Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 232055
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
455 PM EDT SAT MAY 23 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 303 PM EDT SAT MAY 23 2015

STRONG UPPER LEVEL CLOSED LOW OVER SOUTHEAST CANADA...AS WELL AS A
CLOSED LOW OVER THE AMERICAN SOUTHWESTERN STATES...HAS LED TO A
SLIGHT RIDGING PATTERN ACROSS THE PLAINS...MISSISSIPPI RIVER
VALLEY...AND INTO THE OHIO RIVER VALLEY. SEVERAL WAVES OF ENERGY ARE
RIDING UP AND ALONG THIS BROAD RIDGING PATTERN...BUT SHOULD CONTINUE
TO DIMINISH AND REMAIN NEARLY STATIONARY THROUGH TOMORROW AS BOTH
UPPER LEVEL LOWS GAIN STRENGTH AND MOVE EASTWARD. THIS WILL AMPLIFY
THE RIDGING ACROSS THE OHIO RIVER VALLEY AND ESSENTIALLY PREVENT ANY
SHORTWAVES FROM MAKING IT INTO THE REGION. AS SUCH...A VAST AMOUNT
OF CLOUD COVER IS PRESENT ON SATELLITE WEST OF THE MISSISSIPPI RIVER
DUE TO THESE DISTURBANCES. SOME OF THIS CLOUD COVER HAS BEEN
TRANSPORTED EASTWARD AND ACROSS THE STATE OF KY...INCLUDING THE JKL
CWA. HOWEVER...EXPECT THAT ALL CLOUDS SHOULD REMAIN OF THE HIGH
VARIETY...GENERALLY OVER 1000FT. THE ONLY IMPACT THIS SCT CLOUD
COVER WILL HAVE IS TO PREVENT SUCH A LARGE RIDGE VALLEY SPLIT IN
TEMPERATURES OVERNIGHT TONIGHT.

EXPECT THE STRONG UPPER LEVEL LOW OVER THE SW CONUS TO REACH THE
WESTERN PLAIN STATES BY SUNDAY MORNING...CONTINUING TO SHIFT
NORTHEAST...REACHING THE DAKOTAS BY 12Z MONDAY MORNING. DURING THIS
TIME...THE ASSOCIATED UPPER LEVEL TROUGHING WILL EXPAND EASTWARD AS
WELL...PUSHING THE STRONG RIDGE OVER THE OHIO RIVER VALLEY EASTWARD.
SOME SHORTWAVE ENERGY WILL BEGIN IMPACTING MUCH OF THE MISSISSIPPI
RIVER VALLEY DURING THIS TIME...BUT RIDGING SHOULD REMAIN INTACT
ENOUGH ACROSS THE EASTERN PORTION OF THE STATE THAT JKL SHOULD
REMAIN DRY AND GENERALLY IMPACT FREE THROUGH 12Z. THE ONLY EXCEPTION
WILL BE AN INCREASE IN CLOUD COVER...MAINLY ACROSS THE WESTERN CWA
...WITH POPS EXPECTED TO MOVE IN DURING THE DAY MONDAY...JUST AFTER
THE END OF THE SHORT TERM.

WITH A CONTINUED FLUX OF S TO SW WINDS AT THE SURFACE...AND WESTERLY
WINDS ALOFT...EXPECT TEMPS TO CONTINUE TO RISE THROUGHOUT THE SHORT
TERM. HUMIDITY LEVELS WILL ALSO BE ON A SLOW UPTICK AS WELL. HIGH
TEMPS TOMORROW ARE EXPECTED TO TOP OUT IN THE LOW TO MID 80S ACROSS
THE REGION COMPARED TO THE UPPER 70S/LOW 80S OF TODAY.
MEANWHILE...ANY INCOMING CLOUD COVER WILL PROHIBIT SUCH STRONG RIDGE
VALLEY SPLITS OVER THE NEXT TWO NIGHTS COMPARED TO THAT SEEN IN
PREVIOUS NIGHTS. THIS WILL ESPECIALLY BE THE CASE SUNDAY NIGHT.
GENERALLY LOW TO MID 50S ARE EXPECTED TONIGHT...WITH A FEW VALLEY
LOCATIONS POSSIBLY BOTTOMING OUT IN THE UPPER 40S. HOWEVER...BY
TOMORROW NIGHT...OVERNIGHT TEMPS WILL IMPROVE CONSIDERABLY TO THE
UPPER 50S TO LOW 60S.

