Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 300826
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
426 AM EDT SAT MAY 30 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 418 AM EDT SAT MAY 30 2015

AFTER RAINS IMPACTED SECTIONS OF THE CWA YESTERDAY...LINGERING
MOISTURE HAS LED TO DECENT AREAS OF FOG DEVELOPMENT DURING THE
OVERNIGHT HOURS. PATCHY DENSE FOG HAS ALSO BEEN OBSERVED...AND
WILL LIKELY CONTINUE THROUGH THE EARLY MORNING HOURS. AS THE SUN
BEGINS TO RISE THIS MORNING...EXPECT FOG TO LIFT AND GIVE WAY TO
MOSTLY TO PARTLY SUNNY SKIES ACROSS THE REGION THIS MORNING.

UPPER LEVEL RIDGING OFF THE SOUTHEAST ATLANTIC CONUS WILL SLOWLY
BREAK DOWN OVER THE NEXT DAY AS TROUGHING OVER THE MISSISSIPPI RIVER
VALLEY SHIFTS EASTWARD AND ACROSS THE OHIO RIVER VALLEY. THIS SHIFT
WILL BE OUR PRIMARY WEATHER DRIVER OVER THE NEXT 2 DAYS. AT THE
SURFACE...A LOW PRESSURE SYSTEM...CURRENTLY MOVING ACROSS
MISSOURI...WILL REACH WESTERN INDIANA BY THIS EVENING...THEN
CONTINUE TO SHIFT NORTHEAST...JUST NORTH OF THE OHIO
RIVER...THROUGH SATURDAY NIGHT AND INTO SUNDAY MORNING. AS THIS
OCCURS...A COLD FRONT IS EXPECTED TO PUSH THROUGH KENTUCKY. STILL
FAVORING THE GFS SOLUTION OF THE FRONTAL PASSAGE...WHICH SHOULD
TRAVERSE WESTERN KY LATE TONIGHT...CENTRAL KY THROUGH 12Z
SUNDAY...AND STALL OUT ACROSS THE HIGH TERRAIN OF KY BETWEEN 18Z
SUNDAY AND 0Z MONDAY.

FOR TODAY...CONTINUED STRONG WARM MOIST SOUTHERLY FLOW AHEAD OF THE
BOUNDARY WILL BRING YET ANOTHER HIGH HUMIDITY/WARM WEATHER DAY TO
THE REGION...AS WELL AS THE POTENTIAL FOR CONVECTIVE DEVELOPMENT. AS
HAS BEEN THE CASE IN THE PREVIOUS DAYS...BEST CHANCES FOR CONVECTION
WILL BE IN THE AFTERNOON WITH PEAK HEATING AND INSTABILITY. LATEST
FORECAST SOUNDINGS FOR TODAY DON/T LOOK OVERLY IMPRESSIVE FOR SEVERE
POTENTIAL...BUT COULD STILL SEE SOME GOOD RAINERS AND DECENT
LIGHTNING FROM ANY THUNDERSTORM THAT DEVELOPS. AS WE LOSE DAYTIME
HEATING...EXPECT COVERAGE TO DECREASE INTO THE OVERNIGHT
HOURS...ESPECIALLY IN THE SE PORTION OF THE CWA AWAY FROM THE BEST
FORCING OF THE INCOMING FRONT. BEGAN INCREASING POPS AGAIN BY 12Z
SUNDAY AS SUN BEGINS TO INFLUENCE UNSTABLE AIRMASS ONCE
MORE...PEAKING AS THE FRONT BEGINS PASSING OVER DURING THE AFTERNOON
HOURS. FORECAST SOUNDINGS ARE SHOWING BETTER HAIL POTENTIAL DURING
THE DAY SUNDAY...WITH MUCH MORE DRYING ALOFT AND DECENT CAPE VALUES
IN THE 2 TO 3K J/KG RANGE. LAPSE RATES ARE NOT SUPER
IMPRESSIVE...BUT LI/S WILL DROP INTO THE -5 TO -6C RANGE IN SOME
LOCATIONS...INDICATING GOOD POTENTIAL FOR THUNDERSTORM INITIATION.
ALL IN ALL...EXPECT SOME DECENT SCATTERED STORM DEVELOPMENT TO
POTENTIALLY TAKE PLACE OVER SOUTHEAST KY...WHICH CORRESPONDS WELL TO
SPC/S MARGINAL RISK OVER THIS SAME AREA FOR SUNDAY. SOMETHING TO
WATCH OUT FOR. HOWEVER...DID NOTE THE LEVEL OF MOISTURE IN THE
SOUNDINGS ARE QUITE SHALLOW...WITH UNIMPRESSIVE PWATS...SO NOT
EXPECTING MUCH HYDRO CONCERNS...UNLESS STORMS CONTINUE TO IMPACT THE
SAME LOCATIONS MULTIPLE TIMES.

WITH SUCH A STRONG SOUTHERLY FLOW EXPECTED TODAY...TEMPERATURES
COULD WARM WELL INTO THE MID 80S ACROSS MUCH OF THE REGION...WITH
CONTINUED HIGH HUMIDITY VALUES. HOWEVER...WITH INCREASED CLOUD COVER
OVERNIGHT AND INTO TOMORROW...AS WELL AS WINDS SHIFTING TO A MORE NW
DIRECTION BEHIND THE FRONT...EXPECT TEMPERATURES TO ONLY REACH THE
UPPER 70 TO LOW 80 RANGE FOR DURING THE DAY SUNDAY /COOLEST IN THE
WEST/. OVERALL...SUPERBLEND AND GFS WERE THE MODELS OF CHOICE DURING
THE SHORT TERM...THOUGH MOST SHORT TERM MODELS SEEMED TO BE IN
DECENT AGREEMENT WITH ONE ANOTHER.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 235 PM EDT FRI MAY 29 2015

BASED ON MODEL TRENDS OVER THE PAST 24 HOURS...WENT AHEAD AND MADE
SOME FAIRLY SUBSTANTIAL CHANGES TO THE FORECAST FOR NEXT WEEK WHICH
WILL INVOLVE MUCH LESS RAIN CHANCES.

