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000
FXUS62 KRAH 151820
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
220 PM EDT Mon Apr 15 2024

.SYNOPSIS...
A backdoor cold front will slide southward into central NC tonight
and stall across the area through Tuesday. The front will then lift
northward through the area as a warm front Tuesday night.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 1005 AM Monday...

Only minor changes to the forecast through this evening. The
conditional threat for isolated severe storms across the northern
Piedmont and northern Coastal Plain counties remains.

The 12Z surface analysis shows a broad trough over central NC, with
the developing lee trough becoming evident. Temperatures have
already risen into the mid 60s to low 70s as of 8 AM. 12Z upper air
analyses show plenty of dry air over the area, with generally NW
flow aloft and clear skies prevailing.

The Bermuda high will continue to ridge westward into the Southeast
US today and tonight. A surface trough will likely remain in place
over central NC today, with a backdoor cold front sliding southward
into the area tonight. Aloft, a disturbance will progress eastward
through the mid-Atlantic late this aft through this eve, clipping
northeast NC along the NC/VA border. H5 height rises of 30-50m are
expected from 12Z Mon to 00Z Tue, and low level thicknesses are
expected to rise to around 1405m by 00Z Tue. Highs today are still
forecast to be in the mid 80s to around 90 degrees across central NC
today.

Previous discussion (as of 250 AM Monday): There is good agreement
that convection will blossom over central and southern VA during the
afternoon as moderate instability of 1000-1500 J/KG develops
underneath a EML in place across the region. If the storms can
overcome a less favorable storm environment of weaker CAPE and shear
and increasing BL CIN after sunset, isolated storms will be possible
across the northern Piedmont and northern Coastal Plain counties. It
should be noted that NCAR neural network probabilities have
significantly decreased from the previous 12z/14 model guidance.

Any convection should dissipate by 06z with mild overnight lows
ranging from mid/upper 50s north to lower 60s elsewhere.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 200 PM Monday...

A weak stationary front should remain across the forecast area, with
cooler air generally northeast of the Triangle with warmer air to
the south and west. While the morning should remain dry, an upper
level shortwave is forecast to move across the state Tuesday
afternoon into the evening, which should help trigger another round
of showers and thunderstorms along the front. The GFS/GEFS is
currently the most aggressive with coverage of showers and
thunderstorms, although the HREF/SREF also show a decent amount of
coverage, while the 00Z ECMWF/12Z NAM both show a relatively dry
forecast. Only made minor tweaks to the pops, generally keeping
chance pops north of US-64. With the mid-day update, SPC also added
a marginal (level 1 of 5) severe risk generally north and west of
Raleigh, with steepening low-level lapse rates favoring the
potential for damaging wind gusts. As the front pulls north Tuesday
night, the chance for precipitation will come to an end. With the
front bisecting the forecast area, there should be more of a
gradient in high temperatures for Tuesday - locations near the VA/NC
border will stay around 80 degrees while locations across the south
should rise into the upper 80s once again. Low temperatures should
not have quite as much of a spread, ranging from the mid 50s to the
low 60s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 230 AM Monday...

Weak upper ridging across the Southeast Wed will flatten as a trough
lifts NE across the Great Lakes Region late in the day. Energy from
the trough will move across northern portions of central NC Wed
night as a weak low develop across the coastal Mid-Atlantic. At the
surface, high pressure will linger off the Southeast Coast, then a
cold front will approach from the west late Wed. Another warm day is
expected Wed, with widespread highs in the low 80s. Most of Wed is
expected to remain dry, then precipitation chances increase Wed
night across eastern portions of central NC as the weak wave aloft
moves by to the north across an area of increased moisture. Any
rainfall accumulations will be light, generally less than one-tenth
of an inch. Breezy southwesterly winds may develop ahead of late
Wed`s front as surface pressure gradients increase, with gusts of 20-
25 mph possible.

Although winds switch westerly behind the front, increasing
thicknesses will help highs rise into the mid to upper 80s for most
areas by the afternoon on Thu. Conditions dry out late Thu through
Fri as high pressure builds in to the north and weak ridging builds
in aloft.

Confidence then increases in the next round of showers and
thunderstorms late Sat into Sun as a few troughs dig across the
region, and a cold front pushes across the area. The details in
timing and precipitation amount still largely vary between
ensembles, however multiple opportunities for rainfall is looking
more likely through the latter half of the weekend. Cooler air may
spread across the region behind the cold front, with highs changing
from the low to mid-80s Sat to the mid-60s to mid-70s Sun.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
As of 220 PM Monday...

24 hour TAF period: Fairly high confidence VFR conditions will
prevail through the 24-hr TAF period. The exception continues to be
the conditional chance for showers/storms, mainly invof KRWI and
possibly KRDU between 03Z and 06Z this evening. Where showers do
occur, there could be some high end-MVFR vsbys early Tue morn. Given
the conditional nature and lower confidence of occurrence at a
specific terminal, will leave mention out for now. Otherwise, mainly
swly winds of 8-10 kts with intermittent gusts of 15-20 kts will
prevail through sunset, with gusts abating and winds becoming light
and variable through the remainder of the TAF period. -KC

Outlook: A quasi-stationary front will bisect the area through Tue
before moving back north Wed as a warm front Tue night. This
boundary will bring the threat of scattered showers and storms
Tuesday afternoon/early evening, especially across the northern TAF
sites. Sub-VFR fog/stratus may also be possible in rain-cooled air.
VFR is expected to prevail Wed into Fri, although showers are
possible with another boundary approaching later in the week. -CBL

&&

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

&&

$$
SYNOPSIS...KC
NEAR TERM...KC/CBL
SHORT TERM...Green
LONG TERM...JJT
AVIATION...KC/CBL