ALL MODELS SEEM TO HAVE A GOOD HANDLE ON THE SYNOPTIC FEATURES AND
SENSIBLE WEATHER DURING THE SHORT TERM. GENERALLY STUCK WITH A BLEND
OF NEAR TERM MODELS...WITH SOME MANUAL EDITING TO PRODUCE THE
DESIRED RIDGE VALLEY SPLITS...AS WELL AS OVERNIGHT VALLEY REDUCTIONS
IN WIND. NO EXTREME OUTLIERS IN MODELS WERE NOTICED.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 455 PM EDT SAT MAY 23 2015

LOW LEVEL MOISTURE OFF THE GULF OF MEXICO SHOULD MAKE A RETURN AT
THE START OF THE PERIOD. UPPER LEVEL RIDGING OVER THE SOUTHEAST
CONUS WILL ALSO WEAKEN AND MOVE EASTWARD EARLY IN THE PERIOD. THIS
WILL ALLOW THE WESTERLIES AND THEIR EMBEDDED DISTURBANCES TO MOVES
CLOSER. THE COMBINATION OF THE ONSET OF MOISTURE/INSTABILITY AND
AN UPPER LEVEL ENVIRONMENT MORE CONDUCIVE FOR CONVECTION WILL
RESULT IN THE RETURN OF SHOWERS AND THUNDERSTORMS. FEATURES ALOFT
FOR OUR LOCAL AREA ARE STILL EXPECTED TO BE RATHER WEAK...AND A
SIGNIFICANT DIURNAL TREND IS EXPECTED FOR PRECIP...WITH A PEAK IN
POP DURING THE AFTERNOON AND EVENING HOURS EACH DAY. MODELS DO
SHOW A SHORTWAVE TROUGH APPROACHING ON TUESDAY AND PASSING TO OUR
NORTHWEST ON WEDNESDAY. THE HIGHEST POPS OF THE WEEK WILL BE
EXPECTED WITH THIS FEATURE. ONCE THIS PASSES...OUR FLOW ALOFT
BECOMES MUCH WEAKER...WITH A LACK OF DISTURBANCES. HOWEVER...NO
SIGNIFICANT CHANGE IN SURFACE AIR MASS SHOULD OCCUR. THIS SCENARIO
WOULD TEND TO BRING AT LEAST A REDUCTION IN PRECIP COVERAGE...BUT
MAY NOT ELIMINATE IT ENTIRELY. BY SATURDAY...THE GFS SHOWS
ANOTHER COLD FRONT DROPPING IN FROM THE NORTH...IN RESPONSE TO A
STRONG UPPER LEVEL LOW AND TROUGH PIVOTING THROUGH SOUTHEAST
CANADA. THE ECMWF SHOWS THESE FEATURES AS WELL...BUT IS NOT AS
AMPLIFIED WITH EXTENSION OF THE PATTERN OVER THE CONUS...AND AS A
RESULT KEEPS THE SURFACE BOUNDARY FURTHER NORTH. CONFIDENCE IS LOW
IN THE PROGRESS OF THIS FRONT...AND HAVE HELD POPS FAIRLY LOW YET
ON SATURDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 137 PM EDT SAT MAY 23 2015

VFR CONDITIONS UNDER PARTLY TO MOSTLY OPAQUE HIGH CLOUDS WILL PREVAIL
AT THE TAF SITES OVER THE NEXT 24 HOURS WITH LIGHT WINDS /GENERALLY
5 KTS OR LESS AND VARIABLE IN DIRECTION/. WHILE SOME VALLEY FOG
IS POSSIBLE LATE TONIGHT...DO NOT EXPECT TAF SITES TO BE AFFECTED.

&&

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

$$

SHORT TERM...JMW
LONG TERM...HAL
AVIATION...JMW


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