Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 300142
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
942 PM EDT FRI MAY 29 2015

.UPDATE...
ISSUED AT 942 PM EDT FRI MAY 29 2015

MOST OF THE AFTERNOON CONVECTION HAS WANED WITH LOSS OF DAYTIME
HEATING SO HAVE REDUCED POPS AND REMOVED THUNDER FROM THE GRIDS
FOR THE OVERNIGHT PERIOD. THERE IS ONE LONELY STORM IN THE CWA BUT
EXPECT THAT TO WEAKEN OVER THE NEXT HOUR. TEMPS ARE A BIT COOLER
THAN PREVIOUSLY FORECAST DUE TO THE EVENING SHOWER ACTIVITY SO
ADJUSTED THOSE TO BETTER REFLECT THE OBS. OTHERWISE...FORECAST
REMAINS ON TRACK. SENT UPDATED GRIDS TO NDFD AND WEB SERVERS.

UPDATE ISSUED AT 635 PM EDT FRI MAY 29 2015

SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE THROUGH
EASTERN KENTUCKY THIS EVENING. THE MOST PROMINENT SHOWERS AND
STORMS ARE CURRENTLY IMPACTING KNOTT/FLOYD/JOHNSON COUNTIES AND
POINTS EAST...WHERE SEVERAL OUTFLOW BOUNDARIES HAVE COLLIDED
TOGETHER. OTHERWISE...ISOLATED SHOWERS ARE EXPECTED TO CONTINUE
ACROSS THE AREA FOR AT LEAST THE NEXT COUPLE OF HOURS. IN TERMS
OF THE FORECAST...GRIDS APPEAR ON TRACK SO ONLY MADE MINOR
ADJUSTMENTS TO THE TEMP GRIDS TO REFLECT MOST RECENT OBS. SENT
UPDATED GRIDS TO NDFD AND WEB SERVERS.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM EDT FRI MAY 29 2015

18Z SFC ANALYSIS SHOWS HIGH PRESSURE STILL OVER FAR EASTERN
KENTUCKY WHILE LOW PRESSURE IS FOUND TO THE WEST OF THE AREA.
BETWEEN THESE...A SOUTHERLY FLOW OF AIR IS SUPPORTING WARM
TEMPERATURES AND HUMID CONDITIONS. WITH PARTLY SUNNY SKIES THE
INSTABILITY WAS SUFFICIENT TO KICK OFF SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS ACROSS THE AREA BY EARLY AFTERNOON.
THIS CONVECTION IS FAVORING THE WESTERN PORTION OF THE CWA WHERE A
BIT MORE SUNSHINE WAS SEEN EARLIER IN THE DAY AND DEWPOINTS WERE
HIGHER. OTHERWISE...TEMPERATURES MADE IT INTO THE LOW TO MID 80S
BEFORE THE PRECIPITATION KNOCKED THEM BACK INTO THE 70S...FOR A
TIME...IN MANY LOCATIONS. WINDS HAVE BEEN GENERALLY FROM THE
SOUTH AT 5 TO 10 KTS ACROSS THE AREA WHILE DEWPOINTS MADE IT INTO
THE MID AND UPPER 60S IN THE WEST...BUT FELL INTO THE UPPER 50S
IN THE FAR EAST...CLOSER TO THE HEART OF THE HIGH PRESSURE.

THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM
PORTION OF THE FORECAST. THEY ALL SHOW THE WEAK SOUTHEAST RIDGE
SHIFTING OFF TO THE EAST IN THE FACE OF AN APPROACHING TROUGH FROM
THE SOUTHERN PLAINS. THE ENERGY FROM THIS WILL MOVE INTO KENTUCKY
ON SATURDAY AND PASS THROUGH THE STATE BY SUNDAY MORNING...WITH
ITS CORE PASSING BY TO THE NORTHWEST. IMPROVING UPPER LEVEL
CONDITIONS SHOULD FAVOR CONVECTION ACROSS THE AREA DURING THE
AFTERNOON AND EARLY EVENING HOURS WITH THE HIGHER RESOLUTION
NAM12 AND HRRR MODELS FAVORED FOR SPECIFICS.

