Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 191427
Area Forecast Discussion
National Weather Service Raleigh NC
1026 AM EDT FRI AUG 19 2016
-- Changed Discussion --A series of mid-level disturbances will track across the Southern
Middle Atlantic states, atop a lee surface trough through Saturday.
A cold front will move through the area Sunday night bringing
noticeably cooler and less humid air into the area for the first
half of next week.
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.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --As of 1026 AM Friday...
A series or low-amplitude shortwave disturbances riding atop the
flat subtropical high in place will continue to interact with the
high PWAT airmass that stretches from the Southern Plain
northeastward into the Southern Mid-Atlantic States. Coupled with
weak low-convergence along a lee side trough that bisects Central
NC, DPVA will support scattered to numerous showers and storms at
anytime during the next 36 hours, though insolation in cloud
breaks will yield moderate buoyancy this afternoon to support
greatest coverage and storm intensity.
While shear values are expected to range between 20 to 25 kts,
sufficient to support a strong to severe cluster or two, weak mid-
level lapse rates will hamper updraft strength. So, just like recent
days, expect the severe threat to remain low with an isolated wet
downburst possible. With PW`s again around 2 inches, locally heavy
rain will be a threat, mainly in urban and poor drainage areas.
Tempered by greater cloud cover, a couple degrees cooler than
yesterday. Highs in the upper 80s to lower 90s. Lows in the lower to
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.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 330 AM Friday...
More of the same is expected on Saturday as very little is expected
to change in the overall setup. However, some model guidance does
show a little bit drier air moving into northern portions of the
area on Saturday morning/afternoon, which may limit coverage some on
Saturday afternoon/evening across the far northern tier of the RAH
CWA. Thus, will again go with the best chance across the southeast,
with scattered showers and storms expected. Instability looks to be
a bit more tempered on Saturday as well. Given this and only 10 to
15 kts of deep layer shear, expect chances of strong to severe
storms will be low again, though heavy rain will again be a threat
thanks to slow storm motion and still high moisture content air
across the southern/southeastern half of the area. High temps on
Saturday are expected to be in the upper 80s to around 90.
Isolated to locally scattered showers and storms will again be
possible Saturday night as additional disturbances track across
northern portions of the area (though chances look smaller than
tonight). Lows Sunday morning are expected to be in the lower to
mid 70s again.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 335 AM Friday...
A cold frontal passage late Sunday night into early Monday will
bring a much anticipated change in the air mass across central NC in
the form of a drier air mass and less humid conditions.
Sunday... a moist and unstable atmosphere ahead of the approaching
sfc front coupled with a weak mid level shear axis should
trigger/sustain scattered convection across our region. May see a
few showers over the northern piedmont to start the day. Heating
across the east and south sections of our forecast region should
destabilize the atmosphere, leading to decent chances for convection
by mid-late afternoon. The threat for showers and storms will
persist into Sunday night as the sfc front glides southeast across
our region. Based on model timing, front should exit the Piedmont
counties after midnight, and the southern counties prior today break.
A drier more stable air mass will filter into central NC leading to
decreasing cloudiness and inhibiting convective development. Surface
high pressure will build into our region Tuesday and maintain its
position over our area through Thursday.
High temps Sunday dependent upon extent of cloudiness/convective
coverage. Appears that there will be enough heating in the late
morning-afternoon hours to boost temps to near 90-lower 90s. the
advection of the cooler air mass will trim max temps 3-4 degrees
Monday, and back to near or slightly below normal levels Tuesday
through Thursday. High temps generally mid 80s Tue/Wed, and
mid/upper 80s thursday. Comfortable overnight temps in the 60s
anticipated by Monday night, with low-mid 60s common Tuesday night
and Wednesday night.
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
As of 635 AM Friday...
A weak mid/upper level disturbance moving across the area this
morning is supporting some light showers across the northern
portions of the area. Brief MVFR conditions may accompany the
heaviest showers at KRDU and KRWI through 14Z or so. Otherwise, VFR
conditions will continue this morning with a good bid to mid to high
level cloud cover traversing the area.
Another upper disturbance tracking near the NC-VA border today and a
continued hot and unstable airmass will support the potential for
scattered showers and storms this afternoon and evening. Any storms
that develop will have the potential to produce sub-VFR conditions
and gusty winds. Coverage of showers and storms will dwindle with
the loss of daytime heating by late evening. However, isolated to
locally scattered showers and storms will continue to be possible
with a continued threat of mid/upper level disturbances tracking
across the area and interacting with a very moist airmass across the
Looking ahead: Scattered afternoon/evening showers and storm
will be possible through the weekend in advance of a cold front
passage early Monday. In addition, patchy morning stratus/fog will
be possible, especially for locations that receive appreciable