Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 021720
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
120 PM EDT SUN AUG 2 2015

.UPDATE...
ISSUED AT 1038 AM EDT SUN AUG 2 2015

MUCH OF THE FOG THAT DEVELOPED ACROSS THE RIVER VALLEYS THIS
MORNING HAS DISSIPATED. WE ARE LEFT WITH MOSTLY SUNNY TO SUNNY
SKIES UNDER SURFACE HIGH PRESSURE. FORECAST IS ON TRACK AT THIS
POINT WITH ONLY MINOR ADJUSTMENTS MADE OVERALL TOWARDS LATEST OBS
AND TRENDS.

UPDATE ISSUED AT 700 AM EDT SUN AUG 2 2015

TOUCHED UP THE GRIDS THIS MORNING BASED ON THE LATEST OBS AND
TRENDS. THESE HAVE BEEN SENT TO THE NDFD AND WEB SERVERS.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 350 AM EDT SUN AUG 2 2015

07Z SFC ANALYSIS SHOWS HIGH PRESSURE IN PLACE OVER CENTRAL
KENTUCKY. THIS IS HELPING TO KEEP THE SKY MOSTLY CLEAR ACROSS THE
STATE...BUT A SMATTERING OF MID LEVEL CLOUDS ARE DRIFTING OVER
EAST KENTUCKY AND OUT OF THE AREA ATTM. SIMILAR TO THE PAST FEW
NIGHTS...AN INVERSION HAS SET UP WHILE GOOD RADIATIONAL COOLING IS
UNDERWAY. THIS HAS LED TO ANOTHER NIGHT OF RIDGE TO VALLEY
TEMPERATURE DIFFERENCES WITH SOME UPPER 50S FOUND IN THE DEEPER
SPOTS WHILE HILLTOPS ARE RUNNING IN THE MID 60S. WINDS REMAIN
LIGHT TO CALM ACROSS EAST KENTUCKY WITH NOT MUCH EVIDENCE OF FOG
OUT THERE YET. HOWEVER...AGAIN SIMILAR TO THE PAST FEW NIGHTS...
EXPECT THE FOG TO FORM IN THE RIVER VALLEYS BEFORE DAWN ALONG WITH
LOCALLY DENSE PATCHES.

THE MODELS ARE IN PRETTY GOOD AGREEMENT ALOFT AS A BROAD AREA OF
TROUGHING CONTINUES OVER SOUTH CENTRAL CANADA AND DOWN INTO THE
OHIO VALLEY ACROSS TO NEW ENGLAND. A WIGGLE AT THE CORE OF THE
TROUGH TO THE NORTH WILL SEND A LARGE AMOUNT OF ENERGY INTO THE
GREAT LAKES ON MONDAY ALONG WITH A MID LEVEL GRADIENT THAT
TIGHTENS...RESULTING IN FASTER FLOW THROUGH THE OHIO VALLEY. GIVEN
THE AGREEMENT ALOFT WILL FOLLOW A BLENDED SOLUTION WITH EMPHASIS
ON THE HRRR AND NAM12 EARLY ON AND THE BROADER CONSENSUS LATER.

SENSIBLE WEATHER WILL FEATURE ANOTHER PLEASANT DAY WITH FAIRLY LOW
AND COMFORTABLE HUMIDITY LEVELS AND HIGHS GENERALLY IN THE MID
80S UNDER MOSTLY SUNNY SKIES. THIS WILL LEAD INTO ONE MORE NIGHT
OF GOOD RADIATIONAL COOLING AND RIDGE TO VALLEY TEMPERATURE
DIFFERENCES INTO MONDAY MORNING...ALONG WITH PATCHY VALLEY FOG
TOWARDS DAWN. BY MONDAY...THOUGH...THE SFC PATTERN WILL CHANGE
WITH A COLD FRONT PRESSING SOUTH THROUGH THE OHIO VALLEY AND
TOWARD EAST KENTUCKY. THIS WILL LIKELY KICK OFF SHOWERS AND
THUNDERSTORMS NORTH OF THE STATE THAT SHOULD HELP TO SPAWN
ADDITIONAL STORMS TO THE SOUTH WITH TIME THROUGH THE DAY. ANY
STORMS THAT MANAGE TO DEVELOP OUT AHEAD OF THE FRONT IN EAST
KENTUCKY WILL HAVE THE POTENTIAL TO BECOME STRONG TO SEVERE OWING
TO HIGH CAPES AND STRENGTHENING MID LEVEL WINDS. THE BEST CHANCES
WILL BE OVER OUR NORTHERN ZONES CLOSER TO THE FRONT AND SPC HAS
INDICATED A SLIGHT RISK FOR SEVERE STORMS THERE. WILL HIGHLIGHT
THIS CONCERN IN THE FORTHCOMING HWO.

