Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 280607 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
207 AM EDT FRI AUG 28 2015

.UPDATE...
ISSUED AT 207 AM EDT FRI AUG 28 2015

HAVE FRESHENED UP SOME OF THE LOW TEMPERATURES BASED ON THE LATEST
TRENDS IN OBSERVATIONS. SCATTERED CLOUDS HAVE BEEN MOVING INTO FAR
SOUTHEAST KENTUCKY...SLOWING THE DIURNAL DROP OFF...ALTHOUGH THE
LATEST SATELLITE HAS SHOWN SOME DISSIPATION...SO LOWS STILL LOOK
TO GET DOWN INTO THE MID 50S FOR THOSE LOCATIONS.

UPDATE ISSUED AT 1041 PM EDT THU AUG 27 2015

THE FORECAST IS STILL ON TRACK THIS EVENING. SKIES HAVE GONE
MOSTLY CLEAR OVER THE PAST COUPLE OF HOURS AND SHOULD REMAIN THAT
WAY OVERNIGHT. WITH WINDS HAVING GONE CALM OR NEAR CALM ACROSS THE
AREA...THE RIDGE VALLEY TEMPERATURE SPLIT IN THE FORECAST IS STILL
ON TRACK AS WELL. THE LATEST OBS DATA HAS BEEN INGESTED INTO THE
FORECAST TO ESTABLISH NEW TRENDS IN THE DATA. ASIDE FROM THAT...NO
OTHER CHANGES WERE NECESSARY.

UPDATE ISSUED AT 731 PM EDT THU AUG 27 2015

FORECAST RIGHT ON TRACK SO FAR THIS EVENING. SCATTERED MID AND
LOW LEVEL CLOUDS WILL CONTINUE TO DRIFT ACROSS THE AREA OVER THE
NEXT FEW HOURS...BUT THESE SHOULD DISSIPATE QUICKLY ONCE THE SUN
GOES DOWN. VALLEY FOG IS ON TAP LATE TONIGHT...ALONG WITH A WELL
DEFINED RIDGE VALLEY TEMPERATURE SPLIT...BOTH DUE TO CLEAR SKIES
AND CALMS WINDS THAT ARE FORECAST FOR THE OVERNIGHT PERIOD. ALL
THAT SAID...NO CHANGES TO THE FORECAST ARE NECESSARY AT THIS TIME.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 245 PM EDT THU AUG 27 2015

SURFACE HIGH PRESSURE OVER THE GREAT LAKES AND OHIO VALLEY WILL
CONTINUE TO SLIDE EAST. THIS WILL ALLOW A WARMING TREND TO BEGIN
ON FRIDAY...ALONG WITH A GRADUAL INCREASE IN DEW POINTS. WITH THE
HIGH SLIPPING EAST WE SHOULD SEE LARGER RIDGE VALLEY DIFFERENCES
FOR MINIMUM TEMPERATURES TONIGHT AND FRIDAY NIGHT. THE CU AND SC
THAT HAVE DEVELOPED ACROSS THE NORTHERN HALF OF THE FORECAST AREA
WILL DISSIPATE THIS EVENING ALLOWING FOR A MOSTLY CLEAR
NIGHT...AND WE WILL HAVE A MOSTLY SUNNY DAY ON FRIDAY. THE
TYPICAL RIVER VALLEY FOG WILL FORM LATE TONIGHT AND AGAIN FRIDAY
NIGHT.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 245 PM EDT THU AUG 27 2015

