Spring Lake, North Carolina Weather Forecast Discussion

688
FXUS62 KRAH 230825
AFDRAH
Area Forecast Discussion
National Weather Service Raleigh NC
425 AM EDT Tue Sep 23 2025
.SYNOPSIS...
A surface trough will develop in the lee of the central and southern
Appalachians today, while high pressure will otherwise extend from
near Bermuda to the South Atlantic coast through mid-week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 350 AM Tuesday...
NWP guidance indicate a couple of closely-spaced shortwave
perturbations, now evident in GOES-E WV data over cntl KY and srn
IL, will progress ewd and across the srn Appalachians and srn Middle
Atlantic/Carolinas through this evening, then probably phase as they
near and exit the srn Middle Atlantic coast between 00-06Z Wed. They
will be accompanied by a pocket of minus 9-10C 500 mb temperatures
evident over the TN and OH Valleys in 00Z upr air data and preceded
by at least one small convectively-amplified mid-level disturbance
(MCV), now evident in regional radar data over the coalfields of ern
KY and srn WV, which will track through swly to wswly mid-level flow
and across the Virginias and PA through this evening. A couple of
other MCVs may already be present or develop within trailing
convection now stretching wswwd through Middle and wrn TN and follow
a similar path but several hours later as the first. The net result
will be weak, 10-20 meter mid-level height falls and an accompanying
belt of 25-30 kts of swly to wswly mid-level flow over the Virginias
and cntl and ern PA through 00Z Wed, with generally neutral height
tendency, 15-25 kts of mid-level flow, and slight steepening of 850-
500 mb lapse rates to around 6-6.25 C/km over cntl NC. In the wake
of these features, shortwave ridging and 10-30 meter mid-level
height rises will overspread the Carolinas and srn Middle Atlantic
overnight-early Wed.
At the surface, the center of a surface ridge, now evident in
surface observational data from just offshore the Middle Atlantic
coast swwd and across ern NC and cntl SC and GA, will move off the
NC coast today. A warming, sly to sswly return flow will
consequently develop across cntl NC and into an Appalachian-lee
trough forecast to develop across the wrn Piedmont of VA and the
Carolinas.
The aforementioned return flow regime should cause temperatures to
warm 2-4 F on avg over the previous period and range from low-mid
80s north to upr 80s to near 90 F south today and centered in the
mid 60s tonight. Despite the associated unseasonably warm
temperatures and strong insolation, only modest boundary layer
moisture characterized by surface dewpoints in the upr 50s to lwr
60s this morning will limit MLCAPE to around 250-750 J/kg over cntl
NC this afternoon-evening, locally to around 1000 J/kg over the nw
Piedmont. That instability will be uncapped and accompanied by a
spatial maximum of 700 mb RH near and just above the top of the
mixed/boundary layer per point forecast soundings at INT/GSO and
plan view 700 mb RH fields. Given that those moisture and
instability maxima will coincide with a surface convergence maximum
along the lee/Piedmont trough, and there will likely be some degree
of influence/lift provided by the shortwave trough and/or smaller
MCVs, a slight chance of showers/storms remain warranted this
afternoon-early evening over the nw Piedmont, even if the strongest
forcing for ascent accompanying the lead shortwave perturbation
appears as though it will pass that region prior to peak diurnal
heating/destabilization. Although NBM PoPs remain below 10%, CAM
guidance unanimously support the idea of widely scattered convection
over and especially just west of the Triad this afternoon-evening.
The signal in model guidance for fog and stratus is greatest in the
far ern Sandhills and Coastal Plain Wed morning.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 420 AM Tuesday...
Shortwave ridging and height rises will progress across and offshore
the srn Middle Atlantic and Carolinas through early Wed night,
during which time a synoptic trough will consolidate from the lwr
Great Lakes swwd into the lwr MS Valley and srn Great Plains. NWP
guidance indicate the synoptic trough will be preceded by
convectively-perturbed swly flow from the lwr MS Valley to the srn
and cntl Appalachians, with associated weak, 10-30 meter mid-level
height falls likely to overspread the wrn Carolinas late Wed night.
