238
FXUS61 KRLX 221123
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
723 AM EDT THU AUG 22 2019
SYNOPSIS
UPPER LEVEL DISTURBANCES CROSS TODAY THROUGH TONIGHT, AHEAD OF
A COLD FRONT THAT SINKS SOUTH THROUGH THE AREA TONIGHT THROUGH
FRIDAY. HIGH PRESSURE WITH DRY, COOLER WEATHER FOR THE WEEKEND.
NEAR TERM /THROUGH TONIGHT/
AS OF 710 AM THURSDAY...
QUICK UPDATE... MADE A FEW TWEEKS TO POPS AND WX GRIDDS TO
ACCOUNT FOR LINE OF TSTMS GOING ACROSS NE KY AND SE OH ATTM.
LINE CAME IN QUICKER THAN FORECAST. OTHERWISE REST OF FORECAST
PACKAGE LOOKS ON TRACK.
AS OF 510 AM THURSDAY...
A NUMBER OF RIPPLES IN ZONAL UPPER LEVEL FLOW ON THE SOUTH SIDE
OF AN UPPER LEVEL LOW IN EASTERN CANADA, CROSS TODAY AND
TONIGHT, AHEAD OF A COLD FRONT THAT ENTERS THE AREA FROM THE
NORTH TONIGHT. THAT COLD FRONT WILL BE DRIVEN BY A SHORT WAVE
TROUGH EXTENDING WESTWARD FROM THE UPPER LEVEL LOW EARLY THIS
MORNING, WHICH ROTATES SOUTHEASTWARD TODAY AND TONIGHT.
ONE RIPPLE, IN THE FORM OF A CONVECTIVE COMPLEX, WAS APPROACHING
FROM THE LOWER OHIO VALLEY EARLY THIS MORNING, THIS IS LIKELY
TO BRING SHOWERS AND WEAKENING THUNDERSTORMS AT LEAST INTO
SOUTHERN PORTIONS OF THE AREA, BEFORE WEAKENING PER MID MORNING
CLOUD TOP WARMING.
THE TRACK, SPEED AND TIMING OF DECAY OF THIS SYSTEM WILL THEN
INFLUENCE THE AMOUNT OF RECOVERY TO PROVIDE ENERGY FOR THE NEXT
RIPPLE TRAVERSING LATER THIS AFTERNOON, AND THEN FOR CONVECTION
ASSOCIATED WITH THE COLD FRONT ARRIVING FROM THE NORTH TONIGHT.
SHOWERS AND THUNDERSTORMS ALONG THE ADVANCING COLD FRONT MAY
WEAKEN ON LOSS OF HEATING OVERNIGHT TONIGHT, BUT WITH THE FRONT
NOT QUITE THROUGH THE AREA AS DAYBREAK FRIDAY APPROACHES, YET
ANOTHER RIPPLE FROM THE WEST COULD BRING A ROUND OF CONVECTION
INTO THE TUG FORK AREA.
CONFIDENCE DECREASES WITH EACH ROUND OF CONVECTION PER COMPOUNDING
UNCERTAINTY ON INTERVENING RECOVERY, BUT PW VALUES UP AROUND 2
INCHES ACROSS MUCH OF THE AREA SOUTH OF THE FRONT SPELL
POTENTIAL FLASH FLOOD ISSUES WITH REPEATED CONVECTION, AND WPC
HAS PLACE THE AREA SOUTHEAST OF THE OHIO RIVER IN A SLIGHT RISK
FOR EXCESSIVE RAINFALL TODAY AND TONIGHT GIVEN THE ADDED
EFFECTS OF TERRAIN.
DEPENDING UPON HOW MUCH CAPE CAN BE REALIZED, SPC HAS A MARGINAL
RISK FOR SEVERE WEATHER AS BULK SHEAR VALUES CLIMB INTO THE 30S
FOR THIS AFTERNOON AN EVENING, ALTHOUGH THE HIGHEST VALUES ARE
PROGGED ACROSS THE NORTH, CLOSER TO THE APPROACHING COLD FRONT.
