Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 160142
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
942 PM EDT WED APR 15 2015

.UPDATE...
ISSUED AT 941 PM EDT WED APR 15 2015

GENERALLY ISOLATED SHOWERS CONTINUE ACROSS THE CWA LATE THIS
EVENING..WITH MORE SCATTERED ACTIVITY ACROSS THE NORTH CENTRAL
PORTION OF THE STATE ALONG A WEAK BOUNDARY. HEAVIER SHOWERS AND
THUNDERSTORMS REMAIN WELL TO OUR SOUTHWEST ACROSS WESTERN
TN...CLOSER TO THE SURFACE LOW PRESSURE CENTER LOCATED NEAR THE
SAME AREA. THIS LOW WILL CONTINUE TO SLOWLY SHIFT NE THROUGHOUT
THE NIGHT...REACHING FAR WESTERN KY BY 12Z TOMORROW. THIS MAY
ALLOW SOME MORE SHOWERS AND POSSIBLY EVEN AN ISOLATED
THUNDERSTORM TO DEVELOP AND MOVE INTO THE CWA LATER IN THE NIGHT
AND EARLY IN THE MORNING. BUT IN THE MEANTIME...IT LOOKS AS THINGS
ARE STARTING TO SETTLE DOWN ACROSS THE REGION.

CONTINUED CLOUD COVER...A HIGH AMOUNT OF MOISTURE...AND LIGHT
WINDS...WILL HELP TO MODERATE THE TEMPERATURES OVERNIGHT. CURRENT
READINGS OF UPPER 50S HAVE BEEN INCORPORATED INTO THE NEAR TERM
FORECAST...WITH ONLY A 3 TO 5 DEGREE DIURNAL FALL INTO THE LOW TO
MID 50S EXPECTED BY MORNING.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 340 PM EDT WED APR 15 2015

18Z SFC ANALYSIS SHOWS THAT THE INVERTED TROUGH AXIS HAS SHIFTED
EAST TO ALONG THE SPINE OF THE APPALACHIANS WITH THE LOWER
MISSISSIPPI VALLEY LOW/S WARM FRONT LIFTING NORTH INTO KENTUCKY.
THE LIGHT PCPN AND OVERCAST CONDITIONS HAS KEPT MOST OF THE AREA
ON THE COOL SIDE TODAY...ESPECIALLY OUTSIDE OF THE CUMBERLAND
VALLEY. HOWEVER...THINNING CLOUDS AND A BREAK IN THE LIGHT RAIN
SHOULD ALLOW FOR SOME DECENT TEMP RISES OVER THE NEXT COUPLE OF
HOURS FOR ALL BUT THE FAR NORTHEAST. READINGS CURRENTLY VARY FROM
THE UPPER 50S IN THE NORTHEAST TO THE UPPER 60S IN THE SOUTH WHILE
DEWPOINTS RANGE FROM NEAR 60 SOUTH TO THE UPPER 40S IN THE FAR
NORTH. WINDS ARE GENERALLY FROM THE EAST TO NORTHEAST AT 10 TO 15
MPH OVER THE NORTHERN HALF OF THE AREA WHILE THEY ARE A BIT
LIGHTER AND MORE VARIABLE TO THE SOUTH. THE LIFTING WARM FRONT
MAY REINITIATE SHOWERS LATER IN THE AFTERNOON INTO THE EVENING...
PER THE LATEST HRRR AND NAM12...BUT RIGHT NOW THE RADAR SCOPE IS
PRETTY CLEAN. SHOULD CONVECTION REDEVELOP...SOME THUNDER MAY EVEN
BE POSSIBLE GIVEN THE RISING TEMPS/INSTABILITY...ESPECIALLY IN
THE SOUTH.

THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM
PORTION OF THE FORECAST AS A FEW CLUSTERS OF MID LEVEL ENERGY WILL
BRUSH KENTUCKY AS THEY MOVE INTO THE OHIO VALLEY TONIGHT ON THE
NORTHWEST FRINGE OF A BUILDING RIDGE. THE RIDGE FLATTENS A BIT ON
THURSDAY AS ADDITIONAL ENERGY PASSES THROUGH NORTHERN KENTUCKY
THAT AFTERNOON/OVERNIGHT AND INTO FRIDAY MORNING. TO THE WEST...A
SLOW MOVING CLOSED LOW SPINS ESSENTIALLY IN PLACE NEAR THE FOUR
CORNERS REGION OF THE COUNTRY...SERVING AS A SOURCE REGION FOR
ENERGY ABLE TO ESCAPE AND DRIFT EAST IN THE SOUTHERN STREAM THAT
CONTINUES TO DOMINATE KENTUCKY/S WX. GIVEN THE GENERAL MODEL
AGREEMENT HAVE FOLLOWED A BLEND WITH A LEAN TOWARD THE HRRR AND
NAM12 FOR WEATHER SPECIFICS DUE TO THEIR HIGHER RESOLUTION...
THOUGH CURRENT CONDITIONS AND TRENDS ARE ALSO OF HIGH RELEVANCE
INTO THE NEAR TERM PORTION OF THE FORECAST.

SENSIBLE WEATHER WILL FEATURE A POTENTIAL FOR SHOWERS INTO THE
EVENING AS THE SFC FRONT LIFTS NORTHEAST THROUGH THE AREA WITH A
THUNDERSTORM POSSIBLE...AS WELL. ADDITIONAL CONVECTION WILL BE
POSSIBLE INTO THURSDAY MORNING WITH THE SFC LOW TO THE SOUTHWEST
APPROACHING. THIS WILL LIKELY LIFT ANOTHER BOUNDARY THROUGH
EASTERN KENTUCKY DURING THE DAY WITH SHOWERS AND STRAY STORMS A
GOOD BET. THE PCPN CHANCES WILL DIMINISH INTO FRIDAY MORNING BUT
CANNOT GO DRY ATTM GIVEN THE ENVIRONMENT. THIS REMAINS A LOW
CONFIDENCE FORECAST WITH RESPECT TO SPECIFIC DETAILS BUT IN
GENERAL YOU CAB BANK ON RELATIVELY WARM AND MOIST CONDITIONS
CONTINUING.

USED THE SHORTBLEND GUIDANCE AS A STARTING POINT FOR T/TD/WIND
GRIDS THROUGH THE FIRST 18-24 HOURS OF THE FORECAST FOLLOWED BY
THE SUPERBLEND. GIVEN THE HUMID CONDITIONS MADE ONLY MINOR TERRAIN
BASED ADJUSTMENTS TO TEMPERATURES TONIGHT AND THURSDAY NIGHT. AS
FOR POPS...ENDED UP ON THE LOW SIDE OF MOS GUIDANCE TONIGHT AND
THURSDAY...BUT IN LINE FOR THURSDAY NIGHT.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM EDT WED APR 15 2015

THE EXTENDED PERIOD WILL BE DOMINATED BY A LARGE CLOSED LOW OVER THE
FOUR CORNERS REGION WITH SOME SLIGHT RIDGING OVER THE EASTERN CONUS.
AFTER A SHORT WAVE IMPULSE...PROVIDING A ROUND OF RAINFALL TO THE
REGION...PUSHES THROUGH THE TN AND OH VALLEYS FRIDAY MORNING...
FRIDAY EVENING INTO SATURDAY MORNING WILL BE MOSTLY DRY.  ON
SATURDAY...ANOTHER IMPULSE MOVING ALONG THE NORTHERN STREAM PUSHES
EWD TOWARDS THE GREAT LAKES REGION. AT THE SAME TIME...THE CLOSED
LOW EJECTS EWD AS WELL. THE ENERGY FROM THE CLOSED LOW THEN FEEDS
INTO THE NORTHERN STREAM TROUGH AND HELPS DEEPEN/INTENSIFY IT. THIS
SYSTEM WILL PROVIDE THE BEST CHANCE FOR A SIGNIFICANT AMOUNT OF
RAINFALL FOR EASTERN KENTUCKY IN THE SATURDAY NIGHT THROUGH MONDAY
MORNING TIME FRAME. THIS RAINFALL HAS THE POSSIBILITY OF BREAKING
THE JKL/S ALL-TIME APRIL RAINFALL RECORD...CURRENTLY WE HAVE HAD THE
SECOND WETTEST APRIL ON RECORD. IN FACT...THIS SYSTEM WILL SPREAD
PRECIP FROM THE NORTHERN MISSISSIPPI VALLEY REGION ACROSS MOST OF
THE EASTERN CONUS THROUGH TUESDAY. CLOSER TO HOME...TUESDAY AND
WEDNESDAY LOOKS TO BE FAIRLY QUIET...COOLER...AND DRY AS THE UPPER
LEVELS TRANSITION TO MORE OF A ZONAL FLOW PATTERN.

