924
FXUS61 KRLX 081309
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
909 AM EDT WED APR 8 2020
SYNOPSIS
A STRONG COLD FRONT CROSSES THURSDAY. HIGH PRESSURE FRIDAY AND
SATURDAY. LOW PRESSURE CROSSES SUNDAY/SUNDAY NIGHT, WITH A COLD
FRONT MONDAY MORNING. COOLER WITH WEAKER SYSTEMS NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 909 AM WEDNESDAY...
WHILE THUNDERSTORMS REMAIN POSSIBLE THIS MORNING, I DO NOT
THINK THE COVERAGE WILL BE AS HIGH AS PREVIOUSLY THOUGHT. SO I
HAVE LOWERED THUNDERSTORM CHANCES FOR THE REMAINDER OF THE
MORNING.
AS OF 645 AM WEDNESDAY...
FORECAST IS LARGELY ON TRACK THIS MORNING WITH ONGOING
CONVECTION ORIENTED ON A NORTHWEST TO SOUTHEAST AXIS ACROSS THE
CENTRAL PORTIONS OF THE AREA. ACTIVITY IS STILL GOING STRONG,
THOUGH SEVERE POTENTIAL HAS WANED CONSIDERABLY AS OUTFLOW
BOUNDARIES HAVE KEPT INSTABILITY LARGELY ELEVATED AMID AN
ORIENTATION LARGELY PARALLEL TO MEAN FLOW. MODELS INSIST ON THIS
WEAKENING FARTHER THIS MORNING AS IT SLOWLY SAGS SOUTHWARD,
WITH IT REGENERATING A BIT THIS AFTERNOON ALONG AND SOUTH OF
I64. DEPENDING ON HOW MUCH INSOLATION IS REALIZED ACROSS THE
SOUTH, THERE COULD BE A FEW STRONG TO SEVERE STORMS AS THEY EXIT
TO THE SOUTHEAST THIS AFTERNOON.
AS OF 150 AM WEDNESDAY...
QLCS WITH SCATTERED REPORTS OF DAMAGING WIND GUSTS, CURRENTLY
OVER CENTRAL OH AND SOUTHERN PA, WILL CONTINUE TO ADVANCE
SOUTHEASTWARD INTO THE PREDAWN HOURS. A BIT OF A CAPPING
INVERSION EXISTS AROUND H7 ACROSS THE AREA FROM THE EML THAT
OVERSPREAD THE AREA LAST EVENING WITH INSTABILITY BECOMING MORE
ELEVATED WITH EACH PASSING HOUR AS THE SURFACE COOLS.
STILL...GIVEN THE WELL ORGANIZED STRUCTURE AND COLD POOL
PROPAGATION, I EXPECT THE EASTWARD EXTENT OF THIS LINE TO
CONTINUE TO PRODUCE DAMAGING WIND GUSTS AS IT CLIPS OUR
NORTHEAST WV COUNTIES IN THE NEXT FEW HOURS. FARTHER WEST ALONG
THE LINE IN CENTRAL OH, A GRADUAL WEAKENING TREND SHOULD ENSUE
AS IT ADVANCES OUT OF OUR SE OH COUNTIES AND CENTRAL WV IN THE
PREDAWN. MODELS ARE STRUGGLING WITH HOW FAR SOUTH TO TAKE THIS,
WITH THE HRRR SEEMINGLY FLIP FLOPPING WITH KEEPING IT MORE
ACROSS THE CENTRAL AND NORTHERN LOWLANDS TO SAGGING IT SOUTH
INTO THE COAL FIELDS BY SUNRISE. FOR NOW, I WILL PLAY THE
MIDDLE ROAD SOLUTION AND MONITOR TRENDS.
THE ACTUAL COLD FRONT WILL LAG SEVERAL HOURS BEHIND, DECAYING AS
IT MEANDERS INTO THE AREA. MEANWHILE, SURFACE HEATING ACROSS
THE SOUTHERN HALF OF THE AREA WHERE THERE WILL BE LESS CLOUDS
WILL ALLOW INSTABILITY TO BUILD WITH MLCAPE VALUES APPROACHING 2
GRAND WITH DEEP LAYER SHEAR VALUES SUPPORTIVE OF CONVECTIVE
GROWTH. THIS SHOULD ALLOW FOR AN UPTICK IN COVERAGE THIS
AFTERNOON ACROSS SOUTHERN COUNTIES IN THE VICINITY OF THE
BOUNDARY. A FEW OF THESE STORMS COULD BECOME STRONG AS THE
ADVANCE SOUTHEAST OUT OF THE AREA IN THE LATE AFTERNOON.
