300
FXUS62 KRAH 030215
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1015 PM EDT Sun Jun 2 2024

.SYNOPSIS...
Weak disturbances will bring an unsettled pattern with afternoon
showers and storm chances through Thursday. A late week cold front
will bring dry conditions for the weekend.

&&

.NEAR TERM /TONIGHT/...
As of 1010 PM Sunday...

A weak PV anomaly is currently moving through the southern
Appalachians and into western NC as shown in regional water vapor
imagery and SPC mesoanalysis data. Downstream of the weak
disturbance, low level moisture convergence within a moist (PWAT
around the 90th percentile for early June) and weakly unstable
airmass in place is supporting scattered showers and isolated storms
from central SC towards the Triad. A small MCV, evident in a
reflectivity swirl on regional radar, may be providing localized
assistance for ascent within this band to influence deeper
convection and lightning production.

Deep and rich moisture in place will keep the weakly unstable
airmass capable of continuing these conditions through tonight and
into Mon morning. Weak flow through the depth of the atmosphere and
weak instability will not favor any strong storms overnight. Most
locations may only see a trace to very light measurable rain of a
few hundredths of an inch, but any deeper convection that train over
the same area within the slowly eastward propagating forcing may see
0.5 to 1" of rain overnight in localized locations. Overnight lows
will settle into the low to mid 60s.

&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 155 PM Sunday...

The trough axis from Sunday will roughly be over the area to start
our Mon over the central Piedmont and along the US-1 corridor. This
axis will slide SE toward the coast in the afternoon to early
evening, with shortwave ridging building east from TN.

The latest CAMs depict a possible leftover MCV from Sunday`s
convection that may move across the Triangle, Sandhills, and Coastal
Plain in the morning hours. While confidence is low on this feature,
there will be very little CIN and some elevated CAPE of a few
hundred joules to support spotty showers into mid-morning.

As clouds start to erode by early afternoon and heating raises highs
into the low to middle 80s, most guidance indicates instability of
around 1000 J/kg and deep-layer shear of 10-20 kt with little to no
CIN. Most high-res models suggest isolated to widely scattered storm
activity could form just about anywhere in central NC with PW`s near
the 90th percentile of 1.6 inches.

Perhaps the more favored areas for isolated storms would be east of
US-1 along lingering outflows/lift from the MCV and a sea-breeze, as
well as over the northwest Piedmont where a lee trough should favor
storm activity over the higher terrain and tracking ESE with the NW
mid-level flow. We do not expect any storms to reach severe limits
given the low-end shear. Most storm activity should wane after
sunset with loss of daytime heating. Low temperatures should once
again be near the middle 60s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 205 PM Sunday...

Daily shower/storm chances will continue through much of the week
within warm and humid conditions, but odds are tilting in favor of
dry weather and slightly lower humidity by week`s end as we undergo
a pattern shift to deep low pressure over/around the Great Lakes
region.

Tue: Very baggy and narrow mid level ridging will build through E
NOAM Tue, resulting in a weak steering flow over our area and
reduced confidence in forecast details, including exact timing and
placement of convection. Surface features will be ill-defined, but
there`s a good chance of a weak backdoor front pushing into our N
and E sections Tue, separating the high off the Southeast coast with
another cooler high centered over the New England coast. PWs will
continue a slow rise (to 1.5-1.8"), as will surface dewpoints, so
even minor low level confluence along a weak frontal zone may help
induce and/or support showers and a few storms. With the baggy mid
level ridge overhead yielding warm mid levels and poor deep layer
shear, any storms should be weakly organized and not strong. But
slow storm motion, potentially meandering and congealing cell
clusters, and rising moisture content through the column may result
in locally heavy downpours. Will keep pops near or just over
climatology, with a slight focus on afternoon/evening, but with
perturbations trying to push E into our area Tue night as the ridge
starts to exit, rain is possible at any time. Expect slightly above
normal temps, with highs in the mid 80s to near 90 and lows in the
60s.

Wed-Thu: Still appears that pops should be highest these two days.
Northern stream troughing in the Upper Midwest early Wed will
continue to deepen and dig strongly to the SE through the Great
Lakes region and toward the Ohio Valley, leading to strengthening
WNW steering flow at our latitude and, especially, to our W and NW,
as a synoptic cold front slowly approaches from the WNW. Forecast PW
is projected to be quite high, with models suggesting values at or
above 2", nearing records. Models also hint at a pattern favoring
nocturnal backbuilding MCSs in our area and just upstream over the
Mid Miss Valley/Ohio Valley/Mid South, including diffluent
thicknesses over KY/TN into VA/NC, an 850 mb theta-e ridge nosing
into the W Carolinas from the WSW, and increasing low level SW
jetting esp Wed night. This, along with anomalously high PW and the
LREF`s projected 750-1000 J/kg SBCAPE, would suggest considerable
clouds overall and above-normal pops in the good chance to likely
range. Such convection details are tough to pin down at this time
range with any reasonable confidence, but will indicate that
convection potential will be more equally spread throughout the day
and night, instead of focused purely on the afternoon/early evening
hours. Temps should be near to a category above normal.

Fri-Sun: The overall longwave pattern will shift to anomalously low
heights aloft across a large swath of the Great Lakes, adjacent
Canada and the Northeast as a deep northern stream low settles over
or just N of the Great Lakes. Deterministic models and ensemble
modeling systems are all in pretty good agreement on this, although
they still differ in terms of the associated low/trough, including
whether it spreads in a more W-E orientation or remains concentric
and digs S and SE into the Mid South and Carolinas. In either
scenario, we`re likely to see the approaching surface cold front
pushing well into the CWA Fri and to our SE by Sat/Sun, drawing in
markedly lower PWs, slightly cooler-than-normal thicknesses, and
much lower surface dewpoints. Will retain pops Fri but keep just
slight chances NW and near-climo chances SE, although Fri pops may
need to be reduced further if model trends of pushing the cold front
through much of our area by Fri morning hold (and this dry-Fri
scenario is supported by the latest EC-AIFS). Expect dry conditions
Sat/Sun, with temps slightly below normal. -GIH

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 725 PM Sunday...

Mainly light sprinkles across the area at the moment, but conditions
remain VFR. VCSH was included at the TAF sites through around 03z.

Late tonight, most guidance indicates widely scattered showers
across the area as a trough moves through NC. Elected to include a
few hours of VCSH at RDU/FAY/RWI as this trough crosses the area
although confidence in how this late night scenario will play out
is low. There should also be a period of IFR to MVFR cigs at KINT
and KGSO between 06z and 13z.

Outlook: Additional, mainly diurnally driven showers and storms, are
expected through much of this week as we return to a more typical
June pattern. Highest storm chances are likely at INT/GSO although
all 5 TAF sites could see impacts in the form of non-VFR cigs/vsbys
within any showers that develop.

&&

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

&&

$$
SYNOPSIS...Swiggett
NEAR TERM...Swiggett
SHORT TERM...Kren
LONG TERM...Hartfield
AVIATION...PWB/Leins