304
FXUS61 KRLX 170226
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1026 PM EDT TUE JUL 16 2019
SYNOPSIS
THE REMNANTS OF BARRY CROSS WEDNESDAY INTO WEDNESDAY NIGHT.
VERY WARM AND UNSETTLED THURSDAY. DANGEROUS AFTERNOON HEAT
EXPECTED FRIDAY AND SATURDAY.
NEAR TERM /THROUGH WEDNESDAY/
AS OF 1025 PM TUESDAY...
MINOR EDITS TO THE OVERNIGHT LOWS, KEEPING THE POPS AS IS.
ACTIVITY MAINLY WEST AND NORTH, BUT KEEPING WESTERN ZONE POPS IN
DURING THE OVERNIGHT.
AS OF 735 PM TUESDAY...
BULK OF THE ACTIVITY REMAINS WEST OF THE AREA, WITH LITTLE WEST
TO EAST COMPONENTS IN THE MOTION. UNTIL THE UPPER TROUGH GETS
FURTHER EAST INTO THE OHIO VALLEY, WITH THE WANING OF THE
HEATING, THE POPS ARE MORE WARRANTED ALONG THE WESTERN FRINGE
OVERNIGHT.
AS OF 210 PM TUESDAY...
TWO AREAS TO FOCUS ON FOR PULSE TYPE SHOWERS/STORMS HEADING FOR
THE REMAINDER OF THE AFTERNOON HOURS. ONE SUCH AREA IS PAINTED
ACROSS THE RIDGETOPS IN POCAHONTAS/RANDOLPH COUNTY, AIDED BY
WEAK SOUTHERLY FLOW FOR LIFT. HOWEVER, HIGH CLOUDS CONTINUE TO
INHIBIT CUMULUS DEVELOPMENT WHICH HAS KEPT THE MOUNTAINS LARGELY
VOID OF ANY PRECIP THUS FAR. AS A RESULT I'VE BACKED OFF ON
POPS A BIT GIVEN THE CONTINUED CIRRUS CANOPY OVERHEAD. STILL
EXPECTING SOME DEVELOPMENT LATER THIS AFTERNOON THOUGH.
ELSEWHERE, MODELS INDICATE A RIBBON OF WEAK THETA E ADVECTION
WORKING INTO THE AREA FROM THE WEST INTO THE AFTERNOON,
ASSOCIATED WITH THE VERY OUTER PERIPHERAL OF POST TROPICAL
CYCLONE BARRY. LATEST VISIBLE IMAGERY SHOWS AGITATED CUMULUS
ACROSS EAST CENTRAL KY AND ALSO ALONG THE TUG FORK BASIN. THIS
SHOULD SERVE AS AN INSTABILITY AXIS FOR AT LEAST ISOLATED
CONVECTION AS IT PASSES. OTHERWISE, NO DISCERNIBLE AREAS OF
FORCING TO LATCH ONTO FOR ANYTHING OTHER THAN ISOLATED COVERAGE.
ANY SHOWERS OR THUNDERSHOWERS WILL QUICKLY WANE THIS EVENING.
ATTENTION THEN TURNS TO THE APPROACHING REMNANTS OF BARRY. THE
SURFACE REFLECTION WILL TRACK INTO THE OH VALLEY WEDNESDAY
MORNING WHILE THE ASSOCIATED MID LEVEL S/W TROF AXIS CROSSES
IN THE AFTERNOON. SHOWERS WILL OVERSPREAD SOUTHEAST OH DURING
THE MORNING, EXPANDING INTO THE REMAINDER OF THE AREA AS THE DAY
PROGRESSES. LIMITED INSTABILITY WILL HELP MITIGATE CONVECTIVE
POTENTIAL. STILL, PWATS AROUND 2 INCHES AND A DEEP WARM CLOUD
LAYER WILL LEAD TO EFFICIENT RAINFALL RATES. IN ADDITION, ANY
POCKETS OF INSOLATION WOULD LEAD TO HIGHER INSTABILITY AND THUS
A GREATER POTENTIAL FOR TORRENTIAL DOWNPOURS.
