Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 240242
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1042 PM EDT Mon Oct 23 2017

.SYNOPSIS...
A cold front will move east across the Carolinas tonight. A dry
cold front will move across our region Tuesday night. Cool high
pressure will build into the region during the mid and late
portion of the work week.
&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 1040 PM Monday...

A cold front across the NC Foothills late this evening will
push east overnight and approach the coastal region toward
daybreak. The air mass ahead of the front is weakly unstable
with ML CAPE values approaching 500 J/Kg across the Sandhills
and southern Coastal Plain with values around 250 J/Kg to the
north ahead of the front. The flow aloft remains vigorous with
0-6km shear values in excess of 60kts and near surface 0-1km
shear values of 35 to 45 kts. While weak low-level instability
combined with modest mid-level lapse rates has limited deep
convection across most of central NC, the potential continues
for isolated severe weather ahead of the front. The SHERB and
other its family of experimental parameters developed with NC
State researchers and other NWS offices still highlights the
potential for damaging wind gusts and still a chance of an
isolated tornado in a narrow instability axis ahead of the main
convective band. The severe weather threat will be short lived
as the band shifts east and exits the RAH CWA between 5 and 7
UTC.

Recent GOES-16 satellite imagery shows fairly rapid clearing
behind the convection, closely in line with the 850 mb trough
axis. Gusty south to south-southeast winds ahead of the
convection relax quite a bit and become southwesterly at about
10 MPH. If winds relax enough, a short period of fog is possible
toward daybreak. Otherwise, cool advection will allow
temperatures to fall into the lower 50s in the Triad with warmer
lows, only in the lower 60s across the Coastal Plain. -Blaes
&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
As of 325 PM Monday...

After low stratus early Tuesday, skies are expected to become partly sunny.
Highs will be cooler, 60s NW to 70s SE. A secondary cold front will bring
even drier and cooler air Tuesday night through Thursday. Still, readings
are expected to remain above the critical threshold of a killing frost
or freeze, even in the areas that fall into the mid to upper 30s (rural
Piedmont).

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 210 PM Monday...

Cooler and dry weather continues into the latter half of the week
with highs in the upper 50s to mid 60s Thursday and near 70 degrees
for the end of the week. Lows will remain in the 40s for the
majority of the week and then climb back into the upper 40s to lower
50s for the weekend.

The next chance for rain comes from a frontal system that will move
through the area next weekend.  There is uncertainty with regards to
timing and also the evolution of a low pressure system riding up the
southeast coastline prior to the arrival of the cold front that
could cause a chance of precipitation earlier in the weekend.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
As of 820 PM Monday...

A strong cold front will sweep east across central NC overnight.
A line of showers and embedded thunderstorms extending from
KGSO south to near KSOP and KRCZ at 00Z will push east and exit
central NC by around 06Z. An area of IFR-MVFR ceilings, heavy
showers and embedded thunderstorms with strong gusty winds from
130 to 210 degrees with gusts up to 40kts will accompany this
line of convection. The convection will exit the Triad terminals
by 01Z, impact KRDU between 01 and 03Z, and the KFAY and KRWI
terminals between 01 and 05Z. Gradual clearing is expected
behind the front with a weakening of surface winds. There is a
chance of that some low IFR stratus and MVFR fog may develop
just before daybreak. VFR conditions with southwest to westerly
winds are expected on Tuesday at around 10kts with gusts to
18kts.

Looking beyond the 24 hour TAF period...High pressure over the
deep south will extend into the region through the work week. A
cold front will approach the region late in the weekend.

&&

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

&&

$$
SYNOPSIS...BLAES
NEAR TERM...BLAES
SHORT TERM...BADGETT
LONG TERM...JF
AVIATION...BLAES



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