Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 290754
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
354 AM EDT WED JUL 29 2015

.UPDATE...
ISSUED AT 1043 PM EDT TUE JUL 28 2015

CONVECTION IS DWINDLING...WITH ONLY A FEW SHOWERS LEFT IN THE
SOUTHWEST. FORCING WILL BE LACKING OVERNIGHT...AND GIVEN THE
WEAKENING TREND...DO NOT SEE MUCH REASON TO HANG ONTO TO EVEN
ISOLATED POPS AT THIS POINT. BESIDES SOME PASSING HIGHER CLOUDS
FROM THE NORTH...PARTLY CLOUDY TO MOSTLY CLEAR SKIES WILL RULE.
HAVE THEREFORE HIT THE FOG A BIT HARDER. UPDATES HAVE BEEN SENT.

UPDATE ISSUED AT 806 PM EDT TUE JUL 28 2015

MOST CONVECTION EAST OF I-75 HAS WANED...BESIDES A FEW STRAY
LIGHT RETURNS AT TIMES. THE BEST COVERAGE IS CURRENTLY ALIGNED
WEST OF I-75...ASSOCIATED WITH SOME WEAK LOW LEVEL CONVERGENCE AND
A FAIRLY UNTAPPED ENVIRONMENT. THE HIGHER RESOLUTION SHORT TERM
MODELS SHOW THIS AREA OF CONVERGENCE WEAKENING AFTER 01Z...SO HAVE
CONTINUED TO ALIGN THE BEST POPS OVER THE SOUTHWEST FOR THE NEXT
HOUR OR SO...BEFORE DWINDLING. WILL HANG ONTO SLIGHT POPS
ELSEWHERE THROUGH AROUND MIDNIGHT...BEFORE GOING DRY. LOW
TEMPERATURES AROUND 70 AND PLENTY OF FOG LOOK ON TRACK OVERNIGHT.
UPDATES HAVE BEEN SENT.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 359 PM EDT TUE JUL 28 2015

CURRENT CONDITIONS ACROSS EASTERN KENTUCKY FEATURE SHOWERS AND
THUNDERSTORMS ACROSS THE AREA SLOWLY SHIFTING OFF TO THE SOUTHEAST
AS THEY DEVELOP. THE MAIN CONCERN THIS AFTERNOON BEING THE HEAVY
RAINFALL POTENTIAL WITH PWATS IN THE 1.8 TO 2.2 RANGE AND PLENTY
OF INSTABILITY. THIS HAS BEEN OCCURRING WITH A WEAK DISTURBANCE
OVERHEAD WITH A FADED SURFACE BOUNDARY STRETCHING ACROSS THE AREA.
DUE TO THE SATURATED AIR MASS IN PLACE AND INSTABILITY IN
PLACE...WILL GO WITH CHANCE POPS WELL INTO THE EVENING TONIGHT AS
PERSISTENCE WOULD ALSO SUGGEST THIS. WILL CONTINUE WITH THE
MENTION OF HEAVY RAINFALL POSSIBLE IN THE HWO. THIS HAS ALSO
TEMPERED THE HIGH TEMPERATURES THIS AFTERNOON.

HEADING INTO TONIGHT...LINGERING CONVECTION IS EXPECTED TO
CONTINUE INTO THE FIRST PART OF TONIGHT...ESPECIALLY WITH THIS
SATURATED AIR MASS IN PLACE. WITH THIS INSTABILITY WILL BE SLOW
TO WANE ALONG WITH PWATS STILL IN THE 2 INCH RANGE. A BRIEF BREAK
IN PRECIP AND CLOUD COVER WILL LEAD TO FOG DEVELOPMENT LATE
TONIGHT AND WITH DEW POINTS REMAINING IN THE LOWER 70S WITH SOME
MID 70S...FOG WILL BE DENSE IN SOME AREAS. MOIST SOUTHERLY FLOW IS
EXPECTED TO CONTINUE AND REMAIN PRONOUNCED WITH A BETTER DEFINED
FEATURE ON THE WAY IN THE FORM OF A COLD FRONT. THIS WILL PROVIDE
ENOUGH LIFT FOR CONTINUED SHOWER AND THUNDERSTORM DEVELOPMENT INTO
THE AFTERNOON ON WEDNESDAY. IN FACT...INTO WEDNESDAY NIGHT...PWAT
VALUES JUMP BEYOND THE 2 INCH RANGE WITH MODEL PROFILES SATURATED
TO NEARLY 500MB IN MOST LOCATIONS. FOR THIS...HAVE PUT LIKELY POPS
WEDNESDAY EVENING THROUGH WEDNESDAY NIGHT. SPC HAS ALSO MENTIONED
A MARGINAL WIND THREAT WITH THIS ACTIVITY ALONG THE FRONT BUT THE
MAIN IMPACT WILL AGAIN BE SLOW STORM MOTION WITH HEAVY RAINFALL
POSSIBLY CAUSING SOME MINOR FLOODING ISSUES.

