377
FXUS62 KRAH 202017
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
417 PM EDT MON JUL 20 2026
WHAT HAS CHANGED
* NO MAJOR CHANGES FOR THE SEVERE OR FLASH FLOODING THREAT OVER THE
NEXT 3 DAYS.
KEY MESSAGES
AS OF 400 PM MONDAY...
1) A STALLED FRONTAL BOUNDARY WILL PRODUCE SHOWERS AND THUNDERSTORMS
OVER CENTRAL NORTH CAROLINA TODAY. LOCALLY HEAVY RAINFALL AND FLASH
FLOODING WILL BE POSSIBLE.
2) SHOWERS AND STORMS WITH LOCALLY DAMAGING WINDS AND HEAVY RAINFALL
ARE AGAIN POSSIBLE ON TUESDAY, BUT THIS THREAT SHOULD BE MOSTLY
CONFINED TO OUR NORTH.
3) UNSETTLED WEATHER WILL CONTINUE ON WEDNESDAY AND POSSIBLY INTO
LATE WEEK AS A COLD FRONT APPROACHES AND THEN SLOWLY CROSSES NC.
DISCUSSION
AS OF 400 PM MONDAY...
KEY MESSAGE 1... A STALLED FRONTAL BOUNDARY WILL PRODUCE SHOWERS AND
THUNDERSTORMS OVER CENTRAL NORTH CAROLINA TODAY. LOCALLY HEAVY
RAINFALL AND FLASH FLOODING WILL BE POSSIBLE.
A SLIGHT RISK (LEVEL 2 OF 5) FOR BOTH SEVERE THUNDERSTORMS AND
EXCESSIVE RAINFALL/FLASH FLOODING IS IN EFFECT ACROSS CENTRAL NC
TODAY. AN UPPER-LEVEL SHORTWAVE TROUGH AND ASSOCIATED MCVS WILL
PIVOT ACROSS THE REGION THROUGH TONIGHT. AT THE SURFACE, LINGERING
FRONTAL BOUNDARY JUST SOUTH OF THE NC/VA BORDER WILL INTERACT WITH
GOOD DIURNAL HEATING AND THE HUMID AIRMASS WITH PWATS OF ~2.0 INCHES
WILL CONTINUE TO TRIGGER MULTI-CELL CLUSTER STORMS ACROSS THE REGION
THIS AFTERNOON AND EVENING. THE PRIMARY HAZARDS WILL BE DAMAGING
WINDS ASSOCIATED WITH DOWNBURST AND LOCALIZED FLASH FLOODING FROM
SLOW-MOVING OR TRAINING STORMS. AREAS ACROSS THE PIEDMONT AND
NORTHERN COASTAL PLAIN WILL HAVE THE BEST CHANCE FOR STRONGER SLOW
MOVING STORMS THROUGH AT LEAST MIDNIGHT TONIGHT. AFTER THE STORMS
DISSIPATE AND THE FRONT LIFTS TO THE NORTH INTO VA, EXPECT LOW
STRATUS CLOUDS TO MOVE ACROSS THE AREA BEFORE CLEARING SKIES EARLY
TUESDAY MORNING.
KEY MESSAGE 2... SHOWERS AND STORMS WITH LOCALLY DAMAGING WINDS AND
HEAVY RAINFALL ARE AGAIN POSSIBLE ON TUESDAY, BUT THIS THREAT SHOULD
BE MOSTLY CONFINED TO OUR NORTH.
BROAD TROUGHING OVER THE EASTERN US WILL DEEPEN ON TUESDAY DUE TO A
SHORTWAVE MOVING ACROSS SOUTHERN ONTARIO AND QUEBEC. WEAK MID-LEVEL
HEIGHT FALLS WILL RESULT OVER THE MID-ATLANTIC, WHICH MAY REACH AS
FAR SOUTH AS NORTHERN NC DURING THE DAY. MEANWHILE A PERTURBATION
WITHIN THE TROUGH AND ASSOCIATED WEAK SURFACE LOW/TROUGH WILL RESULT
IN AN AREA OF ENHANCED SHOWERS AND STORMS OVER THE OH VALLEY ON
TUESDAY MORNING THAT PROGRESSES EAST INTO THE MID-ATLANTIC THROUGH
THE AFTERNOON AND EVENING.
