Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 221600 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
1200 PM EDT FRI AUG 22 2014

.UPDATE...
ISSUED AT 1200 PM EDT FRI AUG 22 2014

15Z SFC ANALYSIS SHOWS WEAK HIGH PRESSURE THROUGH THE DEEP SOUTH WITH
GENERAL LOW PRESSURE TO THE NORTH AND WEST OF THIS AREA. THIS PLACES
EAST KENTUCKY ON THE NORTHERN FRINGE OF THE SFC RIDGE AND ALSO THE
NORTHEAST EDGE OF THE MID LEVEL ONE PARKED TO THE SOUTHWEST OF THE
AREA. THE STORM TRACK...LIKE THOSE PAST COUPLE OF DAYS...IS PRETTY
CLEAR AS CONVECTIVE CLUSTERS DEVELOP IN NORTHERN ILLINOIS AND
INDIANA...ROLLING SOUTHEAST INTO OHIO BEFORE HITTING THE APPALACHIANS
AT WEST VIRGINIA. THE BEST INSTABILITY REMAINS TO THE SOUTH AND WEST
OF THIS TRACK...LEADING TO A TENDENCY FOR THESE SYSTEMS TO ARC TO THE
SOUTH INTO EASTERN KENTUCKY OR KICKING OFF OUTFLOW BOUNDARIES STRONG
ENOUGH TO INITIATE NEW DEVELOPMENT. THE LATEST HIGH RESOLUTION NEAR
TERM MODELS INCLUDING THE HRRR AND 12Z NAM12 SUGGEST THAT BOTH
SCENARIOS ARE POSSIBLE THIS AFTERNOON WITH THE FORMER FOCUSING ON
SCATTERED DEVELOPMENT THROUGH THE CWA AFTER 18Z AND PERHAPS A MORE
ORGANIZED SYSTEM ARRIVING FROM THE NORTHWEST AFTER 21Z. THE NAM12
FOCUSES ON THE NORTHWEST SYSTEM AND HAS IT PUSH INTO EAST KENTUCKY
BETWEEN 18 AND 21Z WITH LESS AIR MASS CONVECTION AHEAD OF IT.
ALOFT...THE GENESIS WAVE APPEARS TO PASS THROUGH THE SOUTHERN OHIO
VALLEY BY 21Z SO THE NAM12 WITH ITS EARLIER ARRIVAL APPEARS TO BE
REASONABLE. HIGH PWS AGAIN TODAY ALONG WITH GOOD INSTABILITY SUGGEST
THE POTENTIAL FOR FLASH FLOODING...ESPECIALLY FOR PLACES THAT SEE
TRAINING...ALONG WITH STRONG TO MARGINALLY SEVERE STORMS WITH
DAMAGING WIND GUSTS AS THE MAIN THREAT. HAVE UPDATED TO CONVEY THIS
IN THE SKY...POP...QPF...AND WX GRIDS. EAST KENTUCKY WILL ALSO HAVE A
CONTINUANCE OF THE HOT AND HUMID CONDITIONS WITH HIGHS AROUND
90...SUBJECT TO THUNDERSTORM INDUCED COOL DOWNS...AND DEWPOINTS IN
THE STEAMY LOW TO MID 70S. A NEW SET OF ZONES WERE ISSUED TO REFLECT
THE ABOVE AND THE UPDATED GRIDS HAVE BEEN SENT TO THE NDFD AND WEB
SERVERS.

UPDATE ISSUED AT 810 AM EDT FRI AUG 22 2014

THE FORECAST REMAINS ON TRACK THIS MORNING. SHOWERS AND THUNDERSTORMS
WILL LIKELY STEER CLEAR OF THE AREA UNTIL MAINLY THIS AFTERNOON.
FRESHENED UP THE SKY COVER AND HOURLY TEMPERATURES AND DEW POINTS TO
ALIGN BETTER WITH THE LATEST TRENDS IN OBSERVATIONS.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 400 AM EDT FRI AUG 22 2014

THE LATEST SURFACE MAP FEATURES SURFACE HIGH PRESSURE ACROSS THE GULF
COAST STATES...WITH BROADENING LOW PRESSURE ACROSS THE PLAINS. A
STATIONARY FRONTAL BOUNDARY EXTENDS EAST FROM THE PLAINS INTO THE
GREAT LAKES/OHIO VALLEY. ALOFT...AN UPPER LEVEL RIDGE IS CURRENTLY
CENTERED NEAR LOUISIANA WITH ITS INFLUENCE EXTENDING FURTHER NORTH
INTO THE MISSISSIPPI VALLEY. TROUGHING REMAINS POISED ACROSS THE
WESTERN CONUS.

THUNDERSTORM COMPLEXES CONTINUE TO GEN UP ON THE NORTHERN PERIPHERY
OF THE RIDGE AXIS AND THEN PROCEED TO ADVANCE ESE ACROSS THE OHIO
VALLEY. CURRENTLY...A WEAKENING COMPLEX IS SKIRTING NORTHEASTERN
KENTUCKY...LIKELY CLEARING OUR FORECAST AREA IN THE NEXT 2 TO 3
HOURS.

