453
FXUS62 KRAH 011750
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1236 PM EDT Sat Jun 1 2024

.SYNOPSIS...
Canadian high pressure centered across the area will move offshore
late today and tonight. The high pressure will move out into the
western Atlantic by Monday, bringing warmer and more humid air,
along with mainly diurnally driven showers and thunderstorms across
the area through mid week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1001 AM Saturday...

Morning satellite imagery continues to show a thin veil of cirrus
moving into the area from the southwest as a trough moves through
the lower MS valley. Following a relatively chilly start this
morning that saw temps fall all the way into the mid 40s in spots,
mid morning readings have already rebounded into the mid 60s to
lower 70s.

Aside from increasing high clouds throughout the day, sensible
weather impacts should be minimal. It`ll be another day with below
normal temperatures ranging from around 80 in the west, to the lower
80s in the Sandhills/southern Coastal Plain. Late tonight the trough
to our west will arrive in the mountains and there are some
indications of a stray shower in the Triad toward daybreak. Any
showers that make it that far east would be very light with only a
few hundredths of an inch of accumulation. The increasing moisture
coupled with lift from preceding MCVs/convectively-generated
vorticity axis could lead to some spotty light rain over the western
Piedmont towards daybreak. Elsewhere, it should remain dry with
multi-layered cloudiness developing across the area. Not as cool.
Lows 55 to 60.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 250 AM Saturday...

The aforementioned mid-level shortwave trough will continue to
dampen/weaken as it moves east through the southern and mid-Atlantic
states through the period. At the surface, a weak low pressure
trough develops along the lee of the mountains. Weak and difficult
to resolve perturbations may prove to be the primary drivers for
lift and associated isolated to widely scattered weak convection
Sunday afternoon and into Sunday night. Daytime heating within the
seasonably moist airmass should lead to weak buoyancy, mainly across
the NW Piedmont, which is where the highest PoPs will be retained
Sunday afternoon/evening. Then overnight, while the deepest moisture
gradually shift eastward towards eastern/coastal NC, model guidance
suggests an isolated/pop up shower is possible just about anywhere.

Highs ranging from upper 70s/near 80 NW to mid 80s SE. Lows in the
lower to mid 60s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 150 PM Saturday...

Temps and humidity will return to more typical summertime values
this week. Low confidence in Mon/Tue given weak flow within an ill-
defined pattern beneath diffuse mid level ridging over E NOAM. A
pattern shift to troughing centered over the Great Lakes region by
late week should lead to a trend to more organized precip potential
mid week. Confidence then dips again into next weekend with
increasing model spread in the longwave pattern.

Mon-Tue: Between a deep closed low over the NW Atlantic and a potent
trough moving into the PacNW and into the Dakotas and Upper Midwest
through Tue, very baggy and narrow mid level ridging will build
through E NOAM, resulting in a weak steering flow over our area. Our
moisture will increase through the column, including near the
surface where temps will also be on the upswing with good diurnal
heating and a S or SW flow on the back side of the exiting surface
high. Our precip chances will largely be scattered slow-moving or
meandering convection focused on weak and subtly boundaries,
although some models suggest that a backdoor synoptic front will
drop SSW into NC, driven by a cooler/denser air mass being propelled
southward down the Mid Atlantic coast due to the NW Atlantic low.
Will keep pops near or just over climatology, focused on
afternoon/evening, with the potential for isolated heavy totals due
to the expected rising PW, slow cell motion, and perhaps a backdoor
front to focus lift. Expect near normal temps Mon, with highs in the
80s, then a degree or two higher Tue, mid 80s to near 90. Lows in
the 60s.

Wed-Thu: 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 into the Ohio
Valley, leading to strengthening WNW steering flow at our latitude
and, especially, to our W and NW. Forecast PW is quite high, at or
above 2" on deterministic models, nearing records. We could see a
setup favoring nocturnal backbuilding MCSs upstream over the Mid
Miss Valley into the Ohio Valley/Mid South, including diffluent
thicknesses and nighttime low level SW jetting to our W/NW, which
may mean increased clouds overall along with passing convective
debris clouds and/or MCVs spreading in. But we can`t pin down such
details at this time range with any reasonable confidence, so for
now will have pops above climatology (high chances) with convection
potential more spread throughout the day and night (i.e., less
likely to be focused purely on the afternoon/evening hours). Temps
should be near to a category above normal with considerable
cloudiness.

Fri-Sat: The overall longwave pattern is expected to shift to
anomalously low mid level heights across a large swath of the
northeast CONUS 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
differ in terms of the associated trough -- primarily whether this
low digs SE/negatively toward NC or becomes more W-E oriented to our
N. In either scenario, we`re likely to see this culminate in a
surface cold front passage yielding a chance of storms Fri with dry
and less humid weather by Sat. But if the upper trough digs less
strongly toward NC and instead in a more W-E fashion, we could see a
surface front stalling overhead or even holding to our NW, keeping
us in the warmer air or causing a quick rebound back into warmer air
by late Sat. Will have chance pops mainly E Fri, then generally dry
weather Sat with most ensemble members suggesting us getting into
and staying in the drier air Sat. Temps near normal. -GIH

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
As of 1236 PM Saturday...

High confidence in VFR conditions through the period. Clouds will
thicken from west to east this evening/overnight and there could be
some stray showers near INT, but unlikely to affect the terminal
directly. Any morning showers will quickly dissipate after sunrise.
Additional showers are possible around INT/GSO just outside the end
of the TAF period. Dry weather expected elsewhere.

Outlook: Moisture will return to the area on Sunday with increasing
chances for showers through the week, especially at INT/GSO. Showers
likely to be diurnal in nature through Thursday with brief periods
of sub-VFR weather possible within heavier downpours.

&&

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

&&

$$
SYNOPSIS...CBL
NEAR TERM...Leins/CBL
SHORT TERM...CBL
LONG TERM...Hartfield
AVIATION...Leins