HIGHS AND LOWS LOOKED GOOD PER LATEST GUIDANCE, BUT HOURLY
VALUES WILL BE HIGHLY DEPENDENT UPON CONVECTION.
SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/
AS OF 320 AM THURSDAY...
THIS FORECAST STARTS OUT WITH A BROAD TROUGH ASSOCIATED WITH A
STACKED LOW PRESSURE SYSTEM TO THE NORTHEAST AFFECTING THE AREA.
THIS TROUGH WILL MOVE EAST DRAGGING A COLD FRONT SLOWLY THROUGH
THE AREA. ANY CONVECTION OR CHANCES FOR SHOWERS WILL BE
FAIRLY WIDESPREAD EARLY IN THE DAY AND EVENTUALLY BECOME
CONFINED TO THE SOUTHERN HALF OF THE CWA BY MIDDAY. THE SOUTHERN
HALF OF THE AREA IS FORECAST TO BE IN A MARGINAL RISK FOR
EXCESSIVE RAINFALL THROUGH FRIDAY. WITH RISING PWATS AND ENOUGH
INSTABILITY (>2000 J/KG) EFFICIENT RAIN RATES MAY CAUSE FLOODING
ISSUES IN LOW LYING AND POOR DRAINAGE AREAS AT THE VERY LEAST
UNDER ANY CONVECTION. BULK SHEAR WILL BE MODEST AT ~35KT WHICH
CAN HELP PROLONG THUNDERSTORMS AND STRENGTHEN THEM AS WELL. ANY
CHANCES FOR SEVERE WILL BE MINIMAL AND CONFINED AHEAD OF THE
FRONT TO THE SOUTH WITH THE MAIN THREAT BEING POSSIBLE DAMAGING
WIND AND POSSIBLY ISOLATED FLOODING ISSUES.
MOST OF THE INSTABILITY WILL BE USED UP AFTER FRONTAL PASSAGE
AND AS DRY AIR FILTERS IN, CHANCES FOR ANY CONVECTION OR
SHOWERS DIMINISH FROM NORTH TO SOUTH THROUGH FRIDAY AS THE
TROUGH SLOWLY EXITS THE REGION FRIDAY NIGHT. ON SATURDAY A WAVE
OF LOW PRESSURE IS FORECAST TO FORM ALONG THE AXIS OF THE
TROUGH TO THE EAST AND SET UP JUST TO THE NORTH OF WV. THIS
COULD PROVIDE MORE MOISTURE AND LIFTING FOR CHANCES OF DIURNAL
SHOWERS AND POSSIBLE STORMS TO DEVELOP BEFORE A SURFACE RIDGE
FORMS AND DRIES OUT THE AREA LATE SATURDAY. WENT WITH CENTRAL
GUIDANCE AND LEFT CHANCES IN DURING THIS PERIOD. THEREAFTER A
BROAD HIGH JUST TO THE NORTH OVER CANADA WILL SLOW DOWN A
SYSTEM TO THE WEST AND GIVE A BREAK TO THE AREA FOR MOST OF
SUNDAY, HOWEVER THAT SYSTEM IS SLATED TO ENCROACH THE AREA
TOWARDS THE VERY END OF THE WEEKEND.
LONG TERM /MONDAY THROUGH WEDNESDAY/
AS OF 335 AM THURSDAY...
HIGH PRESSURE WILL PREVENT A FRONTAL SYSTEM SLATED TO BE TO OUR
WEST FROM TRAVERSING THE AREA QUICKLY. WITH THAT SAID, THE
FIRST HALF OF THE WORK WEEK WILL EXPERIENCE UNSETTLED WEATHER
FROM THIS SLOW MOVING FRONTAL SYSTEM WHICH WILL PROVIDE GREATER
CHANCES FOR DIURNAL THUNDERSTORMS AND ESPECIALLY DURING FRONTAL
PASSAGE ON WEDNESDAY. THE SYSTEM WILL TAP INTO MOISTURE FROM THE
GULF AND CAUSE PWATS TO BE ANOMALOUSLY HIGH FOR THIS TIME OF
YEAR. WE CAN EXPECT A DECENT AMOUNT OF RAINFALL WHICH COULD
POTENTIALLY LEAD TO FLOODING ISSUES AGAIN IN THE AREA. MODELS
DIVERGE SIGNIFICANTLY DURING THE LATTER PART OF THE WORK WEEK
AND BEYOND.
