Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 281210 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
810 AM EDT THU APR 28 2016

.UPDATE...
ISSUED AT 750 AM EDT THU APR 28 2016

HOURLY GRIDS HAVE BEEN ADJUSTED BASED ON RECENT OBSERVATION...SATELLITE
AND RADAR TRENDS. THIS LED TO HIGHER POPS OVER THE NEXT HOUR OR
TWO ACROSS THE EASTERN THIRD OF THE REGION. OVERALL...THE RECENT
NEAR TERM MODEL GUIDANCE SUPPORTS THE ONGOING CONVECTION MOVING
EAST OF THE AREA OVER THE NEXT COUPLE OF HOURS. HOWEVER...WITH THE
COLD FRONT AND A SHORTWAVE TROUGH STILL UPSTREAM...REDEVELOPMENT
OF CONVECTION AROUND MIDDAY OR EARLY AFTERNOON SEEMS PLAUSIBLE AND
IS WHAT THE MOST RECENT HRRR AND RAP RUNS HAVE. SOME OF THAT
ACTIVITY COULD BE STRONG TO LOCALLY SEVERE AND PRODUCE HAIL AND
STRONG TO LOCALLY DAMAGING WIND GUSTS.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 359 AM EDT THU APR 28 2016

EARLY THIS MORNING...A NEARLY STATIONARY FRONT EXTENDED ACROSS THE
OHIO VALLEY REGION FROM AN AREA OF LOW PRESSURE OVER THE PLAINS
AND MS VALLEY REGION...WITH THE COLD FRONT TRAILING SOUTH INTO
THE MID MS VALLEY AND THEN WEST INTO THE SOUTHERN PLAINS.
ISENTROPIC LIFT IN ADVANCE OF THIS SYSTEM...LEFTOVER OUTFLOWS AND
THE ASSOCIATED MID LEVEL SHORTWAVE IS LEADING TO ISOLATED TO
SCATTERED AREAS OF CONVECTION ACROSS THE COMMONWEALTH AND THE
APPALACHIAN REGION. AT THIS TIME...THE STRONGEST ACTIVITY IS OVER
PARTS OF CENTRAL KY.

OVERALL...THE RECENT ACTIVE WEATHER WILL CONTINUE INTO THIS
EVENING...BEFORE SHORTWAVE RIDGING AND SFC HIGH PRESSURE BUILD
ACROSS THE AREA. THIS WILL LEAD TO CLEARING SKIES TONIGHT INTO
FRIDAY MORNING WITH DRY WEATHER AND MILD TEMPERATURES FOR FRIDAY.

FOR THE REST OF THE NIGHT INTO THIS EVENING...ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS ARE ANTICIPATED AS THE AREA
OF LOW PRESSURE TRACKS EAST ACROSS THE OHIO VALLEY BUT TO THE
NORTH OF THE AREA AND INTO THE CENTRAL APPALACHIANS THIS EVENING
AND THEN TO THE EASTERN SEABOARD BY THE END OF THE PERIOD. THIS
LOW WILL SEND A COLD FRONT ACROSS EASTERN AND SOUTH CENTRAL KY
DURING THE AFTERNOON AND EVENING HOURS. MEANWHILE A WEAK SHORTWAVE
TROUGH WILL MOVE ACROSS THE AREA AS WELL ALTHOUGH THE MAIN MID
LEVEL SHORTWAVE WILL TRACK INTO THE GREAT LAKES. ROUNDS OF
CONVECTION ARE ANTICIPATED THOUGH CONFIDENCE IN TIMING AND THE
DETAILS ARE LOW. THIS PATTERN...HOWEVER...WILL LEAD TO MID LEVEL
DRYING AND COOLING TODAY WITH MODEST FLOW IN THE MID LEVELS.
SUFFICIENT SOLAR INSOLATION MAY OCCUR FOR CAPE BY MIDDAY INTO THE
AFTERNOON TO REACH 1000 J/KG OR HIGHER AT LEAST IN SOME AREAS
PENDING MORNING CONVECTION AND CONVECTIVE DEBRIS CLOUDS. AFTER
ACTIVITY PROBABLY PEAKS THIS MORNING...A SECONDARY PEAK SHOULD
OCCUR IN THE AFTERNOON. THE POTENTIAL EXISTS FOR A COUPLE STRONG
TO POSSIBLY SEVERE THUNDERSTORMS THIS AFTERNOON TO EARLY EVENING.
MARGINALLY SEVERE HAIL AND LOCALIZED DAMAGING WINDS WOULD BE THE
PRIMARY THREATS THOUGH LOCALLY HEAVY RAIN WOULD ALSO BE POSSIBLE.

