Severe Thunderstorm Warning 215, NWS Raleigh, NC

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
439 PM EDT Mon Aug 19 2019

.SYNOPSIS...
An area of high pressure positioned offshore will maintain a warm
and humid air mass over central NC through Thursday while a weak
surface trough remains stationary over the western Piedmont. A cold
front will approach from the northwest late in the work week.

&&

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

Near Term: High amounts of instability and an increase in moisture
across central North Carolina have led to much more convective
activity this afternoon then yesterday. MLCAPE values in excess of
3000 J/kg and very strong low level lapse rates have led to quickly
rising, very slow moving thunderstorms. With DCAPE values of about
1000 J/kg damaging winds would be the most likely severe threat but
overall, heavy rain and localized flooding may be more of a concern
given the slow motion of the storms. Scattered storms will continue
through sunset and then begin to wane thereafter.

A secondary concern this afternoon is the heat with highs in the 90s
and dewpoints remaining in the mid to upper 70s in some locations.
This has lead to heat index values of 100-105 degrees with a few
sites registering brief periods of 105-108 degrees. While this will
not be sustained long enough to need a heat advisory, concern should
still be exercised if outside for prolonged periods this afternoon.
Overnight tonight a some patchy fog and low stratus can be expected.
Lows generally in the lower 70s.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 450 PM Monday...

After fog and low stratus burns off attention will turn to the
Piedmont trough and this is expected to be where convection will be
most prevalent by Tuesday afternoon. Therefore expect higher chances
for thunder and isolated severe thunderstorms west of US highway 1.
In addition to instability, shear will be better on Tuesday with 20-
25 kts of bulk shear expected. In addition, heavy rain may cause
localized flooding. Temperatures once again will be in the 90s with
heat index values near 100 degrees. Lows in the lower 70s.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 250 PM Monday...

Primarily weak flow aloft will transition to more zonal flow in
nature by midweek, with a series of strong upper-level disturbances
expected to help deepen the upper-level trough near the CAN/US
border. At the surface, Bermuda high pressure will maintain
southerly flow across central NC ahead of a cold front, likely to
slide from NW to SE early in the weekend. Behind the front, a cooler
and drier airmass is expected to setup shop by early next week.

Heat and humidity will gradually take a backseat to shower and
thunderstorm chances/coverage by the end of the work-week as weak
WAA continues ahead of the cold front. Prior to the fronts arrival,
the leeside/pre-frontal trough should play host to increasing
thunderstorm coverage each afternoon and evening, with some periodic
enhancement possible thanks to weak sub-tropical impulses continuing
to linger around the western periphery of the subtropical high. Have
trended POPs up each day during at least the diurnally favored time
frame, peaking Friday and Saturday in response to best FROPA forcing
arrival across the area. Albeit a bit against climatology, models
continue to hint at a complete FROPA thanks to a secondary strong
mid level shortwave push from out of the Ohio Valley. In response,
have trended temperatures and POPs down a bit on the backside of the
boundary, likely to continue into early next week. Afternoon high
temperatures should remain near to slightly below normal from Friday
to Monday thanks initially to increased and widespread mid to upper-
level cloud cover, followed by cooler and drier high pressure along
with northeasterly surface flow remaining dominant behind the
frontal boundary. Overnight lows will settle into the middle to
upper-60s during the same time frame.

&&

.AVIATION /18Z MONDAY THROUGH FRIDAY/...
As of 205 PM Monday...

24 Hour TAF Period: Convection already popping up across central NC
this afternoon with a lot of instability in place over the area.
Expect localized convection to not move much once it forms due to
very little wind shear in the area. Scattered showers and storms
will continue through sunset and then beginning to decrease
thereafter. Some chance for fog and low stratus overnight but patchy
in coverage.

Long Term: More unsettled weather for the long term as a wave moves
up from the Gulf of Mexico bringing more moisture to the area and
then a frontal system moves in from the northwest late in the week.
This will keep chances high for periods of adverse aviation
conditions across the area.

&&

.EQUIPMENT...
GSO upper air flights ( both 12Z and 00Z) have been scheduled
through 12Z Friday.

