Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 231142

Area Forecast Discussion
National Weather Service Raleigh NC
742 AM EDT Sun Jul 23 2017

Hot high pressure will remain across the mid-South and southern
Appalachians through today, then gradually weaken by early next


As of 320 AM Sunday...

Dangerously hot conditions will continue across central NC through
this evening.

The surface trough will persist over the region on Sunday. The upper
level trough over the Northeast U.S. will begin to amplify
throughout the day. Meanwhile, a shortwave low will dive southeast
out of Canada and through the Great Lakes within the upper level
trough through tonight.

Continued strong southwesterly flow will result in temperatures
again in the 95-100 range for Sunday, although if convection gets
going early in the afternoon it could dampen temperatures a bit.
Regardless, expect the combination of heat and humidity to result in
heat indices around 105 in the northeast and in the 109-112 range
across the southeast. Overnight lows won`t be much relief, bottoming
out at a balmy 73 to 77 degrees.

The most recent convection allowing models suggest the weather will
stay dry through mid morning across much of central NC. Showers and
thunderstorms will ramp up quickly during the afternoon, mainly
along and southeast of US-1, though a secondary band could develop
in the west later in the aft/eve. Shear will remain relatively weak
in the south and east where the instability is maximized, though
MLCAPE values are around 1500 J/Kg, give or take 500 J/Kg. PWATs in
that region will remain around 2.00" and as a result expect heavy
rainfall with the storms that develop, with isolated strong winds.
Another round of convection could move into the region from the
northwest Sunday night as the upper level disturbance encroaches on
the region. However, the unfavorable diurnal timing could limit
convective development and intensity.


As of 330 AM Sunday...

The upper level trough will remain over the region through Monday
night, as will the surface trough. The difference will be more cloud
cover expected over the region, resulting in high temps slightly
lower than previous days. Highs in the low to mid 90s expected,
resulting in heat indices of 95-102. Lows still expected to be in
the low to mid 70s. Expect more showers and thunderstorms Monday
aft/eve, better chances in the south and east, decreasing overnight.


As of 310 AM SUNDAY...

On Tuesday the upper trough begins to lift out to the northeast as
surface high pressure resides over the great lakes. The residual
frontal boundary will still remain over the southern part of the
state and the Piedmont trough will remain active through the week as
diurnal showers and thunderstorms will be prevalent through much if
not all of the period. Several weak disturbances will periodically
propagate along the frontal boundary providing some extra forcing
for ascent. The most notable of these will be Tuesday night into
Wednesday which could increase chances for rain overnight. Late in
the week a second frontal system will push down from the northwest
and will affect the area by next weekend. Expect high temperatures
in the upper 80s to lower 90s with lows in the low 70s.


As of 740 AM Sunday...

24-Hour TAF period: Expect mainly VFR conditions through the TAF
period. The exception will be where storms develop late this
afternoon and evening. Best chances for convection and the
associated increase in winds and decrease in cigs and visbys may
begin around 18Z at KFAY, however the models have backed off a bit
and restrict most convective activity to the NC/VA border region
after 21Z. Have kept the PROB30 mention of such in at KINT, KGSO,
KRDU, and KRWI for this issuance. Some low stratus may develop
toward daybreak Monday, however chances and confidence in sub-vfr
cigs is low at this time.

Looking ahead: Mainly VFR conditions expected through Tuesday, with
the primary sub-VFR risk coming courtesy of showers and storms that
will grow in coverage each successive day through Tue. Chances for
early morning stratus increase Wednesday through Friday, but
otherwise expect VFR conditions to prevail.


RDU Records:
Date     | High   Year  |  High Min  Year
23 July  |  105   1952  |     78     2011
24 July  |  101   2011  |     79     2011

GSO Records:
Date     | High   Year  |  High Min  Year
23 July  |   99   1952  |     78     2010
24 July  |   99   1914  |     78     2010

FAY Records:
Date     |  High  Year  |  High Min  Year
23 July  |  103   2011  |     79     1998
24 July  |  105   1952  |     79     1945


Excessive Heat Warning until 7 PM EDT Sunday for NCZ010-011-
Heat Advisory until 7 PM EDT Sunday for NCZ007>009-021>025-


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