-- Discussion containing changed information from previous version are highlighted. --
122
FXUS62 KRAH 311831
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
231 PM EDT Fri May 31 2024

.SYNOPSIS...
Canadian high pressure will build across and offshore the Middle and
South Atlantic through Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1105 AM Friday...

A nrn stream shortwave trough and accompanying reinforcing cold
front and convection have moved offshore this morning. In its wake,
a longwave ridge extending this morning from the TN Valley to Hudson
Bay will progress east and extend from the Carolinas to QC by 12Z
Sat. Accompanying strong height rises, maximized in excess of 150
meters at 300 mb over the lwr Great Lakes in 12Z RAOB data, will
spread sewd and across the srn Middle Atlantic. While associated
mid/upr-level subsidence will result over cntl NC, visible satellite
data depict a veil of convective blowoff cirrus/cirrostratus that
will stream across the NC Piedmont and Sandhills, while probably
thinning.

At the surface, the center of 1027 mb Canadian high pressure over OH
will follow the aforementioned height rises aloft and across the srn
Middle Atlantic and become situated squarely over NC tonight, with
nely surface winds today that will become calm tonight.

The presence and influence of the Canadian high will yield
unseasonably cool temperatures in the 70s (~5-10 F below average)
today and in the middle 40s to lwr 50s (~10-15 F below average)
tonight. Observed mean mixing ratios of 2.5 - 4.5 g/kg evident on
the 12Z GSO and RNK soundings suggest surface dewpoints will mix
well into the 30s F throughout the Piedmont today, as wrn Piedmont
locations already have, with some upr 20s possible in nearby
srn/swrn VA. Associated minimum RH in the 20th percentile will
result throughout cntl NC today, making the 70s degree temperatures
feel even more comfortable.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 200 AM Friday...

Canadian high pressure centered over the area will slide eastward
and offshore during the afternoon and evening as transitory
shortwave ridging aloft builds over the area. The cP airmass will
begin to recover as southerly return flow develops over the area.
Warmer, but still slightly below normal for the 1st day of
meteorological summer. Highs 80 to 85 with dewpoints/humidity still
quite comfortable for this time of year.

Upper ridge axis moves offshore Saturday night. Modest moisture
advection associated with a shortwave trough moving east into the
Ohio and TN Valleys will lead to an increase in mid and high clouds
Saturday night, especially across western NC. However, conditions
will remain dry. Not as cool. Lows 55 to 60.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
As of 231 PM Friday...

A series of short wave troughs are forecast by models to move across
our region through much of the period.  Meanwhile at the surface,
high pressure will be centered to our east offshore of Cape Fear at
the start of the period and will generally remain to our east during
the period, with sw low level flow persisting over the Carolinas and
promoting gradual WAA and increasing PWAT through the week.   The
Piedmont trough will develop each day, with the next substantial sfc
front approaching and moving through late Thursday when a deeper
upper trough begins to develop over the Great Lakes region.

The sensible weather as a result of the above pattern will feature
gradually increasing temps and humidity each day as sw low level
flow persists.  Sunday will be the last of the near-normal temp days
for the period, with highs in the mid 80s, but then highs a few deg
either side of 90 will be possible each day the rest of the week.
Most of our CWA should remain dry on Sunday, with the exception of
our western Piedmont zones where a few isold showers/tstms are
possible.   Then for the remainder of the week, well have mainly
diurnal aoa-climo PoPs Monday through Wednesday, then the highest
PoPs late Thursday in response to the approaching front.  The front
should be to our east by Friday morning, with dry weather for the
rest of Friday.
-- End Changed Discussion --

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 210 PM Friday...

Canadian high pressure will build across and offshore NC and favor
VFR conditions through Saturday.

Outlook: Return flow moisture, combined with a lee trough and weak
surface front, will result in a chance of mainly diurnal
showers/storms, and also a small chance of pre-dawn, patchy sub-VFR
restrictions, Sunday through the middle of next week.

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...CBL
LONG TERM...np
AVIATION...MWS