WE WILL SEE A BREAK IN THE ACTION THIS EVENING AS WE AWAIT THE
ARRIVAL OF MUCH STRONGER COLD FRONT. CONVECTION ASSOCIATED WITH
THIS WILL RACE INTO THE AREA AROUND MIDNIGHT OR SHORTLY
THEREAFTER. SPC HAS THE TUG FORK VALLEY PAINTED IN A SLIGHT
RISK WITH AN ENHANCED FARTHER WEST ACROSS MUCH OF THE LOWER OH
VALLEY AND TN VALLEY. DESPITE THE TIME OF NIGHT, MLCAPE VALUES
WILL REMAIN HIGH AND WITH STRONG DEEP LAYER SHEAR AND STEEP MID
LEVEL LAPSE RATES, THE POTENTIAL FOR LARGE HAIL AND ESPECIALLY
DAMAGING WIND GUSTS WILL EXIST ALONG THE QLCS FROM THE TRI-STATE
REGION AND EXTENDING SOUTH INTO THE COAL FIELDS AND SOUTHWEST
VA.
SHORT TERM /THURSDAY THROUGH SATURDAY/
AS OF 345 AM WEDNESDAY...
STRONG COLD FRONT CROSSES THURSDAY MORNING, TAKING THE LAST OF
THE PRE-FRONTAL INSTABILITY OUT OF THE MOUNTAINS FIRST THING.
ALREADY TAPERING OFF WEST OF THE OHIO RIVER AT DAWN, SHOWERS
END FROM WEST TO EAST ACROSS THE REMAINDER OF THE FORECAST AREA
THROUGH THE DAYLIGHT MORNING HOURS.
IN THE WAKE OF THE COLD FRONT, MIXING THROUGH H7, ALONG WITH
STRONG LOW LEVEL WIND FIELDS, WILL PROMOTE STRONG WIND GUSTS
THURSDAY, ESPECIALLY DURING THE AFTERNOON ACROSS NORTHERN
PORTIONS OF THE FORECAST AREA. THESE GUSTY WINDS WILL GRADUALLY
DIMINISH THURSDAY NIGHT THROUGH FRIDAY, WITH A BRIEF PICKUP
POSSIBLE FRIDAY MORNING.
SHOWERS MAY LINGER IN THE MOUNTAINS THURSDAY AFTERNOON INTO
FRIDAY ON WRAP AROUND MOISTURE AND UPSLOPE FLOW. THE COLDER AIR
BEHIND THE SYSTEM WILL ALSO SUPPORT SNOW OVER THE HIGHER
ELEVATIONS OF THE NORTHERN WV MOUNTAINS FRIDAY NIGHT, AND A
SHORT WAVE TROUGH ROTATING DOWN THE BACK SIDE OF AN INTENSE
UPPER LEVEL LOW CHURNING UP THROUGH MAINE, MAY ENHANCE THE WRAP
AROUND UPSLOPE PRECIPITATION OVERNIGHT THURSDAY NIGHT, WITH UP
TO AN INCH OR SO OF SNOW ACCUMULATION OVER THE HIGHER TERRAIN
POSSIBLE.
HIGH PRESSURE BUILDING IN FRIDAY NIGHT WILL ALLOW FROST IF
PATCHY STRATOCU ATOP THE SUBSIDENCE INVERSION IS KEPT TO A
MINIMUM. THE HIGH WILL THEN MOVE EAST OF THE AREA SATURDAY, AND
CLOUDS WILL INCREASE, LOWER AND THICKEN IN DEVELOPING WARM
ADVECTION, AHEAD OF THE NEXT LOW PRESSURE SYSTEM APPROACHING
FROM THE WEST.
OTHER THAN SLOWING DOWN THE PROGRESS OF THE COLDER AIR A BIT
THURSDAY MORNING, CENTRAL GUIDANCE TEMPERATURES AND DEW POINTS
LOOKED GOOD. AFTER FALLING A BIT THURSDAY MORNING, TEMPERATURES
WILL NOT RECOVER MUCH ON THURSDAY, AND BE FURTHEST BELOW NORMAL
THURSDAY NIGHT THROUGH FRIDAY NIGHT, WITH HIGHS FRIDAY MAINLY
IN THE 40S LOWLANDS, 30S ACROSS THE HIGHER TERRAIN. THE HUMIDITY
WILL ALSO BE LOW THURSDAY AND FRIDAY AFTERNOONS AMID GUSTY WINDS
ESPECIALLY THURSDAY AND DRIER FUELS BY FRIDAY.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/
AS OF 345 AM WEDNESDAY...
