867
FXUS62 KRAH 012258
AFDRAH

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

.SYNOPSIS...
Canadian high pressure centered across the area will move offshore
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 241 PM Saturday...

High pressure remains in place at the surface and aloft across the
Mid Atlantic this afternoon. Mid level water vapor imagery shows a
ridge axis from southern NY to SC, with a deepening trough over
KY/TN. Cloud cover associated with this trough continues to stream
eastward, with a thin veil of cirrus in place across much of the
east coast this afternoon. Temps across central NC this afternoon
generally range from the upper 70s to low 80s as of 18Z, with
dewpoints still barely touching 50 degrees.

Tonight, the upper low/trough axis will shift east. As it does so,
moisture advection will increase across the area. Clouds will
thicken up from west to east and dewpoints will begin a slow climb
upward, returning to the upper 50s/lower 60s by daybreak. Showers
presently associated with the trough will also make a run at central
NC as weak forcing for ascent rounds the base of the mountains and
moves into the central Piedmont. Nearly all guidance this afternoon
suggest the development of some widely scattered light showers west
of the forecast area. A few members of the HREF as well as the grand
ensemble produce a few hundredths of an inch of rain across western
Forsyth and Davidson Co`s, and I will maintain 15-20 PoPs in those
areas. Elsewhere, lingering dry air in the boundary layer, combined
with a lack of upper level support, should allow for a dry forecast
tonight.

Lows tonight will be milder compared to this morning, only reaching
the upper 50s to lower 60s.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 241 PM Saturday...

Sunday will continue to see mid level moisture advection into the
area with PW`s gradually climbing into the 1.5 - 1.75 inch range by
late in the day. Meanwhile, lee troughing east of the mountains and
associated surface convergence will likely result in the development
of afternoon showers and isolated thunderstorms, mainly across the
western Piedmont. Instability is meager with only 100-250 J/KG on
offer, so anything that develops should remain well below severe
limits. While most of the showers should dissipate quickly with the
loss of daytime heating, most models suggest a weak mid level
shortwave will move into the area overnight with another round of
widely scattered showers possible into the early morning hours on
Monday.  PoPs will be highest in the west during the daytime hours
(generally between 30-40 percent), then falling to around 20 percent
area-wide during the evening/overnight hours.

Temperatures should be on par with today, perhaps a few degrees
warmer. Highs in the low/mid 80s. Lows in the low 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 /00Z SUNDAY THROUGH THURSDAY/...
As of 700 PM Saturday...

There is high confidence in VFR conditions through the TAF period.
Clouds will thicken and lower overnight into Sunday, but mostly with
mid and high-level bases. Increasing moist flow could favor some
VCSH at INT in the morning Sun. Additionally, a weak disturbance
could bring some isolated showers at INT/GSO Sun afternoon or
evening. Confidence was too low to mention thunder given weak
instability and little agreement amongst the model guidance.
RDU/FAY/RWI should remain dry through the period. South-southwest
winds will persist between 5 and 12 kt, at times gusting to 18 kt at
GSO/INT.

Outlook: Moisture will continue to return to the area in the coming
week, with increasing chances for showers each day, especially at
INT/GSO. Showers are 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...Leins/CBL
NEAR TERM...Leins
SHORT TERM...Leins
LONG TERM...Hartfield
AVIATION...Kren/Leins