IN ADDITION TO THE HEAVY RAINFALL...TEMPERATURES WILL REACH TO
AROUND 90 ON WEDNESDAY AFTERNOON WITH HEAT INDEX VALUES REACHING
AROUND 100 POSSIBLE IN SOME AREAS ADDING ANOTHER IMPACT TO BE
MINDFUL OF.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 354 AM EDT WED JUL 29 2015

WE WILL BE IN A POST FRONTAL REGIME TO START OFF THE EXTENDED
FORECAST AT 0Z FRIDAY. SURFACE HIGH PRESSURE WILL CONTINUE TO TAKE
HOLD THROUGH THE DAY FRIDAY WITH SLIGHTLY COOLER NRLY WINDS AT THE
SURFACE. MEANWHILE...A STRONG UPPER LEVEL LOW WILL BECOME NEARLY
STATIONARY ACROSS HUDSON BAY...ROTATING AROUND THE BAY FROM FRIDAY
THROUGH AT LEAST MONDAY. THIS WILL KEEP A LONGWAVE TROUGHING PATTERN
ACROSS MUCH OF THE MIDWEST AND EASTERN CONUS...CONTINUING THE NW
FLOW REGIME ACROSS THE OHIO RIVER VALLEY. THIS NW FLOW WILL PROVIDE
THE PERFECT SCENARIO FOR SHORTWAVES TO TRACK SE ALONG THE TROUGH AND
INTO THE OHIO VALLEY AS IT ROUNDS THE BASE OF THE TROUGH.
HOWEVER...HIGH PRESSURE WILL HAVE HOLD AT THE SURFACE. THE QUESTION
THROUGHOUT THE EXTENDED IS WHETHER OR NOT THIS HIGH PRESSURE WILL BE
STRONG ENOUGH TO SWAY THE IMPACT OF THESE SHORTWAVES AS THEY MOVE
THROUGH EASTERN KY.

THE FIRST OF THESE SHORTWAVES WILL MOVE THROUGH SATURDAY INTO
SUNDAY. AS OF 0Z FRIDAY...THE ACCOMPANYING SURFACE COLD FRONT IS
POSED TO BE LOCATED ACROSS THE NORTHERN PLAINS AND UPPER GREAT LAKES
REGION...AND WILL SHIFT SOUTHWARD THROUGHOUT THE DAY FRIDAY AS THE
SHORTWAVE NEARS. HOWEVER...THIS BOUNDARY WILL BE MOISTURE DEPRIVED
AND FAIRLY WEAK. LATEST MODELS ARE STILL SHOWING SOME DISAGREEMENT
ON IF THIS BOUNDARY WILL BE ABLE TO SUSTAIN PRECIPITAL MOISTURE AS
IT MOVES INTO THE OHIO RIVER VALLEY. JUST LIKE YESTERDAY...THE GFS
IS POINTING TOWARDS A FEW SCATTERED SHOWERS MAKING IT INTO THE
CWA...WHILE THE ECMWF IS KEEPING US DRY. MEANWHILE...DESPITE THE
PLAN VIEW GFS OUTPUT...THE GFS FORECAST SOUNDINGS ARE ONLY POINTING
AT A NARROW WINDOW OF MID LEVEL MOISTURE WITH ABUNDANT DRY AIR NEAR
THE SURFACE. THIS IS MORE CHARACTERISTIC OF SOME SCT TO BKN CLOUD
COVER RATHER THAN RAINFALL. AS SUCH...WILL CONTINUE TO TREND TOWARD
THE DRIER ECMWF.