STARTED WITH THE SHORTBLEND MODEL FOR THE T/TD/WIND GRIDS THROUGH
THE DAY FOLLOWED BY THE SUPERBLEND INTO MONDAY. DID MAKE SOME
SIGNIFICANT ADJUSTMENTS TO TEMPERATURES THIS MORNING AND TONIGHT
WITH RESPECT TO RIDGE AND VALLEY DIFFERENCES. AS FOR POPS...KEPT
THEM LOW AND IN LINE WITH THE DRY GUIDANCE INTO MONDAY MORNING.
DID GO A BIT HIGHER THAN THE MET AND MAV NUMBERS FOR MONDAY
AFTERNOON TO ACCOUNT FOR THE POTENTIAL INTRUSION OF STORMS...
ORGANIZED OR OTHERWISE...FROM THE NORTH BY EVENING.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 340 AM EDT SUN AUG 2 2015

THE EXTENDED FORECAST PERIOD BEGINS ON MONDAY NIGHT WITH THE UPPER
LEVEL PATTERN MAINTAINING A RIDGE OVER THE WEST AND THE LONGWAVE
TROUGH OVER THE EASTERN CONUS. A CLOSED LOW OVER THE HUDSON BAY AREA
WILL GRADUALLY SHIFT OFF TO THE EAST THROUGH THE EXTENDED AS BY
THURSDAY...A SERIES OF STRONGER TROUGHS COME ASHORE OVER THE WEST AS
THE WESTERN RIDGE BEGINS TO WEAKEN A BIT AND SHIFT EAST. THIS
THROUGH THE LAST PORTION OF THE EXTENDED WILL BE THE FORECAST
CHALLENGE AS THE BASE OF THE EASTERN TROUGH SETS UP OVER THE MID MS
VALLEY AND THROUGH KY. THE GFS AND EURO DOES ALIGN A BIT WITH THIS
SOLUTION.

CLOSER TO THE SURFACE...THE FRONT THAT HAS PASSED THROUGH ON MONDAY
WILL LAG ACROSS NORTHERN KENTUCKY AS A STATIONARY BOUNDARY DEVELOPS.
THIS AREA BECOMES A FOCUS FOR SHOWER AND THUNDERSTORM DEVELOPMENT AS
THE BOUNDARY SLIDES FURTHER SOUTH THROUGH THE DAY ON TUESDAY AND
TUESDAY NIGHT. BY WEDNESDAY...NORTHWEST FLOW SETS UP OVER THE AREA
AS A SERIES OF UPPER LEVEL WAVES TOPPLE OVER THE THE TOP OF THE
WESTERN RIDGE AND TRACK SOUTHEAST INTO THE OH VALLEY. THE SUPER
BLEND HAS THIS IN IT/S SOLUTION AS WELL WITH THE PATTERN FAVORABLE
FOR NOCTURNAL THUNDERSTORMS AS WELL...ESPECIALLY IF THIS PATTERN FOR
MCS/S REMAIN...WHICH SEEMS LIKELY BASED UPON THE GFS AND EURO
SOLUTIONS . THUS WILL STAY CLOSE TO THE SUPER BLENDS SOLUTION
WEDNESDAY THROUGH FRIDAY KEEPING HIGH CHANCE TO LIKELY POPS DURING
THIS PERIOD.

TOWARDS THE END OF THE EXTENDED ON FRIDAY AND SATURDAY...THE UPPER
LEVEL PATTERN LOSES A BIT AMPLITUDE AND BECOMES MORE ACTIVE AS
ANOTHER SHORTWAVE TAKES AIM AT THE OH VALLEY. HOWEVER...THE GFS AND
EURO DO DIVERGE TOWARDS THE END OF THE EXTENDED. THUS...LACKING
CONFIDENCE...WILL GO NEAR OR SLIGHTLY BELOW THE SUPER BLEND ON POPS.
THE LINGERING TROUGH OVER THE EAST AND SAGGING SOUTH THROUGH THE
EXTENDED WILL KEEP HIGHS AT OR SLIGHTLY BELOW NORMAL FOR THIS TIME
OF YEAR. IN SHORT...THE WEDNESDAY THROUGH FRIDAY PERIOD SEEMS TO BE
QUITE ACTIVE AND WET WITH THE END OF THE FORECAST POSSIBLY
CONTINUING THIS TREND WITH A COOLING TREND AS WELL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 120 PM EDT SUN AUG 2 2015

HIGH PRESSURE WILL KEEP TAF SITES MOSTLY VFR THROUGH THE TAF
PERIOD. THE EXCEPTION TO THE RULE WILL BE MAINLY RIVER VALLEY FOG
ACROSS THE REGION OVERNIGHT INTO EARLY MONDAY MORNING. WHILE THIS
WILL NOT AFFECT MOST TAF SITES...GIVEN SIMILAR PATTERN HAVE
INTRODUCED LOWER MVFR VIS SME...SJS...AND SYM WHICH HAD THE MOST
AFFECTS FROM FOG THIS MORNING. THERE IS ALSO AN APPROACHING COLD
FRONT AS WE MOVE INTO AFTERNOON HOURS ON MONDAY...BUT STILL
UNCERTAINTY ON HOW QUICKLY WE WILL SEE CONVECTION ACROSS NORTHERN
TAF SITES. THEREFORE WILL HOLD OFF ON ANY MENTION IN THE TAFS AT
THIS TIME GIVEN LOWER CONFIDENCE. WINDS THROUGH THE PERIOD ARE
EXPECTED TO REMAIN LIGHT AND VARIABLE.

&&

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

$$

UPDATE...DJ
SHORT TERM...GREIF
LONG TERM...SHALLENBERGER
AVIATION...DJ


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