Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 051820 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
220 PM EDT TUE MAY 5 2015

.UPDATE...
ISSUED AT 1217 PM EDT TUE MAY 5 2015

FORECAST IS ON TRACK FOR TODAY SO ONLY MADE MINOR ADJUSTMENTS TO
TEMP AND DEWPOINT GRIDS TO ALIGN THEM WITH RECENT OBS. SENT
UPDATED GRIDS TO NDFD AND WEB SERVERS.

UPDATE ISSUED AT 932 AM EDT TUE MAY 5 2015

QUICK UPDATE TO ALIGN T AND TD GRIDS WITH RECENT OBS.
OTHERWISE...FORECAST REMAINS ON TRACK. SENT UPDATED GRIDS TO NDFD
AND WEB SERVERS.

UPDATE ISSUED AT 643 AM EDT TUE MAY 5 2015

WENT AHEAD AND REMOVED ANY MENTION OF FOG IN THE FORECAST GIVEN
THE LACK OF EVIDENCE ON CURRENT OBS OR SATELLITE. IF ANY FOG IS
IN THE VALLEYS IT SHOULD BE DISSIPATING IN THE NEXT HOUR AS THE
SUN CONTINUES TO RISE ANYWAYS. ALSO TWEAKED TEMPERATURES WITH THE
LATEST OBSERVATIONAL GUIDANCE TO MAKE SURE THEY WERE ON PAR WITH
CURRENT CONDITIONS...WITH YET ANOTHER RAPID INCREASE INTO THE 70
DEGREE RANGE EXPECTED BY NOON OR JUST BEFORE. OTHERWISE FORECAST
SEEMS TO BE WELL ON TRACK...WITH NO UPDATES TO THE CURRENT ZONE
FORECAST NEEDED AT THIS TIME.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 233 AM EDT TUE MAY 5 2015

STRONG HIGH PRESSURE/UPPER LEVEL RIDGING WILL STAY IN CONTROL
THROUGH THE EXTENT OF THE SHORT TERM. LATEST FORECAST SOUNDINGS ARE
STILL POINTING AT JUST ENOUGH MOISTURE TO ALLOW FOR SOME ISL/SCT
AFTERNOON CU DEVELOPMENT BOTH TODAY AND WEDNESDAY...WITH BEST
MOISTURE LIKELY DIRECTED OVER THE HIGH TERRAIN IN THE SE. DESPITE
MODELS TRYING TO PUT PRECIP BACK IN ACROSS THIS SAME AREA ON
WEDNESDAY...STILL BELIEVE DRY AIR NEAR THE SURFACE WILL WIN OUT
AND SO KEPT POPS BELOW 15 PERCENT. OTHERWISE...LIGHT SRLY FLOW AND
GOOD SUN COVERAGE WILL CONTINUE TO BOOST TEMPERATURES. EXPECT LOW
TO MID 80S BOTH TODAY AND TOMORROW FOR HIGHS...WHILE OPTIMAL
RADIATIONAL COOLING OVERNIGHT WILL CONTINUE TO PROMOTE LARGE RIDGE
VALLEY SPLITS IN TEMPERATURE. THIS WILL RESULT IN SOME SIZABLE
DIURNAL TEMPERATURE RANGES FOR VALLEYS BETWEEN MORNING LOWS AND
DAYTIME HIGHS.

.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 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 138 PM EDT TUE MAY 5 2015

EXPECT VFR CONDITIONS THROUGH THE PERIOD. INCLUDED DAYTIME CU
DEVELOPMENT THROUGH THE AFTERNOON HOURS TODAY AND TOMORROW...WITH
SKIES CLEARING DURING THE LATE EVENING HOURS. WINDS SHOULD
GENERALLY BE LIGHT AND VARIABLE BELOW 5 KTS. WHILE AREAS OF VALLEY
FOG ARE POSSIBLE LATE TONIGHT...DO NOT EXPECT TAF SITES TO BE
AFFECTED.

&&

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

$$

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



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