775
FXUS62 KRAH 150753
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
352 AM EDT Thu May 15 2025

.SYNOPSIS...
An upper level trough will exit the area this morning.
Upper level disturbances moving atop an upper level ridge building
across the SE US will support mainly diurnal showers and storms and
unseasonably hot temperatures to end the week.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 350 AM Thursday...

*  Dense Fog Advisory in effect across northern and central NC
   through 9 am

*  Isolated/Widely Scattered Strong/Severe Convection Possible
   across the northern Piedmont and northern coastal plain this
   afternoon/early evening

Early morning: Satellite and sfc obs show areas of dense fog across
portions of northern and central NC, where dewpoint depressions have
fallen below 2 degrees due to partial clearing, saturated soils and
rain-cooled air. Visibilities should rapidly improve after daybreak
as sfc mixing increases.

Meanwhile a zone of strong 850-700mb WAA on the heels of the exiting
upper trough will continue to support widely scattered convection
through daybreak, before moving offshore.

Today:

Upper level ridging will build eastward today, bringing modest 500
mb height rises(40 m) and suppressing widespread convection. However,
strong diurnal heating(afternoon highs mid/upper 80s) within the
residual moist airmass and steep mid-level lapse rates (7.5-8 deg
C/km) from an expansive EML moving into the region from the from the
Southern Plains/Mexico, will create a very unstable environment,
with MLCAPE of 2500-3500 J/kg.

While the primary severe threat is expected to lie across eastern Va
and northeastern NC, if convection moving off the Blue Ridge
Mountains can drift far enough south into the northern Piedmont and
northern coastal plain counties during the afternoon and evening,
the fat CAPE profiles coupled with deep layer shear of 30-35 kts
could support potentially vigorous updrafts and supercells capable
of producing large hail and wind damage. A isolated tornado
is also possible.


Tonight:

The severe threat diminishes after sunset, though some isolated to
widely scattered convection may re-develop overnight. Fog potential
tonight appears significantly lower than the previous 2 nights, but
may still occur in more isolated/patchy variety in areas(northeast)
receiving heavy rain. Warm overnight lows 65-70 F.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 400 PM Wednesday...

Shortwave ridging aloft will extend NE into the Carolinas on Friday
afternoon and evening, with the axis finally pushing offshore on
Friday night as it gets starts to get suppressed by the next deep
closed low that moves east from MN into Lake Superior and the UP of
MI. A lee surface trough will also be in place across the southern
Mid-Atlantic. Despite moderate to potentially even high levels of
SBCAPE (1500-2500+ J/kg), model soundings show we should be fairly
capped and dry with WNW flow in the mid and upper levels. Thus
deterministic and ensemble guidance continue to look mostly dry on
Friday. A few isolated showers or storms will be possible across the
far N, but overall coverage should be quite limited. If any
convection is able to break through the cap, a strong storm can`t be
ruled out as there will be ample mid-level flow with bulk shear on
the order of 40-60 kts. While central NC will begin experiencing
some weak mid-level height falls and forcing for ascent on Friday
night, we should be stable by this point with loss of daytime
heating, so just continue slight chance POPs in the far N and NW.
Hot temperatures will the bigger concern on Friday with the ridging
aloft and SW low-level flow. Forecast highs are in the upper-80s to
mid-90s. Dew points in the upper-60s and lower-70s will result in
heat indices in the mid-90s to 100 from the Triangle to the south
and east. Temperatures will stay mild on Friday night, with lows in
the upper-60s to mid-70s.


&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 400 PM Wednesday...

The mid/upper low and occluded surface low will track east across
southern Ontario and the Upper Great Lakes on Saturday, dragging a
cold front to the south that guidance is in good agreement will pass
through central NC on Saturday evening/night. Instability continues
to look moderate to strong along with 40+ kts of mid-level flow
(similar to Friday). However, moisture with the front does not look
impressive, as the flow aloft is still from a westerly direction,
and we only get a glancing blow in upper forcing with the low
tracking so far to our north. Ensemble mean QPF continues to be less
than a tenth of an inch. So only have slight to low chance POPs in
the afternoon and evening, highest over the northern Piedmont where
again the greatest upper forcing will be. Still can`t rule out a few
strong to severe storms. Saturday`s temperatures may be kept down a
bit by the increased precipitation chances and approach of the cold
front, particularly in the NW. But they should still be quite warm
with highs in the mid-80s to lower-90s. Heat indices in the upper-
90s will again be possible in the SE.

Overall forecast confidence decreases for the rest of the period.
The mid-level flow will turn increasingly NW from Sunday into
Tuesday, as we are caught between the low slowly drifting east over
New England/SE Canada and ridging that strengthens and builds east
from the Plains to the Deep South and TN Valley. At the surface, a
secondary backdoor cold front looks to move through central NC
sometime Sunday night or Monday, as the GFS and ECMWF start to
diverge on how quickly the low over the Canadian Maritimes moves
east into the Atlantic. This front will be quasi-stationary but
should remain draped to our south and west through Tuesday, keeping
us relatively dry and stable. The 12z GFS and ECMWF potential for an
MCS moving through in the NW flow aloft late Monday, but timing and
placement of these systems this far in advance is difficult to
pinpoint. So only have slight chance POPs in the south and west from
Sunday through Tuesday. Guidance depicts the next low moving NE from
the Central Plains into the Upper Great Lakes on Tuesday and
Wednesday, which may help push the boundary back north as a warm
front on Wednesday. But there is still plenty of divergence in
guidance on the low`s strength. Regardless it appears shower/storm
chances will increase on Wednesday, so have chance POPs returning.
Temperature forecast confidence is low from Sunday onward,
especially by midweek, but the overall trend seems to be trending a
bit cooler, especially on the ECMWF. As cool high pressure extends
south from the Hudson Bay into the Eastern US, expect at least a
gradual drop in temperatures, with highs reaching closer to normal.
Dew points should also become more comfortable, dropping into the
50s.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
As of 145 AM Thursday...

Areas of dense fog with IFR to LIFR restrictions is occurring around
the northern TAF sites(KINT,KGSO,KRDU and KRWI), due to a
combination of partial clearing, saturated soils and rain-cooled air
and dewpoint depressions < 2 degrees F. Recent improvements at KINT
and KGSO are likely temporary, as the development of isolated-widely
scattered convection and associated cloud cover continues to move
east, leading to variable and ever changing restrictions.

Fog should lift and dissipate between 12 to 14z.
VFR conditions should dominate, but a cluster or two of storms out
of Virginia may impact KRDU and KRWI this afternoon/evening, with
brief sub-VFR restrictions possible.  Latest model guidance
indicates minimal fog potential tonight/Friday morning.

Outlook: Chances for diurnal isolated to scattered showers and
storms will continue through much of the period.  Morning fog and
low stratus will be possible each morning, especially in areas that
received significant rainfall the previous day.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM EDT this morning for NCZ007>011-
021>028-038>043-076>078.

&&

$$
SYNOPSIS...CBL
NEAR TERM...CBL
SHORT TERM...Luchetti/MWS
LONG TERM...Danco
AVIATION...CBL