BASIN WIDE QPF IS PROGGED TO BE LESS THAN INCH, BUT ISOLATED
AMOUNTS TO 2 INCHES ARE CERTAINLY POSSIBLE SHOULD CONVECTION
DEVELOP IN THE AFTERNOON. THE NORTHERN HALF OF THE CWA REMAINS
WET WITH 1 AND 3HR FFG VALUES A BIT LOW GOING INTO THIS. STORM
MOTIONS WOULD KEEP THINGS SOMEWHAT PROGRESSIVE, THOUGH THE
POTENTIAL FOR BACKBUILDING EXISTS LATER IN THE DAY. I TOYED WITH
THE IDEA OF A WATCH HERE, BUT AFTER COORDINATING WITH
NEIGHBORING OFFICES, I'VE HELD OFF FOR NOW. MEANWHILE, THE
SOUTHERN HALF OF THE AREA HAS BEEN QUITE DRY WITH GENERALLY 25
PERCENT OF NORMAL OBSERVED PRECIP OVER THE PAST WEEK.
SEVERE THREAT IS QUITE LOW, BUT NOT ZERO GIVEN SOME DIRECTIONAL
SHEAR.
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/
AS OF 230 PM TUESDAY...
SHORTWAVE TROUGH AXIS ASSOCIATED WITH THE REMNANTS OF BARRY WILL
PUSH EAST OF THE REGION ON WEDNESDAY NIGHT. AS THE TROUGH PUSHES
EAST AND INSTABILITY WANES, PRECIPITATION ACTIVITY WILL GRADUALLY
DECREASE IN COVERAGE THROUGH THURSDAY MORNING. HOWEVER, NOT
EXPECTING POPS TO COMPLETELY DIMINISH AS LOW LEVEL MOISTURE LINGERS
BEHIND THE DEPARTING TROUGH. THUS, EXPECTING AREAS OF SHOWERS AND
SOME EMBEDDED THUNDER CONTINUING INTO THURSDAY MORNING. IN ADDITION,
PLENTY OF LOW CLOUDS AND/OR FOG WILL BE IN PLACE THURSDAY MORNING IN
THE WAKE OF BARRY'S REMNANTS AND THE RAINFALL ON WEDNESDAY. THERE
SHOULD BE SOME BREAKS IN THE CLOUD COVER BY THE AFTERNOON AS DIURNAL
MIXING INCREASES, WHICH WILL ALLOW FOR AN OPPORTUNITY FOR THE
ATMOSPHERE TO DESTABILIZE. MODELS ARE PROJECTING MODERATE
INSTABILITY WILL BE IN PLACE WITH MLCAPE VALUES EXPECTED TO BE
AROUND 2000-2500 J/KG, BUT FORECAST SOUNDINGS SUGGEST THAT DRIER AIR
ALOFT WILL BUILD IN THROUGH THE DAY COURTEOUS OF BROAD HIGH PRESSURE
ACROSS THE DEEP SOUTH. THIS COMBINED WITH THE MARGINAL SHEAR
EXPECTED SHOULD LIMIT THE THREAT OF ANY ORGANIZED CONVECTION.
HIGHEST POPS ARE EXPECTED TO BE ACROSS EASTERN AREAS GIVEN THE
OROGRAPHIC INFLUENCE AMID NW FLOW IN THE MID/UPPER LEVELS, BUT ANY
PRECIPITATION ACTIVITY SHOULD QUICKLY DIMINISH BY THURSDAY NIGHT.
ATTENTION FROM HERE WILL TURN TO A STRONG UPPER LEVEL RIDGE THAT IS
EXPECTED TO BUILD INTO THE REGION ON FRIDAY, WHICH WILL BE THE
BEGINNING OF WHAT WILL BE A PROLONGED PERIOD OF DANGEROUS HEAT.
