Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 180900 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
500 AM EDT MON AUG 18 2014

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 315 AM EDT MON AUG 18 2014

FEATURES ACROSS EASTERN KENTUCKY CENTER AROUND A SURFACE LOW PRESSURE
SYSTEM MOVING EAST INTO THE AREA THIS MORNING. SHOWERS AND
THUNDERSTORMS CONTINUE TO DEVELOP AHEAD OF THIS FEATURE IN A WELL
MOIST AND UNSTABLE ENVIRONMENT WITH INSTANCES OF HEAVY RAINFALL
MAINLY OVER THE SOUTHERN PORTIONS OF EASTERN KENTUCKY HEADING INTO
THE MORNING HOURS. THIS BEING WHERE THE BETTER LIFT AND FORCING ALONG
AN APPROACHING SURFACE BOUNDARY. RAINFALL RATES HERE AS WELL AS WHAT
IS ADVERTISED LATER IN THE MORNING AND INTO TODAY WILL FEATURE THE
FLASH FLOODING THREAT MAINLY OVER THESE AREAS SOUTH OF THE MOUNTAIN
PARKWAY. WILL CONTINUE TO MENTION THIS THREAT IN THE HWO AS
THANKFULLY...STORM MOTION IS QUITE QUICK AND RESIDENCE TIME OVER A
CERTAIN LOCATION WILL NOT BE AN ISSUE. HOWEVER...A FEW INSTANCES OF
CELLS MOVING OVER THE SAME LOCATION MAY BE ENOUGH FOR A FLASH FLOOD
THREAT INTO THE PREDAWN HOURS.

LATER ON INTO THIS AFTERNOON...A DRY LAYER BEGINS TO DEVELOP IN THE
MID LEVELS. WITH THE SURFACE INSTABILITY ON THE INCREASE AND STILL
SOME MOISTURE IN THE LOWER LEVELS PRESENT...SOME MORE THUNDERSTORM
DEVELOPMENT WILL BE POSSIBLE WITH LESS MOISTURE DEPTH A CHANCE OF A
STORM THUNDERSTORM OR TWO. WILL CONTINUE WITH AREAL COVERAGE INTO
THIS TONIGHT. WITH THE INCREASE IN STORM MOTION AND LACK OF ABUNDANT
MOISTURE FROM THE PAST DAY...THE FLOODING THREAT WILL BEGIN TO
DIMINISH BY TONIGHT. WILL EXPECT A MORE DIURNALLY DRIVEN THUNDERSTORM
DEVELOPMENT BY TUESDAY AS A WEAK DISTURBANCE FOLLOWS THE PREVIOUS
WAVE ON MONDAY. WILL CONTINUE WITH SCATTERED POPS INTO THIS PERIOD AS
WELL. OVERALL...THE CONCERN LIES WITH THE MESOSCALE FEATURES WITH THE
REMNANT MCV TRACKING THROUGH CENTRAL KENTUCKY AND INTO EASTERN
PORTIONS TODAY WITH A LOCALIZED FLOOD THREAT.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 500 AM EDT MON AUG 18 2014

THE MODELS ARE IN GOOD AGREEMENT ABOUT THE GENERAL PATTERN ALOFT
CONSISTING OF A GREAT LAKES CLOSED LOW EARLY ON BEING SHUNTED
EAST BY A BURGEONING RIDGE OVER THE LOWER MISSISSIPPI VALLEY INTO
THE DAY THURSDAY. THE CMC IS THE FIRST TO DROP OUT AS IT SHOWS A
WEAKER RIDGE THROUGH THE MID SECTION OF THE NATION WHILE THE GFS AND
ECMWF MAINTAIN HIGHER AMPLITUDES ACROSS THE MISSOURI VALLEY AND INTO
THE WESTERN PORTION OF THE OHIO VALLEY TO CLOSE OUT THE WORK WEEK.
THE SIMILARITIES OF THESE LATTER MODELS CONTINUED INTO THE WEEKEND
WITH STRONG RIDGING CENTERED OVER ARKANSAS WHILE BROAD TROUGHING
HOLDS TOUGH THROUGH THE NEW ENGLAND STATES. BETWEEN THESE TWO
FEATURES...A STREAM OF SEASONABLY FAST FLOW WILL CARRY A STEADY BATCH
OF SHORTWAVES FROM THE UPPER MIDWEST THROUGH THE OHIO VALLEY AND INTO
THE SOUTHERN APPALACHIANS. THIS PATTERN REMAINS IN PLACE THROUGHOUT
THE WEEKEND...THOUGH THE CRUCIAL STREAM OF SHORTWAVE ENERGY WILL
LIKELY WAVE BACK AND FORTH THROUGH THE WESTERN FOOTHILLS OF THE
APPALACHIANS. GIVEN THE MODEL AGREEMENT AMONG THE GFS AND ECMWF HAVE
FAVORED THEIR SOLUTION FOR THE EXTENDED PORTION OF THE FORECAST.