SENSIBLE WEATHER WILL FEATURE THE SCATTERED CONVECTION SETTLING
DOWN AFTER SUNSET ACROSS THE AREA...THOUGH ISOLATED SHOWERS WILL
BE POSSIBLE THROUGH THE NIGHT. THIS WILL SET THE STAGE FOR PATCHY
FOG DEVELOPING LATER IN THE NIGHT...BECOMING LOCALLY DENSE IN THE
VALLEYS TOWARD DAWN WITH MILD AND MUGGY CONDITIONS IN PLACE. THE
APPROACH OF A COLD FRONT...ASSOCIATED WITH THE SFC LOW PASSING
THROUGH SOUTHERN INDIANA SATURDAY WILL BRING A THREAT OF STORMS
AGAIN FOR THE AREA...MAINLY IN THE MID AND LATE AFTERNOON HOURS
AND OVER THE WESTERN PARTS OF THE CWA. THE GFS HAS THE BEST TIMING
AND PROGRESSION OF THE FRONT AS IT PASSES THROUGH EAST KENTUCKY.
AND WAS USED AS A TEMPLATE THROUGH 12Z SUNDAY. MEANWHILE...THE
NAM12 AND ECMWF SPLIT THE FRONT MOVING IT THROUGH EAST KENTUCKY
LATER SATURDAY NIGHT AND INTO SUNDAY MORNING...TAKING THE MAIN LOW
INTO OHIO AND BYPASSING THIS PART OF THE STATE TO THE NORTH. THIS
TRANSITION MAY LIMIT THE QPF OVER THE CWA COMPARED TO THE WEST AND
NORTH...ALSO SEEN IN THE GFS...LOWERING CONFIDENCE IN A NEEDED
SOAKING RAIN FOR MUCH OF THE AREA. ACCORDINGLY...HAVE KEPT POPS IN
THE MID TO HIGH CHANCE RANGE THROUGH 12Z SUNDAY.

AGAIN USED THE SHORTBLEND AS A STARTING POINT FOR THE T/TD/WIND
GRIDS INTO SATURDAY BEFORE SWITCHING TO THE SUPERBLEND THROUGH
12Z SUNDAY. MADE SOME MINOR RIDGE TO VALLEY TEMPERATURE
ADJUSTMENTS FOR LOWS AND HOURLY TEMPS EACH NIGHT. AS FOR POPS...
ENDED UP A BIT HIGHER THAN A BLEND OF THE DRIER MET AND WETTER MAV
GUIDANCE THROUGH THE SHORT TERM WITH AN EXAGGERATED DIURNAL CYCLE
FOR THE HOURLY POPS/WX GRIDS THROUGH SATURDAY EVENING AND MORE OF
A SYNOPTIC DRIVEN POP GRID FOR SATURDAY NIGHT.

.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 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 745 PM EDT FRI MAY 29 2015

SCATTERED CONVECTION IS EXPECTED TO CONTINUE FOR THE HOUR OR SO
THEN WANE AFTER SUNSET. THIS WARRANTS KEEPING VCTS AT MOST OF THE
TAF SITES THROUGH ABOUT 02Z. ONCE THE CONVECTION DISSIPATES SOME
PATCHY FOG WILL LIKELY DEVELOP AGAIN IN THE VALLEYS AFTER 06Z
AFFECTING MOST OF THE TAF SITES WITH SOME MVFR VIS. IFR VIS MAY
ALSO BE POSSIBLE TONIGHT IN LOCATIONS WHERE IT
RAINED...PARTICULARLY THE SJS...SME AND LOZ TAF SITES.

ISOLATED TO SCATTERED CONVECTION WILL BE POSSIBLE BY EARLY
AFTERNOON ON SATURDAY WITH VCTS AGAIN INCLUDED. WINDS WILL
GENERALLY BE LIGHT AND VARIABLE FROM THE SOUTH THROUGH SATURDAY
MORNING...PICKING UP AGAIN LATER IN THE DAY.


&&

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

$$

UPDATE...JVM
SHORT TERM...GREIF
LONG TERM...KAS
AVIATION...JVM/GREIF


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