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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 130153
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
953 PM EDT Fri Apr 12 2024

.SYNOPSIS...
A vigorous upper-level disturbance will pivot across eastern NC and
offshore this evening. High pressure will otherwise build across and
offshore the Southeast through the weekend.

&&

.NEAR TERM /TONIGHT/...
-- Changed Discussion --
As of 950 PM Friday...

In nwly mid/upr-level flow, a trailing disturbance now over nern KY
will dig sewd and across and offshore the Carolinas tonight. While
an upstream cluster of convection has accompanied this feature west
of the Appalachians, a combination of nwly flow/downslope and
already-overturned instability east of the Appalachians suggest this
convection will dissipate before reaching cntl NC. While
occasionally strong and gusty wly surface winds will linger at times
particularly this evening, they will generally diminish to 10 kts or
less for most of the overnight, with low temperatures in the 40s.

.PREV DISCUSSION... /ISSUED 330 PM EDT FRI Apr 12 2024/

A vigorous mid/upr-level disturbance now over the southern
Appalachians will amplify while pivoting across the Carolinas
through this evening, during which time 50-100 meter/12 hr height
falls and cold air advection at 500 mb will be maximized over srn
NC/nrn SC. Associated ascent will lift and adiabatically cool the
subsidence inversion that was present and centered round 700 mb on
the 12Z-observed GSO and RNK RAOBs and result in a deep layer of
steep, ~8 C/km lapse rates from the surface through around 600 mb,
as the CAA aloft overspreads a strongly heated surface layer. Up to
a few hundred J/kg of high-based MLCAPE will result across cntl NC
and extend through the lightning production layer through early this
evening.

High-based, diurnally-enhanced convection now centered over wrn NC
will consequently spread ewd and across cntl NC between
approximately 20Z-00Z. Despite the meager CAPE, the combination of
very steep lwr-mid-tropospheric lapse rates and 30-40 degree surface
dewpoint depressions (inverted-V profile) will favor diabatically-
cooled/accelerated downdrafts. The showers/storms will consequently
be capable of producing strong (dry microburst-type) downdrafts and
surface wind gusts to around 50 mph, with only very light
precipitation of a Trace to a few hundredths owing to considerable
sub-cloud sublimation/evaporation.

Once the mid/upr-level disturbance/trough and convection move east,
after 00-01Z, it will clear and turn cooler, with low temperatures
generally in the 40s.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 130 PM Friday..

The strong trough which has made for gusty winds the past several
days will slowly move out Sat afternoon and evening as ridging over
the mid-section of the country slides into the TN valley. At the
surface, high pressure will be over the Deep South while low
pressure resides in the far NE US and Canada. These two pressure
centers will make for yet another gusty afternoon with WNW winds of
15-20 mph, gusting to 30 mph. There could be a brief gust to 35 mph
in portions of the Piedmont and Coastal Plain. With dewpoints mixing
out into the 20s and low 30s, RH levels look to dip below 30-
percent. After coordination with the NCFS, an increased fire danger
has been issued for most of central NC. Thicknesses at low-levels
will slowly rise throughout the day, with temperatures topping out
in the upper 60s to lower 70s, right about average. By Sat night,
the pressure gradient finally relaxes as the low becomes further
removed and the high shifts into central FL. Winds should trend calm
overnight with lows close to normal in the mid 40s, except low 40s
in a few outlying areas.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 145 PM Friday...

There are a few periods during the extended forecast where one or
two models suggest the possibility of precipitation. These include
Sunday evening with the 00Z ECMWF, Monday afternoon with the 09Z
SREF, Monday night with the 12Z GFS, and Tuesday afternoon with the
12Z GFS/00Z ECMWF. Considering none of the models showed any
precipitation during any of these time periods 24 hours ago, would
like to see some consensus before adding pops to the forecast.
Meanwhile, the minimal pops that were in the forecast across the
northern border Wednesday have been removed since there is good
model agreement that the warm front associated with low pressure
moving over the Great Lakes will remain farther to the north. High
pressure should dominate the southeastern United States through much
of the week. The primary chance for precipitation will be Friday as
a cold front moves through the region. Temperatures will be well
above normal through the period, with highs in the 80s and lows
ranging from the mid 50s to the mid 60s.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 800 PM Friday...

A cluster of convection and damaging surface wind gusts, which has
now moved east of FAY and all cntl NC TAF sites, will continue to
move across ern NC and offshore this evening. While occasionally
strong and gusty wly surface winds will linger at times particularly
this evening, they will generally diminish to 10 kts or less for
most of the overnight. Low-level wind shear will then result, owing
to steep temperature lapse rates and continued strong wly winds in a
well-mixed layer just above the stable near surface layer overnight.
Strong and gusty wly to nwly surface winds will redevelop with
daytime heating on Saturday, then diminish once again after
nightfall.

Outlook: VFR conditions will continue through the middle of next
week, as high pressure builds across and offshore the Southeast.

&&

.FIRE WEATHER...
Increased fire danger will result across most of central North
Carolina from 10 AM to 7 PM on Saturday. Northwesterly winds of 15
to 20 mph will gust between 25 and 30 mph, along with low relative
humidity as low as 25 percent. Refer to your local burn-permitting
authority on whether you may burn. If you do burn, exercise extreme
caution.

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...Kren
LONG TERM...Green
AVIATION...MWS
FIRE WEATHER...Kren