Severe Thunderstorm Warning 161, NWS Raleigh, NC

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
345 PM EDT Tue Jul 5 2022

.SYNOPSIS...
Warm and humid southerly flow will persist through the rest of the
work week, generating daily scattered showers and thunderstorms,
especially each afternoon and evening.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 310 PM Tuesday...

Still expected a band of storms to drop into north central NC later
this afternoon and translate SSE through the evening. Additional
development is possible later tonight, but there is a lot of
uncertainty with this. Daytime heating has pushed MLCAPE values to
2000-2500 J/kg thus far, and while effective shear remains marginal,
it should improve over the next few hours as the convective complex
and its attendant mid level wave approach from the N and NW. The
pace of ongoing convection to our N and NW is a bit ahead of the
latest CAM guidance, suggesting that it will have a longer residence
time within a moderate CAPE environment and thus may survive intact
further south in the CWA than earlier anticipated. Will raise pops
to likely N and chance S, decreasing overnight. Once this convection
reaches close to the Hwy 64 corridor, it should become more outflow
dominant and begin to wane, esp with loss of heating later this
evening. Still expect a decent wind threat as RAP-based mesoanalyses
shows 1000-1400 J/kg of DCAPE ahead of this line, and mid level
lapse rates are predicted to rise a bit to over 6 C/km. The arrival
of a second MCV later tonight and toward Wed morning may allow
additional storms to blossom, esp given model indications of
residual marginal elevated CAPE overnight, although CAM output is
mixed regarding additional convection overnight. Will have just an
isolated pop overnight, given the low confidence, and will monitor.
Expect muggy lows in the low to mid 70s. -GIH

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 345 PM Tuesday...

...Heat advisory for much of central NC Wednesday...

Wed will be a messy day with multiple hazards possible. Isolated
showers and storms may persist around daybreak across the N, but
again, confidence in this is very low. Otherwise, additional
perturbations and MCVs within the NW steering flow are likely to
move SE into and through NC, and as we'll be within a WAA pattern
with surface dewpoints likely to be well into the 70s for much of
the day, this should push CAPE up to moderate levels by afternoon,
with improving (although still borderline) deep layer shear. The hot
and humid conditions should push heat index values over 100F over
all but the far W and N Piedmont, with values reaching 105F for at
least a couple of hours over much of the Sandhills, far E Piedmont,
and the Coastal Plain, so will issue a heat advisory for these areas
from 11am to 7 pm. The one wrinkle in this plan is the potential for
convective mid clouds to drift over the area, filtering insolation
and cutting temps back a bit, but given one more day in the
succession of hot days without much cooling at night, an advisory
seems warranted. With slow storm motions and a deep warm layer
expected with high PW (aoa a daily-record 2.25") pooling across NC,
heavy downpours with high totals and rates seem likely, although
coverage of such storm clusters is too hard to pin down sufficiently
for a flash flood watch at this time. But we'll continue to monitor
this closely, and most certainly some flood advisories will be
needed tomorrow. The severe threat will persist as well, given the
high CAPE and better shear, with straight line winds the primary
threat once again. Expect highs in the low-mid 90s followed by lows
once again in the low-mid 70s. -GIH

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 345 PM Wednesday...

Have gone with likely pops for Thursday, Friday, and Saturday in the
forecast. It will be hard to pinpoint on any given day where the
heaviest rainfall will be because that will be dependent on where
convective complexes have left boundaries from the previous day to
set up the next round of convection. That being said, the 12Z 3km
NAM shows a complex of storms from Raleigh to the VA/NC border at
the end of its model run at 00Z Friday and the 12Z GEFS shows a
similar area with heavy rainfall along the I-95 corridor Thursday
evening. SPC has included the entire forecast area in a slight risk
(level 2/5) of severe weather for Thursday, and indicated in their
discussion about Friday through Tuesday that they anticipate the
eventual need for a risk area on Friday. In addition, WPC has
included the entire forecast area in a marginal risk (level 1/5) of
excessive rainfall for Thursday.

All of this weather is expected in the warm sector of a front
advancing very slowly to the south from the Ohio Valley. The actual
frontal passage is not expected until Saturday, and even then, there
will be a chance of storms on the cool side of the front Sunday and
a slight chance of storms on Monday.

