Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 060734
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
334 AM EDT WED MAY 6 2015

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 334 AM EDT WED MAY 6 2015

WHILE HIGH PRESSURE WILL REMAIN THE DOMINANT FEATURE THROUGH THE
SHORT TERM...THERE WILL LIKELY BE SOME MODIFICATION THAT WILL AFFECT
THE PRECIPITATION FORECAST. FOR TODAY...EXPECT MUCH OF THE SAME AS
YESTERDAY...WHERE A SLIGHT UPTICK IN MOISTURE WILL LEAD TO DAYTIME
CU DEVELOPMENT ACROSS MUCH OF THE CWA...WHILE HIGH SUN ANGLES AND
LIGHT WINDS WILL HELP BOOST TEMPS INTO THE MID AND EVEN POSSIBLY
SOME UPPER 80S. BEST MOISTURE CONTINUES TO BE PINNED OVER THE FAR SE
PORTION OF THE STATE...SO A FEW STRAY LIGHT SHOWERS DEVELOPING LATE
IN THE AFTERNOON HERE ARE NOT OUT OF THE QUESTION. WENT AHEAD AND
CONTINUED WITH MENTION OF ISL THUNDER IN FORECAST. OVERNIGHT WILL BE
MUCH IN THE SAME AS WELL...WITH LOSS OF DAYTIME HEATING ALLOWING
SKIES TO CLEAR OUT AND OPTIMAL RADIATIONAL COOLING TO
OCCUR...ESPECIALLY IN THE VALLEYS.

BY THURSDAY...HOWEVER...A SUBTROPICAL TROUGH TAKING SHAPE OFF THE
SOUTH ATLANTIC WILL BEGIN FEEDING MOISTURE INLAND. WHILE HIGH
PRESSURE RIDGING WILL REMAIN OVER KY...E TO SE WINDS WILL BRING
ENOUGH MOISTURE OFF OF THE COAST TO ALLOW FOR A DEFINITE UPTICK IN
HUMIDITY AND AFTERNOON CLOUD COVER. IT WILL ALSO MEAN A BETTER SHOT
FOR AFTERNOON CONVECTIVE DEVELOPMENT...ESPECIALLY WITH TEMPS STILL
EXPECTED TO BE IN THE MID AND UPPER 80S. UNFORTUNATELY...MODELS ARE
HAVING A HARD TIME AGREEING ON JUST HOW MUCH MOISTURE WILL ACTUALLY
MAKE IT TO THE SURFACE AS PRECIP. JUST LOOKING AT THE LATEST NAM
MODEL SOUNDINGS...HI RES PLAN VIEW MODELS...AND THE DOWNSLOPING
FLOW...STILL EXPECT MOST PRECIP WILL STAY OVER FAR SE KY...MAINLY
ACROSS THE HIGHEST TERRAIN WITH SCT TO BKN CLOUD COVER ELSEWHERE.
HOWEVER...SOME MODELS /THE GFS FOR INSTANCE/...ARE SPREADING WHAT
SEEMS TO BE AN EXCESSIVE AMOUNT OF MOISTURE ACROSS THE ENTIRE
EASTERN PORTION OF THE STATE. AS SUCH...TRIED TO MATCH UP WITH
NEIGHBORING OFFICES BY FOCUSING MAIN AREA OF PRECIP ACROSS THE FAR
SE CWA IN THE FORECAST...WITH ONLY A SLIGHT UPTICK IN POPS MAKING IT
WESTWARD DURING THE PEAK HEATING OF MID AFTERNOON. ONCE THE SUN
BEGINS TO FADE...EXPECT ANY TRIGGERING FEATURES WILL QUICKLY FADE
AND ANY ONGOING RAIN/TSRA OR EVEN BKN CLOUD COVER WILL BREAK APART.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 220 PM EDT TUE MAY 5 2015

THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE BULK OF THE
EXTENDED FORECAST. THEY ALL DEPICT A MODERATELY STRONG RIDGE
DOMINATING THE EASTERN PORTION OF THE NATION WELL INTO THE WEEKEND.
HOWEVER...THERE ALSO IS AN UNDERCUTTING WEAKNESS OFF THE SOUTHEAST
COAST OF THE NATION AT MID LEVELS THAT COULD LEAD TO SOME
INTERESTING WX THERE BY THE WEEKEND. THE DIRTY RIDGE WILL LIKELY NOT
BE STRONG ENOUGH TO CAP ALL CONVECTION THROUGH EAST KENTUCKY AT PEAK
HEATING EACH AFTERNOON...BUT CHANCES AT ANY ONE LOCATION WILL BE
RATHER LOW. BETTER UPPER SUPPORT FOR CONVECTION WILL ARRIVE LATE IN
THE WEEKEND AS THE RIDGE STARTS TO BREAK DOWN FROM THE NORTHWEST IN
RESPONSE TO A TROUGH MOVING EAST INTO THE HIGH PLAINS WITH ROGUE
BITS OF ENERGY BREAKING OFF AND RUNNING THROUGH THE OHIO VALLEY IN
SOUTHWEST FLOW. THIS TROUGH WILL SLIP INTO THE MISSISSIPPI VALLEY
REGION AND THE MIDWEST LATER MONDAY WITH HEIGHT FALLS IMPACTING
KENTUCKY WHILE ADDITIONAL ENERGY TRACKS OVER THE AREA. THE TROUGH
DOES MOVE MORE COMPLETELY INTO THE OHIO VALLEY AND GREAT LAKES ON
TUESDAY WITH SOME SIGNIFICANT HEIGHT FALLS PROGGED...BY THE ECMWF IN
PARTICULAR...TO AFFECT EAST KENTUCKY BY TUESDAY EVENING. A GENERAL
MODEL BLEND IS ACCEPTED FOR THE BULK OF THE LONG TERM PORTION OF THE
FORECAST GIVEN THE AGREEMENT EARLY ON AND AS A MEANS OF MITIGATING
THE UNCERTAINTY HEADING INTO THE START OF NEXT WEEK. DID SIDE MORE
WITH THE DRIER ECMWF FOR POPS EACH PERIOD.