&&

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

&&

SYNOPSIS...WSS
NEAR TERM...Ellis
SHORT TERM...Ellis
LONG TERM...JJM
AVIATION...Ellis
EQUIPMENT...RAH

Hazardous Weather Outlook
National Weather Service Raleigh NC
347 PM EDT Mon Aug 19 2019

NCZ007>011-021>028-038>043-073>078-083>086-088-089-202000-
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-
347 PM EDT Mon Aug 19 2019

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This afternoon and tonight.

Scattered strong storms are possible this afternoon with damaging
wind the most likely threat. In addition, heavy rain associated with
slow moving thunderstorms could produce localized flooding.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

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Special Weather Statement
National Weather Service Raleigh NC
447 PM EDT Mon Aug 19 2019

NCZ021-192145-
Forsyth NC-
447 PM EDT Mon Aug 19 2019

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL FORSYTH COUNTY UNTIL 545
PM EDT...

At 447 PM EDT, Doppler radar was tracking a strong thunderstorm over
Winston-Salem. This storm was nearly stationary.

Pea size hail and wind gusts up to 50 mph will be possible with this
storm.

Heavy rain and minor flooding and deadly cloud to ground lightning
will also be possible with this storm.

Locations impacted include...
Winston-Salem, Clemmons, Walkertown, Sedge Garden and Pfafftown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter in a nearby building or vehicle. Wind gusts as high as
50 mph are capable of knocking down small or weakened trees and
blowing around trash cans, potted plants, lawn furniture and other
light outdoor objects.

Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning, especially in urban areas where prolonged heavy rain
can quickly lead to flooding.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3618 8034 3616 8012 3602 8012 3603 8017
      3603 8021 3600 8022 3600 8038
TIME...MOT...LOC 2047Z 137DEG 3KT 3611 8025

77

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RALEIGH NC
514 PM EDT MON AUG 19 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0450 PM     TSTM WND DMG     5 N SNOW CAMP           35.94N 79.43W
08/19/2019                   ALAMANCE           NC   911 CALL CENTER

            TREE REPORTED DOWN ON BASS MOUNTAIN ROAD.
            OTHER TREES DOWN NEAR SNOW CAMP.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RALEIGH NC
521 PM EDT MON AUG 19 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0425 PM     TSTM WND DMG     3 S RALEIGH             35.79N 78.66W
08/19/2019                   WAKE               NC   BROADCAST MEDIA

            TREE REPORTED DOWN AT WOODBURN ROAD AND
            HILLSBOROUGH STREET RALEIGH NC. REPORT FROM
            WRAL.

&&

Special Weather Statement
National Weather Service Raleigh NC
525 PM EDT Mon Aug 19 2019

NCZ026-027-041>043-078-192230-
Nash NC-Johnston NC-Franklin NC-Wake NC-Wayne NC-Wilson NC-
525 PM EDT Mon Aug 19 2019

...AN AREA OF SHOWERS AND STRONG THUNDERSTORMS WILL AFFECT
NORTHEASTERN WAYNE...SOUTHWESTERN NASH...NORTHEASTERN WAKE...
WILSON...NORTHEASTERN JOHNSTON AND CENTRAL FRANKLIN COUNTIES UNTIL
630 PM EDT...

At 525 PM EDT, Doppler radar was tracking an area of showers and
strong thunderstorms along a line extending from near Jason to near
Wake Forest. These storms were nearly stationary.

Pea size hail and wind gusts up to 50 mph will be possible with these
storms.

Heavy rain and minor flooding and deadly cloud to ground lightning
will also be possible with these storms.

Locations impacted include...
Raleigh, Goldsboro, Louisburg, Wilson, Wake Forest, Zebulon, Elm
City, Fremont, Walnut Creek and Bailey.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter in a nearby building or vehicle. Wind gusts as high as
50 mph are capable of knocking down small or weakened trees and
blowing around trash cans, potted plants, lawn furniture and other
light outdoor objects.

&&

LAT...LON 3557 7782 3543 7783 3540 7780 3538 7780
      3534 7782 3521 7783 3584 7865 3615 7833
      3576 7773 3573 7772 3568 7766
TIME...MOT...LOC 2125Z 034DEG 1KT 3543 7786 3593 7848

Ellis