SENSIBLE WEATHER WILL FEATURE A CONTINUATION OF OUR MOIST ENVIRONMENT
AND POTENTIAL FOR SHOWERS AND THUNDERSTORMS. THE RIDGING TO OUR
SOUTHWEST WILL BE ENOUGH TO SEND TEMPERATURES INTO AND ABOVE
SEASONABLE NORMS DESPITE THE INCREASED HUMIDITY. THIS WILL ALSO HELP
TO ENHANCE THE DIURNALLY DRIVEN INSTABILITY THROUGH THE AREA
RESULTING IN THE BEST CHANCES OF STORMS EACH AFTERNOON AND EVENING.
HOWEVER...WITH THE ACTIVITY ALOFT AND THE NEARBY SFC BOUNDARIES THE
THREAT OF CONVECTION WILL CONTINUE THROUGH THE NIGHTS AS WELL. THIS
WILL MEAN A WARM...WET...AND STORMY PERIOD FOR EAST KENTUCKY THROUGH
THE UPCOMING WEEKEND. THE CAVEAT WILL BE SHOULD THE RIDGE TO THE
SOUTHWEST TAKE OVER AND SHIFT JUST A BIT NORTHEAST WE MAY INSTEAD BE
IN FOR A HOT AND HUMID TIME INSTEAD. THIS WILL HAVE TO BE
MONITORED...BUT AS OF NOW THE BEST BET IS FOR A CONTINUATION OF OUR
MODERATE CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH MOST PERIODS
IN THE EXTENDED. THE HIGH MOISTURE CONTENT WILL HOLD THE TEMPERATURES
UP AT NIGHT AND LIMIT RADIATIONAL COOLING. LIKEWISE...DAYTIME HIGHS
COULD BE IMPACTED BY THE TIMING AND DURATION OF AFTERNOON
CONVECTION...BUT THE POTENTIAL IS THERE FOR READINGS IN THE UPPER 80S
EACH DAY.

THE CR GRID LOAD PROVIDED A GOOD START TO THE FORECAST FOR THE
EXTENDED...THOUGH DID GIVE THE POPS MORE OF A DIURNAL TREND.
ALSO...ADJUSTED THE LOW TEMPERATURE GRIDS SLIGHTLY EACH NIGHT TO
REFLECT MINOR RIDGE AND VALLEY DIFFERENCES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 125 AM EDT MON AUG 18 2014

SHOWERS AND A FEW THUNDERSTORMS WILL CONTINUE TO ENTER EASTERN
KENTUCKY THROUGH THE EARLY MORNING HOURS. THIS WILL EVENTUALLY BRING
VISIBILITY AND CEILINGS DOWN TO FIELD MINS EVENTUALLY...MAINLY THOUGH
WHERE HEAVIER SHOWERS MOVE OVER A POINT. WILL EXPECT TO KEEP THESE
CONDITIONS THROUGH THE MORNING BEFORE LIFTING THE CEILINGS INTO THE
AFTERNOON AS THE MAIN LIFT AND MOISTURE FINALLY MOVE OFF TO THE EAST.
EXPECT MOST OF THE TAF SITES TO EXPERIENCE BELOW IFR IN 08Z TO 14Z
PERIOD. WINDS WILL MAINLY BE LIGHT THROUGH THE MORNING BUT THEN
PICKING UP OUR OF THE WEST INTO THE AFTERNOON WITH THE PASSAGE OF THE
SURFACE FRONT.

&&

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

$$

SHORT TERM...SHALLENBERGER
LONG TERM...GREIF
AVIATION...SHALLENBERGER





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