moisture could lead to some
patchy fog or low stratus overnight, particularly in the KRWI area.
Although CAM models had been bullish on a few showers overnight, the
latest runs have backed off of this trend. Low temperatures mainly
in the mid 60s.
.SHORT TERM / FRIDAY THROUGH 6 AM FRIDAY/...
As of 245 PM Wednesday...
The high pressure system will
gradually strengthen with the core eventually settling over our area
by early Friday. Continued warming/modification of the air mass will
translate to warmer temps, both afternoon and overnight. Low level
thicknesses Thursday afternoon projected to be a solid 15m warmer
than this afternoon. Based on past afternoons, this warming suggest
max temps Thu near 90 nw Piedmont to the lower 90s elsewhere.
Overnight temps Thu night should be a degree or two within 70.
While patchy cloudiness still expected Thursday and Thursday night,
lack of sufficient moisture through the column and overall sinking
motion will deter convective development across most of central NC
through Thursday night. A caveat to this is the tail end of minor
s/w crossing the northern Mid-Atlantic late Thu/Thu night will clip
the far northern sections of central NC. Available instability
suggest isolated convection possible though whether enough lift and
moisture aloft will be present is questionable. For now will paint a
10-14 PoP across sections of the northern Piedmont late Thu-Thu
evening and see how subsequent model runs evolve this potential.
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 240 PM Wednesday...
Fri-Sun: Quite warm to start this period, followed by moderating
temps, and very low precip chances throughout. Strong mid level
ridging will remain the dominant weather feature heading into the
weekend, with its center drifting slowly from the western Carolinas
early Fri ENE to over eastern VA/NE NC by Sun, all the while
maintaining dry and stable mid-upper levels over our area. A surface
cold front approaching from the NW Fri will drop into and through NC
over the weekend, causing a dip in thicknesses from much above
normal Fri/Sat to near or just slightly above normal starting Sun.
With a weakening low level wind field and no opportunity for
moisture influx at any level, any convection ahead of or with the
front will be feeble and very isolated, likely limited to a few
cells drifting slowly off the higher terrain (extreme NW CWA) and
along an inland-drifting sea breeze (far SE CWA) late in the day
Fri, with perhaps a bit better (but still low) coverage Sat
afternoon over the southwest CWA near weak upglide and low level
mass convergence near the Piedmont trough. The front settles to our
south Sun with a high pressure ridge centered off New England nosing
narrowly to the SW through central NC, supporting a drop in max
temps from the mid 90s Fri/Sat to around 90 or the lower 90s
Mon-Wed: Starting Mon, the mid level ridge weakens and flattens yet
continues to extend W-E across the region. Low level flow from the
east or ENE may be sufficiently strong and onshore-directed to boost
low level moisture profiles and increase diurnal sea-breeze
convection chances in the SE CWA on Mon, although the limited deep
moisture should keep coverage low. Models still vary quite a bit
with the tropical wave now over the northern Leeward Islands which
may be driven toward the WNW by the mid level ridge and may affect a
portion of FL and/or the Gulf Coast by early to mid week. Model
solutions continue to range widely, with the GFS remaining weak with
an erratic motion and the so-far-strongest ECMWF solution showing a
slowing trend with the 12z/24 run, which all results in reduced
confidence in any details this far out. At the very least, the
increasing easterly low-mid level component should draw increasing
amounts of Atlantic moisture into the eastern Carolinas, and we
should see an increase in daily showers and a few storms mainly east
as we head into midweek. We will, of course, continue to monitor the
tropical wave, although by all accounts it will not be a direct
factor in our weather through at least Wed. With thicknesses holding
a bit above normal, temps are expected to peak around 90 to the
lower 90s Mon-Wed, with lows mostly in the lower 70s. -GIH
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --As of 145 AM Thursday...
High confidence in predominately VFR conditions through the TAF
period, as strong high pressure remains in control of the region.
As was the last last night, there will likely be a period of IFR
or LIFR vsby after 08z at RWI, with MVFR vsbys more likely at RDU
AND FAY. Confidence is much higher at RWI. All terminals will
return to VFR by around 12z.
Outlook: Persistence of high pressure over the region will
continue to promote VFR conditions, with early morning fog
possible each morning.
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