MODELS CONTINUE TO SHOW SIGNIFICANTLY DIFFERENT SOLUTIONS WITH
REGARD TO A SHORT WAVE ROUNDING A WESTERN CONUS RIDGE AND MOVING
EASTWARD ACROSS THE UPPER MIDWEST AND OHIO VALLEY. THE 0Z ECMWF
REMAINS CONSIDERABLY SLOWER AND MORE AMPLIFIED WITH THIS FEATURE AND
WEAKER WITH ENERGY MOVING NORTHWARD OUT OF THE GULF OF MEXICO. PER
THE ECMWF SOLUTION...THE NORTHERN STREAM DISTURBANCE ONLY JUST
REACHES LAKE ONTARIO BY SUNDAY MORNING. ON THE OPPOSITE EXTREME THE
06/12Z GFS CONTINUES ITS CONSIDERABLY MORE PROGRESSIVE SOLUTION...
TAKING THE BULK OF THE ENERGY ASSOCIATED WITH THE SHORT WAVE TO THE
EAST THROUGH THE GREAT LAKES AND OUT INTO THE ATLANTIC BY EARLY
SUNDAY. THIS ACTUALLY SEEMS TO BE A FASTER TREND THAN PREVIOUS RUNS.
THE GFS TAKES WHAT IS LEFT OF THIS SHORT WAVE SYSTEM AND TENDS TO
DIG/CARVE OUT A POSITIVELY TILTED TROUGH OVER THE EASTERN CONUS...
WITH SOME HELP FROM SOME SOUTHERN STREAM ENERGY AS IT LIFTS
NORTHWARD OUT OF THE GULF. OTHERWISE...THE EVOLUTION AND END RESULT
OF THE MID AND UPPER LEVEL PATTERNS ARE QUITE SIMILAR. POSITIVELY
TILTED TROUGH OVER THE EASTERN CONUS SUN-MON FILLS AS STRONG WESTERN
CONUS RIDGE EVENTUALLY BUILDS ACROSS THE EASTERN HALF OF THE NATION
IN A RATHER AUTHORITATIVE MANNER. FLOW ALOFT MAY EVENTUALLY EVOLVE
INTO AN EASTERN CONUS REX BLOCK TYPE PATTERN BY THE END OF THE
EXTENDED...ATTM SUPPORTED MORE BY THE GFS WITH ITS STRONGER
TROUGHINESS OVER THE DEEP SOUTH THROUGH THE PERIOD. AT PRESENT BOTH
THE ECMWF AND GFS KEEP ERIKA WELL TO OUR EAST/SOUTHEAST. HOWEVER...
OCCASIONAL RUNS OF THE GFS HAVE HINTED AT THE POSSIBILITY OF ERIKA
TAKING A WESTERLY TURN...ALLOWING MOISTURE TO OVERSPREAD INTO THE TN
VALLEY AND COMMONWEALTH OF KENTUCKY. INTERESTINGLY...A QUICK GLANCE
AT THE 12Z ECMWF HINTS AT A MORE WESTERLY TREND FOR ERIKA. WITH SUCH
LOW CONFIDENCE IN THE OVERALL EVOLUTION OF THE FORECAST ANYTHING IS
POSSIBLE...THOUGH BASED ON ENSEMBLE MEMBERS FEEL IT IS MORE LIKELY
ERIKA WILL HAVE LITTLE IF ANY IMPACT ON OUR AREA.

FOR SENSIBLE WEATHER...WILL CONTINUE TO BROAD BRUSH THE FORECAST TO
ACCOUNT FOR THE DIFFERENCES/INCONSISTENCIES IN THE MID/UPPER LEVEL
PATTERNS. WE APPEAR TO BE HEADING INTO A MORE SEASONABLE LATE SUMMER
TIME TYPE WEATHER PATTERN. LOOK FOR THE RETURN OF HEAT AND MOISTURE
THROUGH THE PERIOD ALONG WITH AN INCREASING THREAT OF MAINLY
DIURNALLY DRIVEN AFTERNOON AND EARLY EVENING SHOWERS AND
THUNDERSTORMS THROUGH THE FIRST HALF OF THE EXTENDED...WITH SUNDAY
BEING THE MOST LIKELY WINDOW OF SEEING SOME RAINFALL. THERE HAS BEEN
A TENDENCY THIS SUMMER FOR THE MODELS TO BE TOO AGGRESSIVE WITH
RIDGING SCENARIOS...AND WARMTH. WITH THAT CAVEAT...IF THE CURRENTLY
ADVERTISED STRONG RIDGING PANS OUT THROUGH THE LATTER HALF OF THE
PERIOD IT SHOULD KEEP CONVECTION AT A MINIMUM...AND DRIVE
TEMPERATURES ABOVE NORMAL LEVELS. IN GENERAL WENT WITH ISOLD ISOLD
TO SCT POPS THROUGH MONDAY THEN DRY UNTIL THURSDAY...THOUGH WE MAY
SEE SOME ISOLD ACTIVITY OVER THE HIGHER TERRAIN TUESDAY.
TEMPERATURES WILL RETURN TO NEAR OR SLIGHTLY ABOVE NORMAL LEVELS
THROUGH THE PERIOD...WITH HIGHS IN THE LOW TO MID 80S TO START AND
MID TO UPPER 80S TOWARDS THE END OF THE FORECAST WINDOW. A FEW
LOCATIONS MAY CLIMB TO AROUND 90 BY THE END OF THE PERIOD. EXPECT
MID 60S FOR MORNING LOWS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 207 AM EDT FRI AUG 28 2015

IFR OR WORSE FOG WILL BE SEEN IN THE DEEPER RIVER VALLEYS THROUGH
13Z BEFORE MIXING OUT. SOME HIGHER BASED CU WILL BE SEEN IN THE
FAR SOUTHEAST THROUGH DAWN...RANGING FROM 6-7K FEET AGL. ONCE THE
FOG BURNS OFF...EXPECT SOME SCATTERED STRATOCU TO DEVELOP IN THE
4-6K FEET RANGE DURING THE DAY. WINDS WILL AVERAGE AROUND 5 KTS OR
LESS THROUGH THE PERIOD.

&&

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

$$

UPDATE...GEOGERIAN
SHORT TERM...SBH
LONG TERM...RAY
AVIATION...GEOGERIAN



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