Highs will continue well into the 90s on Thursday and Friday, with
heat indices approaching heat advisory criteria of 105 both days.
Highs will return to near normal values on Saturday with the frontal
passage, and highs in the 80s Sunday and Monday will likely feel
refreshing after the 90 degree heat this week.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
As of 200 PM Tuesday...

Isolated MVFR cigs persist across central NC but, for the most part,
conditions are VFR across the area at this hour as cloud bases have
risen to VFR levels. Attention now turns to a nearly solid line of
showers and storms across N VA and S WV into E KY, which is dropping
toward the SSE, toward NC. Additional isolated storms over the NC
and VA mountains are moving toward the SE. Both of these are likely
to impact north central NC through the early-mid evening hours,
moving roughly NW to SE, bringing a period of sub-VFR conditions
within heavy rain and gusty winds mainly to the northern terminals
(INT/GSO/RDU/RWI) late afternoon through early evening. The linear
nature of these storms will make them difficult for aircraft to
circumnavigate. Storms will decrease in coverage and intensity as we
approach 05z, with only low chances overnight. The risk for sub-VFR
stratus and fog late tonight is less than it has been the last
couple of mornings, so expect any sub-VFR conditions to be fairly
isolated. Otherwise, conditions will be mostly VFR through the end
of the TAF valid period, although some storms may begin to form in
the 16z-18z time frame N of INT/GSO. Surface winds will stay under
10 knots, mainly from the S and SW becoming SW and W Wed.

Looking beyond 18z Wed, high chances for showers and storms with
strong/gusty/shifting winds and heavy rainfall will bring a threat
for sub-VFR conditions Wed afternoon/evening. Storms will likely
decrease after sunset, but sub-VFR fog and stratus is expected to
form after midnight, lasting into Thu morning. Scattered showers and
storms are possible Thu/Fri, mainly afternoon into evening, with
areas of late-night/early-morning fog/stratus each day through Sat.
Some improvement in aviation conditions and a reduction in shower
and storm chances is expected Sun as a cold front settles to our
south. -GIH

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM to 7 PM EDT Wednesday for NCZ010-011-
023>028-040>043-075>078-083>086-088-089.

&&

SYNOPSIS...JJT
NEAR TERM...Hartfield
SHORT TERM...Hartfield
LONG TERM...Green
AVIATION...Hartfield

Hazardous Weather Outlook...UPDATED
National Weather Service Raleigh NC
349 PM EDT Tue Jul 5 2022

NCZ007>009-021-022-038-039-073-074-061215-
Person-Granville-Vance-Forsyth-Guilford-Davidson-Randolph-Stanly-
Montgomery-
349 PM EDT Tue Jul 5 2022

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This afternoon and tonight.

There is a Marginal Risk (Level 1) of severe weather through this
evening across portions of central NC. Gusty winds, frequent
lightning, and brief periods of heavy rain can be expected with the
strongest storms.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

There is a Slight Risk (Level 2) of severe weather on Wednesday and
Thursday. Gusty winds, frequent lightning, and periods of heavy rain
which could result in flash flooding are all possible Wednesday
afternoon and again Thursday afternoon.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed Wednesday.

NCZ010-011-023>028-040>043-075>078-083>086-088-089-061215-
Warren-Halifax-Alamance-Orange-Durham-Franklin-Nash-Edgecombe-
Chatham-Wake-Johnston-Wilson-Moore-Lee-Harnett-Wayne-Anson-Richmond-
Scotland-Hoke-Cumberland-Sampson-
349 PM EDT Tue Jul 5 2022

...HEAT ADVISORY IN EFFECT FROM 11 AM TO 7 PM EDT WEDNESDAY...

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This afternoon and tonight.

There is a Marginal Risk (Level 1) of severe weather through this
evening across portions of central NC. Gusty winds, frequent
lightning, and brief periods of heavy rain can be expected with the
strongest storms.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Heat Advisory.

In addition, there is a Slight Risk (Level 2) of severe weather on
Wednesday and Thursday. Gusty winds, frequent lightning, and periods
of heavy rain which could result in flash flooding are all possible
Wednesday afternoon and again Thursday afternoon.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed Wednesday.