572
FXUS62 KRAH 212032
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
430 PM EDT TUE JUL 21 2026
WHAT HAS CHANGED
* CONFIDENCE CONTINUES TO INCREASE FOR A THREAT OF HEAVY RAINFALL
AND FLOODING FROM LATE WEDNESDAY INTO SATURDAY, AS THE LATEST
MODELS ARE SLOWER THE PASSAGE OF A MOISTURE-LADEN COLD FRONT.
KEY MESSAGES
AS OF 425 PM TUESDAY...
1) AS A COLD FRONT APPROACHES ON WEDNESDAY AND WEDNESDAY NIGHT,
SHOWERS AND STORMS WILL BECOME MORE WIDESPREAD ACROSS THE NORTHERN
PIEDMONT AND NORTHERN COASTAL PLAIN. EXCESSIVE RAINFALL AND FLASH
FLOODING WILL BE POSSIBLE, AND FLOOD WATCHES MAY NEED TO BE ISSUED.
LOCALLY DAMAGING WINDS ALSO CAN'T BE RULED OUT.
2) WIDESPREAD SHOWERS AND STORMS WITH A RISK FOR FLOODING WILL
CONTINUE INTO AT LEAST FRIDAY AND POSSIBLY EVEN THIS WEEKEND,
PARTICULARLY IN OUR SOUTH AND EAST, AS A COLD FRONT STALLS NEAR THE
NC/SC BORDER.
DISCUSSION
AS OF 425 PM TUESDAY...
KEY MESSAGE 1... AS A COLD FRONT APPROACHES ON WEDNESDAY AND
WEDNESDAY NIGHT, SHOWERS AND STORMS WILL BECOME MORE WIDESPREAD
ACROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN. EXCESSIVE
RAINFALL AND FLASH FLOODING WILL BE POSSIBLE, AND FLOOD WATCHES MAY
NEED TO BE ISSUED. LOCALLY DAMAGING WINDS ALSO CAN'T BE RULED OUT.
CONFIDENCE IS MODERATE-TO-HIGH FOR SHOWERS AND STORMS TO INCREASE IN
COVERAGE ACROSS THE NORTHERN PIEDMONT LATE THIS EVENING INTO EARLY
WEDNESDAY MORNING. A COLD FRONT PUSHING DOWN SLOWLY FROM VIRGINIA
WILL STALL NEAR THE NORTH CAROLINA BORDER OVERNIGHT, BRINGING A RISK
OF CONTINUOUS RAINFALL, WHICH CAN BE HEAVY AT TIMES, TO THE AREAS
ALONG AND SOUTH OF THE NC BORDER AROUND DAYBREAK. WHILE AN ISOLATED
SEVERE STORM WITH DAMAGING WIND GUSTS CAN'T BE RULED OUT TONIGHT,
THE MAIN CONCERN WILL SHIFT INTO WEDNESDAY.
AS MID/UPPER TROUGHING WITH EMBEDDED SHORTWAVE IMPULSES REMAINS IN
PLACE ACROSS THE EASTERN US ON WEDNESDAY, A STRONG COLD FRONT WILL
APPROACH AND THEN SLOWLY BEGIN TO CROSS THE NW PIEDMONT ON WEDNESDAY
NIGHT. WHILE WIDESPREAD CLOUD COVER THROUGH THE DAY WILL LIMIT
DAYTIME HEATING ACROSS THE NORTH, MODELS STILL SHOW WEAK TO MODERATE
INSTABILITY (UP TO 1000-1500 J/KG OF CAPE) THERE. ABOVE-NORMAL PW
VALUES OF 2-2.5 INCHES WILL ALSO PREVAIL AHEAD OF THE FRONT, OWING
IN LARGE PART TO HIGHLY ANOMALOUS MOISTURE BEING DRAWN IN FROM THE
CIRCULATION OF TROPICAL STORM BERTHA OVER THE NORTHERN GULF.
CAMS GENERALLY SHOW A BAND OF SHOWERS AND STORMS ASSOCIATED WITH A
PREFRONTAL TROUGH THAT IS MAINLY CONCENTRATED NEAR THE NC/VA BORDER
ON WEDNESDAY MORNING. THIS BAND WILL INCREASE IN COVERAGE AND
INTENSITY AS IT SAGS SE INTO THE NORTHERN/WESTERN PIEDMONT AND
NORTHERN COASTAL PLAIN IN THE AFTERNOON AND EVENING, CONTINUING INTO
THE OVERNIGHT HOURS. HOWEVER, TIMING OF THIS BAND IS STILL SOMEWHAT
UNCERTAIN, AS IT HAS SLOWED DOWN IN GUIDANCE LIKE THE GFS AND NAM
COMPARED TO THE LAST COUPLE DAYS. IF THE 12Z NAM NEST IS ACCURATE IT
WON'T REALLY GET GOING ACROSS OUR NORTH UNTIL THE EVENING AND
OVERNIGHT HOURS, WHILE THE SOUTH STAYS MOSTLY DRY. SO WILL HAVE TO
WATCH IS THIS TREND CONTINUES.
