Morrisville, North Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

325
FXUS62 KRAH 141420
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1019 AM EDT Wed May 14 2025

.SYNOPSIS...
An upper level trough will move through the region through tonight.
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 1019 AM Wednesday...

* Another Marginal/Level 1 Risk of of Severe Storms this
  afternoon/early evening

Limited changes this morning as the inherited forecast is on track.
Regional composite mosaic radar depicted a fast moving area of
convection over the western Piedmont this morning.  The MCV
generating this convection will continue ene over the next several
hours. We`ve seen plenty of breaks in the clouds over the central to
northern Piedmont. Given the rich moisture in place, it won`t take
long for additional MCV-induced convection to pop over the Piedmont.
Effective shear through early to mid afternoon is pretty marginal
(~20 to 25 kts). As such, not entirely convinced the earlier
convection will produce any severe weather. However, as we progress
through the late afternoon and early evening, models do hint at
stronger shear potential along and east of the I-95 corridor.  Thus,
think any convection that develops in that vicinity today will have
the best chance to potentially generate isolated large hail or
damaging wind gusts.  The latest NCAR HRRR Neural Network run
highlights highest probabilities for severe weather in this vicinity
as well.

This evening`s convection should largely wane with loss of heating.
However, additional showers and elevated convection will be possible
as weak impulses migrate overhead.

Otherwise, patchy fog will again be possible tonight.


Previous discussion from 335 AM:

A mid-level shortwave trough over the southern Appalachians(remnant
of a former closed low) will advance east through the region through
this evening and exit off the mid-Atlantic coast late tonight/early
Thursday.

As the upper trough dynamics and forcing moves into the area,
scattered showers and storms will initiate over the western Piedmont
late this morning into midday. Convection will likely increase in
coverage and intensity as the storms shift east where moderate
instability of 1000-1500 J/KG of MLCAPE will be maximized along and
east of US 1. Given 25-30 kts, the convection could very well evolve
into a linear convective system. Damaging winds is the greatest
threat, with one or two embedded supercells possible.

Most of the convection should exit eastern areas by ~00z Thu.
However, the proximity of the upper trough and related upper
disturbances could result in the re-development if isolated to
widely scattered weak convection overnight.

Similar to tonight, partial clearing overnight may lead to fog
development, potentially dense between 06-12z, especially along and
north of Highway 64.

Highs today ranging from mid/upper 70s NW to lower 80s SE. Lows
tonight in the lower to mid 60s, with some upper 50s possible in
outlying rural areas over the northern Piedmont.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 430 AM Wednesday...

Downstream of a mid/upr-level cyclone that will develop and deepen
across the nrn Plains and upr MS Valley, progressive shortwave
ridging from the lwr MS to OH Valleys at the start of the period
will migrate ewd and across the Middle and South Atlantic through
12Z Fri. Seasonably strong nwly to wnwly mid-level flow will result
and prevail across the srn Middle Atlantic and Carolinas, as will
warm air advection maximized in the 700-850 mb layer that will
precede the arrival of an extensive elevated mixed layer plume from
the srn Plains and Mexican Plateau.

At the surface, a warm front will strengthen and retreat newd across
the OH Valley and Virginias, while broad troughing will otherwise
remain across the srn Middle Atlantic and Carolinas.

The aforementioned WAA regime may support an ongoing area of
elevated convection over or near cntl NC Thu morning, before moving
ewd and offshore through midday. That WAA regime, including through
the low-levels with the aforementioned surface warm frontal retreat,
will likely spread nwd across the Virginias coincident with daytime
heating. A separate area of convection will probably result and
develop along and east of the Blue Ridge in VA, with other, more-
isolated cells across the NC ne Piedmont and nrn Coastal Plain - all
with a generally sewd storm motion that would favor slight to low
chance PoP roughly along and north of I-40 during the afternoon-
evening. Forecast hodographs are elongated and clockwise-curved
particularly between 2-5 km, with weaker flow in the lowest
kilometer. Associated shear profiles combined with upr-end moderate
instability (ie. 2000-2500 J/kg), owing to the presence of steep mid-
level lapse rates within the EML, atop a strongly-heated (into the
mid/upr 80s F) and unseasonably moist boundary layer, would favor
supercells with large hail (some significant >2") and damaging wind
gusts.

While convective and associated debris clouds should clear through
midnight, a plume of mid/high-level moisture will overspread the
region Fri morning, with low temperatures mostly mid-upr 60s.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 500 AM Tuesday...

The models are in good agreement with the progression of a mid/upr-
level cyclone across the Great Lakes Fri through the weekend, with
increasing model spread regarding how quickly it moves across the
Northeast and lingers near or offshore Atlantic Canada through the
middle of next week. While it progresses across the Great Lakes
early in the period, glancing height falls, the stream of an
energetic srn branch jet, and the continued presence and influence
of an EML plume, will all result across NC Fri-Sat. A high amplitude
ridge will then progress slowly ewd from the Plains and MS Valley
Sun to the Southeast and Great Lakes through early-mid next week.

At the surface, a lee trough over the srn Middle Atlantic and
Carolinas Fri-Sat will precede the passage of a lead, weak cold
frontal passage in cntl NC Sat night. A stronger, reinforcing cold
front will follow and settle south across cntl NC probbaly Sun
night. That front will then likely stall and become quasi-stationary
from the srn Appalachians nwwd to the upr MS Valley early to mid
next week, equatorward of high pressure that will extend from e-cntl
Canada to the Middle Atlantic.

It appears increasingly-likely that the dry and capping EML
influence, and deep layer wly to wswly flow that will include a
considerable downslope component in the lee of the Appalachians,
will limit the probability of deep convection over cntl NC Fri-Sat.
The exception will be primarily over the far nrn NC Piedmont, where
height falls and forcing for ascent will be maximized at the base of
the passing cyclone across the Great Lakes. The airmass over cntl NC
will otherwise be hot, with high temperatures both days in the upr
80s to lwr-mid 90s.

Progressively less hot, but still unseasonably warm conditions, will
follow in the post-frontal regime across cntl NC Sun through mid-
week, along with low precipitation chances that will be shunted swwd
and nearer the stalled frontal zone across the srn Appalachians and
wrn Carolinas.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
As of 215 AM Wednesday...

Given the better upper trough dynamics and forcing across
western NC, scattered weak convection may persist or re-develop
overnight hours around KINT and KGSO. Elsewhere, mostly dry
conditions are expected, with the main aviation concern focused on
the development of fog, potentially dense in some locations. Latest
model guidance indicates IFR to LIFR restrictions are most likely
at KRWI and KRDU. This fog layer could impact KINT and KGSO
if the the convective cloud cover clears out enough to allow
surface cooling.

Fog is expected to dissipate between 12 to 13z.

Scattered to numerous showers and thunderstorms
expected to develop initially across the western Piedmont
by late morning/midday, then shift eastward
through the afternoon/early evening.

Most of the convection should exit eastern areas by ~00z Thu,
but some isolated/widely scattered showers could re-develop
across the area overnight.

Outlook: Chances for diurnal 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...
None.

&&

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