985
FXUS62 KRAH 181044
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
642 AM EDT Thu Jul 18 2024

.SYNOPSIS...
A cold front will approach the region today, bringing showers and
storms to the area. The front will remain stationary through the end
of the week resulting in unsettled weather and cooler temperatures.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 312 AM Thursday...

Lingering convection over the northern Coastal Plain early this
morning will continue to diminish over the next few hours.  Aloft,
water vapor imagery depicts broad swly flow over the southeast
associated with an upper trough currently lifting into the
northeast.

At the sfc, latest obs displayed a cold front draped across western
TN extending northeast into western PA. This front will slowly sag
into our northern areas this evening.  Ahead of the front, MLCAPE
will rise well into the 2000 to 3000 J/kg range this afternoon. As
the upper trough continues to eject eastward, a few triggering
mechanisms will promote scattered to numerous showers and storms
this afternoon and evening. First, an MCV currently generating
convection over central TN will pivot across the NC/VA border later
today.  Outflow out ahead of this feature will combine with remnant
outflow from yesterday`s convection (and likely also weak sfc
convergence along a lingering sfc trough) and likely trigger showers
and storms early this afternoon across the Piedmont/northern Coastal
Plain. This convection will then likely pivot southeast and move
towards the coast late tonight.

Bulk-layer shear will reach upwards to 30 to 35 kts (peaking across
the north) and thus there should be a decent chance for multi-
cellular/linear structures to develop later today into the late
evening period.  Forecasted hodographs appear rather straight over
much of central NC. Thus, if any stronger/organized storms do
develop today, the main concern would be the potential for damaging
wind gusts to occur (with large hail a secondary threat). The HRRR
Neural Network Convective Hazard Forecast (which accurately depicted
yesterday`s severe storms across the NC/VA border) suggests that the
highest probabilities for any severe weather hazard would be across
the northern Piedmont/Coastal Plain between ~19 to 23Z. This makes
sense conceptually, as effective shear will maximize in this
vicinity.

While the mean-layer flow will be relatively strong this afternoon,
the shear orientation to the boundaries will be relatively parallel.
As such, training convection and instances of flash flooding are
possible especially for those south and east of Raleigh.

Max temps today will hover in the upper 80s (N) to lower 90s (S).
Overnight lows in the upper 60s/lower 70s.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 312 AM Thursday...

The front will become quasi-stationary over central NC on Friday
while the anomalously moist airmass lingers. Shear will weaken
Friday afternoon as the upper jetstreak pulls off into eastern
Canada. As such, upper forcing during the daytime will be minimal as
weak ridging builds over the southeast. However, given the presence
of the front, and the anomalously moist airmass, scattered showers
and storms will likely develop during peak heating Friday afternoon.
Overall coverage will likely be less compared to Thursday, but given
slower expected storm motion, any training cells could lead to
instances of localized flash flooding.  The greatest threat for
flash flooding Friday will be south and east of Raleigh, areas that
will likely receive the highest rainfall on Thursday. Convection
should generally wane with loss of heating Friday evening.

Max temperatures Friday will reach the upper 80s. Overnight lows
will remain warm in the 70s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 225 AM Thursday...

As the extended forecast period begins, an unseasonably strong upper
low will be over Quebec, with an upper level trough extending south
into the Gulf of Mexico. While the upper low will move east over the
Atlantic Ocean by Monday, the trough will remain nearly stationary
over the Mississippi River valley into next week. Weak southerly
flow will allow continued advection of moist air from the Atlantic
Ocean and Gulf of Mexico, and with the trough to the west acting as
a constant forcing mechanism, showers and thunderstorms can be
expected every day. Went with likely pops Saturday through Monday,
then capped pops at high chance Tuesday and Wednesday because of the
convective nature of the precipitation and uncertainty this many
days out. Most of the region will continue to be under a marginal
(level 1 of 4) risk for excessive rainfall with any stronger
thunderstorms that have high rainfall rates, despite nearly the
entire forecast area being in moderate drought. While the weather
will remain quite humid, daytime highs limited to the upper 80s and
lower 90s with the widespread cloud cover should keep heat indices
under 100 degrees, so no heat headlines are expected.

&&

.AVIATION /11Z THURSDAY THROUGH MONDAY/...
As of 642 AM Thursday...

Scattered to numerous showers and storms are expected to develop
this afternoon and evening, peaking near KRDU/KRWI/KFAY later today.
As such, expect temporary flight restrictions to develop at these
sites at times later today and tonight.  The bulk of the heavier
rain should move east of central NC late tonight, however MVFR to
IFR ceilings are expected to fill in over much of the eastern two
thirds of central NC starting near 03Z and persisting through the
end of the 24 hr TAF period.

Beyond 12Z Friday: A cold front will sag into and stall across the
region Friday through Sunday which will increase the chances for sub-
VFR conditions through this weekend.

&&

.CLIMATE...

Record High Minimum Temperatures:

July 18: KGSO: 76/1986 KRDU: 79/1887 KFAY: 77/2019

July 19: KGSO: 75/2016 KFAY: 77/2023

July 20: KGSO: 75/2019 KRDU: 76/2020

July 21: KGSO: 76/2011 KRDU: 78/1932 KFAY: 80/2017

July 22: KRDU: 78/2011

July 23: KRDU: 78/2011

July 24: KRDU: 79/2011 KFAY: 79/1945



&&

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

&&

$$
SYNOPSIS...Leins
NEAR TERM...Luchetti
SHORT TERM...Luchetti
LONG TERM...Green
AVIATION...Luchetti
CLIMATE...RAH