TEMPERATURES WILL REMAIN SEASONABLE UNTIL FRONTAL PASSAGE WHERE
HIGH PRESSURE AND DRIER AIR WILL CAUSE THEM TO INCREASE TO JUST
ABOVE NORMAL THROUGH THE LATTER PART OF THE WEEK.
AVIATION /11Z THURSDAY THROUGH MONDAY/
AS OF 215 AM THURSDAY...
VFR TO START THE FORCAST OVERNIGHT, BUT SHOWERS EXPECTED TO
FORM ACROSS EASTERN KENTUCKY AND SOUTHERN WV EARLY THIS THURSDAY
MORNING, AHEAD OF A CLUSTER OF SHOWERS AND THUNDERSTORMS TO
WEST, MAY BRING MVFR CONDITIONS TO HTS, CRW AND/OR BKW. FOG
FORMING FARTHER NORTH IS EXPECTED TO DROP VISIBILITY TO MVFR AT
CKB AND IFR AT EKN. HOWEVER, DENSE FOG IS NOT EXPECTED, ON
ACCOUNT OF MVFR STRATOCU ALREADY FORMING IN THE NORTHERN AND
CENTRAL MOUNTAINS OF WV.
ANY FOG WILL DISSIPATE FIRST THING THIS MORNING, AND THE
SHOWERS WILL MOVE OFF TO THE EAST AND/OR DISSIPATE LATER THIS
MORNING. MVFR STRATOCU IN THEN MOUNTAINS WILL LIFT THROUGH
AROUND NOON.
THE FORECAST FOR THURSDAY AFTERNOON AND EVENING DEPENDS UPON THE
TIMING AND SURVIVAL OF A THUNDERSTORM COMPLEX TO THE WEST.
FASTER TIMING AND SLOWER WEAKENING WOULD BRING MVFR TO IFR
CONDITIONS LATER THURSDAY MORNING INTO THURSDAY AFTERNOON.
SLOWER TIMING AND SLOWER WEAKENING WOULD BRING MVFR TO IFR
CONDITIONS IN SHOWERS AND STRONG THUNDERSTORMS THURSDAY
AFTERNOON.
THE STRENGTH OF THUNDERSTORMS AHEAD OF A COLD MOVING IN FROM
THE NORTH THURSDAY EVENING WILL DEPEND UPON AFTERNOON HEATING,
WHICH WOULD BE ENHANCED BY FASTER TIMING AND FASTER WEAKENING
OF THE EARLIER COMPLEX.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM FOR FLIGHT RULES. LOW FOR CONVECTIVE
TIMING.
ALTERNATE SCENARIOS: COVERAGE OF OVERNIGHT AND MORNING
CONVECTION COULD BE GREATER THAN INDICATED. IF STORMS HOLD OFF
OVERNIGHT INTO THURSDAY MORNING, THEN GREATER COVERAGE OF
FOG/LOW CLOUDS MAY OCCUR, AND THEN STRONGER STORMS COULD OCCUR
THURSDAY AFTERNOON. OTHERWISE, STRONGER STORMS COULD OCCUR NORTH
THURSDAY EVENING.
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 10 11 12 13 14 15 16 17 18 19 20 21
EDT 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
CRW CONSISTENCY H L L M M M H H H H H H
HTS CONSISTENCY H M M M L L M H H H H H
BKW CONSISTENCY M M M M M M M H H H H M
EKN CONSISTENCY L L L M M M M H H H H H
PKB CONSISTENCY M L L L M H H H H H H H
CKB CONSISTENCY L M M M H H H H H H H H
AFTER 12Z FRIDAY...
IFR POSSIBLE IN STRATUS AND POSSIBLE FOG FRIDAY MORNING.
RLX WATCHES/WARNINGS/ADVISORIES
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
SYNOPSIS...TRM/JZ
NEAR TERM...JS/TRM
SHORT TERM...JZ
LONG TERM...JZ
AVIATION...TRM
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