922
FXUS62 KRAH 181805
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
205 PM EDT Tue Jun 18 2024

.SYNOPSIS...
High pressure will remain over the Mid Atlantic and Carolinas
through much of this week. Moisture will increase across the area
late this week into this weekend, bringing some increased rain
chances to the Sandhills/Southern Coastal Plain.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1030 AM Tuesday...

Broad ~1030 mb surface high pressure centered south of the Canadian
Maritimes will continue to extend SW into the Mid-Atlantic through
tonight. Looking aloft, water vapor imagery shows a large area of
dry air along and east of the Northeast US and Mid-Atlantic coasts.
These below-normal PW values will gradually get advected into
central NC by deep (but weak) easterly flow around an anomalous
mid/upper anticyclone centered just to our north. Thus the broken
stratocumulus across roughly the western half of our region will
push to our west through this afternoon and get replaced by mostly
sunny skies. With similar low-level thicknesses to yesterday, high
temperatures should again be in the upper-80s to lower-90s. Dry air
aloft and good boundary layer mixing beneath a strong inversion at
750-800 mb will help dew points decrease to the lower-60s in many
places this afternoon, with even some upper-50s possible. So while
it will be hot, heat indices will be very similar to the air
temperatures. Lows tonight will again be in the mid-to-upper-60s.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 106 AM Tuesday...

The anomalous mid-level ridge will continue to deepen across the mid-
Atlantic/northeast US on Wednesday, with heights peaking 2 to 3
standard deviations above climatology. A stream of drier air will
continue to advect across our area, as PWAT remains near ~70 to 80 %
of normal. As such, dew points will once again mix out into the
lower 60s Wednesday afternoon.  Daytime highs will once again max
out in the upper 80s to around 90.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 200 PM Tuesday...

The anomalously strong upper level anticyclone will be centered over
the mid-Atlantic on Thu, then slowly drift westward to over the TN
Valley Thu night. The high will remain over the TN/mid-MS Valley Fri
into Sat before migrating further westward through the southern
Plains to the Desert Southwest over the weekend as a northern stream
trough tracks eastward through the Great Lakes and into the
Northeast. The trough should progress eastward through the Northeast
and mid-Atlantic Mon/Mon night. At the surface, somewhat flat high
pressure off the East Coast will drift slowly southward Thu and Fri,
while still ridging westward into the area. As the surface
wave/inverted trough associated with the weak low aloft moves inland
over FL/GA Thu/Fri, a warm front will slowly creep northward toward
central NC. By Sat, any lingering, ely/nely flow and relatively dry
air associated with the ridge will be gone and the now sely/sly
return flow around the high will result in an influx of warm, moist
air into the area from the Atlantic. Southerly/swly flow will then
dominate through Sun night/Mon, when trough strengthens over the
area ahead of an approaching cold front moving through the OH
Valley. There continue to be significant differences between the
medium-range guidance wrt this front, so it remains unclear whether
it will impact central NC or not, and when.

Temperatures: The big weather story continues to be the potential
heat risk this weekend into early next week. Initially under the
upper level high on Thu, the position of the surface high/ridge Thu
and Fri may help keep temps/apparent temps down across central NC.
However, as that ridge breaks down and the high aloft retreats
westward, central NC will be under the influence of nwly flow and
subsidence aloft and sely/southerly return flow at the surface,
resulting in increasing low-level thicknesses and surface dewpoints.
The result will be an increasingly hot forecast through the weekend
into early next week. For now, Sun appears to the the hottest day,
with highs in the mid to upper 90s and heat index values in the 100-
104 range across the eastern Piedmont, Sandhills, and Coastal Plain
regions of central NC. Highs on Sat and Mon should also top out in
the mid to upper 90s with heat index values mainly in the 94-101
range. There will also be limited relief from the heat overnight
from Sat night through Mon night, with temps struggling to dip below
70 degrees.

Precipitation: Since any rain associated with the area of low
pressure expected to move westward and inland over FL/GA on Fri/Sat
should remain south of central NC, the forecast remains dry through
at least Saturday. Showers and storms could develop Sun/Mon with the
trough extending from the Northeast through the mid-Atlantic and
Carolinas, however the models disagree on the chances and potential
coverage.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
As of 145 PM Tuesday...

VFR conditions will prevail through the next 24 hours, as any
lingering stratocumulus this afternoon in the west remains above the
VFR threshold and clears out by this evening. More stratocumulus is
expected tomorrow morning and afternoon. A brief MVFR ceiling can`t
be entirely ruled out tomorrow morning, particularly south and east,
but don`t have enough confidence to include mention of it in the
TAFs at this time. Winds will be light (around 7 kts or less) and
generally from the east through the period.

Outlook: Dry weather and VFR conditions will persist through Friday.
Moisture and a slight chance for showers will return in the far SE
on Saturday, and areawide on Sunday.

&&

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

&&

$$

SYNOPSIS...Leins
NEAR TERM...Danco
SHORT TERM...Luchetti
LONG TERM...KC
AVIATION...Danco