Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 201100
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
700 AM EDT WED MAY 20 2015

.UPDATE...
ISSUED AT 644 AM EDT WED MAY 20 2015

IR SAT SHOWING SOME THIN HIGH CLOUDS MOVING ACROSS PORTIONS OF
EASTERN KENTUCKY THIS MORNING. THE LOCATION OF THE SURFACE HIGH
HAS ALLOWED MORE MIXING OVERNIGHT...SO NOT SEEING MUCH OF THE
RIDGE/VALLEY SPLIT. ALSO A FEW MAINLY RIVER VALLEY SPOTS ARE
SEEING SOME FOG THIS MORNING AND IS EVIDENT ON A COUPLE OF
AREA WEBCAMS/OBS...BUT THIS WAS WANED COMPARED TO YESTERDAY BY
THE MIXING. DID KEEP THE PATCHY FOG GIVEN AREA WEBCAMS/OBS AND
UPDATED WITH LATEST OBS AND TRENDS. NO MAJOR CHANGES NEEDED THIS
UPDATE.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)

ISSUED AT 345 AM EDT WED MAY 20 2015

03Z SURFACE ANALYSIS SHOWS FRONT HAS MOVED SOUTH OF THE TENNESSEE
VALLEY AND CANADIAN HIGH PRESSURE BROADLY CENTERED ACROSS THE
UPPER PLAINS. IN THE UPPER LEVELS THE RIDGING THAT HAS BEEN IN
PLACE HAS FLATTENED WITH MORE OF A ZONAL FLOW IN THE WAKE. MUCH
DRIER AND COOLER CONDITIONS PREVAIL BEHIND THE FRONT THAT USHERED
IN NORTHERLY FLOW. WE HAVE BEEN ABLE TO STAY FAIRLY MIXED
OVERNIGHT GIVEN THE PLACEMENT OF THE SURFACE HIGH...SO SEEING A
MORE SUBTLE RIDGE/VALLEY SPLIT THIS MORNING. DID OPT KEEP MENTION
OF VALLEY FOG...HOWEVER GIVEN THE MIXING MOST PLACES WILL SEE
LITTLE IF ANY ISSUES THIS MORNING. TODAY WILL FEATURE MOSTLY SUNNY
DAY WITH SOME HIGH CLOUDS STREAMING IN FROM THE WEST. A FEW MORE
CLOUDS WILL WORK THERE WAY INTO THE FAR WEST LATE IN THE DAY.

ALL EYES THEN TURN TO UPPER LEVEL DISTURBANCE CURRENTLY ACROSS
THE PLAINS. THIS WILL BE THE NEXT FEATURE TO BRING POSSIBILITY OF
SHOWERS ACROSS EASTERN KY TONIGHT INTO THURSDAY. A COUPLE OF
ISSUES TO MENTION IS THE VERY DRY AIR IN PLACE AHEAD OF THIS
SYSTEM AND THE FACT THAT THE UPPER LEVEL SYSTEM DOES WEAKEN/SHEAR
OUT AS IT MOVES EAST...HOWEVER THAT SAID MODEL TRENDS CONTINUE TO
INCREASE POP CHANCES WITH GFS BEING THE WEAKEST. GIVEN THIS TREND
DID COME UP SOME WITH REGARDS TO POPS BUT STAYED IN THE HIGH RANGE
OF CHANCE. ALSO DID KEEP ALL ACTIVITY AS JUST RAIN SHOWERS AT THIS
POINT...HOWEVER NAM FORECAST SOUNDINGS DO HINT AT A BIT MORE
INSTABILITY ACROSS THE SOUTH NEAR THE TN BORDER. THIS WILL HAVE
TO BE LOOKED AT CLOSER IN SUBSEQUENT FORECAST UPDATES BUT WOULD
THINK WE WOULD ONLY BE LOOKING AT ISOLATED CHANCES IF THAT.
OTHERWISE DID BUMP PREVIOUS FORECAST HIGHS DOWN FOR THURSDAY GIVEN
THE TREND FROM THE THE GUIDANCE AND THE CLOUD COVER/GENERAL NW
FLOW IN PLACE. THESE HIGH TEMPS WILL BE NEARING 10 DEGREES BELOW
NORMAL FOR THIS TIME OF YEAR WITH NORMAL THIS TIME OF YEAR 75 AT
JKL AND 77 AT LOZ.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 418 AM EDT WED MAY 20 2015