THE ABOVE FEATURES WILL COMBINE WITH A MOIST AND MODERATELY UNSTABLE
AIR MASS (PW VALUES 100-125% OF NORMAL AND MLCAPE VALUES OF 1500-
2500 J/KG) TO RESULT IN A CHANCE FOR ISOLATED TO SCATTERED SHOWERS
AND STORMS OVER CENTRAL NC ON TUESDAY AFTERNOON AND EVENING.
HOWEVER, PRECIPITATION CHANCES WILL MOSTLY BE CONFINED TO OUR
NORTHERN COUNTIES AS GUIDANCE DEPICTS A WEDGE OF RELATIVELY DRIER
AIR (PW VALUES OF 1.5-2") MOVING ACROSS OUR SOUTH AS TROPICAL
DEPRESSION TWO SLOWLY DRIFTS WEST NEAR THE NORTHERN GULF COAST. MID-
LEVEL FLOW WILL INCREASE WITH THE DEEPENING TROUGH, AND 30-40 KTS OF
BULK SHEAR IS POSSIBLE ACROSS OUR FAR NORTH. THUS THE NORTHERN
PIEDMONT AND NORTHERN COASTAL PLAIN ARE WHERE SPC HAS A SLIGHT
(LEVEL 2 OF 5) RISK FOR SEVERE WEATHER AND WPC HAS A MARGINAL TO
SLIGHT (LEVELS 1-2 OF 4) RISK FOR EXCESSIVE RAINFALL. HOWEVER,
CAPPED POPS AT CHANCE GIVEN THE BEST FORCING WILL BE ACROSS VA AND
COVERAGE IN THE CAMS DOES NOT LOOK WIDESPREAD. SIMILAR TO RECENT
DAYS, THE MAIN SEVERE THREAT WILL BE DAMAGING STRAIGHT-LINE WINDS.
ADDITIONAL ISOLATED SCATTERED CONVECTION WILL BE POSSIBLE ON TUESDAY
NIGHT AS A PREFRONTAL SURFACE TROUGH SETS UP AHEAD OF A STRONG COLD
FRONT OVER THE OH VALLEY. ONCE AGAIN THIS CHANCE IS MOSTLY ACROSS
OUR NORTH, AND THE SEVERE THREAT WILL BE LESS WITH THE LOSS OF
DAYTIME HEATING.
KEY MESSAGE 3... UNSETTLED WEATHER WILL CONTINUE ON WEDNESDAY AND
POSSIBLY INTO LATE WEEK AS A COLD FRONT APPROACHES AND THEN SLOWLY
CROSSES NC.
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 CENTRAL NC FROM THE NW ON
WEDNESDAY EVENING/NIGHT. WEAK TO MODERATE INSTABILITY IS AGAIN
EXPECTED TO DEVELOP, THOUGH IT MAY BE SOMEWHAT MITIGATED BY MORNING
CLOUD COVER. STILL, MOISTURE ALONG AND AHEAD OF THE FRONT LOOKS
PLENTIFUL WITH PW VALUES OF 2-2.5 INCHES. SO THE PREFRONTAL TROUGH
MAY PROVIDE A FOCUS FOR AFTERNOON CONVECTION, FOLLOWED BY A LINE OF
SHOWERS AND STORMS ASSOCIATED WITH THE COLD FRONT MOVING THROUGH
FROM NW TO SE ON WEDNESDAY EVENING/NIGHT. POPS ARE CATEGORICAL
ACROSS THE ENTIRE REGION, AND WPC HAS ALL OF CENTRAL NC IN A SLIGHT
(LEVEL 2 OF 4) RISK FOR EXCESSIVE RAINFALL. QPF IS IN THE 1-2 INCH
RANGE ON AVERAGE, AND LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE. DEEP-
LAYER SHEAR OF 30-40 KTS COULD RESULT IN SOME STORMS BECOMING STRONG
TO SEVERE, AND OUR ENTIRE REGION IS ALSO IN A SLIGHT (LEVEL 2 OF 5)
RISK FOR SEVERE WEATHER. DAMAGING WINDS WILL AGAIN BE THE MAIN
THREAT.