REGARDLESS, ONCE THE BAND DOES SET UP, EXCESSIVE RAINFALL IS LOOKING
INCREASINGLY LIKELY GIVEN THE VERY MOIST AIR MASS AND STRONG SIGNAL
FOR STORM TRAINING, AS THE MEAN FLOW IS FROM THE WSW (ROUGHLY
PARALLEL TO THE FRONT). WPC QPF IS IN THE 1-2.5 INCH RANGE ACROSS
OUR FAR NORTHERN COUNTIES, BUT HREF LPMM DEPICTS POTENTIAL FOR 3-5+
INCHES IN LOCALIZED SPOTS. SOME OF THESE AREAS HAVE ALREADY RECEIVED
1-3 INCHES OVER THE LAST 2 DAYS. THUS AFTER INTERNAL COLLABORATION
WITH WPC, THEY ARE ISSUING A MODERATE (LEVEL 3 OF 4) RISK FOR
EXCESSIVE RAINFALL IN OUR FAR NE PIEDMONT AND NORTHERN COASTAL PLAIN
NEAR THE VA BORDER FOR WEDNESDAY AND WEDNESDAY NIGHT. ELSEWHERE, A
SLIGHT (LEVEL 2 OF 4) RISK IS IN EFFECT. FLOOD WATCHES MAY
EVENTUALLY BE NEEDED FOR PARTS OF OUR AREA AS WELL. FORECAST
RAINFALL AMOUNTS THROUGH WEDNESDAY NIGHT QUICKLY DECREASE TO THE
SOUTH, WITH THE 12Z HREF MEAN DEPICTING AROUND A QUARTER INCH OR
LESS IN OUR SOUTHERNMOST TIER OF COUNTIES.
FURTHERMORE, DEEP-LAYER SHEAR OF 30-40 KTS ACROSS OUR NORTHERN
COUNTIES COULD RESULT IN SOME ORGANIZED STORM CELLS/CLUSTERS THAT
BECOME STRONG TO SEVERE IN THE AFTERNOON AND EVENING. THUS MOST OF
CENTRAL NC OUTSIDE OF THE SOUTH IS UNDER A SLIGHT (LEVEL 2 OF 5)
RISK FOR SEVERE WEATHER. DAMAGING WINDS WILL AGAIN BE THE MAIN
THREAT, AND WHILE 0-1 KM SRH LOOKS LIMITED, AN ISOLATED TORNADO
CAN'T BE TOTALLY RULED OUT.
KEY MESSAGE 2... WIDESPREAD SHOWERS AND STORMS WITH A RISK FOR
FLOODING WILL CONTINUE INTO AT LEAST FRIDAY AND POSSIBLY EVEN THIS
WEEKEND, PARTICULARLY IN OUR SOUTH AND EAST, AS A COLD FRONT STALLS
NEAR THE NC/SC BORDER.
THE COLD FRONT WILL MOVE ONLY SLIGHTLY SOUTH AND EAST ON THURSDAY,
AND WITH RICH GULF MOISTURE CONTINUING TO FUNNEL NE ALONG THE FRONT,
ANOTHER DAY OF HEAVY RAINFALL AND POSSIBLE FLASH FLOODING IS
EXPECTED, THIS TIME ACROSS ALL OF CENTRAL NC. WPC QPF IS 1-2 INCHES
ON AVERAGE ACROSS THE REGION, BUT THIS TIME THE HEAVIEST RAINFALL
AXIS IS SHIFTED A BIT SE. ONCE AGAIN, LOCALLY HIGHER AMOUNTS WILL BE
POSSIBLE. THUS AFTER INTERNAL COLLABORATION, WPC IS ALSO ISSUING A
MODERATE (LEVEL 3 OF 4) RISK FOR EXCESSIVE RAINFALL ACROSS EASTERN
NC THAT INCLUDES SOME OF OUR COASTAL PLAIN COUNTIES, WITH A SLIGHT
(LEVEL 2 OF 4) RISK FOR MOST OF THE REST OF CENTRAL NC.
THIS THREAT FOR HEAVY RAINFALL UNFORTUNATELY LOOKS TO CONTINUE
ACROSS AT LEAST OUR SE ZONES ON FRIDAY AND POSSIBLY EVEN SATURDAY AS
THE COLD FRONT STALLS OR DRIFTS VERY SLOWLY SOUTH SOMEWHERE NEAR THE
NC/SC BORDER. WPC QPF FROM FRIDAY INTO SATURDAY DEPICTS ANOTHER 1-3
INCHES FROM RALEIGH SOUTH AND EAST. THERE IS STILL DISAGREEMENT
AMONG THE MODELS ON EXACT FRONTAL PLACEMENT, WHICH WILL DICTATE
WHERE THE HEAVY RAINFALL THREAT WILL BE. HOWEVER, GUIDANCE HAS
GENERALLY BEEN SLOWING DOWN ITS SOUTHWARD PROGRESSION AND AS A
RESULT KEEPS SHOWERS AND STORMS ACROSS CENTRAL NC FOR LONGER.
