179
FXUS61 KRLX 172344
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
744 PM EDT THU SEP 17 2026
WHAT HAS CHANGED
740 PM UPDATE...
~00Z AVIATION FORECAST DISCUSSION UPDATE.
208 PM UPDATE...
THE SPS FOR HOT AND HUMID CONDITIONS ACROSS THE CENTRAL AND
SOUTHERN LOWLANDS HAS BEEN EXTENDED THROUGH THIS EVENING DUE TO
HEAT INDICES IN THE MIDDLE-UPPER 90S. THE FORECAST FOR THE REST
OF TODAY AND INTO EARLY NEXT WEEK REMAINS ON TRACK, WITH ONLY
MINOR ADJUSTMENTS MADE.
A SLIGHT ADJUSTMENT TO THE AVIATION DISCUSSION HAS BEEN MADE
COMPARED TO ITS PREVIOUS ISSUANCE AT 131 PM EDT.
KEY MESSAGES
1) CHANCES FOR HEAVY SHOWERS AND THUNDERSTORMS REMAIN ON THE DOCKET
FOR THIS AFTERNOON AND TONIGHT, ALONG WITH HOT TEMPERATURES ACROSS
THE LOWLANDS.
2) RAIN AND STORM CHANCES LINGER ACROSS THE SOUTHERN AND MOUNTAINOUS
AREAS FRIDAY AFTERNOON, WITH A LULL IN RAIN HEADING INTO SATURDAY
BEFORE MORE CHANCES ARRIVE SATURDAY NIGHT AND BEYOND.
DISCUSSION
KEY MESSAGE 1...
IN THE MID/UPPER-LEVELS, THE CENTER OF THE SUBTROPICAL RIDGE, WHICH
WAS OBJECTIVELY ANALYZED AT 600 DAM PER THE 12Z UA CHARTS, WAS
LOCATED OVER THE LOWER MS RIVER VALLEY AND CONTINUES TO RETROGRADE
WESTWARD. FARTHER NORTH, A WELL-DEFINED SHORTWAVE TROUGH WAS DIGGING
SOUTHEASTWARD TOWARDS THE JAMES BAY, WITH THE BASE OF THE INTENSE
JETLETS TRANSLATING OVER THE GREAT LAKES REGION. SEVERAL SERIES OF
SMALLER-SCALE PERTURBATIONS WERE PROGRESSING EASTWARD OVER THE RUST
BELT AND HAVE GENERATED A FEW BANDS OF GENERAL THUNDERSTORMS ACROSS
THE NORTHERN COUNTIES OVER THE LAST FEW HOURS. GOES-EAST VISIBLE
TRENDS HAVE RECENTLY SHOWN ADDITIONAL BANDS OF CONGESTED CU FORMING
TO THE NORTH OF THE I-64 CORRIDOR BETWEEN CRW-HTS DUE THE SUBTLE
INFLUENCE OF AN EJECTING SHORTWAVE PERTURBATION OVERHEAD. THERE ALSO
APPEARS TO BE A TRAPPED MOUNTAIN WAVE ON WATER-VAPOR IMAGERY THAT IS
AIDING IN THE FORMATION OF THE DIURNALLY-DRIVEN CU. THE 12Z RAOB
FROM WFO ILN SAMPLED A STOUT EML, CHARACTERIZED BY SB/MUCAPE VALUES
EXCEEDING 3,000 J/KG AND AN EQUILIBRIUM LEVEL UP TO 125 MB WITHIN
THE BELT OF BROADLY CYCLONIC FLOW. HOWEVER, FARTHER SOUTHEAST AT
RNK, LARGE-SCALE SUBSIDENCE REMAINED INTACT ATOP THE LOWER TRANCHE
OF THE EML ADVECTING OVER THE APPALACHIAN MOUNTAINS, WHICH SHOULD
KEEP THE CU FIELD SUPPRESSED UNTIL PEAK HEATING IS REACHED. THE
SUBTROPICAL RIDGE WILL CONTINUE RETROGRADING OVER THE NEXT 24 HOURS,
WHICH WILL KEEP THE CWA POSITIONED ALONG THE EDGE OF THE THICKNESS
GRADIENT AND SOUTH OF THE MORE-INTENSE FLOW ALOFT THROUGH FRIDAY.