THE MODELS REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM...WITH THE
UPPER LEVEL RIDGE GRADUALLY AMPLIFYING ACROSS THE MISSISSIPPI VALLEY.
DETAILS ASSOCIATED WITH CONVECTIVE INITIATION CONTINUE TO BE
PROBLEMATIC HOWEVER...AND HAVE STUCK WITH A GENERAL MODEL
BLEND...WHICH FAVORS MORE VIGOROUS CONVECTION DURING THE WARMER PART
OF THE DAY. TODAY LOOKS TO BE SOMEWHAT OF A REPEAT OF
YESTERDAY...WITH STOUT INSTABILITY BUILDING BY EARLY THIS AFTERNOON.
WHILE THE MCS TRACK HAS SHIFTED A BIT FURTHER NORTHEAST TODAY
COMPARED TO YESTERDAY...OUTFLOW BOUNDARIES CONTINUE TO BE THE MAIN
PLAYER...LEAVING MOST LOCATIONS IN THE LINE OF FIRE AT SOME POINT.
SOME SEVERE THUNDERSTORMS CAN NOT BE RULED OUT ONCE AGAIN
TODAY...ALONG WITH ISOLATED FLASH FLOODING...WHERE STORMS CAN ALIGN
ALONG OUTFLOW BOUNDARIES PARALLEL TO THE STEERING FLOW. ANOTHER HOT
AND HUMID DAY LOOKS TO BE ON TAP...WITH A FEW SPOTS NEARING THE 100
DEGREE MARK IN HEAT INDICES.

STORMS WILL GRADUALLY WEAKEN INTO THE EVENING HOURS...ALTHOUGH SOME
NOCTURNAL ACTIVITY REMAINS AT LEAST SOMEWHAT OF A POSSIBILITY. LOWS
WILL BE MUGGY ONCE AGAIN AROUND THE 70 DEGREE MARK. SATURDAY WILL
FEATURE ANOTHER WARM AND HUMID DAY...ALONG WITH THE THREAT OF MORE
SCATTERED CONVECTION ACROSS THE AREA. THERE WILL BE LESS INSTABILITY
AVAILABLE AS MID-LEVEL WARMING TAKES PLACE FROM THE INFLUENCE OF THE
UPPER RIDGE. THIS WILL KEEP THE SEVERE AND FLASH FLOOD THREAT LOWER.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 400 AM EDT FRI AUG 22 2014

UPPER LEVEL RIDGING WILL REMAIN IN PLAY DURING THE DURATION OF THE
EXTENDED...WITH HEIGHTS EXPECTED TO BUILD AS THE HIGH SHIFTS NEWARD
ACROSS THE OHIO RIVER VALLEY. BUILDING HEIGHTS WILL THEN TRANSLATE
TO RISING TEMPERATURES. HOWEVER...MID AND UPPER LEVEL WINDS WILL
GENERALLY REMAIN OUT OF THE NORTH DURING THE FIRST FEW DAYS OF THE
EXTENDED. THIS...COUPLED WITH CLOUD COVER THAT WILL HAMPER MAXIMUM
SOLAR RADIATION...WILL KEEP HIGHS IN THE MID AND UPPER 80S THROUGH
TUESDAY. TEMPS MAY THEN COOL DOWN A COUPLE DEGREES AFTER TUESDAY AS
HIGH PRESSURE SITS OVERHEAD AND UPPER LEVEL HEIGHTS ASSOCIATED WITH
THE RIDGE BECOME MORE STATIC.

BASED ON THE LATEST FORECAST SOUNDINGS...WILL AGREE WITH PREVIOUS
FORECAST THAT EACH DAY SHOULD POSE A SHOWER/THUNDERSTORM THREAT
MAINLY IN THE AFTERNOON AND EVENING. GIVEN THE MID LEVEL DRYING FROM
MONDAY ON...WOULDN/T BE SURPRISED IF SOME OF THESE STORMS PRODUCE
SOME POTENTIAL HAIL. IN PROMISING NEWS...WITH THE RIDGING PATTERN IN
PLACE...WE WILL EXPERIENCE NO BOUNDARY FORCING UNTIL VERY LATE IN THE
FORECAST...SO THIS WILL HAMPER SOME OF THE BEST INSTABILITY AND
WIDESPREAD INITIATION. WINDS WILL BE LIGHT AT THE SURFACE...AND
REMAIN SO AS WE HEAD UP HIGHER INTO THE ATMOSPHERE. THAT BEING
SAID...AFTERNOON CAPE VALUES WILL BE ABOVE THE 2K J/KG RANGE THROUGH
MUCH OF THE EXTENDED...AND LAPSE RATES WILL RISE SLIGHTLY BY TUES/WED
TO 6 TO 6.5 C/KM...SO AFTERNOON HEATING AND INSTABILITY MAY BE ALL
THAT IS NECESSARY FOR SCATTERED CELL DEVELOPMENT EACH DAY. A BOUNDARY
WILL FINALLY PUSH INTO THE AREA BY THURS/FRI DAY 7/8 /PER THE LATEST
GFS MODEL RUN/. THIS WILL BRING A MORE WIDESPREAD CHANCE FOR RAIN AND
THUNDERSTORMS ACROSS THE AREA. HOWEVER...THERE IS QUITE A BIT OF
DISAGREEMENT IN THE EXTENDED MODELS THIS FAR OUT...SO DECIDED TO LEAN
ON THE ALLBLEND FOR POPS AT THIS TIME.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 810 AM EDT FRI AUG 22 2014

PATCHY IFR OR WORSE FOG WILL LIFT AND DISSIPATE BY AROUND 13Z THIS
MORNING. CONVECTION WILL THREATEN ONCE AGAIN THIS AFTERNOON...WITH
LOCATIONS ALONG AND NORTHEAST OF A LINE FROM KIOB TO KJKL TO KI35
SEEING THE BETTER CHANCE OF MORE SUSTAINED CONVECTION. THE THREAT
WILL DIMINISH THIS EVENING...WITH FOG SETTING IN ONCE
AGAIN...PARTICULARLY AT ANY LOCATIONS THAT SEE HEAVIER RAINFALL.

&&

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

$$

UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...JMW
AVIATION...GEOGERIAN





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