FURTHERMORE, A SHORTWAVE TROUGH MOVING THROUGH THE TN VALLEY AND
SOUTHERN APPALACHIANS MAY ACTUALLY ENHANCE THE MOIST AIR MASS AGAIN
ON SATURDAY AS PW VALUES INCREASE TO 2-2.5 INCHES, ALONG WITH
PROVIDING ADDITIONAL FORCING FOR ASCENT.
ONE SILVER LINING IS THE SEVERE THREAT AT LEAST LOOKS TO DECREASE ON
THURSDAY AND ESPECIALLY BY FRIDAY AND SATURDAY. THIS IS DUE TO THE
EASTERN US TROUGHING FLATTENING, RESULTING IN A WEAKENING OF THE MID-
LEVEL FLOW, ALONG WITH LESS INSTABILITY TO WORK WITH AS THE FRONT
SLOWLY SINKS SOUTH. HOWEVER, A FEW STRONG STORMS WITH WATER-LOADED
DOWNBURSTS STILL CAN'T BE RULED OUT MAINLY IN THE SE.
THERE IS HIGHER CONFIDENCE IN DRIER CONDITIONS FROM SUNDAY THROUGH
TUESDAY AS THE MID/UPPER TROUGHING FINALLY PUSHES TO OUR EAST AND
THE FLOW ALOFT TURNS NORTHWESTERLY. HOWEVER, AS TEMPERATURES HEAT
BACK UP, ISOLATED DIURNALLY-DRIVEN CONVECTION STILL CAN'T BE RULED
OUT EACH DAY.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
AS OF 150 PM TUESDAY...
HIGH CONFIDENCE EXISTS IN MAINLY VFR CONDITIONS OUTSIDE OF ANY
CONVECTIVE ACTIVITY THROUGH THE TAF PERIOD, ALONG WITH GUSTY
SOUTHWESTERLY SURFACE WINDS THIS AFTERNOON AND LLWS OVERNIGHT.
HOWEVER, OVERALL FORECAST CONFIDENCE REMAINS LOW REGARDING THE EXACT
TIMING, COVERAGE, AND SPATIAL DISTRIBUTION OF AFTERNOON AND EVENING
THUNDERSTORMS THAT WILL DEVELOP NEAR OR OVER THE TERMINALS.
THIS LOW CONVECTIVE CONFIDENCE IS PRIMARILY DRIVEN BY TWO FEATURES:
A LINGERING FRONTAL BOUNDARY NEAR THE VA/NC BORDER AND HOW FAR
INLAND SEA BREEZE STORMS CAN DEVELOP. THE LINGERING BOUNDARY ACROSS
THE NORTH WILL BE THE PRIMARY DRIVER FOR ISOLATED TO SCATTERED
STORMS NEAR THE TRIAD TERMINALS, WHERE PROB30 GROUPS FOR TSRA, MVFR
VISIBILITIES, AND STRONG GUSTY WINDS WILL BE POSSIBLE FROM ABOUT 20Z
TO 01Z. THEN, SEA BREEZE CONVECTION PUSHING INLAND FROM THE
SOUTHEAST COAST GIVES UNCERTAINTY FOR THE EASTERN TERMINALS.
THEREFORE, HAVE PROB30 GROUPS FOR KFAY AND KRWI BETWEEN 19Z AND 23Z
FOR ANY LOCALIZED THUNDERSTORM IMPACTS, WHILE KRDU IS EXPECTED TO
REMAIN LARGELY DRY WITH ONLY VCSH FOR THE TIME BEING.
CONVECTIVE ACTIVITY ALONG WITH GUSTY WINDS SHOULD DIMINISH LATER
TONIGHT. A STRENGTHENING 35 TO 45 KNOT LOW-LEVEL JET MOVING ACROSS
THE AREA COULD DEVELOP WIDESPREAD LLWS FOR THE NORTHERN TAF SITES.
LLWS HAS BEEN INCLUDED AT KINT, KGSO, KRDU, AND KRWI STARTING
BETWEEN 01Z AND 03Z WITH WINDS AROUND 2K FT OUT OF THE SOUTHWEST AT
40 TO 45 KNOTS, BEFORE MIXING OUT AFTER 12Z TUESDAY.
OUTLOOK: WHILE THE SURFACE FRONT MAY SETTLE INTO SC AND SERN NC
LATER THU-FRI, "OVERRUNNING" LIFT ATOP THE FRONTAL ZONE WILL FAVOR
CONTINUED ABOVE AVERAGE CHANCES OF FLIGHT RESTRICTIONS AND
RAIN/STORMS THROUGH THE END OF THE WEEK, WITH HIGHER CHANCES AT ERN
SITES VERSUS WRN ONES.
RAH WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY FROM NOON TODAY TO 7 PM EDT THIS EVENING FOR NCZ078-
085-086-088-089.
DISCUSSION...DANCO/CA
AVIATION...CA/MWS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page