GFS AND ECMWF MODELS ACTUALLY HAVE GOOD AGREEMENT WITH THE EVOLUTION
OF THIS MAJOR SYSTEM. ADDITIONALLY...THERE LOOKS TO BE A STRONG
SURGE OF GULF MOISTURE WITH PW VALUES REACHING 1.50 INCHES IN SOME
LOCATIONS WITH SOME INSTABILITY PRESENT. THEREFORE...HAVE DECIDED TO
INCLUDED SLIGHT CHANCES OF THUNDER THROUGHOUT THE EXTENDED PERIOD
WITH LIKELY THUNDER DURING THE SUNDAY AFTERNOON THROUGH MONDAY
MORNING TIME FRAME. PROBABLY COULD HAVE UPPED POPS TO GO CATEGORICAL
ON SUNDAY/MONDAY MORNING BUT HAVE REMAINED CONSISTENT WITH NEIGHBORS
FOR NOW AND KEPT LIKELY POPS IN THE GRIDS. ALL IN ALL...BASED ON THE
CONTINUED WET PATTERN...THE MAIN CONCERN DURING THE EXTENDED PERIOD
WILL BE HEAVY RAINFALL WITH LOCALIZED FLOODING CONCERNS...ESPECIALLY
IN AREAS THAT RECEIVE SEVERAL ROUNDS OF RAINFALL AND WHERE RIVERS
AND CREEKS ARE STILL RUNNING HIGH.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 757 PM EDT WED APR 15 2015

A BIT OF AN UNSETTLED TAF OVER THE NEXT 24 HOURS. ISOLATED TO
SCATTERED SHOWERS CONTINUE ACROSS THE CWA THIS EVENING...BUT ARE
SHOWING A DISSIPATING TREND AS LOW LEVEL FLOW SLOWLY SHIFTS TO A
MORE SOUTHEASTERLY DIRECTION FOR TONIGHT. THIS DRIER DOWNSLOPING
FLOW WILL DO ONE OF TWO THINGS. IT WILL EITHER HELP TO SCOUR OUT
THE LOWER CIGS...OR IT COULD LEAD TO A STRONG INVERSION WHICH
TRAPS SOME OF THE MOISTURE IN THE FORM OF A LOW STRATUS DECK AT
SOME OF THE TAF SITES. AS SUCH... CONFIDENCE IS LOW AS TO WHICH
WILL OCCUR...WITH SOME SITES LIKELY FLUCTUATING BETWEEN MVFR AND
IFR CIGS. EITHER WAY...EXPECT CIGS TO IMPROVE WITH DAYTIME HEATING
TOMORROW MORNING. HOWEVER...VCSH WILL LIKELY STILL POSE A THREAT
THROUGHOUT THE DAY...WITH CIGS FLUCTUATING ONCE MORE BETWEEN MVFR
AND VFR. VIS SHOULD REMAIN VFR...THOUGH SOME OF THE HEAVIER
SHOWERS COULD CAUSE SOME TEMPORARY RESTRICTIONS. WINDS ARE
EXPECTED TO REMAIN LIGHT AND VARIABLE.


&&

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

$$

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


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