AT THE SURFACE, THE QUASI-STATIONARY FRONT REMAINED ALONG AND NORTH
OF THE I-70 CORRIDOR, BUT HAS SINCE BECOME CONVECTIVELY-REINFORCED,
AND WILL BEGIN SAGGING SOUTHWARD INTO SOUTHEASTERN OH AND NORTHERN
WV BY THIS EVENING. AHEAD OF THE FRONT, THE AIRMASS IS ESSENTIALLY A
CLONE OF YESTERDAY LESS SOME CONVECTIVE CLOUD DEBRIS, WITH DEWPOINTS
IN THE LOWER-MIDDLE 70S AND HOT SURFACE TEMPERATURES THAT HAVE
BREACHED 90 DEGREES, PARTICULARLY IN THE OH RIVER VALLEY. THIS WILL
RESULT IN HEAT INDICES IN THE MIDDLE 90S TO NEAR 100 DEGREES FOR
SOME LOCALES THIS AFTERNOON, AND THE SPS HIGHLIGHTING THE HEAT AND
HIGH HUMIDITY HAS BEEN REISSUED THROUGH 23Z, OR 7 PM EDT, THIS
EVENING FOR PORTIONS OF THE LOWLANDS. ADDITIONAL STORM DEVELOPMENT
IS EXPECTED ACROSS THE LOWLANDS THROUGH THIS EVENING DUE TO THE
UNCAPPED AIRMASS, WITH THE MEAN CONVECTIVE MOVEMENT GOVERNED BY
PROPAGATION ALONG ANY BOUNDARIES. HEAVY RAINFALL WILL BE THE PRIMARY
HAZARD, LEADING TO LOCALIZED INSTANCES OF FLASH FLOODING. FOLLOWING
SUNSET, THERE WILL BE A TEMPORARY LULL IN SHOWERS AND STORMS UNTIL
THE COLD FRONT ARRIVES DURING THE OVERNIGHT HOURS.
AS THE COLD FRONT ARRIVES, ANOTHER SHORTWAVE IMPULSE WILL PROPAGATE
OVER THE CWA, WITH INDICATIONS POINTING TOWARDS THE POTENTIAL FOR
SEMI-ORGANIZED BANDS OF TRAINING STORMS TO DEVELOP ALONG THE SLOW,
SOUTHWARD-MOVING COLD FRONT. CORFIDI VECTORS FAVOR FRONTAL-PARALLEL
BACK-BUILDING OF INDIVIDUAL CELLS WHILE THE TOTAL PROPAGATION VECTOR
ORIENTS SOUTHWARD ALONG THE EDGE OF THE THICKNESS GRADIENT. THE
TALL, SKINNY CAPE PROFILES; ANOMALOUSLY HIGH PWAT CONTENT, MEAGER
LENGTH OF THE SHEAR VECTORS, AND MOIST-ADIABATIC LAPSE RATES WILL
GALVANIZE THE HEAVY RAIN POTENTIAL WITH STORMS TONIGHT INTO THE
PREDAWN HOURS FRIDAY. HOWEVER, THERE EXISTS UNCERTAINTY WITH RESPECT
TO THE SPATIOTEMPORAL EXTENT OF STORMS DURING THE EARLY MORNING
HOURS FRIDAY. AS A RESULT, CONFIDENCE IS STILL NOT HIGH ENOUGH TO
WARRANT THE ISSUANCE OF A FLOOD WATCH, ALTHOUGH IT WILL CONTINUE TO
BE EVALUATED IN FORTHCOMING PROGNOSTICATIONS. THE SEVERE WEATHER
THREAT IS OTHERWISE LOW, BUT A STRONG WIND GUST OR TWO CANNOT BE
RULED OUT WITH COLLAPSING CORES OVERNIGHT.
KEY MESSAGE 2...
STORM CHANCES WILL WANE FROM NORTH-TO-SOUTH AFTER SUNRISE FRIDAY,
WITH AN EXPECTATION FOR RIVER VALLEY FOG TO RETURN FOLLOWING STORMS
LATE TONIGHT AND AN OVERCAST SKY LASTING INTO THE AFTERNOON HOURS
ACROSS MOST OF THE CWA. NORTHWESTERLY FLOW WILL ADVECT OVER THE CWA
BY MID-DAY FRIDAY AS THE SHORTWAVE TROUGH CURRENTLY DIGGING INTO THE
JAMES BAY EJECTS EASTWARD TOWARDS THE CANADIAN MARITIMES. ELEVATED,
POST-FRONTAL SHOWERS MAY DEVELOP ACROSS PORTIONS OF THE LOWLANDS AND
MOUNTAINS DURING THE AFTERNOON HOURS FRIDAY, WITH BETTER CHANCES FOR
LIGHTNING ACROSS THE COAL FIELDS, WHICH WILL BE IN CLOSER PROXIMITY
TO THE DEPARTING COLD FRONT. THE FLASH FLOODING POTENTIAL IS VERY
LOW FRIDAY NOR IS SEVERE WEATHER EXPECTED WITH ANY RENEGADE CELLS
THAT DEVELOP FRIDAY AFTERNOON. HIGHS ARE EXPECTED TO BE A FEW
DEGREES COOLER AREA-WIDE FRIDAY, ALBEIT STILL VERY WARM, WITH HEAT
INDICES PEAKING IN THE LOWER 90S FOR THE SOUTHWESTERN ZONES.
