Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 240656
Area Forecast Discussion
National Weather Service Raleigh NC
256 AM EDT SUN JUL 24 2016
An area of high pressure aloft will extend across the region through
Tuesday, bringing a period of hot and humid conditions to central NC.
Chances for afternoon convection will increase by the later half of
the work week.
.Near Term /Rest of tonight/...
As of 1025 PM Saturday...
Given the combination of post-sunset cooling BL temps and sinking/
drier air aloft advancing across our cwa from the north (as seen on
the water vapor), this evening`s isolated storms have ended across
our area. At this point, it appears that our cwa should remain dry
the rest of tonight. However, it`s worth noting that the last few
runs of the HRRR have been suggesting that an isolated sprinkle or
two could drift into and across our far northeast zones (northern
coastal plain) later overnight, left-over from the showers/tstms to
our north across east-central VA as they drift southward. But given
current coverage and latest radar trends, for now we`re fairly
confident in leaving the forecast dry for the rest of the night.
Lows in the low-mid 70s still appear to be on-track.
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
As of 225 PM Saturday...
This still looks like our hottest day, and convection chances appear
to be very minimal. Models take the core of the upper ridge overhead
Sun, with continued steady warming aloft evident on forecast
soundings, cutting down considerably on the potential for
destabilization despite surface temps peaking in the upper 90s. CAMs
and models with parameterized convection favor virtually dry weather
tomorrow, with only an isolated cell or two at most. Will keep an
isolated thunder mention in the extreme west and extreme SE, with
the potential for drifting terrain-induced cells and sea-breeze
convection, respectively. Statistical guidance and model thicknesses
support highs in the upper 90s, very close to earlier forecasts.
With dewpoints remaining high but dipping a bit in the afternoon
with mixing, heat index values are likely to reach 100-106, with the
highest values along and east of the Highway 1 corridor. Will go
forward with a heat advisory for these eastern sections. Even if
some spots only reach close to 105 for an hour, given that we will
have been atypically warm for a few days already, and with it being
a Sunday and folks likely spending time outdoors, the risk for heat
illnesses will be elevated. Any isolated convection is apt to
dissipate quickly toward sunset, with fair and muggy conditions Sun
night. Lows in the mid 70s. -GIH
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
-- Changed Discussion --As of 250 AM Sunday...
Medium range models continue to be in general agreement depicting a
mid/upper level ridge located just to our southeast, extending into
our region some to start the period, with a general trough to our
north. At the surface a weak remnant cold front/surface trough is
forecast to sink a bit further southward on Wednesday and help to
focus scattered to numerous showers and storms across central NC,
with locations across the north standing the best chance of seeing
convection (closer to the actual boundary where better coverage is
expected). Given this and central NC on the southern fringe of the
better westerly mid level flow (maybe around 20-25 kts at 500 mb
across the north) we may see some multi-cell clusters of storms.
Given this and expected mlcape values of around 1500 J/KG or higher
during the afternoon into the evening and expected frontal zone
placement we may see a better chance for severe storms on Wednesday
than past days (especially across the northern half of the area).
Though hard to time disturbances/mcv`s from upstream convection can
and will have and impact on the eventual convective chances and
placement. High temps on Wednesday are again expected to be above
normal despite increasing chances for storms. Expect high temps to
range from the lower 90s north to the mid to even upper 90s south,
with heat index values from around 100 north to around 103-105
degrees southeast. Lows Wednesday night are expected to generally be
in the mid 70s.
A general broad trough is expected to develop across our area and
points northward as the mid level ridge is forecast to be suppressed
a bit further south late week into the weekend. This should lead to
scattered showers and storms each afternoon/evening, with more in
the way of isolated showers and storms generally expected during the
overnight/morning hours. However, with a lack of any airmass change
we should still remain hot an humid through the period, with the
possibility of heat advisories needed thanks to the number of days
with heat index values of 100+ across the eastern/southeastern
portions of the area. Highs are generally expected to be in the
lower to mid 90s with lows in the mid 70s.
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.Aviation /06Z Sunday through Thursday/...
As of 210 AM Sunday...
High probability that VFR conditions will persist across central NC
through Monday as an area of high pressure aloft strengthens
There is a good probability that VFR conditions will persist through
mid-week. Chances for afternoon-evening scattered convection will
increase the later half of the work week, along with the possibility
of early morning fog and low clouds.
Heat Advisory from noon to 8 PM EDT Sunday for NCZ010-011-