ANY LINGERING CONVECTION DURING THE EVENING SHOULD TAPER OFF FROM
WEST TO EAST AS THE COLD FRONT MOVES ACROSS THE AREA AROUND
SUNSET. THEREAFTER...THE RESPITE FROM THE RECENT ACTIVE WEATHER
WILL BEGIN...THOUGH IT WILL BE SHORT LIVED AS ACTIVE WEATHER IS
EXPECTED TO RETURN DURING THE LONG TERM PERIOD...OVER THE WEEKEND.
CLEARING SKIES AND LINGERING LOW LEVEL MOISTURE SHOULD SET THE
STAGE FOR SOME VALLEY FOG TONIGHT...AND IT COULD BECOME DENSE IN
SOME LOCATIONS. CONFIDENCE IN DENSE FOG HOWEVER WAS TOO LIMITED AT
THIS POINT TO INCLUDE AS TIMING AND EXTENT OF CLEARING IS
UNCERTAIN.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 405 AM EDT THU APR 28 2016

THE PERIOD WILL BE MET WITH INCREASING CLOUDS UPPER LEVEL
DIVERGENCE AND UPPER WAVE APPROACHING. ALONG WITH THIS A WARM
FRONT WILL PROGRESS NORTH AND ISENTROPIC LIFT WILL BRING INCREASE
IN SHOWERS FROM SW TO NE THROUGH THE MORNING AND CONTINUE INTO
SATURDAY. DO KEEP SHOWERS IN THE AM BEFORE TRANSITIONING TO
CHANCE STORMS IN THE AFTERNOON. BEST CHANCES OF SEEING RAIN WILL
BE TOWARD TO AFTERNOON AND EVENING ON SATURDAY AS MAIN WAVE AND
LOW LEVEL JET COME ACROSS EASTERN KY.

NOW SUNDAY WE SEE MORE PHASING IN THE UPPER LEVELS...WHILE WE
RESIDE IN THE WARM SECTOR AT THE SURFACE AS WARM FRONT TRACKS
NORTH. THIS PHASING WILL BRING DECENT BAND OF WESTERLIES ALOFT
RIGHT ACROSS KY...AND AT THE SURFACE A LOW PRESSURE DEEPENS SOME
AS IT APPROACHES THE SOUTHERN OHIO VALLEY. THESE ELEMENTS WILL
ALIGN TO ESTABLISH DEEP LAYER SPEED SHEAR...HOWEVER CLOSER TO THE
FRONTAL INTERSECTION YOU COULD SEE SOME DIRECTIONAL SHEAR. THE
QUESTION WOULD BE HOW MUCH RECOVERY AND DESTABILIZATION DO WE SEE
AHEAD OF THIS SYSTEM. THE GFS WOULD SUGGEST WE SEE AMPLY
DESTABILIZATION AND CERTAINLY AS THE TROUGH APPROACHES MID LAPSE
RATES UP TICK TO AROUND 7 C/KM. CAPE VALUES BECOME FAT WITH IN THE
COLUMN...WITH THE SOUNDING SUGGESTING MUCAPE VALUES CLIMBING TO
AT OR ABOVE 2000 J/KG. IF WE REALIZE SOME OF THE FORECAST
SOUNDINGS WE WOULD BE IN FOR A GOOD CHANCE OF SEVERE WEATHER...AND
ALL ELEMENTS OF SEVERE WEATHER WOULD BE IN PLAY. WILL ALSO SAY THE
CIPS ANALOG DOES SHOW SOME SIGNAL MAINLY ALONG AND SOUTH OF I64
AND SPC MARS HAS SOME WEAK SIGNAL. GIVEN THE UNCERTAINTIES AND THE
FACT THAT WE ARE STILL ABOUT 4 DAYS OUT WILL NOT RAMP UP HWO JUST
YET...BUT WORTH WATCHING OVER THE NEXT FEW DAYS.

DO TRANSITION THIS TO SHOWERS SUNDAY NIGHT INTO MONDAY AS
INSTABILITY LOOKS TO WANE. THIS SYSTEM WILL EXIT TO THE EAST BY
MONDAY NIGHT. THESE FALLING HEIGHTS WILL LEAD TO COOLER TEMPS THAN
WE HAVE SEEN LATELY...AS WE FALL BACK TO MORE AVERAGE TEMPS FOR
THIS TIME OF YEAR. BY TUESDAY MORNING WE DROP BACK INTO THE UPPER
40S FOR LOWS AND THIS MAY FEEL COOL. ANOTHER COLD FRONT MOVES SE
LATE WEDNESDAY AND SHOWERS CHANCES INCREASE. BEHIND THIS WE COULD
SEE A DECENT SHOT OF COLD AIR IF THE GFS COMES TRUE SHOWING 850 MB
TEMPS IN THE 0 TO -2 RANGE...BUT WAY TOO EARLY TO CALL THIS ONE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 755 AM EDT THU APR 28 2016

CONVECTION IS AFFECTING MAINLY JKL AND SJS AND THIS SHOULD SHIFT
EAST INTO WV BY 14Z OR 15Z. IFR OR LOWER IS EXPECTED AT TIMES WITH
THIS THOUGH MANY LOCATIONS SHOULD ONLY BE REDUCED TO MVFR. ONCE
THIS DEPARTS...VFR IS ANTICIPATED. HOWEVER...AN APPROACHING COLD
FRONT AND UPPER LEVEL DISTURBANCE COULD LEAD TO REDEVELOPMENT OF
ISOLATED TO SCATTERED CONVECTION WITH BRIEF PERIODS OF IFR OR MVFR
BY THE 16Z TO 19Z PERIOD. THAT ACTIVITY SHOULD WANE BY 0Z OR
SUNSET. LINGERING LOW LEVEL MOISTURE COULD LEAD TO VALLEY FOG WITH
MVFR OR IFR VIS BY THE 6Z TO 12 PERIOD. WINDS WILL AVERAGE OUT OF
THE SOUTH AT 10KT OR LESS THROUGH 16Z...THEN BECOMING WESTERLY AND
GUSTY UNTIL THE COLD FRONT PASSES.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...JP
SHORT TERM...JP
LONG TERM...DJ
AVIATION...JP



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