Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 271845
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
245 PM EDT THU AUG 27 2015

.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 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 118 PM EDT THU AUG 27 2015

HIGH PRESSURE OVER THE GREAT LAKES AND OHIO VALLEY WILL CONTINUE
TO CONTROL OUR WEATHER INTO FRIDAY...WITH VFR CONDITIONS
PREVAILING. SCATTERED TO BROKEN CU AND SC HAVE DEVELOPED OVER THE
NORTHERN HALF OF THE FORECAST AREA EARLY THIS AFTERNOON. MOST
CEILINGS ARE ABOVE 4K FEET...BUT A FEW LOCAL CEILINGS AROUND 3K
FEET ARE BEING OBSERVED. ANY MVFR CEILINGS WILL LIFT TO VFR BY MID
AFTERNOON. SKIES WILL CLEAR THIS EVENING...AND RIVER VALLEY FOG
WILL FORM LATE TONIGHT. FOG IS NOT EXPECTED TO IMPACT THE TAF
SITES. A FEW N TO NE WIND GUSTS OF 12 TO 18 KNOTS FROM CAN BE
EXPECTED THIS AFTERNOON...BUT OVERALL LIGHT WINDS WILL PREVAIL
THROUGH THE FORECAST PERIOD.


&&

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

$$

SHORT TERM...SBH
LONG TERM...RAY
AVIATION...SBH



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