Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 301912
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
312 PM EDT THU JUL 30 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 312 PM EDT THU JUL 30 2015

WEST NORTHWEST FLOW ALOFT IS IN PLACE ACROSS THE REGION BETWEEN A
MID LEVEL RIDGE CENTERED OVER THE SOUTHERN PLAINS AND CLOSED LOW
AND ASSOCIATED TROUGH CENTERED OVER THE HUDSON BAY REGION AND
EXTENDING INTO THE GREAT LAKES AND NORTHEASTERN STATES. AT THE
SFC...A COLD FRONT THAT CROSSED THE AREA LATE LAST NIGHT AND EARLY
THIS MORNING...CONTINUES TO DEPART TO THE EAST OF THE REGION. A
RIDGE OF SFC HIGH PRESSURE CONTINUES TO BUILD EAST INTO THE OH
VALLEY REGION...AND IS USHERING DRIER AIR ON NW FLOW. DEWPOINTS
ARE AS LOW AS THE UPPER 50S IN NORTHERN KY...WITH LOW TO MID 50S
OVER PARTS OF INDIANA.

THROUGH FRIDAY NIGHT...THE PATTERN IS EXPECTED TO AMPLIFIED. THE
MID LEVEL RIDGE WILL RETROGRADE TO THE WEST AND BECOME CENTERED
NEAR THE FOUR CORNERS REGION WITH RIDGING NORTH BUILDING NORTH
ACROSS THE WESTERN CONUS. MEANWHILE...THE CLOSED LOW WILL MEANDER
TO FAR NORTHERN ONTARIO THROUGH THE END OF THE PERIOD WITH THE
AREA IN NW FLOW ALOFT BETWEEN THE RIDGE AND TROUGH...ALTHOUGH THE
AXIS OF THE TROUGH SHOULD REMAIN GENERALLY EAST OF THE AREA. A FEW
WEAK SHORTWAVES PASSING BY IN THE FLOW SHOULD BRING NOTHING MORE
THAN A FEW CLOUDS FROM TIME TIME. A SFC LOW PRESSURE SYSTEM
ASSOCIATED WITH ONE OF THESE SHORTWAVES SHOULD TRACK ACROSS
ONTARIO AND INTO QUEBEC LATE IN THE PERIOD...WITH THE TRAILING
MOISTURE STARVED COLD FRONT POSSIBLY DROPPING SOUTH OF THE GREAT
LAKES LATE FRI NIGHT.

WITH THE RIDGE BUILDING IN TONIGHT...COLDER OVERNIGHT LOWS...UP TO
10 DEGREES OR MORE COLDER THAN THIS AM ARE EXPECTED. DEWPOINTS
MOVING INTO THE NORTH SUGGEST A FEW LOWS IN THE UPPER 50S FOR
VALLEYS ALONG AND NORTH OF THE MTN PARKWAY. COOP MOS GUIDANCE ALSO
SUPPORTS THOSE NUMBERS. THE LIGHT WINDS AND CLEAR SKIES SHOULD
ALSO FAVOR SOME VALLEY FOG DEVELOPING ALONG A FEW OF THE LARGER
CREEKS AND NEAR AREA RIVERS AND LAKES.

FRIDAY SHOULD FEATURE HIGHS NEAR NORMAL FOR LATE JULY UNDER THE
INFLUENCE OF HIGH PRESSURE...WITH MUCH MORE COMFORTABLE DEWPOINTS
AND HUMIDITIES COMPARED TO RECENT DAYS. THE RIDGE SHOULD CONTINUE
TO DOMINATE LATE IN THE PERIOD...ON FRIDAY NIGHT...WITH OVERNIGHT
LOWS IN MOST LOCATIONS A DEGREE OR TWO WARMER TO TONIGHT. THE
EXCEPTION TO THIS WILL BE THE FAR SOUTH AND SOUTHEAST
VALLEYS...WHERE THE DRIER AIR WILL BE A TAD SLOWER TO MOVE
IN...AND LOWS FRI NIGHT MAY BE A DEGREE OR TWO COLDER COMPARED TO
TONIGHT.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 246 PM EDT THU JUL 30 2015

FORECAST MODELS INDICATE THAT A TROUGH WILL REMAIN IN PLACE OVER
THE EASTERN U.S. THROUGHOUT THE PERIOD. HIGH PRESSURE WILL REMAIN
IN PLACE AT THE SURFACE OVER OUR AREA THROUGH MONDAY KEEPING OUR
FORECAST DRY AND SEASONABLY WARM. A WEAK FRONT WILL DROP INTO THE
OHIO VALLEY ON MONDAY. MODELS ARE QUITE DIFFERENT IN HOW THEY
HANDLE THIS FRONT FROM TUESDAY THROUGH THE REST OF NEXT WEEK AND
THIS LOWERS FORECASTER CONFIDENCE. WHILE THE GFS INDICATES A QUICK
FRONTAL PASSAGE TUESDAY INTO TUESDAY NIGHT...FOLLOWED BY DRY
WEATHER WEDNESDAY AND THURSDAY...THE GEM AND ECMWF INDICATE A
STALLED FRONT TO OUR NORTH OR OVERHEAD WITH A BETTER CHANCE OF
SHOWERS AND THUNDERSTORMS. A MODEL BLEND GIVES SLIGHT CHANCE TO
CHANCE POPS TUESDAY THROUGH THURSDAY AND THAT SEEMS PRUDENT GIVEN
THE MODEL DIFFERENCES. TEMPS SHOULD REMAIN NEAR SEASONAL NORMS
NEXT WEEK WITH THE RIDGE ALOFT CENTERED WELL TO OUR WEST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 145 PM EDT THU JUL 30 2015

HIGH PRESSURE BUILDING INTO THE REGION WILL BRING MAINLY VFR
THROUGH THE PERIOD. THE EXCEPTION WILL BE A BIT OF VALLEY FOG
LATE TONIGHT. VFR FOG MAY AFFECT LOZ...SME...SJS AND SYM DURING
THE 8Z TO 13Z WINDOW. HOWEVER...THE FOG COULD REDUCE VIS TO
IFR... OR PERHAPS TO AIRPORT MINS AT SOME OF THE NON TAF
LOCATIONS. ANY FOG SHOULD LIFT AND DISSIPATE AROUND 13Z...GIVING
WAY TO VFR IN ALL LOCATIONS TO END THE PERIOD.


&&

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

$$

SHORT TERM...JP
LONG TERM...ABE
AVIATION...HAL


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