AT THE START OF THE PERIOD...ON SUNDAY...A VORT MAX WILL BE LIFTING
NORTHWARD ACROSS WESTERN KENTUCKY INTO INDIANA AND OHIO. THIS SYSTEM
WILL HAVE SOME GOOD DYNAMICS ASSOCIATED WITH IT TO PRODUCE GOOD
COVERAGE OF SHOWERS AND PERHAPS SOME STORMS OVER THESE AREAS.
HOWEVER...THIS FORCING JUST GRAZES THE BLUEGRASS REGION OF EASTERN
KENTUCKY...WITH MOST OF THE FORCING STAYING TO OUR NORTH.
HOWEVER...THIS WAVE WILL SEND A FRONTAL BOUNDARY SOUTH ACROSS THE
AREA AND WITH THE POSSIBILITY OF SOME INSTABILITY DEVELOPING ON
SUNDAY...WE COULD SEE SHOWERS AND STORMS INCREASE IN COVERAGE AS THE
BOUNDARY PUSHES EAST THROUGH THE DAY. STILL PLENTY OF OPPORTUNITY
FOR THE INSTABILITY TO NOT MATERIALIZE AND WE END UP DRIER THAN
EXPECTED.  SAFE TO SAY...CONFIDENCE IS NOT HIGH ON RAIN CHANCES ON
SUNDAY. IN FACT...THE GFS GUIDANCE HAS BECOME MUCH MORE PESSIMISTIC
ON RAIN CHANCES ON SUNDAY. ECMWF REMAIN A BIT SLOWER WITH THIS WAVE
AND FRONT...WHICH WOULD PROVIDE BETTER SUPPORT FOR RAIN ON SUNDAY IF
THE FRONT CAN STALL OVER OUR REGION.

BY SUNDAY NIGHT INTO MONDAY...IT LOOKS LIKE BOUNDARY WILL SHIFT
SOUTH AND EAST...WITH PERHAPS SOME SLIGHT CHANCES FOR SHOWERS
LINGERING INTO MONDAY ACROSS SOUTHEAST KENTUCKY. HOWEVER...MODELS
ARE COMING INTO BETTER AGREEMENT ON DRY WEATHER FROM LATE MONDAY
THROUGH WEDNESDAY NIGHT AS HIGH PRESSURE BUILDS EAST ACROSS THE OHIO
RIVER VALLEY. THIS WARRANTS REMOVING RAIN CHANCES FROM MONDAY NIGHT
ONWARD.  AS THE HIGH SETTLES EAST BY THURSDAY...SOME RETURN FLOW MAY
DEVELOP WITH SOME MOISTURE RETURNING...WHICH COULD BRING BACK THE
POSSIBILITY OF AN AFTERNOON SHOWER OR THUNDERSTORM.
REGARDLESS...RAIN CHANCES WILL REMAIN LOW THROUGH THE END OF NEXT
WEEK.  A BRIEF COOL DOWN...WITH LOWER HUMIDITIES WILL BE SEEN EARLY
IN THE COMING WEEK BEHIND THE FRONTAL BOUNDARY...BUT TEMPERATURES
WILL RETURN TO ABOVE NORMAL BY MIDDLE TO END OF NEXT WEEK ALONG WITH
HIGHER HUMIDITY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 426 AM EDT SAT MAY 30 2015

WITH LOSS OF DAYTIME HEATING...DIURNALLY DRIVE CONVECTION HAS
CEASED ACROSS THE REGION OVERNIGHT. HOWEVER...CONTINUED MOISTURE
AND WARM TEMPERATURES HAS LED TO AREAS OF FOG DEVELOPMENT
...ESPECIALLY IN THE VALLEYS AND IN AREAS THAT RECEIVED RAIN
YESTERDAY. PATCHY DENSE FOG HAS ALSO BEEN OBSERVED. SO FAR THE
TAF SITES HAVE ONLY HAD MINIMAL IMPACTS. EXPECT TAF SITES TO
GENERALLY REMAIN MVFR TO VFR THROUGH 12/13Z...THOUGH A BRIEF DROP
TO IFR CANNOT BE RULED OUT AS THE FOG BEGINS TO LIFT OUT OF THE
VALLEYS. AFTER THIS POINT...FOG WILL QUICKLY BURN OFF AND VFR
CONDITIONS WILL TAKE HOLD THROUGH MUCH OF THE DAY. STRONG
SOUTHERLY FLOW WILL CONTINUE THE TREND OF WARM MOIST CONDITIONS
ACROSS THE REGION. THIS WILL RESULT IN AFTERNOON CU DEVELOPMENT
AND SCATTERED SHOWERS AND THUNDERSTORMS. GIVEN THAT THE EXACT
LOCATION OF THESE STORMS IS STILL UNKNOWN...CONTINUED WITH MENTION
OF VCTS FOR THE HOURS WHEN STORMS ARE MOST LIKELY EXPECTED.
DAYTIME MIXING WILL ALSO LEAD TO SOME DECENT WIND GUSTS IN THE 10
TO 20KT RANGE DURING THE AFTERNOON HOURS. BY THIS
EVENING...CONVECTION WILL BEGIN A DOWNWARD TREND AS WE LOSE BEST
INSTABILITY AND HEATING.

&&

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

$$

SHORT TERM...JMW
LONG TERM...KAS
AVIATION...JMW


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