Severe Thunderstorm Warning 243, NWS Raleigh, NC

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
415 PM EDT Thu Oct 31 2019

.SYNOPSIS...
A strong cold front will cross the area late this afternoon and
through the evening. Chilly high pressure will follow the front
Friday into the weekend.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 415 PM Thursday...

...A line of strong to severe thunderstorms capable or producing
damaging winds and isolated tornadoes will move through the area
this afternoon and evening...

An upper level low and associated strong shortwave trough over the
mid MS Valley this morning will continue to intensify as it moves
NEWD through the Ohio and Tn Valleys today and then across the NE US
and mid-Atlantic states tonight. This powerful system will supply
strong large-scale /ascent as well as equally impressive kinematic
wind fields( 45-50 kt @ 850 mb and ~100 kt @ 500 mb) across the
region, which in turn will drive a narrow but strongly forced band
of frontal convection across central NC between 5pm to 11 pm.

Within an axis of dewpoints 70F, partial heating has resulted in the
development of 1000 to 2000 J/Kg of MLCAPE across central NC. The
arrival of the front and line of showers and embedded thunderstorms
will become strengthen/become better organized as the convection
intercepts this moderate instability in place across central NC.
Although the latest CAMS show a slight uptick in some discrete pre-
frontal convection, the severe threat will be with the squall line
as it races east through the area. Damaging wind gusts of 50 to 60
kts will be the primary threat, but given the strength of the wind
fields, there is also the threat for a few embedded supercells to
produce an isolated tornado or two. Unfortunately, the severe threat
will coincide with the the peak Halloween trick or treat hours,
especially across the western two-thirds of the forecast area,
including the Triad and Triangle. Anyone planning to be outdoors
late this afternoon and evening should closely monitor the weather
and be prepared to quickly move indoors to a safe location.

The cold front and convective line will move east of the area by 03
to 05z, with strong post-frontal dry cold air advection leading to
west to east clearing overnight/Friday morning.

In advance of the front, expect breezy southerly winds of 25 to 35
mph this afternoon, nearly matched by NWLY post-frontal gusts
tonight. Highs ranging from mid 70s NW to lower 80s SE. Lows Friday
morning ranging from near 40 NW to upper 40s/near 50 south.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 235 PM Thursday...

With the primary cold front continuing to slide east off the NC
Coast Friday morning, a much quieter, cooler, and drier airmass will
begin to setup shop across the region. Temperatures will be the
primary forecast obstacle Friday through Sunday, with afternoon
highs to remain a good 5 to 10 degrees below normal (rising into the
upper 50s to low 60s) as high pressure slowly fades overhead. This
will be exacerbated on Sunday thanks to a secondary dry cold front,
progged to push through the region late Saturday night, once again
reinforcing the NWLY flow of cooler and drier air. By Sunday,
stronger Canadian High pressure will slide east of the Appalachians,
helping to clear skies and calm the wind a bit.

Overnight lows will consistently settle into the 30s Friday,
Saturday, and Sunday nights thanks to mostly clear skies and good
decoupling conditions present. Lowest fcst low-level thicknesses on
the magnitude of 1305 - 1325 will arrive late Saturday/early Sunday
behind the front, helping to drop portions of the NW Piedmont/Triad
region to near freezing conditions. Frost/Freeze products may be
warranted during this period, especially areas along and west of US-
1 Saturday and Sunday nights.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 235 PM Thursday...

By Monday, high pressure will slowly progress off the east Carolina
coast, allowing southerly to southeasterly flow to reestablish
across the region. This slow warming/moistening trend will provide
for increasing POPs by mid to late week as several weak subtropical
waves begin to slide in the vicinity of the NC Coastal Plain and a
cold front approaches the region from the northwest. A persistent
troughing and active weather pattern looks likely to continue well
into next weekend.

&&

.AVIATION /18Z THURSDAY THROUGH MONDAY/...
As of 215 PM Thursday...

In advance of a strong cold front and accompanying line of showers
and embedded thunderstorms approaching from the west, the IFR to
MVFR ceilings across all of central NC is forecast to lift to low-
end VFR (3-5 kft)ceilings between 18 to 20z. During this same time,
SWLY wind gusts will continue to increase, peaking at 25-30kts,
strongest across the western terminals.

A line of showers and embedded thunderstorms will move west to east
through the area with associated impacts to occur at KINT and KGSO
between 22 to 01z, at KRDU between 00 to 02z at KRDU, and KRWI and
KFAY between 01 to 04z. Sub-VFR conditions in heavy rain along with
strong and potentially damaging wind gusts of 40 to 55 kts will be
possible within this line, especially at KINT, KGSO, and KRDU.
Once the line passes, strong post-frontal cold dry air advection
will lead to abrupt west-east clearing between 03z and 06z Fri
with a period of gusty NW winds 15 to 25 kts expected overnight.

VFR conditions expected Friday with NW winds at 10-15kt.

Outlook: VFR conditions expected Friday night through Sunday night
and possibly Monday.

&&

.CLIMATE...

Date High-Min (Year)

GSO  10/31  63 (1971)

RDU  10/31  64 (1896)

FAY  10/31  67 (1971)

&&

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

&&

SYNOPSIS...CBL/Badgett
NEAR TERM...CBL
SHORT TERM...Smith
LONG TERM...JJM
AVIATION...CBL
CLIMATE...CC

Hazardous Weather Outlook
National Weather Service Raleigh NC
351 PM EDT Thu Oct 31 2019

NCZ007>011-021>028-038>043-073>077-083>086-012000-
Person-Granville-Vance-Warren-Halifax-Forsyth-Guilford-Alamance-
Orange-Durham-Franklin-Nash-Edgecombe-Davidson-Randolph-Chatham-Wake-
Johnston-Wilson-Stanly-Montgomery-Moore-Lee-Harnett-Anson-Richmond-
Scotland-Hoke-
351 PM EDT Thu Oct 31 2019

...TORNADO WATCH 688 IN EFFECT UNTIL 11 PM EDT THIS EVENING...

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This afternoon and tonight.

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

   Tornado Watch.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Much colder temperatures can be expected Friday through Sunday
night. Patchy frost is possible Saturday, Sunday and Monday mornings,
mainly in the colder low-lying areas of the Piedmont.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.

NCZ078-088-089-012000-
Wayne-Cumberland-Sampson-
351 PM EDT Thu Oct 31 2019

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This afternoon and tonight.

A line of strong to severe thunderstorms capable of damaging wind
gusts to 60 mph and isolated tornadoes are possible late this
afternoon into the evening. The threat is greatest between 900 PM to
midnight.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Much colder temperatures can be expected Friday through Sunday
night. Patchy frost is possible Sunday and Monday mornings, mainly in
the colder low-lying areas of the Piedmont.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.