Severe Thunderstorm Warning 101, NWS Raleigh, NC

Area Forecast Discussion
National Weather Service Raleigh NC
400 PM 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 /THROUGH TONIGHT/...
As of 300 PM Wednesday...

Convection thus far today has been sub-severe, with the strongest
gust of 30 kts observed at KRDU earlier.  As this broken line of
showers and storms move east into the I-95 corridor, there remains
the potential for a few isolated cells to grow strong to severe
(CAPE is forecast to reach 3000 j/kg over this vicinity in the next
few hours).  Outflow via sea-breeze induced convection along the
coast from earlier is also racing towards our broken line of storms.
As such, outflow collisions in the Coastal Plain may also briefly
enhance updrafts the next few hours.   The main threats remain
isolated damaging wind gusts and perhaps some larger hail. Overall
though, the severe risk remains low today and this evening.

CAMs are still generating some additional showers/elevated
convection later tonight through early Thursday morning. However,
the bulk of precipitation should wane with loss of heating this
evening. Otherwise, expect patchy to locally dense fog to form
across northern areas again tonight.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 300 PM Wednesday...

12Z guidance this morning has done little in terms of changing our
thinking about how Thursday will evolve. There remains uncertainty
wrt to coverage Thursday afternoon, especially given the influence
of the approaching upper ridge. If convection does reach central NC,
it still appears to be most likely over the northern Piedmont and
northern Coastal Plain later in the day. Decided to maintain just
chance POPs in this vicinity centered around mid to late afternoon
and early evening. Otherwise, the description of potential hazards
and associated rationale remains accurate from the previous
discussion listed below.

Previous discussion from 430 AM...

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 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.

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 /18Z WEDNESDAY THROUGH MONDAY/...
As of 127 PM Wednesday...

Scattered showers and storms have blossomed across central NC early
this afternoon. This activity should continue to migrate eastward
with time through this evening.  Expect brief periods of sub-VFR
conditions at all TAF sites if impacted by any convection, with the
best chances being at KRDU/KFAY/KRWI through this evening.
Otherwise, additional showers and elevated convection will be
possible overnight, with best chances at KINT/KGSO.

Expecting fog/stratus to re-develop tonight and possibly impact the
northern terminals.  Any fog/stratus should lift by early to mid
Thursday morning.

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
SHORT TERM...Luchetti/MWS
LONG TERM...Danco
AVIATION...Luchetti/CBL

Hazardous Weather Outlook
National Weather Service Raleigh NC
1107 AM EDT Wed May 14 2025

NCZ021-022-038>040-042-073>078-083>086-088-089-151515-
Forsyth-Guilford-Davidson-Randolph-Chatham-Johnston-Stanly-
Montgomery-Moore-Lee-Harnett-Wayne-Anson-Richmond-Scotland-Hoke-
Cumberland-Sampson-
1107 AM EDT Wed May 14 2025

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This afternoon and tonight.

Severe storms are possible this afternoon and early evening.
Damaging wind and severe hail are the primary threats. Some minor
flooding is also possible, especially in areas where creeks and
streams are already high from recent heavy rain.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

NCZ007>011-023>028-041-043-151515-
Person-Granville-Vance-Warren-Halifax-Alamance-Orange-Durham-
Franklin-Nash-Edgecombe-Wake-Wilson-
1107 AM EDT Wed May 14 2025

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This afternoon and tonight.

Severe storms are possible this afternoon and early evening.
Damaging wind and severe hail are the primary threats. Some minor
flooding is also possible, especially in areas where creeks and
streams are already high from recent heavy rain.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Although coverage may be limited, any thunderstorms Thursday
afternoon through early evening will be capable of producing large
hail, some up to two to two and half inches in diameter, and
damaging
wind gusts.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.

Special Weather Statement
National Weather Service Raleigh NC
133 PM EDT Wed May 14 2025

NCZ025-041-141830-
Durham NC-Wake NC-
133 PM EDT Wed May 14 2025

...STRONG THUNDERSTORMS WITH VERY HEAVY RAIN WILL IMPACT WAKE AND
SOUTHEASTERN DURHAM COUNTIES THROUGH 230 PM EDT...

At 129 PM EDT, Doppler radar was tracking a cluster of strong
thunderstorms near RDU International and Morrisville, moving north-
northeast at 15 mph.

HAZARD...Wind gusts up to 40 mph.

SOURCE...Radar indicated.

IMPACT...Rainfall rates in excess of 1.5 inches in 30 minutes may
         produce flash flooding. Frequent lightning is occurring
         with these storms.

Locations impacted include...
Raleigh, Durham, Cary, Wake Forest, Garner, Zebulon, RDU
International, Apex, Holly Springs, and Morrisville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Take shelter indoors until the storm passes.

&&

LAT...LON 3612 7881 3609 7881 3607 7878 3608 7869
      3599 7846 3594 7839 3593 7835 3591 7835
      3590 7831 3587 7828 3585 7827 3561 7899
      3585 7891 3587 7891 3587 7895 3614 7890
TIME...MOT...LOC 1729Z 193DEG 12KT 3583 7884

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

PWB

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Preliminary Local Storm Report
National Weather Service Raleigh NC
538 PM EDT Wed May 14 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0400 PM     Hail             3 SSE Dunn              35.27N 78.60W
05/14/2025  M1.00 Inch       Harnett            NC   Public

            Picture of quarter sized hail received. Time
            estimated based on radar.

&&

LH

Special Weather Statement
National Weather Service Raleigh NC
548 PM EDT Wed May 14 2025

NCZ040-041-076-077-142245-
Lee NC-Chatham NC-Harnett NC-Wake NC-
548 PM EDT Wed May 14 2025

...STRONG THUNDERSTORMS WILL IMPACT NORTHERN HARNETT...LEE...
SOUTHERN WAKE AND CHATHAM COUNTIES THROUGH 645 PM EDT...

At 546 PM EDT, Doppler radar was tracking a cluster of strong
thunderstorms from Moncure to New Hill and Apex, moving east at 35
mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Cary, Garner, Fuquay-Varina, Angier, Apex, and Holly Springs.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3582 7855 3578 7832 3571 7847 3552 7871
      3549 7866 3547 7865 3544 7861 3540 7870
      3539 7915 3553 7923 3584 7906
TIME...MOT...LOC 2146Z 272DEG 30KT 3564 7882

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

PWB