THE NEXT SHORTWAVE AND SURFACE BOUNDARY WILL MOVE THROUGH TUESDAY
INTO WEDNESDAY AS WE FINISH OUT THE 7 DAY FORECAST. GRANTED...THIS
IS FAR OUT IN THE FORECAST...BUT MODELS ARE IN SURPRISINGLY GOOD
AGREEMENT IN THE UPPER LEVELS...SO CONFIDENCE IS A BIT HIGHER. THIS
PARTICULAR UPPER LEVEL SHORTWAVE WILL SHOW SIGNIFICANT DIGGING AS IT
NEARS THE OHIO VALLEY REGION...LENDING TO A STRONGER SURFACE
BOUNDARY. IF THIS PROVES TO BE TRUE...WE MAY SEE OUR NEXT BETTER
CHANCE FOR SHOWERS AND THUNDERSTORMS DURING THIS TIME.

AS FOR TEMPERATURES...

THE POST FRONTAL CONDITIONS AND DRIER NW FLOW WILL BRING IN SLIGHTLY
COOLER TEMPERATURES TO START OFF FRIDAY. HOWEVER...STRONG SURFACE
HIGH PRESSURE IN PLACE AND CLEAR SKIES WILL PROMOTE MAXIMUM DAYTIME
RADIATION...SO THE TEMP DROP WILL NOT BE THAT GREAT...STILL
MAINTAINING LOW TO MID 80S. PERHAPS MORE NOTICEABLE THAN THE SLIGHT
CHANGE IN TEMPERATURES WILL BE THE DECREASE IN HUMIDITY...AS LIGHT
WINDS AT THE SURFACE AND NW FLOW ALOFT WILL PROMOTE LOWER RH VALUES.
AS HIGH PRESSURE REMAINS IN PLACE THROUGH MUCH OF THE
EXTENDED...EXPECT TEMPS TO GRADUALLY WARM A DEGREE OR TWO EACH
DAY...STAYING IN THE MID 80S THROUGH THE WEEKEND AND INTO NEXT WEEK.
MEANWHILE...MAXIMUM RADIATIONAL COOLING DURING THE OVERNIGHT WILL
KEEP OVERNIGHT LOWS IN THE LOW TO MID 60S THROUGH THE BEGINNING OF
NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 209 AM EDT WED JUL 29 2015

CONDITIONS VARIED WIDELY AT THE START OF THE PERIOD. HOWEVER...THE
TREND WILL BE FOR WORSENING CONDITIONS...WITH A DESCENT TO LIFR
OR VLIFR EXPECTED FOR MOST PLACES BEFORE DAWN. THERE WERE STILL
SOME SLOW MOVING SHOWERS OVER THE SOUTHEAST PART OF THE STATE.
FORECAST SOUNDINGS SHOW A POTENTIAL FOR THEM THROUGH THE EARLY
MORNING HOURS...BUT WHERE AND WHEN THEY WILL DEVELOP IS TOO
UNCERTAIN TO FORECAST.

FOG AND ASSOCIATED LOW CLOUDS WILL LIFT AND DISSIPATE AFTER
SUNRISE...GIVING WAY TO LARGELY VFR BY LATE MORNING. HOWEVER...
THE DAYTIME WARMING SHOULD ALSO LEAD TO ADDITIONAL SCATTERED
SHOWERS AND THUNDERSTORM DEVELOPMENT BY AFTERNOON. THEY WILL BRING
LOCALIZED IFR. THE SHOWERS AND THUNDERSTORMS SHOULD THEN LARGELY
DIMINISH IN THE EVENING WITH LOSS OF HEATING.


&&

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

$$

UPDATE...GEOGERIAN
SHORT TERM...SHALLENBERGER
LONG TERM...JMW
AVIATION...HAL



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