At the surface, a cyclone will progress across the OH Valley and lwr
Great Lakes, with a trailing synoptic cold front that will likely
reach the mid-South and lwr MS Valley by 12Z Thu - well west of cntl
NC. However, a separate area of frontogenesis is forecast ahead of
that front, from the lwr MS and TN Valleys newd and into the vicinity
of a preceding lee trough axis across the Foothills and wrn Piedmont
of the Carolinas and VA. That developing and initially loosely-
defined frontal zone will probably become convectively-reinforced,
focused, and modulated by clusters of convection that develop and
are maintained along it, including into the nw NC Piedmont of cntl
NC by Wed night.
Given that most of cntl NC will remain in the warm sector east of
both frontal zones, except the nw Piedmont by late Wed-Wed night,
unseasonably and persistently warm conditions will result over cntl
NC. It should also be mostly dry over all but the nw Piedmont, where
PoPs will increase into the 20-30% range by Wed night. Humidity
levels will also be on the increase, as onshore flow across the
South Atlantic coast should yield an increase in surface dewpoints
into the upr 60s-lwr 70s Wed night-Thu morning, with similar-valued
low temperatures.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 345 AM Tuesday...
A strong upper trough will continue to deepen on Thursday extending
strong swly flow from the Deep South up through to New England. This
trough and associated jet streak will move across and off the
eastern seaboard through early Sunday morning. An upper low will cut
off from the departing trough and remain semi-stationary somewhere
across the Deep South/Gulf late this weekend before possibly lifting
across the southeast early to middle of next week.
Thursday through Saturday: Upper forcing associated with the trough
should generate periods of pre-frontal showers and storms with the
heaviest rain most likely falling late Thursday through Friday
night. Given the likely n-s oriented storm motion, good training
potential may lead to isolated flash flooding during this period.
Otherwise, increasing shear Thursday may combine with steep low-
level lapse rates (high temps will reach the upper 80s/lower 90s on
Thursday) and promote some chance for isolated severe storms.
Temperatures on Friday will be a bit cooler in the lower 80s, and as
such it may be a bit more difficult to get enough instability to
generate stronger storms. However, lingering stronger shear
associated with the exiting upper trough could surely support a
stronger storm or two Friday afternoon and evening.
The eastward ejecting upper jet will linger over central NC
Saturday, likely generating additional showers and a few storms
Saturday afternoon and evening. However, as the upper jet moves east
of our area Saturday night, ensembles suggest drier air should start
filtering in across our area through Sunday morning.
Sunday through Tuesday: Predictability decreases for Sunday into
early next week as deterministic guidance disagrees with the position
of the aforementioned cutoff low and how to handle anomalous
moisture associated with the system.  The GFS develops the upper low
further south over the Gulf waters largely shunting anomalous
moisture off the southeast coast (with strong sfc high pressure
extending into our area from New England). Alternatively, the Euro
positions the upper low a bit further north, drawing rich Atlantic
moisture northward across the southeast promoting more unsettled
weather through early to middle of next week. To handle the
uncertainty, maintained just slight to low-end chance PoPs peaking
each afternoon during this period.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
As of 220 AM Tuesday...
The exception to prevailing VFR conditions and light sswly surface
winds through the TAF period will be calm this morning and an
accompanying risk of shallow, radiation mist/fog and associated low
cloud bases and/or vertical visibility restrictions at RWI, FAY, and
perhaps also INT. Despite relatively richer and deeper low-level
moisture at ern terminal that would otherwise favor fog, the
presence of multi-layered mid and high clouds related to a
disturbance tracking through the ern Carolinas may limit fog
coverage and intensity there. A spatially separate area of fog/low
clouds may result from near CLT to INT, within a secondary low-level
moisture maximum and region of relatively clear skies favorable for
stronger radiational cooling and fog development. Where fog/low
clouds do develop, they should disperse quickly by 13-14Z.
Otherwise, widely scattered showers/storms will be possible at and
around INT and GSO this afternoon-evening, with limited (~20%)
probability of occurrence best reflected with a VCSH there for now.
Outlook: Areas of stratus and fog will be possible again Wed and Thu
mornings, mainly at and east of RWI and FAY. Scattered showers/
storms are expected at INT/GSO again Wed afternoon-night. Their
probability of occurrence will increase and overspread all of cntl
NC Thu-Fri, with associated flight restrictions, then linger into
the upcoming weekend, as a slow-moving trough aloft and surface cold
front slowly traverse our region.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...MWS
LONG TERM...NTL
AVIATION...MWS

NWS RAH Office Area Forecast Discussion