Special Weather Statement, NWS Raleigh, NC

Area Forecast Discussion
National Weather Service Raleigh NC
345 PM EDT FRI JUL 22 2016

.SYNOPSIS...
A hot mid level ridge of high pressure will expand from the central
U.S. across the mid-Atlantic states and Carolinas into early next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 330 PM Friday...

A band of storms which formed over the higher terrain of NC earlier
this afternoon continues to drift toward the SE, approaching our
western counties, while other very isolated cells form further east
over the eastern Piedmont where PW is slightly greater. These are
being assisted by weak DPVA but are facing a bit of hostility in the
environment with marginal to poor mid level lapse rates, very weak
deep layer shear, and slightly below normal PW. However, given the
good low level lapse rates, MLCAPE up to 2000 J/kg, and downdraft
CAPE over 1200 J/kg, these western cells still have a favorable
environment to work with, so will adjust pops a bit to expand slight
risk further east and raise pops on the far western fringe of the
CWA for the next several hours as this convection eases toward the
SE. A few of these storms could generate enhanced downdrafts given
the high D-CAPE, along with heavy rain due to slow movement. The
latest CAM runs show convection gradually diminishing by mid evening
in our CWA, and will trend pops down accordingly after nightfall.
With light winds and high dewpoints, would expect to see another
round of patchy light fog late tonight. Movement of convective
debris cloudiness from the NNW late tonight along with a light
breeze should curb radiational cooling from a hot ground overnight,
so temps should be warmer than last night, falling to 70-75. -GIH

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 345 PM Friday...

The environment on Saturday should be similar to today, although PW
values are expected to rise steadily, with thicknesses continuing to
climb. We'll also be on the anticyclonic side of MCVs dropping
southward through the southern Appalachians, with no other dynamic
forcing mechanisms evident. So we'll be relying on purely
thermodynamic lift, it appears, focused on differential heating in
the higher terrain as well as subtle boundaries, a few of which may
be leftover from the current convection over western NC. Will expand
the low shower/storm chances a bit from today's pops, but still
expect coverage and upscale growth to be limited by warm and
somewhat dry mid levels. Thicknesses and new guidance indicate highs
of 94-98, and with dewpoints dropping no further than around 70 over
much of the area, heat index values should peak in the 99-104 range
for a couple of hours. This is below advisory criteria, so will
stick with a mention in the HWO for now, but this will certainly be
revisited tonight. Lows Sat night in the low-mid 70s, not allowing
much recovery from the heat stress. -GIH

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 245 PM Friday...

To begin the long term period, the strong upper ridge that provided
multiple days of intense heat across the Central Plains will have
dampened and became elongated in east-west fashion, extending into
the region. As it does, heights will rise over central NC through
the weekend. As such, max low level thickness values are progged to
top out in the low to mid 1440s on Sunday (slightly lower than
previous runs), with similar values on Monday. This combined with
mostly dry conditions and temps not cooling off much as night, temps
will be able to rise well into the mid 90s, maybe even the upper 90s
(warmest on Sunday). This combined with a moist air mass may
necessitate the issuance of a heat advisory, most likely across at
least the eastern half of the forecast area, where heat index values
will approach or exceed 105 degrees. With regards to precip chances,
overall they will stay rather low through early next week, but will
not be zero as there will be a persistent Piedmont trough that could
be a focus for convective development, as well as the sea breeze
and/or any weak disturbances that move through aloft.

The aforementioned ridge will continue to dampen and shift more
offshore through the middle of the week. Also, a shortwave trough is
progged to cross southern Canada and the Great Lakes Monday into
Tuesday. This will propel a cold front towards the region Tuesday
into Wednesday, but as can be expected this time of the year, there
is disagreement with just how far south it will make it and it will
likely stall near or just north of the area and then meander for a
few day. Another shortwave crossing the Ohio Valley will approach
towards the end of the week. Therefore, with us gradually losing the
influence of the upper ridge and with a cold front in the vicinity,
precip chances will start to increase, at least back to the normal
diurnal range, especially towards the middle to end of the week. The
increased cloud cover and precip chances should allow temps to
"cool" back to the low to mid 90s (however, still slightly above
normal). -KRD

&&

.AVIATION /18Z Friday through Wednesday/...
As of 1205 PM Friday...

High probabilities of VFR conditions persisting through the next 24
hours. Warm and dry air aloft will suppress most shower/storm
activity over Central NC this afternoon through midday Sat, with
clouds generally scattered and bases above 4 kft. Any isolated
storms would be circumnavigable. The better chances of a stray storm
would be near INT/GSO and FAY, although chances are too low to
include as a prevailing condition. As always, erratic gusty winds
and lightning can be expected in and near any storms. There is a
small chance for patchy shallow MVFR fog in low-lying areas late
tonight into early Sat morning at all TAF sites, but chances are too
small to mention at this time. Surface winds will remain light
through Sat, mainly from the southwest under 10 kts.

Looking beyond 18Z Sat: A few storms are possible late Sat afternoon
into Sat night, primarily at INT/GSO/FAY. Areas of MVFR fog may
develop late Sat night into Sun morning. Shower/storm chances will
start to improve late Sun into Sun night, with scattered daily
storms possible through Wed as the air mass moistens more deeply
over Central NC. Fog is possible early each morning Mon-Wed. -GIH

&&

.CLIMATE...
Record high temperatures and the year in which the record was most
recently set at Raleigh, Greensboro, and Fayetteville.

      Sat Jul 23  Sun Jul 24  Mon Jul 25

RDU    105/1952    101/2011    102/2010
GSO     99/1952     99/1914    101/1914
FAY    103/2011    105/1952    103/1914

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

SYNOPSIS...Hartfield
NEAR TERM...Hartfield
SHORT TERM...Hartfield
LONG TERM...KRD
AVIATION...Hartfield
CLIMATE...BLAES

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RALEIGH NC
301 PM EDT FRI JUL 22 2016

NCZ007>011-021>028-038>043-073>078-083>086-088-089-231915-
PERSON-GRANVILLE-VANCE-WARREN-HALIFAX-FORSYTH-GUILFORD-ALAMANCE-
ORANGE-DURHAM-FRANKLIN-NASH-EDGECOMBE-DAVIDSON-RANDOLPH-CHATHAM-WAKE-
JOHNSTON-WILSON-STANLY-MONTGOMERY-MOORE-LEE-HARNETT-WAYNE-ANSON-
RICHMOND-SCOTLAND-HOKE-CUMBERLAND-SAMPSON-
301 PM EDT FRI JUL 22 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NORTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

HOT AND HUMID CONDITIONS ARE EXPECTED SATURDAY THROUGH MONDAY.
HEAT INDEX VALUES ARE LIKELY TO APPROACH OR EXCEED 100 DEGREES
EACH DAY. SOME LOCATIONS, MAINLY ACROSS THE EASTERN HALF OF THE
FORECAST AREA, MAY REACH OR EXCEED A HEAT INDEX OF 105 DEGREES
FOR A FEW HOURS, WHICH WOULD NECESSITATE A HEAT ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

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