MODELS SUGGEST THAT HEIGHTS ALOFT MAY REACH AS HIGH AS 594 DAM,
YIELDING TEMPERATURES IN THE LOW/MID 90S AND DEWPOINTS IN THE MID
70S ACROSS LOWER ELEVATIONS. THIS SHOULD SUPPORT HEAT INDICES AROUND
OR SLIGHTLY ABOVE 105F. EVENTUAL HEAT HEADLINES WILL LIKELY BE
NEEDED AND DID THINK ABOUT ISSUING AN EXCESSIVE HEAT WATCH TODAY,
BUT AFTER SOME DISCUSSION WITH NEIGHBORING WFOS, WILL JUST CONTINUE
TO MENTION IN THE HWO FOR NOW. IN ADDITION TO THE HEAT ON FRIDAY, A
FEW ISOLATED SHOWERS AND STORMS WILL BE POSSIBLE. GREATEST THREAT
FOR ANY CONVECTION ON FRIDAY WILL BE IN THE MOUNTAINS, BUT THE
THREAT APPEARS TO BE VERY SMALL ACROSS THE LOWLANDS AS THE
ATMOSPHERE WILL BE PRETTY CAPPED. HEAVY DOWNPOURS WILL BE THE
GREATEST THREAT WITH ANY ACTIVITY THAT DOES DEVELOP AS SHEAR IS
FORECAST TO BE ESSENTIALLY NON-EXISTENT.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
AS OF 233 PM TUESDAY...
HIGH PRESSURE BUILDS BY THE END OF THE WEEK ALLOWING FOR LIGHT
WIND, PLENTY OF SUNSHINE AND HOT AFTERNOON TEMPERATURES
PARTICULARITY FRIDAY AND SATURDAY. MODELS SUGGEST H850
TEMPERATURES WILL REACH 20C, WARMEST H850 SO FAR, SUGGESTING
HOTTER SURFACE TEMPERATURES.
WITH HIGHS IN THE MID 90S, AND DEW POINTS IN THE LOWER TO MID
70S, APPARENT TEMPERATURES WILL RESULT INTO THE LOWER TO MID
100S FRIDAY AND SATURDAY AFTERNOONS. THESE HEAT INDICES WOULD
WARRANT HEAT ADVISORIES (100 DEGREES), OR EVEN EXCESSIVE HEAT
WATCHES/WARNINGS (105 DEGREES). THE INTERVENING NIGHTS WILL BE
OPPRESSIVELY WARM AND MUGGY. DIURNALLY-DRIVEN CONVECTION WILL
BE A POSSIBILITY IN THE AFTERNOON WITH NO SHORTAGE OF HEAT AND
HUMIDITY IN PLACE AS DEWPOINTS HOVER AROUND THE MID 70S. BY
SATURDAY NIGHT, A NORTHERN STREAM TROUGH WILL PUSH A COLD FRONT
INTO THE OHIO VALLEY.
COLD FRONT EXPECTED NEXT WEEK COULD ALLEVIATE SOME OF THE HEAT.
HOWEVER, ITS TIMING AND SOUTHWARD PROGRESS WILL DEPEND UPON THE
TIMING AND AMPLITUDE OF THE DRIVING UPPER LEVEL SHORT WAVE
TROUGH.
AVIATION /03Z WEDNESDAY THROUGH SUNDAY/
AS OF 735 PM TUESDAY...
NO TSRA IN THE FORECAST THROUGH THE REMAINDER OF THE NIGHT. PKB
AND HTS ARE MOST PRONE AT THIS POINT AND MAY NEED A QUICK AMD
IF A ROGUE CELL APPROACHES ONE OF THESE TERMINALS.
THE TRIGGER FOR ALL OF THIS IS THE REMNANTS OF BARRY THAT ARE
PUSHING EASTWARD THROUGH THE OHIO VALLEY. IT IS A SLOW PROCESS,
BUT EXPECT AN INCREASE IN SHOWER CHANCES HEADING INTO WEDNESDAY.
FOR NOW, NOT INCLUDING THUNDER IN THE FORECAST, BUT THIS MAY BE
ADDED IN FOR THE LATE AFTERNOON HOURS WEDNESDAY WITH THE NEXT
ISSUANCE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z THURSDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: NO FOG IN FORECAST. CLEARING MAY
NECESSITATE AT EKN.
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.
DATE WED 07/17/19
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H M M M M
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H M M M L L L L
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 00Z THURSDAY...
IFR POSSIBLE IN SHOWERS WEDNESDAY NIGHT, AND IN LOW CLOUDS AND
FOG DURING THE OVERNIGHT AND EARLY MORNING HOURS THURSDAY AND
FRIDAY.
RLX WATCHES/WARNINGS/ADVISORIES
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
SYNOPSIS...ARJ/30/RG
NEAR TERM...26/30
SHORT TERM...RG
LONG TERM...ARJ
AVIATION...26
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