UNCERTAINTY INCREASES FOR LATE WEEK AS MODELS DIFFER ON WHETHER THE
COLD FRONT IS ABLE TO PUSH SOUTH ENOUGH TO CLEAR ALL OF CENTRAL NC
OR WHETHER IT WILL GET HUNG UP OVER OUR REGION. BEHIND THE FRONT,
MUCH DRIER AIR WILL BRING CLEARING AND MUCH LOWER PRECIPITATION
CHANCES. OVERALL IT LOOKS LIKELY FOR SHOWERS AND STORMS TO CONTINUE
IN OUR SE ON THURSDAY, BUT THE NW MAY BE LARGELY DRY. BY FRIDAY AND
SATURDAY, THE GFS SAGS THE FRONT TO OUR SOUTH AND KEEPS ALL OF
CENTRAL NC MAINLY DRY, WHILE THE ECMWF AND CMC ARE SLOWER WITH THE
FRONT AND KEEP US WETTER. GIVEN HOW DIFFICULT IT CAN BE FOR FRONTS
TO PASS THROUGH THIS TIME OF YEAR, LIKELY POPS IN THE SE STILL SEEM
WARRANTED, BUT THIS COULD CHANGE AS WE GET CLOSER. THERE IS BETTER
AGREEMENT IN DRIER CONDITIONS BY SUNDAY AND MONDAY AS THE MID/UPPER
TROUGHING FINALLY PUSHES TO OUR EAST AND THE FLOW ALOFT TURNS
NORTHWESTERLY.
AVIATION /18Z MONDAY THROUGH SATURDAY/
AS OF 230 PM MONDAY...
VFR TO MVFR CONDITIONS WILL START OFF THIS AFTERNOON ACROSS CENTRAL
NC TERMINALS WITH LIGHT AND VARIABLE SURFACE WINDS AND SCT/BKN MID
LEVEL CLOUD DECKS. SCATTERED STORMS ARE BEGINNING TO DEVELOP ACROSS
THE ENTIRE AREA AND AROUND ALL THE TERMINALS. EXPECT THIS THIS
CONTINUE THROUGH THE AFTERNOON AND EVENING HOURS. VCTS AND VCSH ARE
PREVAILING FOR EACH TAF SITE WITH STORMS EXPECTED TO BE ON AND OFF
THROUGH AT LEAST 2Z OR 3Z.
FOR OVERNIGHT & EARLY TUESDAY POST-CONVECTIVE STABILIZATION WILL
LEAD TO WIDESPREAD REGIONAL FLIGHT CATEGORY DETERIORATION. HAVE
MODERATE CONFIDENCE IN DEVELOPMENT OF IFR TO LIFR CEILINGS WITH LOW
STRATUS DEVELOPING ALONG WITH ISOLATED AREAS OF VISIBILITY
REDUCTIONS. ADDITIONALLY, A WEAK LOW-LEVEL JET ACROSS THE AREA COULD
CAUSE LLWS AROUND 1500-2000FT WITH 25–35 KTS ACROSS ALL TERMINALS
BETWEEN ROUGHLY 04Z AND 12Z.
CONDITIONS WILL IMPROVE IN THE MORNING WITH SOUTH/SOUTHWESTERLY
WINDS 5-10 KT. LIFR/IFR STRATUS AND LLWS WILL DISSIPATE ACROSS ALL
TERMINALS BY 14Z, RETURNING CENTRAL NC TO VFR CONDITIONS THROUGH THE
REMAINDER OF THE 18Z PERIOD.
OUTLOOK: AFTERNOON SHOWERS AND STORMS THROUGH LATE WEEK WILL RESULT
PERIODS OF VFR AND PERIODS OF AFTERNOON AND EVENING SUB-VFR
CONDITIONS.
RAH WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...CA/DANCO
AVIATION...CA
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