346
FXUS62 KRAH 121310
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
910 AM EDT Sun May 12 2024

.SYNOPSIS...
High pressure will build across the Southeast and Mid Atlantic
region today, then shift off the Southeast coast tonight through
Monday. A storm system will move in from the west Monday night
through Wednesday, bringing unsettled weather. Weak high pressure
moving in briefly for Thursday will be quickly followed by another
storm system arriving Friday.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 910 AM Sunday...

A quiet, dry, and seasonable day ahead. Mostly sunny skies are
likely to hold today with incoming surface high pressure. A few mid
clouds associated with a weak shear axis aloft will track through
far N and NE sections over the next few hours, and high thin clouds
will stream from the Mid South across our SW sections, plus we`ll
see a few high base flat cu this afternoon. All in all, though,
quite a bit of sunshine is expected today. Morning thicknesses are
about 15-18 m below normal, but modifying air balanced with abundant
insolation favors near-normal highs of 74 to 82, with a few gusts
around 15-20 mph. Very dry air is noted aloft (0C at 925 mb on the
12Z GSO sounding), and with good mixing expected today, we should
see very low RH well down into the 20-30% range this afternoon. -GIH

Earlier discussion from 330 AM: Radar echos have finally completely
dissipated across the Sandhills and southern Coastal Plain, with
just a deck of clouds there that will exit in the next couple hours.
Elsewhere there will be clear skies the rest of the night. A few
sites have reported reduced visibilities from fog/mist, but the rain
that fell this evening was so light that the fog/mist should stay
very isolated.

Dry NW flow will prevail today across central NC between ridging
over the lower-mid MS Valley and a closed mid/upper low that water
vapor imagery depicts currently spinning over Lake Erie. At the
surface, low pressure will move SE from Upstate NY and weaken, as
high pressure drifts east from the TN Valley to stretch from VA/NC
to off the NJ coast on Monday morning. PW values today are only
modeled to be around half an inch (40-50% of normal) with good
mixing and downsloping helping dew points bottom out in the lower-to-
mid-40s. Statistical guidance even shows upper-30s dew points in the
far NW Piedmont. A dry and very pleasant Sunday will result, with
only some scattered cumulus below the subsident inversion at about
700 mb. NW winds could gust up to 15-25 mph during the day. Today`s
1000-850 mb thicknesses will be about 10 m higher than yesterday,
supporting high temperatures from the mid-70s to lower-80s.

As winds diminish to mostly calm Sunday evening/night, decent
radiational cooling conditions will help lows drop to the mid-40s to
lower-50s, though high clouds spreading in from the SW could inhibit
cooling a bit.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
As of 330 AM Sunday...

Shortwave ridging will move across central NC on Monday, ahead of a
shortwave trough (or closed low) that slowly moves east across KS
and MO. Meanwhile surface high pressure will shift fully offshore,
helping the low-level flow turn southerly. This WAA will be offset
by broken mid and high clouds overspreading the area as the flow
aloft turns southwesterly. So high temperatures should be similar to
Sunday, in the upper-70s to lower-80s. Clouds will lower and further
thicken Monday evening and Monday night as the aforementioned low
pushes a warm front through the Southeast US and mostly light rain
from isentropic lift begins to spread into central NC from SW to NE.
Models differ on timing, with the NAM fastest and GFS slowest, but
currently the best guess is for rain to begin in the southern and
western Piedmont on Monday evening and in much of the NE Piedmont
and Sandhills overnight Monday night. It may not begin in the
Coastal Plain until Tuesday morning. Lows Monday night will be much
milder, in the upper-50s to mid-60s.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 305 AM Sunday...

Surface low pressure should be over southern Illinois at the
beginning of the extended forecast and precipitation will extend
well to the east, with rain increasing in coverage through the day.
Models begin to diverge with the surface feature Tuesday night, with
the 00Z GFS showing two low centers by Wednesday morning (over KY/TN
and DE) while the 00Z ECMWF has one broad center over OH. Regardless
of which scenario plays out, think that a bit of a dry slot will
develop over the Carolinas Tuesday night and there should be a bit
of a lull in shower coverage. The last two runs of the ECMWF are
suggesting that the upper trough helping to support the surface low
could close off into an upper low over the mid-Atlantic on
Wednesday, helping to intensify the surface low as it passes to the
north. While some rain could linger Wednesday evening, conditions
should then dry out as high pressure settles over Quebec and a ridge
extends along the eastern seaboard on Thursday. Meanwhile, the next
system will be developing in the Plains, and with models indicating
it may move east a little more slowly, have removed all pops from
the forecast Thursday night. Had enough confidence to add likely
pops across western counties Friday, but the models diverge too much
after this to go with anything higher than chance pops through
Saturday. Tuesday remains the coolest day in the forecast with
widespread highs in the 70s and possibly even upper 60s near the
Virginia border, otherwise temperatures should be near climatology,
around 80 and 60 degrees.

&&

.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
As of 620 AM Sunday...

VFR conditions will prevail through the next 24 hours. Skies
have cleared and with winds calm to very light (less than 5 kts),
some very isolated fog/mist has been reported at a few spots, but
not at any of the TAF sites. Any fog/mist will stay very isolated
and dissipate after 12z. Scattered cumulus is possible during the
day today, but it will stay above the VFR threshold. NW winds will
pick up by late morning, gusting up to 15-20 kts, which will last
into the afternoon before diminishing in the evening. Skies will
clear in the evening before scattered high clouds start to move in
from SW to NE overnight.

Looking beyond 12z Mon: VFR conditions and dry weather are expected
through Mon. Rain and isolated storms, with a high chance of sub-VFR
conditions and increasing winds aloft, are expected to overspread
the area from SW to NE starting Mon night. Sub-VFR conditions will
last through Wed morning, although shower chances will persist
through Wed and sub-VFR may come back Wed night. Dry VFR conditions
should return for Thu.

&&

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

&&

$$
SYNOPSIS...Hartfield
NEAR TERM...Hartfield/Danco
SHORT TERM...Danco
LONG TERM...Green
AVIATION...Danco/Hartfield