SURFACE HIGH PRESSURE BUILDING IN FROM THE WEST WITH A DRY AIR
MASS WILL RESULT IN DRY WEATHER AND CLEAR TO PARTLY CLOUDY SKIES
THURSDAY NIGHT AND FRIDAY. TEMPERATURES SHOULD BE BELOW
NORMAL...ESPECIALLY MORNING LOWS DUE TO LOW DEW POINTS AND GOOD
RADIATIVE COOLING.

A COLD FRONT WILL APPROACH FROM THE NORTH FRIDAY EVENING...BUT IS
EXPECTED TO DISSOLVE AS IT ARRIVES. MOISTURE WILL BE LIMITED...AND
NO PRECIP IS EXPECTED. HIGH PRESSURE PASSING BY TO OUR NORTH
BEHIND THE FRONT WILL BRING A REINFORCING PUSH OF COOL AND DRY AIR
TO TAKE US INTO THE WEEKEND.

BY SUNDAY THE HIGH WILL SLIP AWAY OFF THE EAST COAST AND OUR LOW
LEVEL FLOW WILL TURN TO THE SOUTH...WHILE UPPER LEVEL RIDGING
DEVELOPS OVER THE SOUTHEAST CONUS. THIS WILL BRING WARMING
TEMPERATURES AND DEW POINTS. ENOUGH MOISTURE MAY RETURN TO SUPPORT
A FEW SHOWERS/THUNDERSTORMS ON SUNDAY AFTERNOON AND EVENING. AS
HEAT AND HUMIDITY BUILDS EARLY IN THE WEEK...AN OVERALL INCREASE
IN POPS IS ALSO FORECAST. THE BETTER CHANCE OF RAIN WILL INITIALLY
BE TO OUR NORTH AND WEST...FURTHER REMOVED FROM THE UPPER RIDGE.
THE RIDGE SHOULD BE BREAKING DOWN BY TUESDAY AND A DISSIPATING
COLD FRONT WILL APPROACH FROM THE NORTHWEST...WITH HIGHER POPS
SHIFTING SOUTHEAST TOWARD KY. OTHERWISE...NOT MUCH IN THE WAY OF
FEATURES CAN BE DISCERNED IN THE FLOW ALOFT...AND IT IS QUITE A
DISTANCE OUT IN TIME...SO HAVE USED A DIURNAL TREND FOR PRECIP
WITH PEAK POPS IN THE AFTERNOON AND EARLY EVENING HOURS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 700 AM EDT WED MAY 20 2015

IR/WV SAT INDICATING A SLIGHT RETURN IN MOISTURE WITH SOME HIGH
THIN CLOUDS STREAMING IN FROM THE WEST. NO AFFECTS ON TAFS WITH
SITES COMING IN AT VFR THIS MORNING. WHILE THERE IS SOME PATCHY
DENSE FOG IN MAINLY VALLEY LOCATIONS THIS MORNING...THE TAF SITES
ALL REMAIN VFR AND NO FOG. THESE HIGH CLOUDS STREAMING ARE IN
ASSOCIATION WITH A DISTURBANCE ACROSS THE PLAINS WITH A WEAK
SURFACE LOW ACROSS OKLAHOMA THIS MORNING. THIS SYSTEM WILL PUSH
EAST THROUGH THE DAY INTO TONIGHT. CLOUDS WILL BE ON THE INCREASE
LATER TODAY ACROSS THE WEST AND SPREAD EAST OVERNIGHT. ALSO RAIN
SHOWERS WILL BE ON THE INCREASE...SO DID INTRODUCE VCSH LATER
TONIGHT. RIGHT NOW AM KEEPING SITES VFR...HOWEVER TOWARD THE END
OF THE TAF PERIOD MVFR OR LOWER CIGS ARE POSSIBLE. CONFIDENCE IS
LOW ON THIS SO WILL LEAVE OUT OF TAFS AT THIS JUNCTURE.

&&

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

$$

UPDATE...DJ
SHORT TERM...DJ
LONG TERM...HAL
AVIATION...DJ



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