THE COLD FRONT IS FORECAST TO CLEAR TO THE SOUTH OF THE CWA LATE
FRIDAY NIGHT AND BECOME QUASI-STATIONARY ONCE AGAIN AS THE
SUBTROPICAL RIDGE FLATTENS VIA A NEUTRALLY-TILTED SHORTWAVE TROUGH
EMERGING OVER THE CENTRAL ROCKY MOUNTAINS. PROGRESSIVE FLOW ALOFT
WILL PERSIST TO THE NORTH OF THE CWA SATURDAY, AND MOSTLY DRY
CONDITIONS ARE FORECAST, WITH THE EXCEPTION OF THE MOUNTAINOUS
TERRAIN WHERE DIURNALLY-DRIVEN, PULSE-LIKE SHOWERS AND STORMS MAY
DEVELOP IN THE AFTERNOON HOURS. THE QUASI-STATIONARY FRONT TO THE
SOUTH OF THE CWA WILL ALSO UNDERGO WARM-FRONTOGENESIS AND LIFT
NORTHEASTWARD ACROSS THE CWA THROUGHOUT THE DAY SATURDAY, WITH
BENIGN SURFACE WINDS TRANSITIONING TO THE SOUTHEAST BENEATH THE
PREVAILING WESTERLIES ALOFT. BY SATURDAY NIGHT, ANOTHER SERIES OF
SHORTWAVE PERTURBATIONS WILL EJECT OVER THE CWA FOLLOWING THE
PASSAGE OF THE WARM FRONT, WITH RENEWED CHANCES FOR HEAVY SHOWERS
AND STORMS ARRIVING OVERNIGHT SATURDAY INTO SUNDAY. ACTIVE WEATHER
CONTINUES TO BE FORECAST THROUGH EARLY NEXT WEEK AS THE SUBTROPICAL
RIDGE FINALLY BREAKS DOWN DUE TO AN EVOLVING SPLIT-FLOW PATTERN.
AVIATION /00Z FRIDAY THROUGH TUESDAY/
VFR CONDITIONS CONTINUE INTO THE EVENING AS SHOWERS AND
THUNDERSTORMS EXIT EAST. KEPT VCTS AND TEMPO GROUPS FOR THE
FIRST FEW HOURS OF THE TAF AT MANY SITES AS POP-UP CONVECTION IS
POSSIBLE. OVERALL, SUNSET WILL BE KILLING THESE CHANCES.
SKIES WILL BE CLEARING SOME TONIGHT, ESPECIALLY ACROSS THE
SOUTH. AREAS OF DENSE VALLEY FOG ARE LIKELY TO FORM AS A RESULT.
IFR OR LOWER CONDITIONS WILL BE POSSIBLE, MOSTLY AT CRW AND EKN.
MODELS ARE SHOWING ANOTHER COMPLEX OF HEAVY SHOWERS AND A FEW
THUNDERSTORMS THAT WILL MOVE IN FROM THE WEST BETWEEN ~08-13Z
FRIDAY MORNING. IFR AND MVFR RESTRICTIONS ARE EXPECTED THIS THIS
COMPLEX AS IT CROSSES. MVFR CIGS WILL LIKELY BE SLOW TO RECEDE
AS A RESULT, ESPECIALLY ACROSS THE MOUNTAINS. MORE CHANCES FOR
SHOWERS AND THUNDERSTORMS RETURN IN THE AFTERNOON.
WINDS WILL BE LIGHT TO CALM TONIGHT,BECOMING N'RLY AND LIGHT
TOMORROW.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY...
FORECAST CONFIDENCE: MEDIUM
ALTERNATE SCENARIOS: THE COVERAGE AND TIMING OF SHOWERS AND
THUNDERSTORMS TONIGHT AND EARLY FRIDAY MAY VARY FROM THE
FORECAST. THE EXTENT AND DENSITY OF FOG EARLY FRIDAY MORNING
MAY ALSO VARY FROM THE FORECAST.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 21 22 23 00 01 02 03 04 05 06 07 08
EDT 1HRLY 17 18 19 20 21 22 23 00 01 02 03 04
CRW CONSISTENCY H H H H H H H H H L L M
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H M M H
EKN CONSISTENCY H H H H H H H M M M H H
PKB CONSISTENCY H H H H H H H H L M L M
CKB CONSISTENCY H H H H H H H H H M H H
AFTER 00Z SATURDAY...
LOW CIGS WILL GRADUALLY IMPROVE TO VFR BY ~00Z FRIDAY, WITH THE
POTENTIAL FOR LINGERING -SHRA/-TSRA TO AFFECT SOME OF THE
TERMINALS FRIDAY AFTERNOON. VALLEY FOG OR LOW STRATUS EXPECTED
EACH MORNING THROUGH THE WEEKEND AT MOST SITES.
RLX WATCHES/WARNINGS/ADVISORIES
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
DISCUSSION...SINCAVAGE
AVIATION...LTC
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