-- Discussion containing changed information from previous version are highlighted. --
679
FXUS62 KRAH 190029
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
825 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/...
-- Changed Discussion --
As of 825 PM Tuesday...

The inherited forecast was in good shape, with just some minimal
tweaks made to hourly temperatures and sky grids for the evening
update. Previous discussion follows.

As of 330 PM 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 over the eastern Mid-Atlantic. Deep easterly flow around an
anomalous mid/upper anticyclone centered just to our north continues
to spread these below-normal PW values west into central NC and help
pin any convection well to our west in the mountains. Scattered
cumulus persists this afternoon but is capped by a strong inversion
at 750-800 mb. Dry air aloft and good boundary layer mixing is
helping dew points bottom out in the upper-50s to lower-60s in many
places. So while it is hot with afternoon highs in the upper-80s to
lower-90s, heat indices are kept down by the lower humidity and are
very similar to the air temperatures. Slightly lower low-level
thicknesses compared to this morning will support lows tonight in
the mid-to-upper-60s.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 350 PM Tuesday...

Tomorrow will be more of the same as the anomalously strong
mid/upper anticyclone remains centered over the northern Mid-
Atlantic and even strengthens a bit further, keeping us under
easterly flow aloft and at the surface. More flat cu is expected,
but it will be dry under the influence of the ridge. PW values will
only be 70-80% of normal. Slightly lower low-level thicknesses
compared to today will result in high temperatures maybe a degree or
two lower on average, still in the upper-80s to lower-90s. Dew
points will again mix out to the upper-50s to lower-60s in the
afternoon, helping keep heat indices down. Lows Wednesday night will
again be in the mid-to-upper-60s.

&&

.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 /00Z WEDNESDAY THROUGH SUNDAY/...
As of 727 PM Tuesday...

VFR conditions will prevail through the next 24 hours.

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...Green/Danco
SHORT TERM...Danco
LONG TERM...KC
AVIATION...Danco