LOW PRESSURE APPROACHES SATURDAY NIGHT, AND THEN CROSSES SUNDAY
AND SUNDAY NIGHT, DRAGGING A COLD FRONT ACROSS THE AREA MONDAY
MORNING. THE INCREASING CHANCE FOR RAIN SHOWERS OVERNIGHT
SATURDAY NIGHT INTO SUNDAY MORNING DEPENDS UPON LOW LEVEL DRY
AIR BENEATH THE MID LEVEL WARM ADVECTION MOISTURE AND LIFT, BUT
SUNDAY AFTERNOON WILL BE WET, ALONG WITH THE CHANCE FOR
THUNDERSTORMS.
SHOWERS AND POSSIBLE THUNDERSTORMS WILL END FROM WEST TO EAST
OVERNIGHT SUNDAY NIGHT INTO MONDAY MORNING. A DRY RESPITE IS
THEN POSSIBLE TO START THE NEW WORK WEEK, BUT THE TIMING OF ANY
LIGHT PRECIPITATION AFTER THAT NEXT WEEK THEN DEPENDS UPON THE
TIMING OF SHORT WAVE TROUGHS ROTATING ABOUT A LARGE UPPER LEVEL
LOW OVER EASTERN CANADA, AND EVEN WHETHER THAT LOWS ROLLS ON
EAST, OR JUST LINGERS NEAR HUDSON BAY.
AFTER NEAR NORMAL TEMPERATURES TO START THE WEEK, CENTRAL
GUIDANCE SHOWERS TEMPERATURES FALLING BACK BELOW NORMAL HEADING
INTO MIDWEEK, WITH ANOTHER FROSTY NIGHT POSSIBLE IF WE COULD
SNEAK A NIGHT BETWEEN SYSTEMS.
AVIATION /13Z WEDNESDAY THROUGH SUNDAY/
AS OF 645 AM WEDNESDAY...
LINE OF ELEVATED CONVECTION ORIENTED IN A NORTHWEST TO SOUTHEAST
AXIS WILL SLOWLY SAG SOUTH OVER THE NEXT FEW HOURS TO AFFECT CRW
WITH TSRA IN MVFR CONDITIONS AND PERHAPS HTS. BRIEF IFR IS
POSSIBLE IN ANY ROBUST INDIVIDUAL CELLS WITHIN THE LINE. LINE
SHOULD CONTINUE TO WEAKEN THIS MORNING AS IT SAGS SOUTH, PERHAPS
REGENERATING A BIT THIS AFTERNOON, POSSIBLY AFFECTING BKW.
A PERIOD OF MVFR STRATUS AS THE LINE CROSSES THIS MORNING,
BEFORE SCATTERING THIS AFTERNOON.
ANOTHER, MUCH STRONGER, COLD FRONT WILL CROSS IN THE 06-12Z TIME
FRAME TONIGHT WITH ANOTHER ROUND OF CONVECTION, POTENTIALLY WITH
STRONG WINDS FOR HTS/CRW/BKW.
GUSTY AND VARIABLE WINDS POSSIBLE WITH ANY THUNDERSTORMS THROUGH
15Z WITH WEST TO NORTHWESTERLY BEHIND THE FRONT, BECOMING GUSTY
IN THE AFTERNOON TO 20 KTS THIS AFTERNOON.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY...
FORECAST CONFIDENCE: MEDIUM 12Z-15Z, HIGH THEREAFTER.
ALTERNATE SCENARIOS: LINE OF CONVECTION MOVING THROUGH 15Z WILL
CREATE HIGHLY VARIABLE CIG/VIS IN THE HEAVIEST DOWNPOURS.
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 12 13 14 15 16 17 18 19 20 21 22 23
EDT 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H M L L H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY L L H H H H H H H H H H
CKB CONSISTENCY H H L H H H H H H H H H
AFTER 12Z THURSDAY...
IFR CONDITIONS POSSIBLE IN SHOWERS AND THUNDERSTORMS LATE
SUNDAY.
RLX WATCHES/WARNINGS/ADVISORIES
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
SYNOPSIS...TRM/30
NEAR TERM...JSH/30
SHORT TERM...TRM
LONG TERM...TRM
AVIATION...30
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