SENSIBLE WEATHER WILL FEATURE AN EARLY SUMMER-LIKE PATTERN BENEATH
THE UPPER RIDGE AND A WEAK SFC HIGH. THERE WILL BE NO DRIVING FACTOR
FOR CONVECTION THROUGH THE WEEKEND ASIDE FROM DIFFERENTIAL HEATING
AND MINOR TERRAIN ENHANCEMENT. ACCORDINGLY...WITH RATHER DRY AIR IN
PLACE BENEATH THE SFC HIGH...WILL KEEP ANY SMALL CHANCES FOR
CONVECTION LIMITED TO THE HIGHER TERRAIN IN THE FAR SOUTHEAST AND
ONLY AT OR JUST AFTER PEAK HEATING. EACH NIGHT SKIES SHOULD CLEAR
FOLLOWING THE AFTERNOON/S DIURNALLY DRIVEN CU DEVELOPMENT WITH MILD
RIDGE TOP TEMPERATURES AND COOLER VALLEYS. IN FACT...A MODERATE TO
LARGE RIDGE TO VALLEY SPLIT IN THE TEMPERATURES IS EXPECTED EACH
NIGHT IN THIS PATTERN...THROUGH THE WEEKEND. BY SUNDAY AFTERNOON...
THE MID LEVEL ENERGY AND A SFC LOW MOVING INTO THE CENTRAL PLAINS
MAY BE ENOUGH FOR CONVECTION TO MOVE INTO OUR WESTERN ZONES. MONDAY
WILL ALSO SEE A POTENTIAL FOR DIURNALLY DRIVEN CONVECTION BY LATE
AFTERNOON...BUT THE BEST CHANCES FOR MORE WIDESPREAD CONVECTION
LOOKS TO HOLD OFF UNTIL TUESDAY WHEN THE SFC LOW MOVES INTO THE OHIO
VALLEY AND ITS COLD FRONT CROSSES KENTUCKY. THE INCREASE IN CLOUDS
AND BETTER PCPN CHANCES FOR THE START OF NEXT WEEK WILL ALSO RESULT
IN COOLER TEMPS THAN WE WILL SEE FOR THE REST OF THIS WEEK AND INTO
THE WEEKEND.

THE CR GRID BLEND CAME IN ON THE WET SIDE FOR MOST PERIODS SO HAVE
ADJUSTED THE POPS DOWN BASED MORE ON THE ECMWF AND THE DIURNAL CYCLE
THROUGH MONDAY. DID ALSO MAKE SOME RATHER LARGE CHANGES TO LOWS EACH
NIGHT GIVEN THE TERRAIN AND ANTICIPATED STRONG INVERSIONS. MONDAY
NIGHT SHOULD SEE A MORE MIXED AIR MASS...ESPECIALLY IN THE WESTERN
PARTS OF THE CWA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 152 AM EDT WED MAY 6 2015

HIGH PRESSURE AT THE SFC AND ALOFT SHOULD BRING VFR CONDITIONS
THROUGH THE PERIOD. WINDS SHOULD GENERALLY BE LIGHT AND VARIABLE
AND REMAIN BELOW 10 KTS. AREAS OF VALLEY FOG IN SOME RIVER VALLEY
LOCATIONS ARE POSSIBLE LATE TONIGHT...BUT THE TAF SITES SHOULD NOT
BE AFFECTED. CU DEVELOPMENT IN THE 5 TO 7K FT RANGE IS POSSIBLE
ONCE MORE THIS AFTERNOON...WITH SOME ISOLATED LIGHT SHOWER
CHANCES IN THE FAR SE PORTION OF THE STATE. EXPECT TAF SITES WILL
REMAIN DRY. SKIES WILL CLEAR OUT ONCE MORE BY TOMORROW EVENING.


&&

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

$$

SHORT TERM...JMW
LONG TERM...GREIF
AVIATION...JMW



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